CA3027250A1

CA3027250A1 - Methods and systems for water treatment by flocculation

Info

Publication number: CA3027250A1
Application number: CA3027250A
Authority: CA
Inventors: Stewart A.H. Adams; Pierre B. Brosseau; Jean-Philippe Levesque; Michael Patrick Mckay; Susan Wei Sun; Holger Werner Ruediger Beaujean
Original assignee: Cenovus Energy Inc; FCCL Partnership
Current assignee: Cenovus Energy Inc; FCCL Partnership
Priority date: 2017-12-22
Filing date: 2018-12-12
Publication date: 2019-06-22

Abstract

Described herein are methods for treating a contaminated water, which may include steps of: subjecting the contaminated water to reducing or oxidizing conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water; thereby producing a treated water. Systems for performing such methods on a contaminated water are also provided. In certain embodiments, the contaminated water may include a produced water from an oilfield operation, for example.

Description

METHODS AND SYSTEMS FOR WATER TREATMENT BY FLOCCULATION
FIELD OF INVENTION
The present invention relates generally to methods and systems for the treatment of contaminated water. More specifically, the present invention relates to methods and systems for water treatment which provide for removal of contaminants by flocculation.
BACKGROUND
Water treatment systems and methods are very important aspects of many industrial operations.
Process waters are frequently contaminated with one or more components which must be removed prior to subsequent use of the water, or prior to disposal of the water. Hydrocarbon recovery operations, for example, utilize water for a number of purposes, and efficient and effective water treatment systems and methods are highly sought-after.
Hydrocarbon recovery operations involving Steam-Assisted Gravity Drainage (SAGD), for example, utilize steam to mobilize hydrocarbons in subterranean reservoirs. Contaminants in water used for steam generation can cause significant issues, including scaling of boilers and other such effects.
Methods for treating water prior to steam injection are of great interest in the field.
Furthermore, many oilfield operations produce water from subterranean reservoirs to the surface. These waters, known as produced waters, often contain components which must be removed before the water can be recycled to generate steam, or before the water can be otherwise used or disposed of. Recycling of produced water typically involves removal of suspended solids, dissolved solids, oil, and/or scale-forming agents which would otherwise affect steam generation and handling equipment. Conventional produced water treatment equipment and processes are costly and high-maintenance. Further, produced waters are typically received at high temperatures and pressures, both of which typically must be reduced using heat exchangers before treatment using conventional processes and systems. This also means that post-treatment, substantial re-heating of the water is required to produce steam for injection downhole. Conventionally, produced water treatment involved use of Lime Softeners (such as Warm Lime Softener (WLS)) and related equipment.

More generally, common water treatment techniques include electrocoagulation and electrofloatation treatments, which are typically performed at ambient temperatures and which typically involve use of sacrificial iron electrodes for introducing iron salts into the contaminated water and triggering flocculation to allow for contaminant separation. However, use of such sacrificial electrodes requires frequent maintenance and upkeep in conventional electrocoagulation and electrofloatation water treatment systems.
Alternative, additional, and/or improved methods and/or systems for the treatment of contaminated waters is desirable.
SUMMARY OF INVENTION
Described herein are methods and systems for the treatment of contaminated water. In certain embodiments, methods and systems described herein may provide for removal of contaminants from, for example, a produced water from an oilfield operation. Such contaminants may include, for example, calcium, magnesium, silica, hardness, and/or organics, among others.
Systems and methods provided herein may be operated at elevated temperatures and pressures, such as those typically encountered in a SAGD operation, which may be particularly beneficial when the contaminated water input is at an elevated temperature and/or when the treated water output is intended for use in an operation requiring the water to be heated.
Heat energy may thus be conserved, thereby saving on heating costs. As well, methods and systems as described herein may allow for certain conventional water treatment apparatus to be omitted. Further, in certain embodiments, methods and systems described herein may allow for water treatment without the use of sacrificial iron electrodes to treat the contaminated water, thereby reducing or removing the need for electrode maintenance and/or replacement.
The present inventors have discovered that certain contaminated waters, such as those produced during a SAGD operation, may contain one or more flocculation inhibitors which interfere with contaminant removal by flocculation with flocculating ions such as iron; and have further discovered that such flocculation inhibitor(s) may be destroyed prior to flocculation by an electro- and/or chemical- reduction and/or oxidation step, thereby allowing for contaminant removal via flocculation. Flocculation may thus be achieved through addition of a flocculating

2 ion-enriched aqueous solution into the contaminated water, which may reduce complexity and/or water treatment equipment demands.
Select embodiments of the present disclosure relate to, a method for treating a contaminated water, said method comprising:
subjecting the contaminated water to reducing or oxidizing conditions;
introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water;
thereby producing a treated water.
In select embodiments of the present disclosure, the flocculating ion comprises iron, aluminum, or a combination thereof.
In select embodiments of the present disclosure, the step of subjecting the contaminated water to reducing or oxidizing conditions comprises a step of electroreduction.
In select embodiments of the present disclosure, the step of electroreduction uses one or more non-sacrificial electrodes.
In select embodiments of the present disclosure, the step of subjecting the contaminated water to reducing or oxidizing conditions comprises a step of electrooxidation.
In select embodiments of the present disclosure, the step of electrooxidation uses one or more non-sacrificial electrodes.
In select embodiments of the present disclosure, the step of subjecting the contaminated water to reducing conditions comprises a step of chemical reduction.

3 In select embodiments of the present disclosure, the step of chemical reduction uses a chemical reduction agent which is NaHS03, Na2S03, Na2S204, Na2S203, nascent hydrogen, or a combination thereof.
In select embodiments of the present disclosure, the step of subjecting the contaminated water to oxidizing conditions comprises a step of chemical oxidation.
In select embodiments of the present disclosure, the step of chemical oxidation uses a chemical oxidation agent which is H202, Na0C1, or a combination thereof.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution comprises an aqueous solution of Fe2+ ions.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution comprises a solution generated: by electro-flocculation using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in water; from a solution of iron vitriol; or a combination thereof.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution is introduced into the contaminated water as a slipstream.
In select embodiments of the present disclosure, the introducing of the flocculating ion-enriched aqueous solution comprises: a step of pH adjustment to render silica or other ionic contaminants in the contaminated water reactive; a step of pH adjustment to promote formation of the flocculating ion flocks; or a combination thereof.

4 In select embodiments of the present disclosure, the step of pH adjustment to render silica or other ionic contaminants in the contaminated water reactive comprises adjusting the pH to between about 2 and about 4.
In select embodiments of the present disclosure, the pH is adjusted using HCl, H2SO4, another acid, or a combination thereof.
In select embodiments of the present disclosure, the step of pH adjustment to promote formation of the flocculating ion flocs comprises adjusting the pH to between about 7 and about 11.
In select embodiments of the present disclosure, the pH is adjusted using NaOH, steam blowdown, another base, or a combination thereof.
In select embodiments of the present disclosure, the method further comprises adding an H2S
scavenger, a chelant, a polymer, a sulphite, or a combination thereof to the contaminated water during treatment.
In select embodiments of the present disclosure, the flocculating ion flocs are separated using filtration or flotation.
In select embodiments of the present disclosure, the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.
In select embodiments of the present disclosure, the contaminated water is maintained at or above about 80 C during treatment.
In select embodiments of the present disclosure, the contaminated water is maintained at or above about 100 C during treatment.

5 In select embodiments of the present disclosure, the contaminated water is a produced water.
In select embodiments of the present disclosure, the produced water is a produced water from a SAGD operation.
In select embodiments of the present disclosure, the one or more contaminants removed from the contaminated water comprise calcium, magnesium, silica, an organic contaminant, or a combination thereof.
In select embodiments of the present disclosure, the method further comprising a step of subjecting the treated water to an electrochemical oxidation treatment or a chemical oxidation treatment to render organics in the treated water insoluble, and separating the organics from the treated water.
In select embodiments, the present disclosure relates to a method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam, water, or a combination thereof into the subterranean reservoir;
producing a produced water and a hydrocarbon to the surface;
treating at least a portion of the produced water using a method as defined herein thereby generating a treated water stream; and using the treated water stream to provide steam, water, or a combination thereof for re-injection into the subterranean reservoir to produce more hydrocarbons to the surface.
In select embodiments, the present disclosure relates to a method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam into the subterranean reservoir via an injection well;

6 producing a produced water stream and a hydrocarbon stream to the surface via a production well, or producing a mixed produced water and hydrocarbon emulsion stream from the subterranean reservoir via a production well and separating the mixed produced water and hydrocarbon emulsion stream into a produced water stream and a hydrocarbon stream;
treating at least a portion of the produced water stream using a method as defined herein, thereby generating a treated water stream; and using the treated water stream to provide steam for re-injection into the subterranean reservoir via the same or a different injection well to produce more hydrocarbons to the surface.
In Select embodiments, the present disclosure relates to a system for treating contaminated water, the system comprising:
an input for a contaminated water;
a reducing or oxidizing unit configured to receive the contaminated water from the input and generate reducing or oxidizing conditions in the contaminated water;
a separation unit downstream of the reducing or oxidizing unit and in fluid communication therewith, the separation unit configured to receive the contaminated water from the reducing or oxidizing unit and remove flocculating ion flocks with captured contaminant from the contaminated water;
an input for a flocculating ion-enriched aqueous solution, the input configured for introducing the flocculating ion-enriched aqueous solution into the contaminated water upstream of the separation unit, at the separation unit, or a combination thereof; and an output for outputting a treated water from the separation unit.

7 In select embodiments of the present disclosure, the flocculating ion comprises iron, aluminum, or a combination thereof.
In select embodiments of the present disclosure, the reducing or oxidizing unit comprises an electroreduction apparatus for generating reducing conditions in the contaminated water.
In select embodiments of the present disclosure, the electroreduction apparatus comprises one or more non-sacrificial electrodes.
In select embodiments of the present disclosure, the electroreduction apparatus comprises an input for introducing a chemical reductant for generating reducing conditions in the contaminated water.
In select embodiments of the present disclosure, the chemical reductant is NaHS03, Na2S03, Na2S204, Na2S203, nascent hydrogen, or a combination thereof.
In select embodiments of the present disclosure, the reducing or oxidizing unit comprises an electrooxidation apparatus for generating oxidizing conditions in the contaminated water.
In select embodiments of the present disclosure, the electrooxidation apparatus comprises one or more non-sacrificial electrodes.
In select embodiments of the present disclosure, the electrooxidation apparatus comprises an input for introducing a chemical oxidant for generating oxidizing conditions in the contaminated water.
In select embodiments of the present disclosure, the chemical oxidant is H202, Na0C1, or a combination thereof.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution comprises an aqueous solution of Fe2+ ions.

8 In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution comprises a solution generated: by electro-flocculation using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in water; from a solution of iron vitriol; or a combination thereof.
In select embodiments of the present disclosure, the input for the flocculating ion-enriched aqueous solution comprises a slipstream line.
In select embodiments of the present disclosure, the system further comprises at least one input for a pH adjustment agent for: adjusting pH to render silica or other ionic contaminants in the contaminated water reactive; adjusting pH to promote formation of the flocculating ion flocks;
or a combination thereof.
In select embodiments of the present disclosure, the adjusting the pH to render silica or other ionic contaminants in the contaminated water reactive comprises adjusting the pH to between about 2 to about 4.
In select embodiments of the present disclosure, the pH adjustment agent comprises HC1, H2SO4, another acid, or a combination thereof.
In select embodiments of the present disclosure, the adjusting the pH to promote formation of the flocculating ion flocks comprises adjusting the pH to a range between about 7 and about 11.
In select embodiments of the present disclosure, the pH adjustment agent comprises NaOH, steam blowdown, another base, or a combination thereof.

9 In select embodiments of the present disclosure, the system further comprises one or more inputs configured for introducing an H2S scavenger, a chelant, a polymer, a sulphite, or a combination thereof to the contaminated water.
In select embodiments of the present disclosure, the separation unit comprises a filtration apparatus or a flotation apparatus for separating flocculating ion flocs from the contaminated water.
In select embodiments of the present disclosure, the system is configured to maintain the contaminated water at high temperature throughout treatment, thereby generating the treated water at high temperature.
In select embodiments of the present disclosure, the system is configured to maintain the contaminated water at or above about 80 C during treatment.
In select embodiments of the present disclosure, the system is configured to maintain the contaminated water at or above about 100 C during treatment.
In select embodiments of the present disclosure, the contaminated water comprises a produced water.
In select embodiments of the present disclosure, the produced water is a produced water from a SAGD operation.
In select embodiments of the present disclosure, the one or more contaminants removed from the contaminated water by the system comprise calcium, magnesium, silica, an organic contaminant, or a combination thereof.
In select embodiments of the present disclosure, the system further comprises:

a downstream electrochemical oxidation unit which is configured to receive the treated water output from the separation unit and to subject the treated water to an electrochemical oxidation treatment to render organics in the treated water insoluble; and a downstream organics separation unit for removing insoluble organics from the treated water.
In select embodiments of the present disclosure, the system further comprises:
a downstream chemical oxidation unit which is configured to receive the treated water output from the separation unit and to subject the treated water to a chemical oxidation treatment to rendering organics in the treated water insoluble; and a downstream organics separation unit for removing insoluble organics from the treated water.
Select embodiments of the present disclosure relate to a system for producing hydrocarbons from a subterranean reservoir, the system comprising:
a wellbore system comprising at least one well contacting the subterranean reservoir, wherein the wellbore system is configured for injecting steam, water, or a combination thereof into the subterranean reservoir and for producing a produced water and a hydrocarbon to the surface; and a system for treating contaminated water as defined herein, wherein the system for treating contaminated water is configured: (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the wellbore system or to a different wellbore system for re-injection into the subterranean reservoir.
In select embodiments, the present disclosure relates to a system for producing hydrocarbons from a subterranean reservoir, the system comprising:
an injection well and a production well contacting the subterranean reservoir, wherein the injection well is configured for injecting steam into the subterranean reservoir, and wherein the production well is configured for producing a produced water stream and a hydrocarbon stream, or a mixed produced water and hydrocarbon emulsion stream, to the surface; and a system for treating contaminated water as defined herein, wherein the system for treating contaminated water is configured: (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the same, or a different, injection well for re-injection into the subterranean reservoir.
In select embodiments of the present disclosure, the injection well and the production well are a SAGD well pair.
In select embodiments, the present disclosure relates to a method for treating a contaminated water, said method comprising:
introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water;
thereby producing a treated water.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution is introduced into the contaminated water as a side-stream or a slip-stream.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution is generated: by electro-flocculation of a carrier water using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in a carrier water; from a solution of iron vitriol; or a combination thereof.

In select embodiments of the present disclosure, the ion flocculation comprises adjusting the pH to render silica or other ionic contaminants in the contaminated water reactive.
In select embodiments of the present disclosure, the ion flocculation comprises adjusting the pH to promote formation of the flocculating ion flocks.
In select embodiments of the present disclosure, the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.
.. Select embodiments of the present disclosure relate to a system for treating contaminated water, the system comprising:
an input for a contaminated water;
a separation unit configured to receive the contaminated water and remove flocculating ion flocks with captured contaminant from the contaminated water;
an input for a flocculating ion-enriched aqueous solution, the input configured for introducing the flocculating ion-enriched aqueous solution into the contaminated water upstream of the separation unit, at the separation unit, or a combination thereof; and an output for outputting a treated water from the separation unit.
In select embodiments of the present disclosure, the input for the flocculating ion-enriched aqueous solution is a side-stream or a slip-stream.
In select embodiments of the present disclosure, the flocculating ion-enriched aqueous solution is generated: by electro-flocculation of a carrier water using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in a carrier water; from a solution of iron vitriol; or a combination thereof In select embodiments of the present disclosure, the flocculating ion comprises iron, aluminum, or a combination thereof.
In select embodiments of the present disclosure, the system further comprises at least one input for a pH adjustment agent for: adjusting pH to render silica or other ionic contaminants in the contaminated water reactive; adjusting pH to promote formation of the flocculating ion flocks;
or a combination thereof.
In select embodiments of the present disclosure, the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.
These and other features will be better understood with reference to the following Drawings and accompanying descriptions.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 shows an example of a conventional water treatment system for treating produced water from a SAGD operation to remove contaminants therefrom;
FIGURE 2 shows a flow diagram of an embodiment of a water treatment method and system as described herein, which avoids certain conventional apparatus and which includes steps of subjecting contaminated water to reducing or oxidizing conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water;
FIGURE 3 depicts another embodiment of a water treatment method and system as described herein, in which produced water is subjected to electro-flocculation treatment, followed by pH
adjustment, and then at least some of at least one contaminant is removed from the contaminated water by flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water. The depicted embodiment uses an electro-flocculation unit which employs iron-based sacrificial electrodes to introduce iron ions, and therefore the iron electrodes have maintenance and upkeep considerations;
FIGURE 4 depicts an embodiment of a water treatment method and system in which the contaminated water is not subjected to electro-flocculation, and instead a separate carrier water (for example, fresh water, brackish water, or a side stream of produced water) is subjected to electroflocculation to generate an iron ion-enriched solution, which is then introduced into the contaminated water, and a pH adjustment is performed on the contaminated water to promote flocculation to allow for contaminant separation in a filtration or flotation unit. However, as described in the examples section below, when the depicted embodiment was used to treat a produced water sample containing flocculation inhibiting compound(s), suitable separation was not achieved, although in other embodiments, treatment of other contaminated waters containing little or no flocculation inhibiting compound(s) is expected;
FIGURE 5 depicts an embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing a flocculating ion-enriched aqueous solution into the contaminated water, the solution being generated by separate treatment of a carrier water (brackish water, fresh water, or a side stream of produced water, for example) by electroflocculation to introduce iron ions from a sacrificial electrode; a pH
adjustment step to promote flocculation; and a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water;
FIGURE 6 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing an H2S scavenger to inhibit contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; and a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water;
FIGURE 7 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pll adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
FIGURE 8 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via chemical reduction); introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
FIGURE 9 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to oxidizing conditions (via electrochemical oxidation (ECO) treatment); introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions;
introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH
adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
FIGURE 10 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to electrical or chemical reduction conditions; introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; a step of subjecting the treated water to electrochemical oxidation (ECO) treatment to render organics in the treated water insoluble, and separating the insoluble organics via filtration or floatation; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
Figure 11 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to chemical oxidation conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
FIGURE 12 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to electrical or chemical reduction conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, .. whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; a step of subjecting the treated water to chemical oxidation treatment to render organics in the treated water insoluble, and separating the insoluble organics via filtration or floatation; and steps of introducing a chelant (to bind residual hardness to reduce scaling) and/or a sulphite (to bind oxygen to reduce corrosion);
FIGURE 13 shows increase in iron ion concentration in a brackish water (BW) sample over time during treatment in a Miniflot;

FIGURE 14 shows an efficiency curve relative to p1-1 for brackish water (BW);
FIGURE 15 shows increase in total and dissolved iron concentration as a function of operating time in a boiler feed water (BFW) sample;
FIGURE 16 shows increase in iron concentration in a brackish water (BW) sample over time during a long term treatment run with constant parameters;
FIGURE 17 shows increase in iron concentration as well as efficiency, calculated from the data in Figure 16 (efficiency over operating time). A flattening was observed after the fifth hour of operation in this experiment;
FIGURE 18 shows the titration curve obtained when checking stored Fe-ion solutions (using brackish water as carrier) for degradation and decomposition;
FIGURE 19 shows dependency between amperage and voltage, electrode separation, and conductivity for an Oil Removal Filter (ORF) outlet water sample with a conductivity of 2.8 mS/cm;
FIGURE 20 shows the observed trend of pH over time during treatment of an ORF
outlet water sample during testing with pH as a variable using a lab unit;
FIGURE 21 shows the observed dependency of amperage to change in voltage over time. 10 V values were used to calculate subsequent Miniflot operation parameters. The data suggests that low amperage was sufficient to destroy the inhibiting compound(s);
FIGURE 22 shows the observed trend in change of pH over treatment time for titanium electrodes and, for comparison, the trend for graphite electrodes. Titanium and graphite electrodes showed different behavior when treating ORF water;
FIGURE 23 shows the amperage versus voltage curves for titanium at different voltages (20V
and 10V) over time. The behavior is quite different for titanium, when compared to graphite.
The curves show a solution with similar conductivity after 30 to 40 minutes of treatment;
FIGURE 24 shows observed increase of Fe2+ concentration in a brackish water (BW) sample over time during studies as described in Example 4;

FIGURE 25 shows mg/I concentrations measured for hardness during testing.
Independent of the type of electrode used in pre-treatment, i.e. whether graphite or titanium, target was met in almost all cases;
FIGURE 26 shows mg/1 concentrations measured for silica during testing. Target for active Silica was 50 mg/l. In general, this target was met with average values for silica of about 18 ¨
20 mg/1. Only two tests using titanium electrodes, in combination with higher flow rate, showed values higher than 50 mg/1;
FIGURE 27 shows silica concentrations (reactive, colloidal, and total) for untreated process waters from field tests that were executed at elevated temperatures.
FIGURE 28 shows silica concentrations (reactive, colloidal, and total) for treated process waters from field tests that were executed at elevated temperatures.
FIGURE 29 shows hardness concentrations (calculated, Ca2+, and Mg2+) for untreated process waters from field tests that were executed at elevated temperatures.
FIGURE 30 shows hardness concentrations (calculated, Ca2 , and Mg2+) for untreated process waters from field tests that were executed at elevated temperatures.
FIGURE 31 shows degradation (removal) of naphthenics at pH values of 5, 7, and 9 (A-C, respectively) during electrolytic reduction. The slope of the degradation curve was almost independent of pH value;
FIGURE 32 shows degradation of naphthenic acids at pH 7 at temperatures of 20 and 50 C;
and at pH 9 and at temperatures of 20 and 50 C (A and B, respectively), during electrolytic reduction treatment. All other parameters were kept constant;
FIGURE 33 compares the observed degradation of naphthenic acids at room temperature and a pH of 7 with current, as conducted through graphite electrodes, used as a variable. All parameters were kept constant, with exception of current, which was changed (3 series) from 5 A, 8.3 A and finally to 10 A. The trend lines for 5 A and 8.3 A show a low level of degradation;
FIGURE 34 shows observed degradation of phenols during electro-chemical reduction at pH
5, 7, and 9 (A-C, respectively). Degradation rates for phenols/phenolics were somewhat higher than the degradation rates observed for naphthenic acids (at least at room temperature);
FIGURE 35 shows observed increasing degradation rates with increasing temperature for phenols (20 and 50 C at pH 7 in A, 20 and 50 C at pH 9 in B) during electrolytic reduction;
FIGURE 36 shows the observed influence of current in the degradation of phenols during electrolytic reduction. The trend lines are according to normal standard;
FIGURE 37 shows the observed concentration of naphthenic acids and total organic carbon (TOC) versus treatment time using an EGO lab unit set-up. After 20 min of treatment naphthenic acids concentration was decreased from 18 to 7.1 mg/I, while general TOG
concentration was reduced from 250 to 170 mg/1;
FIGURE 38 shows that removal of naphthenic acids using EGO took place faster than the total removal of organic carbon. At the point when approximately 50 % of naphthenic acids are removed, 30 % of total organics are removed (based on 18 mg/1 naphthenic acids in feed and 250 mg/1 TOG in feed);
FIGURE 39 shows estimated design values for an EGO plant. As shown, it is estimated that a reduction of naphthenic acids from 18 to about 3.4 mg/1 may take a residence time of about 2 min in such a design;
FIGURE 40 depicts a proposed design schematic of an embodiment of a design for a direct injection flocculation treatment pilot plant developed for the treatment of SAGD process water as described in Example 5;
FIGURE 41 depicts a proposed general layout of an embodiment of a design for a direct injection flocculation treatment pilot plant developed for the treatment of SAGD process water as described in Example 5; and FIGURE 42 depicts an embodiment of a reduction vessel (A), and an embodiment of reduction vessel specifications (B), of a proposed design for a direct injection flocculation treatment pilot plant developed for the treatment of SAGD process water as described in Example 5.
DETAILED DESCRIPTION

Described herein are methods and systems for the treatment of contaminated water. It will be appreciated that embodiments and examples are provided for illustrative purposes intended for those skilled in the art, and are not meant to be limiting in any way.
Conventionally, water treatment methods may have included a step of electrocoagulation, in which an iron-based sacrificial electrode was used to introduce Fe ions into contaminated water, which form iron flocks that capture contaminants and facilitate their removal from the water. However, such electrocoagulation treatment was typically performed at ambient temperature, or at temperatures between about 5 to about 90 C, and required significant maintenance (which may even require process streams to be taken offline for servicing) and operational costs to keep the sacrificial electrode(s) operational.
The present inventors sought to develop water treatment methods and systems which are capable of operating at high temperatures and pressures; which employ a flocculating ion-enriched aqueous solution, which may be separately prepared, to reduce or eliminate use of in-line sacrificial electrodes; and which do not require treatment of the contaminated water with conventional electrocoagulation. The development of such methods and systems proved highly challenging, due at least in part to the discovery that certain contaminated waters such as those produced from an oilfield operation may contain one or more flocculation inhibiting compounds. Indeed, experiments as described in further detail hereinbelow revealed that foregoing electrocoagulation treatment in favor of adding a flocculating ion-enriched aqueous solution to the contaminated water, while effective for certain contaminated waters, failed to achieve water treatment of certain contaminated water samples due to the presence of one or more flocculation inhibiting compounds in the contaminated water samples, which prevented flocculation and thus did not achieve contaminant removal.
It has now been discovered that subjecting the contaminated water to reducing or oxidizing conditions may be used to destroy or inactivate the flocculation inhibiting compound(s) in the contaminated water, thereby allowing for a flocculating ion-enriched aqueous solution, which may be prepared separately from the contaminated water, to be used for contaminant removal in a manner which does not require use of sacrificial electrodes, does not require performing electrocoagulation on the contaminated water, and which is fully compatible with elevated temperatures and pressures. In certain embodiments, the flocculating ion-enriched aqueous solution may be prepared separately, and may even be prepared at ambient temperatures and pressures, reducing complexity and operational costs. In certain embodiments, the flocculating ion-enriched aqueous solution may comprise a solution obtained by treating an aqueous carrier fluid with a conventional electrofloatation apparatus (which may be conducted at ambient temperature outside the main process stream, for example), a solution prepared by dissolving flocculating ion salts in water, or even a flocculating ion-enriched aqueous solution obtained or prepared from mining waste such as iron vitriol or green salt.
As described in detail herein, by combining a reducing or oxidizing pre-treatment step with the use of a flocculating ion-enriched aqueous solution to remove at least some of at least one contaminant from a contaminated water by ion flocculation, methods and systems have now been developed which may provide advantages and/or alternatives to conventional approaches as described in further detail hereinbelow.
In an embodiment, there is provided herein a method for treating a contaminated water, said method comprising:
subjecting the contaminated water to reducing or oxidizing conditions;
introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water;
thereby producing a treated water.
The contaminated water to be treated may comprise any suitable fluid with an aqueous component contaminated with one or more contaminants for removal. The contaminated water may be fully aqueous, or may be an emulsion, for example, an aqueous emulsion with oil. The contaminated water may comprise a waste water, or an industrial process water, for example.
In certain embodiments, the contaminated water may comprise, for example, a produced water from an oil field operation. By way of example, the waste water may comprise a produced water from a Steam-Assisted Gravity Drainage (SAGD) operation, or a produced water from another subterranean hydrocarbon mobilization process. The produced water may, or may not, be in an emulsion with oil(s), for example. In certain embodiments, the contaminated water may comprise a produced water emulsion with up to about 2,000 ppm oil, for example.
In certain embodiments, the contaminated water may comprise one or more contaminants to be removed therefrom. The contaminants to be removed may include, but are not limited to, calcium, magnesium, silica, other water hardness, or an organic contaminant, or any combination thereof.
In certain embodiments, the contaminated water to be treated may be a contaminated water which has been subjected to one or more pre-treatment steps. By way of example, in certain embodiments, the contaminated water to be treated may be a contaminated water which has been filtered (using, for example, an ORF), or subjected to another such treatment step, prior to treatment with the methods described herein.
Subjecting the contaminated water to reducing or oxidizing conditions may comprise any suitable process step in which the contaminated water is treated under electroreduction and/or chemical reduction conditions, or under electrooxidation and/or chemical oxidation conditions, which are sufficient to destroy, degrade, remove, or inactivate at least a portion of inhibitory contaminants in the contaminated water (if present) which would otherwise prevent or interfere with subsequent flocculation of the contaminated water using a flocculating ion-enriched aqueous solution. In certain embodiments, it is not necessary that contaminated water actually comprise such inhibitory contaminant(s); rather, such a reducing or oxidizing step may be used to expand process versatility to both inhibitory and non-inhibitory contaminated waters, thereby removing the need to test for inhibitory contaminant presence in contaminated water to be treated.
In certain embodiments, the contaminated water may be subjected to reducing conditions via electroreduction. Electroreduction may comprise treating the contaminated water by electrolytic reduction such that electrons are introduced into the contaminated water to destroy, degrade, remove, or inactivate inhibitory compound(s) which would otherwise prevent flocculation. In certain embodiments, electroreduction treatment may employ non-sacrificial (i.e. non-consumptive) electrode(s), such as graphite and/or titanium electrodes, for electrolytic reduction. Non-sacrificial electrodes are generally lower maintenance as compared to consumptive electrodes. Generally, in certain embodiments, electroreduction treatment may comprise treatment with, for example, graphite plates installed at between about 2cm and about 10cm separation distance, and a voltage from about 5 to about 20 volts and between about 1 and about 16 amps of current may be applied. When using graphite plates, for example, the information provided in Figure 19, Figure 21, Figure 22, and Figure 23, or other such information, may be used to assist in selecting suitable configuration and conditions for .. electroreduction for a particular application, for example.
In certain embodiments, the contaminated water may be subjected to chemical reduction-based reducing conditions. Chemical reduction may comprise treating the contaminated water with a suitable chemical reducing agent such that electrons are introduced into the contaminated water to destroy, degrade, remove, or inactivate inhibitory compound(s) which would otherwise prevent flocculation. In certain embodiments, chemical reducing agents may include one or more of NaHS03, Na2S03, Na2S204, Na2S203, nascent hydrogen, or a combination thereof.
In certain embodiments, the contaminated water may be subjected to a combination of electroreduction- and chemical reduction-based reducing conditions.
In certain embodiments, reducing conditions may include those generated by DC
electroreduction with a voltage of between 4 and 20 volts, for example.
Without wishing to be bound by theory, in certain embodiments reducing conditions may facilitate Kolbe electrolysis.
During such electrolysis, electrons introduced into the system may have a role in destroying flocculation inhibitor compound(s) in the contaminated water, due to high energy. In certain embodiments, reducing conditions may include those generated by a chemical reduction agent.
In such examples, redox potential in chemical reduction may be around 0.45 v or less.
In certain embodiments, the contaminated water may be subjected to electrooxidation-based oxidizing conditions. Electrooxidation may comprise treating the contaminated water by electrolytic oxidation such that flocculation inhibiting compound(s) in the contaminated water which would otherwise prevent flocculation are destroyed, degraded, removed, or inactivated by oxidation. In certain embodiments, electrooxidation treatment may employ non-sacrificial (i.e. non-consumptive) electrode(s), such as graphite and/or titanium electrodes, for electrolytic oxidation. Non-sacrificial electrodes are generally lower maintenance as compared to consumptive electrodes. Generally, in certain embodiments, electrooxidation treatment may comprise treatment with, for example, graphite plates installed at between about 2cm and about 10cm separation distance, and a voltage from about 5 to about 20 volts and between about 1 and about 16 amps may be applied.

In certain embodiments, oxidizing conditions may be those generated by electrochemical oxidation (ECU), for example. Where flocculation inhibiting compound(s) in the contaminated water are oxidized (i.e. degraded) more quickly than the average total organic loading, oxidizing conditions may be of particular interest. In certain embodiments, where flocculation inhibiting compound(s) in the contaminated water are more readily oxidized than other bulk organic acids or free oil (for example), oxidizing conditions may be of particular interest.
In certain embodiments, the contaminated water may be subjected to chemical oxidation-based oxidizing conditions. Chemical oxidation may comprise treating the contaminated water with a suitable chemical oxidizing agent such that flocculation inhibiting compound(s) in the contaminated water which would otherwise prevent flocculation are destroyed, degraded, removed, or inactivated. In certain embodiments, chemical oxidizing agents may include one or more of H202 or Na0C1, or another suitable oxidizing agent, or a combination thereof.
In certain embodiments, the contaminated water may be subjected to a combination of electrooxidation- and chemical oxidation-based oxidizing conditions.
In certain embodiments, both reducing and oxidizing conditions may be used.
For example, low-powered ECU may be used to provide reduction/oxidation, as ECU may include a joint electrolytic/chemical reduction step (ECU may produce oxidizing and reducing agents). In certain embodiments, ECU may be employed to remove soluble organics from contaminated water, either as a pre-treatment step or a post-treatment step, during water treatment.
In certain embodiments, after the contaminated water has been subjected to the reducing or oxidizing conditions, a flocculating ion-enriched aqueous solution may then be introduced into the contaminated water. In another embodiment, the flocculating ion-enriched solution may be introduced into the contaminated water before, during, or after the contaminated water being subjected to the reducing or oxidizing conditions, where conditions may be selected such that the flocculating ions are not appreciably deactivated (see, for example, Example 7 below).
Flocculating ion-enriched aqueous solutions may include any suitable solution comprising a water-based carrier fluid and at least one flocculating ion component.
Flocculating ions may include, for example, iron ions or aluminum ions or both. In certain embodiments, the flocculating ion may comprise Fe2+, and the flocculating ion-enriched aqueous solution may be an Fe2tenriched aqueous solution. In certain embodiments, it is additionally contemplated that the flocculating ion-enriched solution may be a non-aqueous, or partially aqueous, solution, slurry, or other such formulation of flocculating ions suitable for introduction into the contaminated water. The flocculating ion-enriched solution may comprise any suitable solution which provides flocculating ions to the contaminated water when introduced thereto, thus creating flocks which allow for separation of contaminants from the water.
Flocculating ion-enriched solutions may be separately produced or pre-made, for example, by dissolving flocculating ion salts in a carrier water, or by treating a carrier water (such as fresh water, brackish water, a side stream of produced water, or boiler feed water, for example) using a consumptive electrode which introduces flocculating ions into the carrier water (i.e. by using an iron-based consumptive electrode of an electroflotation apparatus, for example). In certain .. embodiments, the flocculating ion-enriched aqueous solution may comprise a solution generated by electro-flocculation or electroflotation using a sacrificial iron or aluminum electrode, a solution generated by dissolving iron or aluminum salts in water, a solution of iron vitriol or green salt, or any combination thereof. In certain embodiments, the flocculating ion concentration of the flocculating ion-enriched aqueous solution may be adjusted to suit the particular application, apparatus, and contaminated water being used, so as to provide for contaminant removal via flocculation.
In certain embodiments, references herein to introducing a flocculating ion-enriched aqueous solution into the contaminated water may include one or both of introducing flocculating ions which are already in solution form into the contaminated water, and/or introducing flocculating ions which are in the form of a solid (or in another non-solution or non-aqueous form) into the contaminated water where the flocculating ions enter solution to produce the flocculating ion-enriched aqueous solution using water already in the contaminated water. By way of example, in certain embodiments, a step of introducing a flocculating ion-enriched aqueous solution into the contaminated water may comprise adding a solid or powder of a flocculating ion salt to the contaminated water, where the flocculating ion will dissolve into the contaminated water to form the flocculating ion-enriched aqueous solution therein.
As will be understood, the flocculating ion-enriched aqueous solution may be introduced into the contaminated water in any suitable manner. In certain embodiments, the flocculating ion-enriched aqueous solution may be introduced into the contaminated water as a slip-stream, for example. In certain embodiments, the flocculating ion-enriched aqueous solution may be introduced into the contaminated water via any suitable injection method known to the person of skill in the art having regard to the teachings herein.

Following introduction of the flocculating ion-enriched aqueous solution into the contaminated water, flocculation occurs, whereby flocks are formed in the contaminated water which allow for capture of contaminants in the contaminated water. Contaminants and flocks may then be separated from the contaminated water using any suitable separation technique known to the .. person of skill in the art. By way of example, flocks and contaminants may be separated from the contaminated water by filtration or floatation. In certain embodiments, induced static floatation (ISF), induced gas floatation (IGF), filter press, sand filter, mixed bed filter, walnut shell filter, cartridge filter, bag filter, stainless steel or composite filter, and/or compact floatation unit (CFU) equipment (with either single or multiple stage floatation) may be used for separation, for example. Removal of the flocks and contaminants thereby produces a treated water, in which a level of at least one contaminant is reduced as compared to the contaminated water before treatment.
In certain embodiments, the step of removing at least some of at least one contaminant from the contaminated water by ion flocculation may optionally include adjusting pH
of the contaminated water to promote formation of ion flocks. In certain embodiments, the pH may be adjusted, for example, to a pH within a range of about 7 to about 11 in order to promote formation of flocks. In certain embodiments, the pH adjustment may be performed before, concurrently with, or after, introduction of the flocculating ion-enriched aqueous solution into the contaminated water, to facilitate the removal of contaminants from the contaminated water.
In certain embodiments, the pH may be adjusted generally any suitable time before (or during) flocculation such that the pH of the contaminated water is suitable for promoting formation of ion flocks during flocculation, as reflected in the dotted line in selected Figures.
In certain embodiments, the step of pH adjustment of the contaminated water may be performed in two stages. In the first stage, pH may be adjusted to render silica or other ionic contaminants .. in the contaminated water reactive; and in a second stage, pH may be adjusted to promote formation of the flocculating ion flocks. By way of example, in the first stage, pH may be adjusted to about 2 to about 4, and in the second stage pH may be adjusted to within a range of about 7 to about 11. As will be understood, pH may be adjusted in any suitable manner known to the skilled person. By way of example, pH may be lowered using HCI, H2SO4, or another .. acid, and pH may be raised using NaOH, steam blowdown, or another base, for example.
In certain embodiments, methods as described herein may further comprise a step of adding one or more of an H2S scavenger, a chelant, a polymer, or a sulphite additive to the contaminated water during treatment. For example, in certain embodiments, an H2S scavenger may be added to abrogate contaminant(s) which would otherwise consume or block flocculating ions, to promote flocculation and/or to reduce the amount of flocculating ion to be used. In certain embodiments, H2S scavenger may be added at any suitable time prior to or during flocculation, and may be added to the contaminated water, or to the flocculating ion-enriched solution which is then added to the contaminated water. In certain embodiments, a chelant may be added to the water post-treatment (i.e. post removal of one or more contaminants by ion flocculation), to bind with residual hardness ions to reduce scaling. In certain embodiments, a polymer may be added to the contaminated water before or during flocculation, to aid with coagulation. In certain embodiments, a sulphite may be added to bind with free oxygen and prevent corrosion. For example, an H2S scavenger may be added to the contaminated water prior to introduction of an iron ion-enriched solution, so as to prevent the iron ions from being blocked by (i.e. reacting with) sulfur. In certain embodiments, a polymer may be added to enhance flocculation and facilitate contaminant removal, for example.
.. In certain embodiments, treated water may additionally be treated by a step of subjecting the treated water to electrochemical oxidation (ECO) or chemical oxidation treatment to render remaining organics in the treated water insoluble, and separating the organics from the treated water. Since residual organics may create a varnish-like scale in a boiler, for example, such oxidation treatment may be performed to make the organics insoluble and/or separable (i.e. to precipitate and/or separate organics) to avoid or reduce such scaling.
Techniques for removing the insoluble organics from the water may include any suitable separation methods and apparatus known to the person of skill in the art.
In certain embodiments, temperatures and pressures under which methods and systems as described herein may be operated may include any of those at which fluids produced from, for example, a SAGD process, may typically experience:
Conventional processes for separating produced emulsion for oil sales and further water treatment involve a number of distinct steps, as follows. Oil-water emulsion from the reservoir may vary in temperature, for example from 80 C-250 C, more typically 180 C-220 C, and with a pressure of about 1,200-2,000 kPag. After emulsion is recovered from the reservoir it may be degassed and then cooled to from 130 C-to allow for diluent aided separation. The cooled emulsion is then treated for coarse oil-water separation, for example in free-water knock out (FWKO) unit(s), and/or other emulsion treaters, typically operating at about 800-1,500 kPag and 130 C-140 C
for traditional gravity separation, or alternatively operating at much lower pressures of between 100-800 kPag and 130 C-140 C for flash treating. These conventional emulsion treating systems typically use diluent to aid in separation of oil and water, where the diluent is traditionally a pentane rich natural gas liquid (NGL) or a synthetic crude oil, and where the diluent remains in the dewatered oil that is then cooled and sent to sales oil tanks.
Conventional processes for treating the produced water for re-use in steam generation may involve a number of distinct steps, as follows. Conventionally, produced water from emulsion treatment is cooled, using for example one or more heat exchangers, before it is subjected to de-oiling and further water treatment. This heat exchange process may for example decrease the produced water temperature from 130 C-140 C
to 80 C-95 C. De-oiling typically comprises several units, such as a skim tank for bulk oil separation, a flotation (floatation) type unit such as an induced gas or induced static flotation unit (IGF/ISF) for further removal of oil and suspended solids, and a filtration type unit such as an oil removal filter (ORF). Subsequent water treatment typically includes, for example, a warm lime softener (WLS), which increases the pH of the water and adds MagOx (Magnesium Oxide) to remove silica. The WLS is typically followed by an ion exchange unit where removal of scaling ions occurs. Scaling ions typically include dissolved calcium, magnesium, lithium and iron. A significant decrease in temperature of the produced water stream entering de-oiling is generally performed for operational reasons, particularly so that surge capacity may be carried out at atmospheric pressure in tanks. Typical water quality from de-oiling and water treatment may be less than 50 ppm silica, less than 0.1 ppm hardness, and less than 1 ppm oil.
In certain embodiments, water treatment methods and systems as described herein are compatible with operation at elevated temperatures and pressures, such as those typically encountered during steam generation, produced water recovery, and treatment in a SAGD
facilities process. Water treatment methods and systems as described herein are also compatible with operation at a variety of other temperatures such as ambient or room temperatures, cooler temperatures, warmer temperatures, and temperatures therebetween, for example.
In certain embodiments, water treatment methods and systems as described herein may be operable at temperatures above about 100 C, or above about 125 C, or above about 150 C, for example.
In certain embodiments, water treatment methods and systems may be configured for operation at a temperature between about 135 C to about 250 C, for example. Accordingly, in certain embodiments, the contaminated water to be treated may be maintained at high temperature throughout treatment, thereby generating the treated water at high temperature, saving on energy requirements when using the treated water for injection of further steam or water downhole, for example. In applications where an output of treated water at high temperature is desired, the contaminated water may be heated during treatment by the methods and systems described herein; or, when the contaminated water to be treated is already received at high temperature, no heating, or reduced heating, during treatment may still yield a heated treated water. As will be understood, in certain embodiments, methods and systems described herein do not require a heat sink/cooling phase, and do not require heat input, during treatment of contaminated water. Rather, methods and systems described herein may be configured to suit the particular application, based on the temperature of the contaminated water being received and/or on the desired temperature of the treated water output. In certain embodiments, the contaminated water may be maintained at or above about 80 C during treatment, or at or above about 100 C during treatment, for example, thereby producing a heated treated water.
In still another embodiment, there is provided herein a method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam and/or water into the subterranean reservoir;
producing a produced water and a hydrocarbon to the surface;
treating at least a portion of the produced water using a method as defined herein, thereby generating a treated water stream; and using the treated water stream to provide steam and/or water for re-injection into the subterranean reservoir to produce more hydrocarbons to the surface.
In certain embodiments, the injecting and producing may be performed as part of a thermal in-situ hydrocarbon recovery operation. In certain embodiments, the injecting and producing may be performed using an injection well and production well of, for example, a SAGD well pair.
In certain embodiments, the injecting and producing may be performed using a Cyclic Steam Stimulation (CSS) well setup. In certain embodiments, the injecting and producing may be performed as a solvent-aided process (SAP) well setup, for example. In certain embodiments, the injecting and producing may be performed using one or more wells of another suitable hydrocarbon recovery operation involving steam and/or water injection for hydrocarbon recovery.
In yet another embodiment, there is provided herein a method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam into the subterranean reservoir via an injection well;
producing a produced water stream and a hydrocarbon stream to the surface via a production well, or producing a mixed produced water and hydrocarbon emulsion stream from the subterranean reservoir via a production well and (optionally) separating the mixed produced water and hydrocarbon emulsion stream into a produced water stream and a hydrocarbon stream;
treating at least a portion of the produced water stream using a method as described herein, thereby generating a treated water stream; and using the treated water stream to provide steam and/or water for re-injection into the subterranean reservoir via the same or a different injection well to produce more hydrocarbons to the surface.
As will be understood, in certain embodiments, the produced water stream may be produced to the surface as an aqueous solution which may be an emulsion with hydrocarbons, depending on the particular operation. The produced water may, in certain embodiments, include both an aqueous component and an oil component, as an emulsion, for example. Where the produced water comprises an emulsion, the emulsion may be processed to first remove at least a portion of the oil-based component (either downhole or at the surface), or the emulsion may be used directly as contaminated water to be treated using methods and systems as described herein. In certain embodiments, the contaminated water may comprise a produced water emulsion stream with up to about 2,000 ppm oil, for example.

In certain embodiments, the injection well and production well may be a SAGD
well pair, for example. In certain embodiments, the injection well and production well may be a single well, or wells, of another hydrocarbon recovery operation involving steam and/or water injection.
In yet another embodiment, there is provided herein a system for treating contaminated water, the system comprising:
an input for a contaminated water;
a reducing or oxidizing unit configured to receive the contaminated water from the input and generate reducing or oxidizing conditions in the contaminated water;
a separation unit downstream of the reducing or oxidizing unit and in direct or indirect fluid communication therewith, the separation unit configured to receive the contaminated water from the reducing or oxidizing unit and remove flocculating ion flocks with captured contaminant from the contaminated water;
an input for a flocculating ion-enriched aqueous solution, the input configured for introducing the flocculating ion-enriched aqueous solution into the contaminated water upstream of the separation unit, at the separation unit, or a combination thereof; and an output for outputting a treated water from the separation unit.
As will be understood, such systems may be for use in performing a water treatment method as described herein.
In certain embodiments, the reducing or oxidizing unit may be for subjecting the contaminated water to reducing or oxidizing conditions in which the contaminated water is treated under electroreduction and/or chemical reduction conditions, or under electrooxidation and/or chemical oxidation conditions, which are sufficient to destroy, degrade, remove, or inactivate at least a portion of inhibitory contaminants in the contaminated water which would otherwise prevent or interfere with subsequent flocculation of the contaminated water using a flocculating ion-enriched aqueous solution.
In certain embodiments, the reducing unit may be an electroreduction-based reducing unit.
Electroreduction may comprise treating the contaminated water by electrolytic reduction such that electrons are introduced into the contaminated water to destroy, degrade, remove, or inactivate inhibitory compound(s) which would otherwise prevent flocculation.
In certain embodiments, the electroreduction-based reducing unit may employ non-sacrificial (i.e. non-consumptive) electrode(s), such as graphite and/or titanium electrodes, for electrolytic reduction. By way of example, in certain embodiments a non-sacrificial electrode may include a doped electrode, or an Inconel, Monel, Super Duplex, or other such non-reactive anode. Non-sacrificial electrodes are generally lower maintenance as compared to consumptive electrodes.
In certain embodiments, for example, electroreduction-based reducing units may comprise a vessel (which may be pressurized or non-pressurized), with graphite or titanium grids operating between about 5 and about 20 volts and about 1 to about 16 amps, for example.
In certain embodiments, the reducing unit may be a chemical reduction-based reducing unit.
Chemical reduction may comprise treating the contaminated water with a suitable chemical reducing agent such that electrons are introduced into the contaminated water to destroy, degrade, remove, or inactivate inhibitory compound(s) which would otherwise prevent flocculation. In certain embodiments, chemical reducing-based reducing units may comprise units for introducing one or more of NaHS03, Na2S03, Na2S204, Na2S203, or nascent hydrogen reducing agents, or a combination thereof, into the contaminated water. In certain embodiments, a chemical reduction-based approach may include, for example, direct injection of one or more chemical reducing agents into a flowline, tank, or vessel, with or without a static mixer, which allows for sufficient reaction time (for example, between about

10 seconds and about 5 minutes, or another suitable reaction time appropriate for the particular application/implementation) with the contaminated water.
In certain embodiments, the reducing unit may be a hybrid electroreduction-based and chemical reduction-based reducing unit.
In certain embodiments, the oxidizing unit may be an electrooxidation-based oxidizing unit.
Electrooxidation may comprise treating the contaminated water by electrolytic oxidation such that flocculation inhibiting compound(s) in the contaminated water which would otherwise prevent flocculation are destroyed, degraded, removed, or inactivated by oxidation. In certain embodiments, electrooxidation-based oxidizing units may employ non-sacrificial (i.e. non-consumptive) electrode(s), such as graphite and/or titanium electrodes, for electrolytic oxidation. Non-sacrificial electrodes are generally lower maintenance as compared to consumptive electrodes. Generally, in certain embodiments, electrooxidation-based oxidizing units may comprise a vessel (which may be pressurized or non-pressurized), with graphite or titanium grids operating between about 5 and about 100 volts and about 1 to about 50 amps, for example.
In certain embodiments, the oxidizing unit may be a chemical oxidation-based oxidizing unit.
Chemical oxidation may comprise treating the contaminated water with a suitable chemical oxidizing agent such that flocculation inhibiting compound(s) in the contaminated water which would otherwise prevent flocculation are destroyed, degraded, removed, or inactivated. In certain embodiments, chemical oxidation-based oxidizing units may comprise units for introducing one or more of H202 or Na0C1 oxidizing agents, or a combination thereof, into the contaminated water. In certain embodiments, a chemical oxidation-based approach may include, for example, direct injection of one or more chemical oxidation agents into a flowline, tank, or vessel, with or without a static mixer, which allows for sufficient reaction time (for example, between about 10 seconds and about 5 minutes, or another suitable reaction time appropriate for the particular application/implementation) with the contaminated water.
In certain embodiments, the oxidizing unit may be a hybrid electrooxidation-based and chemical oxidation-based oxidizing unit.
In certain embodiments, a reducing-and-oxidizing unit may be used. For example, low-powered ECO may be used to provide reduction/oxidation, as ECO may include a joint electrolytic/chemical reduction step (ECO may produce oxidizing and reducing agents). In certain embodiments, ECO may be employed to remove soluble organics from contaminated water, either as a pre-treatment step or a post-treatment step, during water treatment.
In another embodiment, the system may further comprise a flocculating ion-enriched aqueous solution generator, comprising an electro-flocculation reactor employing sacrificial iron or aluminum electrode(s), which is configured to generate the flocculating ion-enriched aqueous solution and provide the solution to the input for introducing the solution into the contaminated water. In certain embodiments, such a flocculating ion-enriched aqueous solution generator may be used for preparing the flocculating ion-enriched aqueous solution on-site.
In certain embodiments, the input for the flocculating ion-enriched aqueous solution may be an input which is configured to introduce a separately prepared flocculating ion-enriched aqueous solution into the contaminated water. In certain embodiments, for example, the input for the flocculating ion-enriched aqueous solution may comprise a slipstream line feeding into a contaminated water line. In certain embodiments, input flocculating ion-enriched aqueous solution may be input at or upstream of a suitable mixing location, which may comprise, for example, a vessel, or a pipe, with or without a static mixer.
In still further embodiments, the system may further comprise at least one input for a pH
adjustment agent, which is configured for:
optionally, adjusting pH to render silica or other ionic contaminants in the contaminated water reactive; and adjusting pH to promote formation of the flocculating ion flocks.
By way of example, the one or more inputs for the pH adjustment agent may be configured for:
optionally, adjusting pH of the contaminated water to a pH of about 2 to about 4 to render silica or other ionic contaminants in the contaminated water reactive;
and adjusting pH of the contaminated water to a range of about 7 to about 11 to promote formation of the flocculating ion flocks.
In certain embodiments, the one or more inputs for the pH adjustment agent may be configured for adjusting pH of the contaminated water at generally any suitable time before (or during) flocculation such that the pH of the contaminated water is suitable for promoting formation of ion flocks during flocculation. By way of example, where pH of the contaminated water is adjusted to a pH of between about 7 to about 11 to promote flocculation, the one or more inputs for the pH adjustment agent may be positioned for adjusting pH of the contaminated water at generally any suitable time prior to or during flocculation in the separation unit (i.e. may be upstream or at the separation unit). Where pH of the contaminated water is first adjusted to render silica or other ionic contaminants in the contaminated water reactive, for example by adjusting pH to between about 2 to about 4, the one or more inputs for the pH
adjustment agent for such pH adjustment may be positioned for adjusting pH of the contaminated water at .. generally any suitable time prior to flocculation in the separation unit (i.e. may be upstream of the separation unit).
In certain embodiments, systems as described herein may further comprise one or more inputs configured for adding one or more of an H2S scavenger, a chelant, a polymer, or a sulphite to the contaminated water during treatment. For example, in certain embodiments, an H2S
scavenger may be added to the contaminated water via an input, to abrogate contaminant(s) which would otherwise consume/block flocculating ions, to promote flocculation and/or to reduce the amount of flocculating ion to be used. In certain embodiments, H2S
scavenger may be added at any suitable time prior to or during flocculation, and may be added to the contaminated water, or to the flocculating ion-enriched solution which is then added to the contaminated water. In certain embodiments, the H2S scavenger input may be positioned to input H2S scavenger prior to introduction of the flocculating ion-enriched aqueous solution into the contaminated water. In certain embodiments, a chelant input may be included to add chelant to the water post-treatment (i.e. post removal of one or more contaminants by ion flocculation), to bind with residual hardness ions to reduce scaling. In certain embodiments, a polymer may be added to the contaminated water before or during flocculation, to aid with coagulation. In certain embodiments, a sulphite input may be configured to add a sulphite at any suitable time to bind with free oxygen and prevent corrosion. For example, an H2S scavenger input may be included prior to the flocculating ion-enriched solution input, so as to prevent the flocculating ions from being consumed/blocked by sulfur. A polymer input may be included for injecting polymer to enhance flocculation and facilitate contaminant removal, for example.
In another embodiment of systems as described herein, the separation unit may comprise, for example, a filtration or flotation apparatus for separating flocculating ion flocs from the contaminated water. Contaminants and flocks may be separated from the contaminated water using any suitable separation unit known to the person of skill in the art. In certain embodiments, the separation unit may comprise an induced static floatation (ISF) unit, an induced gas floatation (IGF) unit, filter press, sand filter, mixed bed filter, walnut shell filter, cartridge filter, bag filter, stainless steel or composite filter, and/or a compact floatation unit (CFU) (with either single or multiple stage floatation), for example.
In yet another embodiment, systems as described herein may additionally comprise:
a downstream electrochemical oxidation (ECO) or chemical oxidation unit, which is configured to receive the treated water output from the separation unit and subject the treated water to electrochemical oxidation (ECO) or chemical oxidation treatment, rendering organics in the treated water insoluble; and a downstream organics separation unit for removing insoluble organics from the treated water.
In still another embodiment, there is provided herein a system for producing hydrocarbons from a subterranean reservoir, the system comprising:

a wellbore system comprising at least one well contacting the subterranean reservoir, the wellbore system for injecting steam and/or water into the subterranean reservoir and for producing a produced water and a hydrocarbon to the surface;
and a system for treating contaminated water as defined herein, the system for treating contaminated water configured (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the same, or a different, wellbore system for re-injection into the subterranean reservoir.
In certain embodiments, the wellbore system may be a wellbore system of a thermal in-situ hydrocarbon recovery operation. In certain embodiments, the wellbore system may comprise an injection well and production well of, for example, a SAGD well pair. In certain embodiments, the wellbore system may comprise a Cyclical Steam Stimulation (CSS) well setup. In certain embodiments, the wellbore system may comprise one or more wells of another suitable hydrocarbon recovery operation involving steam and/or water injection.
In yet another embodiment, there is provided herein a system for producing hydrocarbons from a subterranean reservoir, the system comprising:
an injection well and a production well contacting a subterranean reservoir, the injection well for injecting steam into the subterranean reservoir and the production well for producing a produced water stream and a hydrocarbon stream, or a mixed produced water and hydrocarbon emulsion stream, to the surface; and a system for treating contaminated water as described herein, the system for treating contaminated water configured (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the same, or a different, injection well for re-injection into the subterranean reservoir.
In certain embodiments, the produced water stream may be produced to the surface as an aqueous solution, or as an emulsion, depending on the particular operation.
The produced water may thus in certain embodiments include both an aqueous component and an oil component, as an emulsion, for example. Where the produced water comprises an emulsion, the emulsion may be processed to first remove the oil component (either downhole or at the surface) in an emulsion separation unit of the system, or the emulsion may be used directly as contaminated water to be treated using methods and systems as described herein.
In certain embodiments, the injection well and production well of the system may be a SAGD
well pair, for example. In certain embodiments, the injection well and production well may be wells of another hydrocarbon recovery operation involving steam injection.
Figure 1 depicts an example of a conventional water treatment system for treating produced water from a SAGD operation to remove contaminants therefrom. The system includes several treatment apparatus, including a warm lime softener (WLS) and associated components, which are used to treat the contaminated water. Figure 2, in contrast, depicts an embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing or oxidizing conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water. The depicted method does not require WLS
apparatus, and instead provides for water treatment via a distinct process.
Figure 3 depicts another embodiment of a water treatment method and system as described herein, in which produced water is subjected to electro-flocculation treatment, followed by pH
adjustment, and then at least some of at least one contaminant is removed from the contaminated water by flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water. The depicted embodiment uses an electro-flocculation unit which employs iron-based sacrificial electrodes to introduce iron ions, and therefore the iron electrodes have maintenance and upkeep considerations.
In contrast, Figure 4 depicts an embodiment of a water treatment method and system in which the contaminated water is not subjected to electro-flocculation, and instead a separate carrier water (brackish water in this example) is subjected to electroflocculation to generate an iron ion-enriched solution, which is then introduced into the contaminated water, and a pH
adjustment is performed on the contaminated water to promote flocculation to allow for contaminant separation in a filtration or flotation unit. However, as described in the examples section below, when the depicted embodiment was used with a produced water sample containing flocculation inhibiting compound(s), suitable separation was not achieved.
Figure 5 depicts an embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing a flocculating ion-enriched aqueous solution into the contaminated water, the solution being generated by separate treatment of a carrier water (brackish water) by electroflocculation to introduce iron ions from a sacrificial electrode; a pH
adjustment step to promote flocculation; and a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water.
Figure 6 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; and a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water.
Figure 7 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via electroreduction); introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
Figure 8 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to reducing conditions (via chemical reduction); introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
Figure 9 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to oxidizing conditions (via ECO
treatment); introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
Figure 10 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to electrical or chemical reduction conditions; introducing an H2S scavenger to abrogate contaminants which would otherwise consume/block flocculating ions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; a step of subjecting the treated water to electrochemical oxidation (ECO) treatment to render organics in the treated water insoluble, and separating the insoluble organics via filtration or floatation; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
Figure 11 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to chemical oxidation conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
Figure 12 depicts another embodiment of a water treatment method and system as described herein, which includes steps of subjecting contaminated water to electrical or chemical .. reduction conditions; introducing a flocculating ion-enriched aqueous solution into the contaminated water; a pH adjustment step to promote flocculation; a removal step of removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water, thereby producing a treated water; a step of subjecting the treated water to chemical oxidation treatment to render organics in the treated water insoluble, and separating the insoluble organics via filtration or floatation; and steps of introducing a chelant and a sulphite for further reducing hardness and preventing scaling.
As indicated, each of the embodiments depicted in Figures 2-12 may be used to avoid, substitute, reduce, or replace use of a conventional treatment apparatus such as shown in Figure 1 (such as a WLS, for example). In the embodiments depicted in Figures 3-12, conventional treatment apparatus which is being replaced is indicated within a shaded box.
EXAMPLE 1 ¨ Generation of Iron Ion-Enriched Aqueous Solutions While treatment of the produced water with conventional electro-flocculation achieved contaminant removal, cost-benefit analysis showed that costs were similar to current WLS-based designs for treating produced water form an oilfield operation. As well, the flow-through configuration was problematic at high temperature, because high-maintenance plates were required in a pressure vessel for such electro-flocculation treatment, complicating applications where it is desirable to maintain the water at elevated temperatures/pressures.
Accordingly, studies were performed to determine if a separately produced flocculating ion-enriched solution could be introduced to the contaminated produced water to remove contaminants via flocculation, without requiring electroflocculation/electrocoagulation treatment of the contaminated water. These initial experiments sought to determine whether a flocculating ion-enriched solution, in this example an iron ion-enriched aqueous solution, could be separately produced, and then slipstreamed into contaminated produced water to achieve contaminant removal via flocculation.
Generation of Iron Ion-Enriched Aqueous Solutions Since treatment of industrial contaminated waters, such as produced water from an oilfield .. operation, is desirable, initial studies investigated options for preparing iron ion-enriched solutions. IGF columns are apparatus commonly employed in oilfield operations, and these may be operated with flow rates of several hundred m3 per hour of Skim Tank Water, i.e. 250 m3/h. Thus, options for preparing solutions compatible with these types of operational parameters were investigated. It was initially hypothesized that Fe2+
concentrations of about 50 ¨ 100 mg/1 would be suitable for removing contaminants from water efficiently (concentrations are further studied below). Initial assumptions were that a concentration of 75 mg/1 may be used. Based on this assumption, the total hourly amount of Fe' for a flow rate of 250 m3/h would be about 20 kg (exactly 18.75 kg).
Accordingly, these studies, in part, sought to determine whether production of enriched Fe2+
solution with an iron concentration of about 2 to 5 g/I using electrolytic dissolution of iron would be possible, and under what operating conditions. This target range would then allow use of only a small side stream to introduce suitable amounts of iron for water treatment. The volume of the side stream depends on the level of Fe2+ enrichment achieved.
This small volume side stream would have a negligible effect on the main stream of process water (i.e. pH, temperature, etc., impact from the small volume of iron enriched concentrate would be inconsequential).
Therefore, based on the following assumptions:
STW flow rate 250m3/h;
Fe' for treatment of 75 mg/1;
18.75 kg Fe2+/h; and Enriched Fe2+ solution of 5g/1, the volume of the side stream would be about 3.75 m3/h.

The only data available for solubility of Fe2+ constants were for pure water and at low concentrations. However, pure water has a low conductivity which is not preferable for electrode configurations (only a single value is given at a pH of 7, 25 C:
Solubility 7.2 g/1).
Boiler Feed Water (BFW) and Brackish Water (BW), on the other hand, have conductivities in the higher range, measured respectively at 3.23 mS/cm (pH 9.16) for BFW and 18.57 mS/cm (pH 9.772) for BW. These are more preferable, as level of conductivity is sufficiently high to start the process.
For these tests, Brackish Water (BW), Boiler Feed Water (BFW) were used as the carrier water.
Characteristics of these waters were as follows:
Brackish Water was clear, contained about 6 g/I salt, mainly in the form of NaCl, a small amount of hardness and almost no DOC. Conductivity of BW was measured at 18.57 mS/cm, the pH 9.77. Color was clear. Other characteristics included:
SiO2: 11 mg/1 Hardness: 0.977 mg/1 TOCtotal: 32.58 mg/1 Oil + grease: < DL
Fewt. : 0.052 mg/I; Fechss. : 0.031 mg/1 Due to the high concentration of NaCl, BW was very suitable to the production of Fe2+ solution in an electrolytic dissolution reactor.
Boiler Feed Water contained some organics that turn the color to dark brown.
Main characteristics of BFW were:
Conductivity: measured at 3.23 mS/cm, the pH 9.16.
Color: clear, dark, red-brown Other Characteristics included:
SiO2: 52 mg/I

TOC total. = 360.9 mg/1 DOC : 359.1 mg/1 Oil + grease: 23.78 mg/1 Fetot. : 0.1523 mg/1 Due to the high concentration of NaC1, the water was very suitable to the production of Fe2+
solution in an electrolytic dissolution reactor. The organic compounds in BFW
may initially cause foaming during EF, which disappeared mostly after some hours of operation.
Iron ion-enriched aqueous solutions were generated using a Miniflot S-200 apparatus, which is a compact and mobile electroflocculation plant. The plant included a feed pump; a pH pre adjustment with automatic HC1 dosing station; an electro flotation reactor with up to 19 iron electrodes, power supply with up to 10 V DC and 100 A and automatic pole reversal capability;
a pH after-adjustment with automatic NaOH dosing station; a filter press feed pump; and a filter press for sludge separation and removal. After setting process parameters, the plant operates automatically.
For the production of enriched Fe2+ solution, the plant was operated in a closed circuit from the feed pump via pH pre-adjustment and reactor tanks to the pH after-adjustment tank back to the feed pump. The dosing pump for NaOH was shut off during this operation. Flow rate was set to 2001/h, and the pH value setting in the feed adjustment was varied from 9.8 (Brackish Water, BW) down to 3. Optimal operating conditions for production of enriched Fe2+
solution with the Miniflot were 100 A and between 4 V and 10 V. These conditions are dependent on the conductivity of feed water and the distance between the iron electrodes. The distance between the electrodes may be equal for all electrode pairs. The Miniflot plant is equipped with 19 positions for electrodes, and the system can therefore hold between 2 and 10 electrode pairs, depending on the conductivity of the water. For example, 10 pairs of electrodes are used in treating water with low conductivity. On the other hand, 2 or 3 pairs are used for water with relatively high conductivity. During testing, 3 to 6 electrode pairs were used. In certain embodiments, an industrial reactor may have one defined set of electrodes, for example. During testing, the number of electrode pairs was varied, as conductivity of feed water changed with pH value and concentration of Fe2+.

Water was pumped directly into the Miniflot. During each test phase, the water remained in the Miniflot in a closed circuit. In total, 3 tests were undertaken; first, a test with BW to find optimal process parameters. Then, a second test with BFW in the same manner as the first test.
In the third test, optimal process parameters from the first test were taken to produce Fe2+
solution in a long-term test run. After finishing a particular Fe2+ enrichment run, about 50 I of solution was removed from all the chambers (pH pre-adjustment, reactor tank and pH after-adjustment tank) into a smaller container and mixed. pH was controlled and the solution was checked for residual flocks and other solid by-products. About 3 I were then filtrated using standard folded fluted filters for use in subsequent lab tests.
In such manner, the following three types of Fe2+ solutions were generated:
I. Brackish Water carrier with an iron content of about 4.8 g/1 soluble iron (first test) 2. Boiler Feed Water carrier with an iron content of about 2.65 WI
3. Brackish Water carrier from long-term run with an iron content of about 3.124 g/1 Most of the remaining water in the Miniflot, as well the water from the small mixing tank, was then transferred into an empty tote for disposal. Total volume of produced enriched water was 145 1 per test.
The Miniflot plant was filled under automatic operating conditions with the appropriate pH
setting in the pH pre-adjustment tank. The reactor plant was set to operate at 10V with increasing amperage as the reactor basin filled up. Once the fill level reached just below the overflow into flock basin B 1.4, the feeding pump was stopped and a direct connection from tank B I .3 to the feed pump was made. This enabled the Miniflot to operate in a closed circuit without activating the filter press stage of the process. At this point, the feed pump was started again and various test runs were commenced under different conditions.
Initially, the first run with Brackish Water was undertaken without any pH adjustment (at pH 9.8).
During testing, pH was decreased gradually until no flocks were observed in the reactor (acidic atmosphere).
All subsequent tests started with parameters obtained on first run with Brackish Water.
The electrodes in the Miniflot are made of black steel without any additives and have the following dimensions: width 0.32 m x height 0.58 m, which corresponds to a surface area of 0.2 m2 and a thickness of 0.01m. Before the start of each test run, the total weight of the electrodes was measured to determine and to compare iron consumption with the analytical data. At the start of the test program, the total weight of electrodes was ¨96.1 kg. During test runs, the distance of separation of the electrodes had to be changed due to changes in conductivity. 4 electrodes were used in some runs, and as many as 7 in others.
At the end of the runs, the final weight was measured to determine iron consumption for all electrodes.
Brackish Water as Carrier:
Brackish Water was pumped into the Miniflot pH pre-adjustment reactor and pH
after-adjustment tanks to overflow level. Dosing pump for NaOH was disabled during all tests.
During the initial few hours of this run with Brackish Water, the pH dosing pump for HCl was also disabled. Due to this, feed water was at first treated without any pH
adjustment.
As the BW was expected to have high conductivity once dissolved iron concentration in the range of about 5 g/1 Fe2+ was reached, only 4 electrodes were installed in the reactor. As a result of this the Miniflot operated at less than full power initially. Amperage increased gradually with increased runtime as conductivity increased due to an increase in dissolved Fe. Eventually flocks appeared on top of the reactor, as solubility of formed Fe(OH)2 was exceeded. In the range of feed pH used, the solubility of Fe(OH)2 is only about 1 ¨2 mg/l. On top of the reactor some Fe(OH)2 flocks may therefore appear. In this area due to direct contact with air, a thin layer of flocks can oxidize into orange-brown Fe2O3 (rust). The pH value was reduced in the feed about every hour based on the assumption that quick test results would confirm increasing concentration of Fe2+ in solution. Operating parameters of the first BW test are shown in Table 1 below:
Operat Total pH Amperage Power Number Fe- Fe Total ing operat feed of conc.. conc. Iron hours ing electrodes total diss, dissol hours mg/1 ved A Ali 1.18 2.18 9.8 44.2 53.3 4 0.47 1.65 3.9 45.6 44.2 4 1 0 2.65 3.5 49.g 483 4 2.0 4.65 8.0 940 746 135 _ LOS. 5.73 7.5 100 128 7 2238 1001 324 2.0 7.23 7.0 100 150 7 1.0 8,73 6.5 100 150 7 2.0 10.73 6.0 100 153 7 2892 2430 419 7.5 18.23 3.0 97 436 4 5218 4990 757 (Table 1: Operating Parameters of the first BW Test) Increase in iron ion concentration in the BW is shown in Figure 13.
Efficiency of iron production varied depending on pH. Efficiency in the transfer of iron into solution was calculated. A standard of 100 % efficiency is defined as the point when all electrons, generated by electricity, transfer into the same amount of valences in the water or into other substances in water. This value is measured using super clean water and standard platinum electrodes. Based on this standard, efficiency curve relative to pH
for BW is given in Figure 14.
Boiler Feed Water as Carrier:
The procedure to pump Boiler Feed Water into the Miniflot was identical to the procedure used with Brackish Water. The plant was ran on the first day with a pH of around 7.5 in the feed (slightly alkaline). On the second day the pH was changed to a slightly acidic condition, i.e. a pH of around 5. During this test run, some optimization testing was performed by varying the time between pole reversals. Some interesting side reactions were observed when Brackish Water was ran and the time of pole reversal varied, and this was followed up during this run.
Here, pole reversal time was initially set to 15 min in the first half of the day and 60 min in the second half of the day.
Tests were carried out with 7 electrodes. A significant amount of foaming was observed at the top of the reactor during the first set of runs of day one. On the second day, foaming was considerably less. Organic compounds in this water were likely responsible for the foaming observed during start-up of the operation in the electrolytic reactor.
Overtime, foaming mostly disappeared.
Main operating parameters are shown in Table 2:
Operati Total pH of Amperage Pole Number Fe- Fe Total rig operat feed revers of conc. conc. Iron hours ing al time electrodes total diss, dissol hours min mg/I mgil ved A
3.5 3.5 7.57.6 73.7 15 7 750 481 109 3.5 7 75-7.6 100 60 7 1247 (401.5) 180 3.5 105 5.0 100 15 7 2812 2563 407 3.5 14 5.0 100 60 7 2645 2297 383 (Table 2: Operational parameters of the second BFW as carrier medium test) Increase in iron concentration during the test as a function of operating time is shown in Figure 15.
A third run investigating Brackish Water as carrier over a long term run was also performed.
During test run 1 with BW, a number of parameters were changed in order to determine optimal operating conditions. The assumption of better results under acidic operating conditions was made. Based on this, the feed water was set to a pH value of about 4. Under these conditions the outlet out of reactor would have a pH value of about 6. Based on solubility data, this pH
level should be sufficiently acidic to keep dissolved iron in solution. Pole reversal time was set to 15 minutes and pH in feed water showed considerable fluctuation due to overdosing with HC1. Start-up and general operation parameters were similar to those of the other runs.
Main operating parameters are shown in Table 3:
Operat Total pH Amperage Power Number Fe- Fe Total ing operat feed of conc. cam, Iron hours ing electrodes total diss. dissol hours mgil mgf I ved A Ni 2.75 235 1.2 100 275 7 1588 1283 230.3 3.0 5.75 3.4 100 300 7 2357 2207 341_8 3.0 8.75 2.9 100 300 7 2565 2427 371.9 3.25 12 3.7 81.6 265.2 4 2817 2601 412.8 4.0 16 2.9 97.6 390 4 1114 3121 199.6 (Table 3: Operational Parameters during the third long term BW run) .. Figure 16 shows increase in iron concentration in BW (long term run with constant parameters).
Increase of iron concentration as well as efficiency was calculated from this data, as shown in Figure 17 (efficiency over operating time). This curve is interesting in that a flattening was observed after the fifth hour of operation.
Side reactions were also investigated. During operation of the Miniflot, green flocks were observed both in the water and on top of the reactor. This is considered normal during most Miniflot operations. These green flocks are the Iron Oxy-hydroxide flocks responsible for absorption of contaminants out of water. They will not appear, as produced iron stays in solution if the pH is maintained at a sufficiently low level (acidic). This normal situation is found, when initial feed pH is about 4 and when it is increased during electrolysis to about 6 (see treatment of BW, optimized run). The specific formula of these green flocks is Fe50(OH)9.
This formula shows that they are a mixture of Fe' and Fe3+ oxy-hydrates. Fe3+
is formed within the water due to oxidation with dissolved oxygen.
These green flocks can form other oxy-hydrates with iron, and can also oxidize in the presence of air to an orange-brown iron oxy-hydrate Fe(OH)2Fe0(OH), which is a pre-product of rust (Fe2O3). This pre-product of rust does not disturb the dissolution of iron or the water treatment process using electro flotation.
A black coating on some of the electrodes was also observed after the process was stopped.
This coating was relatively easy to remove (with light rinse and light brushing). It mostly disappeared when a pole reversal was applied at a frequency of 15 minutes.
Using this frequency, the process was not affected by this coating. Although not directly measured, it appeared that there was, at least qualitatively, no impact on efficiency. This black material consists mostly of Magnetite, with the compositional formula of Fe2+(Fe3+)204, i.e. a mixture of Fe2+ and Fe3+ and oxide compound.
Storage of Enriched Fe Solutions:
After completing each of the test runs, the water was drained out of all 3 working chambers of the Miniflot (i.e. pH pre-adjustment, reactor, after-adjustment tanks). The water was mixed and filtered using a fluted paper filter. The residue remaining in the fluted filters was identified as Fe2O3. A sample was taken for analysis to determine the amount of total and dissolved Iron in the filtrate. The values from these analyses were identical to those taken directly out of the Miniflot. Samples were stored in closed glass bottles.
After at least a week, the stored Fe solutions were checked for degradation and decomposition.
BW Fe solution was then used to measure the titration curve and the behavior of the solution.
The titration curve is shown in Figure 18. The behavior exhibited by the titration curve was absolutely normal. It is a standard "typical" curve that represents the behavior of the Fe2+
solution across a pH range. It basically shows that Fe2+ is being dealt with and not with Fe3+, showing product stability. During flocking, flocks always appear green, as expected, and flocks become denser with time. Filtrate after filtering Fe solution at a pH of 10 confirmed that no iron was present.

Overall, iron ion-enriched aqueous solutions were successfully prepared by electroflocculation both Brackish Water and Boiler Feed Water, and prepared solutions were generally stable for storage. Such iron ion-enriched aqueous solutions were next investigated for water treatment by flocculation.
Results indicate that iron-enriched solutions could be produced using electrolysis of, for example, brackish water (BW) or boiler feed water (BFW). By way of example, studies indicate that even enriched Fe2+ solutions of about 5 g Fe2 /1, or more, may be produced in this manner.
With BW a concentration of almost 5 g/1 was obtained, and with BFW a value of about 2.5 g/1 was reached. These values were not maximum values, but rather represent concentrations reached by the time the reactor was stopped. Best results during operation were achieved when the carrier solution had a pH of about 5 at the input stage of the reactor.
Under these operating conditions the solution leaving the reactor had a pH of 6 ¨7. pH of the product Fe concentrate was not higher than 7, as solubility equilibrium of Fe2+ /Fe(OH)2 at this pH
value is given at 7.6 g Fe2+ in literature. Under these conditions the efficiency of the process is about 60 to 70 % and there was no need to handle any high acid or caustic streams. The efficiency is defined as the ratio of direct energy input (in kWh/h) versus production of dissolved Fe2+ (in g/h). The produced Fe solution stayed relatively stable and did not change in composition over the course of the experiments. This was tested and confirmed with a titration curve.
Thus, enriched Fe2+ solutions may be produced using electrolysis within an electro-flotation .. circuit, for example. For water treatment testing, solutions having Fe2+
concentration of about 40-50mg/1, and those as low as 30mg/1, were prepared and used.
EXAMPLE 2: Introduction of Iron Ion-Enriched Aqueous Solutions for Flocculation of Contaminated Water Tests were performed to investigate flocking in Skim Tank Water (STW) contaminated water sample following introduction of iron ion-enriched solutions such as those generated in Example 1 above. Studies sought to investigate the lower limits of Fe2+
concentration in the main stream STW to demonstrate flocking, and to reduce SiO2, oil and grease and hardness.
Tests were prepared and undertaken under normal operating conditions using STW.

Skim Tank Water was used as a process water to be treated.
Pre-treatment compositional analysis showed an unusually high content of SiO2 in the STW
sample, and as a result of this, a second sample of STW, was also tested.
Characteristics of both STW's are as follows:
Parameter Sample 1 Sample 2 co lor murky, dark grey/green Light grey-brown pH 7.1 6.75 Conductivity in ms/cm 2.92 2.915 5102 in mg/I 4D0 300 TOC total in me 357.6 502.3 DOC in mg/I 349.7 394.9 Oil greae 191.2 141.6 Fe, in mg/ 11152 1.326*
(Table 4: STW Sample Characteristics) While such an approach was of interest because it was hypothesized that the contaminated water could be maintained at high temperature and pressure, and because the iron ion-enriched aqueous solution was separately prepared and introduced into the contaminated water, results of these studies indicated that suitable water treatment and contaminant removal was not achieved in this contaminated water. STW produced water was not effectively flocculated following injection of Fe' solution separately produced by electrolytic iron dissolution using an EF reactor, since unforeseen difficulties were encountered. It was hypothesized that one or more unknown contaminants, perhaps one or more organics of unknown composition and origin, were interfering with flocculation-based contaminant removal from the water sample.
During this test phase, about 3 1 of Skim Tank Water was added to each of 5 glass bottles. Into each of these bottles was then added a certain amount of Fe" solution (concentrate) based on the original concentration of the Fe" solution and the desired Fe"
concentration in each of the test bottles. Fe" concentrations of 25, 50, 75, 100 and 125 mg Fell within each of the test bottles were tested. It was observed that these tests could not be carried out using the Skim Tank Water. After pH adjustment for testing, STW turned red and no flocks were observed.

The lab equipment included 1 gallon (4 liter) glass bottles, each with a magnetic stirrer. The general procedure for a set of tests was as follows:
A volume of about 20 liters of Skim Tank Water (STW) was conditioned and prepared for testing by adjusting the pH to 9.5. This pH adjusted STW was then used to fill 1 gallon glass bottles to a level of 3 liters. Various amounts of enriched Fe" solution from tests with brackish water (BW) and boiler feed water (BFW) as carrier water were added to each of the bottles, so that Fe" concentration in the bottles varied from 25 mg/1, 50 mg/1, 75 mg/1 to 100 mg/I. The exact dissolved Fe2+ concentration in BF and BFW carrier water was respectively 4,806 mg/I
and 2,645 mg/I, measured after completing the Fe" enrichment runs. It was assumed that the pH stayed about the same after addition of Fe" solution since only very small volumes were added to each bottle. After the addition of Fe' solution, the content of each bottle was mixed for 20 seconds. Mixing was stopped and the formation of flocks and their precipitation was observed and documented.
During these tests, it was found that the color of Skim Tank Water turned a red-black and this made observation very difficult. Re-tests in small beakers showed absolutely no flocking. Tests with BFW water did show flocks after 2 days of storage, which was more in line with initial expectations. When these tests were repeated with BFW after 2 days of storage, however, it was found to be impossible to re-create flocks (in BFW).
Indeed, flocculation lab tests using enriched Fe" solution were undertaken by adding enriched Fe" solution to a number of water samples, including STW and BFW in its un-adjusted pH
state and then adjusting the pH to around 9.5, where optimum flocculation was expected. Flock development was not observed in these tests. When Fe" solution was added to BFW and STW
at a pH of 7, and then at a pH of 9.5, even less flocking was observed at the higher pH. This was consistent, since at lower pH more Fe' was in solution for flocking.
As described, the results of these studies were unexpected. None of the tested STW samples showed flocking when using the Fe' solutions. Instead of flocking, the color of STW turned from grey-brown to red-black under alkaline conditions. No flocks appeared, but a minor amount of very small, black, and unfilterable particles were observed.
As a comparator, STW was treated using an EF lab unit. The EF lab unit comprised a small EF
reactor with a total volume of about 3.8 1 as well as a power supply rated at 20 V, 10 A. The higher voltage with the power supply of the lab unit compensated for different conductivities in test water. It did not affect the treatment results as this is dependent on the amperage (constant 10 V DC). A laboratory hose pump was used to fill the reactor and to provide a circular flow. After treatment, the water was pumped out of the reactor for further treatment, i.e. pH after-adjustment and filtration. Flocculation using the EF lab unit was confirmed.
Again, studies were undertaken to repeat flocking tests with Fe" solutions.
Five different concentrations of Fe" solutions for adding Fe' to STW under different pH
conditions were used. The flocking pH used in all cases was 9.5 or a bit higher. This was tested on STW and BFW, as well as demineralized water, drinking water and oil/water emulsion.
Results are shown in Table 5. Normal flocking behavior was observed in some of the tested samples, but no flocking was observed in BFW and STW samples at pH 7. Almost no flocking was observed at pH 9. This indicated that with the addition of Fe" solution, better flocking was observed at low pH value. At lower pH there is a higher amount of dissolved iron that is available for flocking. No flocking at all was observed with BFW and STW.
Test no pH Amount pH re- Appearance pH after NaOH
pH atter Appearance of re in solutio after addition addition dosing dosing after pH
sample n adjustment I. Tests with de.
mineralize tt Water 1õ1 6.49 1E0 70 Evean szakx 593 9.8 53385

11

12 6.49 150 7.7 Dnyeal, 311W.y 5.16 955

13,65,ex:en floats 6.49 110 2.2 r3r1wn. 55818,y 553 9.53 BlaVtir:
gmen 52285. bad 2 6.49 150 95 Brown, 81,3115 5.51 ? 19.25 Brawe .7555 115282:, 52*
.L Test with drinking water 21 8.1 150 70 Brewnlreen. 7.22 = 19.09 Brewn weer, =IT
22 8.1 150 7' 797 941 Urepsr 8ree6 2.3 41 150 412 7.81 9.7 2.2 2.1 150 9 5 G 9 13 E8836, 06:
1 Test with emulsion 3.1 9.62 1E0 Gieenitecit5 542 it, .. Greenwinde Mite Walw 45, 32 9.62 150 7.7 Green fledc2, .. 8.73 .. 955 width walw 19*82, 5 why .2w5, 3) 96* 15.0 l2 Green 41ecks 5.61 9.62 Gf-en.,n8e v2512, kame, 5625, 586.4,y 34 9.52 1E0 95 1192 921 le ',vale-, water 4. Test with BM

4,1 9.4 150 771 Srree sfro0 fI,71 5h74 &eel Neck S1E:sok flocSss .õõ
4,2 9.271 150 7,7 flame sterSi 9,46 9..46 Sun' L,ICe Siam aRCS:f:
11r 4,1 9.4 150 42 Semester:I 954 54434 Stre4 btack UTt slaOk flocks 4,4 9.271 150 9,5 Seem solti CIA 171 16 Small temJr time flocks ik,:etnetts 5. Test %vile sriv 13.1 7.47 150 74) Sone env 6.69 9.64 ::;rseell s 44d Jr flcsks [L.. s, ': 10,1e 5.2 7,47 150 77 Scne err? mail 7.15 9 7 Small bin*
Neck flocks 5:3 7.47 150 517 S:sne very Mel 7,9 9.8 Srr Itons õate 5,4 7.7 150 9,5 Ssyne g = 9,4 s slack flusks onflflerabk (Table 5: Flock Tests with different waters using Fe2+ solution) Tests were next performed using electroflocculation (via the EF test unit) in combination with iron ion-enriched solution. About 3.81 of STW were used to fill the reactor to its capacity and the unit was then operated without pH adjustment. The operating procedure was then undertaken with different concentrations of Fe in steps. About 80 mg/1 Fe was used to start, and increased up to 160 mg/1 Fe. The treated water was then pH adjusted to about 9.5 using NaOH and then set on the laboratory table for observation of flocking and of sedimentation.
As the SiO2 content in STW was unusual high, a second set of test runs were undertaken with diluted STW (50 % STW, 50% drinking water). This took SiO2 content to about 200 mg/l. The second set of tests were carried out in the same way as the first, but iron concentration started at 30 mg/1. Results are shown in Table 6:

Reaction Fe content pH after EF pH after adj., Visual result time min mel 51W pure 0 0 6,95 7 84.1 7.26 9.68 no visual flocking 8 96.1 7.33 9.91 no visual flocking 9 108.1 7.56 9.54 first sedimentation 120.1 6..95 9.94 good tlocks/sedimentation 11 132.2 7.96 9.47 good flocks/sedimentation 12 144.2 8.2 10.03 good flocks/sedimentation 13 156.2 8.35 10,12 good flocks/sedimentation 51W5050) 5 30.0 10.21 good flocks/sedimentation 6 36.0 10.26 good flocks/sedimentation 7 42.0 9.94 good flocks/sedimentation 8 48.0 9.5 good flocks/sedimentation (Table 6: Optimization of iron content for flocking using EF lab unit) Treatment results during addition of Fe2+ are shown in Table 7, and EF
flocking results using a further sample of STW are shown in Table 8:

Conc. of iron Iron in Hardness Si01 Oil+grease -- TOC --DOC
during product treatment mgil mg/I mg/P mel mg/1 m8/I meil STW 0 0.88 7,54 400 191.2 357.6 349.7 Feed 72.1 19.69 6.14 100 22.10 227.7 232 132,2 0.702 5.59 20 20.77 176 177 STW 0 0.44 40 200 96 178 175 (50;41) 18 2.97 39.14 50 11.31 97.15 94.93 36 0.394 29.58 10 10.53 78.25 80.71 (Table 7: Treatment results for EF plus iron ion-enriched solution) Reaction Fe - content pH after EF pH after-adj. Visual result time min mai STW pure 06,05.2016 0 6.98 2 24.0 7.10 9.68 no visual flocking 3 36.1 7.18 9.91 first sedimentation 4 48.1 7.3 954 good fiocksisedi mentation 60.2 7.41 9.94 good flocks/sedimentation 6 72.2 7.5 9_47 good floirksJsedimentation (Table 8: Treatment results for EF plus iron ion-enriched solution on additional STW sample) Thus, STW did not flock using Fe2tenriched solutions, but did flock when EF
was applied.
5 EXAMPLE 3 ¨ Investigating Flock-Supressing Compounds It was hypothesized that the one or more unknown contaminants interfering with flocculation-based contaminant removal in Example 2 could be destroyed prior to flocculation, thereby allowing for contaminant removal. It was suspected that an organic substance in STW may be blocking the formation of flocks. It was hypothesized that some organic complex such as organic thiocyanate or a similar compound might be to blame. Investigations began by treating a small volume of STW with an ECU lab unit to effectively destroy organics in STW. After this treatment, it was hypothesized that flocking could again be possible.
A small ECU lab test unit was utilized. The system was basically a simple ECU
lab test unit, designed for qualitative testing. It included a power supply (same as that used for the EF lab test unit), a specialized set of electrodes, a magnetic stirrer, and a laboratory beaker. The ECO
lab test unit determined whether a wet oxidation process based on ECU can remove soluble organics, bacteria and other organic carbon containing compounds. Given the unexpected observations described above made during flocking tests with STW and BFW, the ECU unit was used to investigate the behavior of production water treated by hydroxyl radicals generated by ECU. Specifically, the aim was to destroy certain organics in Skim Tank Water prior to re-testing for flocking with Fe concentrate solution.
Results indicated that the ECU treated STW sample, after addition of Fe2+
solution and pH

adjustment, showed good flocks, supporting a hypothesis that an organic compound may be to blame for inhibiting flocculation. During ECO operation, TOC was reduced from 357.6 mg/I
to 41.09 mg/1 (DOC from 349.7 to 40.64). These results, in which ECO destroyed of about 90% of organics, support a hypothesis that one or more organic compounds in BFW and STW
may be preventing Fe flocking.
Experiments thus indicated that a pre-treatment step employing ECO to treat the contaminated produced water prior to iron flocculation via injection of a separately produced iron ion-enriched solution was able rescue flocculation and provide for contaminant removal. It was hypothesized that ECO oxidized soluble organics, perhaps including the one or more compounds interfering with the flocculation, using highly reactive hydroxyl radicals generated at the electrodes.
Dilution experiments, in which STW and BFW samples were diluted with demineralized water, indicated that the concentration of the inhibitory compound(s) which prevented iron flocking were generally present in lower concentration in BFW versus STW. Furthermore, comparing two different STW samples indicated that one contained about twice the concentration relative to the other. When STW and BFW were first diluted, and the 8mL of BW-based Fe2+ solution (5g/1) was added, good flocking was observed when STW and BFW was sufficiently diluted (i.e. between about 1:4 and about 1:10 depending on the sample.
A variety of typical oil field additives were also tested to determine whether they inhibit Fe flocculation. Tested additives included Petrolite RBW987; Petrolite DM08648;
Petrolite RBW747; BPW 76325; Bulab 5901; Bulab 9773; and Bulab 9567. None were identified as candidates for inhibiting iron flocculation.
Further, BFW and STW samples did not contain thiocyanate (or levels were below detection limits), and so this was unlikely to be the inhibitor.
.. In presence of the inhibiting compound(s), results indicated that, instead of producing the expected Fe(OH)2 flocks, a new compound was formed, which contains the iron produced (Fe2+
and/or Fe3+), has a red color, and is soluble in water. It is formed at pH
values that are higher than 8 and it also remains soluble under caustic conditions. The inhibitor(s) were not present in brackish water that was tested.

The identity of the contaminant(s) inhibiting flocculation remains unknown.
However, it was identified that ECO treatment was able to destroy, degrade, remove, inactivate, or otherwise inhibit the inhibiting contaminant(s), restoring flocculation following addition of iron ion-enriched aqueous solution.
EXAMPLE 4A ¨ Electroreduction, Followed by Injection of an Iron Ion-Enriched Aqueous Solution for Flocculation of Contaminated Water, the Iron Ion-Enriched Aqueous Solution Being Pre-Made Experiments were performed to further investigate the nature of the inhibiting contaminant(s), and more importantly to identify further options for destroying or inactivating these inhibiting contaminant(s) which would be compatible with high temperature and high pressure operation, and which would facilitate the flocculating ion-enriched aqueous solution injection approaches detailed herein.
As discussed in Example 2, electro-chemical oxidation (ECO) rescued treatment of STW by iron flocculation via injection of a separately produced iron ion-enriched solution, providing for contaminant removal. While the identity of the inhibiting contaminant(s) was not determined, it was hypothesized that it might be possible to destroy/inactivate/remove these inhibiting contaminants using other treatments. In particular, studies were performed to investigate whether electrolytic reduction could abrogate the inhibiting effects of the contaminant(s). Further, studies were performed in particular to determine whether electrolytic reduction using non-consumptive electrodes could be used, since non-consumptive electrodes may allow for reduced maintenance and upkeep demands as compared to consumptive electrodes.
A test system was established using non-consumptive electrodes made of graphite or titanium (instead of iron), mounted in an electro-flotation reactor. Studies were performed to determine whether non-consumptive electrodes can be used to create an electrolytic reduction reaction that destroys/inactivates/removes the inhibiting compound(s), thereby permitting flocculation by direct injection of Fe2tenriched solution.
The lab unit included a small reactor that can hold a volume of 2.6 to 3.4 1 (depending on the type of electrodes used). It ran on a power supply rated at 20 V, 10 A. The higher voltage available with the power supply of the lab unit compensated for different conductivities found in test waters. This did not affect the treatment results, as these depend on the amperage (constant 10 V DC). A laboratory hose pump is used to fill the reactor and to provide a circular flow. After treatment, the water was pumped out of the reactor for further treatment, i.e. pH
after-adjustment and filtration. The apparatus used titanium electrodes to treat ORF outlet water. A Miniflot setup was further utilized, the Miniflot being a compact, mobile, and fully equipped electro-flotation plant, normally used for electro -flotation treatment of waste water.
The equipment configuration can be altered to permit other electrolytic processes, as used in the production of enriched Fe' solution (see Example 1) and electro-chemical reduction processes using different electrodes than those normally used in electro-flotation. Maximum process flow rate was 2001/h. The plant included the following process steps:
pH-adjustment;
electrolytic reactor with up to 19 electrodes including power supply and pole reversal capability; pH after-adjustment; optional capability of polymer dosing; filter press with pump for flock separation; transfer pump for filtrate; and control board for manual or for automatic operation.
Graphite Electrodes: Graphite plates installed in the lab unit and the Miniflot were of a composition normally used for applications such as heating elements, although graphite plates typically used for water treatment are also contemplated.
Main specifications of the graphite used are:
Specific resistivity: 13 plIm Thermal conductivity: 104 W/mK
Shore hardness: 56 Graphite electrodes used in the lab test unit had a thickness of 10 mm, and a total area of 138 cm2. This correspond to a maximum specific amperage of 0.2 mA/cm2, which is far below the limits. Tests were carried out with sets of 2, 3 and 4 electrodes. The Miniflot plant was equipped with 10 graphite electrodes of same quality, but a thickness of 20 mm. Main dimension were:
Width: 30 cm, height: 54 cm, area per electrode: 1,620 cm2, specific amperage:
0.2 mA/cm2.
The total reactor volume using graphite electrodes was 52.2 1, and the actual reaction volume for process water was up to 36.45 I once the electrodes were taken into account. After use, no coating, fouling or other signs of corrosion were observed on the electrode surface. Electrodes looked as new or unused (white spots at the bottom were caused by dried foam).
Titanium Electrodes: Titanium electrodes had the following composition: 90 %
titanium, 4%
vanadium, 6 % aluminum. This type of alloy is generally produced for the aircraft industry.
Thickness of the titanium plates used for both the lab unit and Miniflot was 2 mm. In general, titanium has good resistance to acids, caustics, and chlorine containing fluids, etc. It is normally resistant to corrosion. Dimensions of the Ti electrodes for lab test unit were 11.5 x 14 cm with an area of 161 cm2. Specific amperage was 0.39 mA/cm2, slightly higher than with graphite electrodes. After use, some coating on the positive electrodes was observed.
The titanium electrodes for the Miniflot were of the same alloy composition as for the lab unit. The dimensions were 58 cm x 30 cm with an area of 1,740 cm2. Specific amperage using 10 electrodes was about 0.1mA/cm2, which was considered to be near ideal. The rectifier power supply for the Miniflot delivered 10 V DC with 100 A. The amperage could decrease during operation if the distance of the electrodes was too great for the conductivity of the water to be treated. The total volume of the reactor using titanium electrodes was greater than when using graphite electrodes because of the thinness of the titanium plates compared to graphite. Total reactor volume was 62.4 1, and the effective reaction volume 45.6 1.
After the tests were completed, electrodes were taken out of the reactor for inspection. Titanium electrodes looked worn and showed a high degree of pitting corrosion on the surface, which was not expected. The electrode surface not immersed in process water during operation was not affected by corrosion and was clean.
Runs on lab test unit with graphite and titanium electrodes The lab unit was used to carry out initial and general tests to observe the behavior of graphite and titanium electrodes in the electrolytic process. Test runs with the lab test unit took about one hour (excluding final laboratory work). Miniflot, test runs took up to four hours, due to the time spent reaching operating equilibrium.
Tests were focused on investigating whether electrolysis process using graphite or titanium electrodes could be used to destroy the inhibiting compound(s), thereby permitting flocking by direct injection of Fe2+ solution. In addition to this, the following parameters were investigated:

pH value for treatment;
pH trend during treatment;
voltage for treatment;
amperage for treatment; and distance of electrode separation.
The data was used to calculate the set up for the Miniflot, as well as to determine main process parameters, such as pH for treatment. The data gave an initial idea on reaction time, to permit an adjustment to flow rate in the Miniflot, as well as on the amount of Fe' solution for forming flocks. During tests, no coating on the electrode surface or other unusual behavior of electrodes was observed. Tests performed are shown in Table 9.
Test nr Water Electrode Test purpose treated material LGr 1 ORF(FC) Reference test LGr 2 ORF(FC) Graphite Basic test, settings: 20 V, 30 min LGr 3 ORF(FC) Graphite Like basic test, but only half amperage, 20 V, 30 min LGr 4 ORF(FC) Graphite Like basic test, but pH changed into caustic conditions LGr 5 ORF(FC) Graphite Like basic test, but add Fe-solution before treatment LGr 6 ORF(FC) Graphite Like basic test, but 10 V instead of 20 V
(like Miniflot) LGr 7 ORF(FC) Graphite Like LGr 6, but measuring pH trend LGr 8 STVV(FC) Graphite Like basic test, treatment of STW (FC) LGr 9 STW(CL) Graphite Like basic test, treatment of STW (CL) LGr 10 ORF(CL) Graphite Like basic test, treatment of ORF (CL) LGr 11 ORF(FC) Graphite Like basic test, production of samples for laboratory LTi 1 ORF(FC) Titanium Basic test, settings: 20 V, 30 min LTi 2 ORF(FC) Titanium Like basic test, but pH changed into caustic conditions LTi 3 ORF(FC) Titanium Like basic test, but 10 V instead of 20 V (like Miniflot) LTi 4 ORF(FC) Titanium Like 3, but flock test LTi 5 ORF(FC) Titanium Like LTi 4, but measuring pH trend LTi 6 ORF(FC) Titanium Like basic test, to measure reaction time (Table 9: Tests performed using the Lab Unit) Runs on Miniflot The Miniflot plant can run automatically after setting all operating parameters i.e. flow rate, pH, dosing rate, etc. In this case the adaption of the system was undertaken in two steps, due to the presence of a relatively high amount of H2S. H2S will form FeS in the presence of Fe2+
immediately, based on a solubility product of 10-19 mo12/12 (The solubility product of Fe(OH)2 is with 1045 mo13/13, much higher). This FeS forms black virtually unfilterable flocks. Only in the presence of Fe(OH)2 can this be filtered. The consequence of this is a higher consumption of Fe2+ solution.
First Step: Miniflot was run with the following process steps: Transfer of feed water using feeding pump into reactor - pH adjustment chamber (but without pH pre-adjustment) - gravity drain, final drain with drain pump into waste container. In the outlet of the reactor a small sampling system was installed, allowing samples to be taken directly and conveniently during the test run without having to stop the process. The samples were then treated with different concentrations of Fe2+, use of polymer, etc.
Second Step: Miniflot was run with the complete process step: Transfer of feed water using feed pump into reactor, pH adjustment chamber, dosing of Fe2+ solution, pH
adjustment to 9.5, drain, and finally, drain pump into the waste container. Samples for filtration at the laboratory were taken at the drain.
Tests performed are shown in Table 10.
Test nr Water Electrode Test purpose*
treated material MGr 1 ORF(FC) Graphite Test full process, 92 l/h, 130 mg/I Fe, flock tests etc, MGr 2 ORF(FC) Graphite Reactor only, 92 l/h, tests 125 mg/ - 300 mg/I, sampling MGr 3 ORF(FC) Graphite Reactor only, 2311/h, tests 100 mg/ - 225 mg/I, sampling MGr 4 ORF(FC) Graphite Reactor only, 3081/h, tests 100 mg/ - 250 mg/I, polym., sampling MGr 5 ORF(FC) Graphite Reactor only, 1541/h, tests 100 mg/ - 250 mg/I, polym., sampling MGr 6 ORF(FC) Graphite Reactor only, determination of reaction time MGr 7 ORF(FC) Graphite Full process, 921/h, 100 mg/I Fe, polym., sampling MGr 8 ORF(FC) Graphite Full process, 3081/h, 130 mg/1 Fe, polym., sampling MGr 9 ORF(FC) Graphite Full process, 921/h, scay., 130 mg/1 Fe, polym., sampling MGr10 ORF(FC) Graphite Full process, 92 l/h, scay., 25 - 150 mg/1 Fe, polym., sampling MTi 1 ORF(FC) Titanium Reactor only, 921/h, tests 25 mg/ - 175 mg/1 Fe, polym., sampling MTi 2 ORF(FC) Titanium Reactor only, 60 l/h, tests 50 + 100 nnel Fe, polym., sampling MTi 3 ORF(FC) Titanium Reactor only, 60 l/h, scay., tests 50 + 100 mg/1 Fe, polym., sampling MTi 4 ORF(FC) Titanium Full process, 60 l/h, scay., 50 mg/1 Fe, polym., sampling MTi 5 ORF(FC) Titanium Full process, 60 l/h, 50 mg/I Fe, polym., sampling MTi 6 ORF(FC) Titanium Full process, 162 l/h, scay., 50 mg/1 Fe, polym., sampling MTi 7 ORF(FC) Titanium Full process,1621/h, 50 mg/1 Fe, polym., sampling * Remark: All concentrations are based on calculations, analytical data (Table 10: Tests performed using the Miniflot Unit) Production of Fe2+ Solution:
Fe2+ solution for step 2 of the Miniflot tests was produced by electrolysis using the Miniflot with iron electrodes. Final Fe2+ concentration was measured at between 4 and 5 WI. Carrier water used to generate the =Fe2+ was BW, which is generally used as technical water, i.e. for dilution of chemicals, etc. The process of generating Fe2+ concentrate by this method was tested successfully and confirmed in Example I.
Using Miniflot and BW, about 100 1 of Fe2+ solution was generated with a concentration of dissolved Fe2+ of about 4 g/1. For lab tests we also used some of the previously generated Fe2+
solution. This solution had a concentration of 4.5 g Fe2+ /I.
Table 11 shows dosing of Fe2+ solution in Miniflot as a function of flow rate and concentration.
This data was used to set flow parameters of the Miniflot. For example, at a flow rate of 1001/h, and a desired Fe2+ concentration of 100 mg/I, dosing pump may be set to 2.5 1/h.

flow rate conc. Fe desired Fe amount of solution conc. Fe sol.
l/h g/I mg/I l/h 60 3.98 100 1.5 60 3.98 125 1.9 60 3.98 150 2.3 60 3.98 175 2.6 60 3.98 200 3.0 100 3.98 100 2.5 100 3.98 125 3.1 100 3.98 150 3.8 100 3.98 175 4.4 100 3.98 200 5.0 150 3.98 100 3.8 150 3.98 125 4.7 150 3.98 150 5.7 150 3.98 175 6.6 150 3.98 200 7.5 200 3.98 100 5.0 200 3.98 125 6.3 200 3.98 150 7.5 200 3.98 175 8.8 200 3.98 200 10.1 (Table 11: Dosing of Fe2+ solution in Miniflot as a function of flow rate and concentration) Characteristics of treated and untreated water:
The following SAGD process waters were used:
= Brackish Water (BW): Brackish water was used as carrier for Fe2+ solution only.

= Oil Removal Filter Outlet (ORF) water: Main tests were carried out using ORF Outlet water.
In total, 6 totes were used to operate lab unit and Miniflot test runs.
= Skim Tank Water (STW): About 20 1 of STW were provided for bench scale tests.
= Skim Tank water (STW) from a second source: About 20 1 of STW from a second source were provided for bench scale tests.
= Oil Removal Filter Outlet (ORF) from a second source: About 20 1 of ORF
from a second source were provided for bench scale tests.
Initial analytical data on input feed waters BW, and ORF and STW from the first source are shown in Table 12:
Type pH Con Ca Mg Fe Hard- Silica TOC DOC Oil+ H2S
of water duc ness grease tivity mS/cm mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I
BW 9.87 11.6 <2 <2 <0.1 <10 n.d. <0.05 n.d. <5 n.d.
(9.58) (12.42) (0.24) (0.12) (0.20) (1.11) (10) (8.371) (3.289) (b.d.) (n.d.) ORF 7.28 2.9 4.6 0.6 <0.02 14 n.d. 500 n.d. 17 30 (7.53) (2.801) (3.0) (0.31) (0.60) (8.75) (260) (646.3) (488.8) (50.5) (n.d.) STW 7.33 2.95 3.4 <0.4 0.02 8.4 n.d. 476 n.d. 21 n.d.
(7.12) (2.830) (2.89) (0.38) (0.20) (8.79) (265) (488.3) (432.9) (29.5) (n.d.) Remarks: n.d.: not detected .. b.d.: below detection limit (Table 12: Analytical data of selected untreated waters) Reference Testing:
As described in the Examples above, no flocking was observed in STW after addition of Fe2+

solution and pH adjustment. Color of the treated water after addition of Fe"
solution turned red-black, and no flocking was observed. On the other hand, tests using electro-flotation with iron electrodes achieved separation by formation of flocks. For base reference and prior to the scheduled tests and trials, the following two reference tests were performed:
1. After taking a small sample of ORF into a beaker, Fe" solution was added to a concentration of about 150 mg/1 and the solution was adjusted to a pH of 9.5 using NaOH. The water turned immediately black and no flocks were observed. This supports previous Example results.
The same feed water was treated on the following day with the lab unit, but this time the feed water was treated with graphite electrodes first and Fe' solution was added after treatment.
Flocking and precipitation was observed immediately. This test showed that electroreduction treatment with non-consumptive graphite electrodes and Fe' solution functions to destroy/inactivate/remove the inhibitory compound(s) which otherwise prohibit formation of flocks.
2. After production of Fe" solution, the Miniflot was cleaned and the plant was operated with Fe electrodes to treat ORF. This reference test indicated that previous results could be replicated with the feed water used in the subsequent testing of this Example.
Flocculation Testing using the Lab Unit and ORF Outlet Water Tests were carried out to observe the general behavior of graphite electrodes, and the ability to create flocks using these electrodes after addition of Fe" solutions.
Tests with Graphite electrodes:
Basic parameters were defined as dependent on a relationship between amperage and voltage, electrode separation, and conductivity. These values, and the calculated specific amperage in mA/cm2, were used to calculate the electrode set-up. The dependency for ORF
outlet with a conductivity of 2.8 mS/cm is given in Figure 19. Miniflot normally operates at a maximum voltage of 10 V. At this voltage, the separation of electrodes should be such as to permit total amperage of about 100 A. Using 10 V values and an active area of 414 cm2 in the lab unit, the separation of 10 electrodes in the Miniflot was calculated to be about 25 mm to reach 100 A.

Later test showed operating values between 96 and 100 A, which was consistent and supports the calculation.
Tests with treatment time or residence time as a variable:
The lab unit was operated at 10 V and about 4.5 A for a period of approximately 30 minutes.
Samples were taken after 15 and 30 minutes. These samples were then injected with Fe2+
solution of 150 mg Fe2+/1 and pH adjusted. In both cases, good flocks were observed. This suggests that reaction time may be less than 15 min in these studies. Using the Miniflot, reaction time to destroy the inhibiting compound(s) was observed to be relatively fast, i.e. less than one minute with graphite electrodes.
Tests with pH as a variable:
Two different test runs were carried out with the lab unit to investigate the pH parameter. In the first run the behavior of the process with different pH-values with ORF
outlet water was tested before treatment (pH 6.4 ¨ as delivered- and adjusted to 8.5). In the second test the trend of the pH-values during treatment was measured. Every minute a small sample was taken for measurement. The first runs with two different feed pH values showed no observable difference. Good flocking was observed with both runs and, as a result of this, ORF outlet water was treated without any pH adjustment in the feed. Trend of pH during treatment of ORF outlet water is shown in Figure 20 (pH of ORF changed during storage period from 6.4 to 7.3).
Values from test runs indicated three different phases during reaction:
Treatment time up to 2 mins (first degradation); Treatment time of 3-4 mins operating time (second degradation or result of first degradation); and Treatment time after 4 mins (typical behavior of water electrolysis reaction). These results suggest that an initial reaction takes place within the first 2 minutes and another reaction after 3 ¨4 minutes.
At the end of these tests, and after Fe' addition and pH after-adjustment, good flocks were observed.
Tests with voltage as a variable:
Most tests were run with 20 V to apply a high amperage at this operating voltage. In addition, tests with 10 V were carried out to confirm treatment possibilities using Miniflot (10 V, as a dependency of voltage in treatment of organics could not be excluded). Figure 21 shows the dependency of amperage to change in voltage in these studies. 10 V values were used to calculate Miniflot operation. The data suggests that low amperage is sufficient to destroy the inhibiting compound(s). All tests showed good flock development and precipitation.
Flocculation Testing using the Miniflot and ORE Outlet Water Lab unit tests suggested an initial Miniflot electrode separation of 25mm.
Runs were undertaken without pH pre-adjustment, even if pH of stored waters showed changed over time.
Miniflot tests could run at flow rates between 60 1/h up to 2001/h. Earlier lab tests suggested a fast reaction time, and hence a low residence time in the reactor. Initial Miniflot tests were conducted using only the reactor, without dosing with Fe" solution and without pH after-adjustment. Sampling occurred directly at the reactor outlet. Samples were then tested for flocking using different amounts of Fe' solution (representing different Fe' concentrations in the processed water).
After having identified an optimal Fe" concentrations for the Miniflot, a complete demonstration run of the entire process was undertaken with both graphite and titanium electrodes, Fe" solution dosing and pH after-adjustment. Samples were taken at the drain of the flock basin.
Tests with titanium and graphite electrodes:
Graphite and titanium runs were performed to compare the behavior of each of the electrodes, their comparative ability to destroy the inhibiting compound(s), the cost, and overall relative advantages and disadvantages of using graphite and titanium.
Tests with treatment time or residence time as a variable:
Reaction time using graphite electrodes was less than one minute. Taking this into account, when running the lab unit with titanium electrodes, operation was initially for two minutes. At the end of the first minute, the first sample was taken, and at the end of the second minute the second sample was taken. Voltage was 20 V, amperage was about 17 A in the first minute, 10 A during the second minute (reduced amperage was caused by a reduced fluid level in lab unit after removal of the first sample). The first sample was then injected with Fe" solution and pH adjusted. The sample turned black and showed no flocks. The second sample, after similar treatment, showed good flocks and good precipitation. These results indicated that titanium electrodes had a reaction time somewhat higher than graphite electrodes.
Tests with pH as a variable:
The trend of pH-values during treatment with titanium electrodes was also measured. Every minute a small sample was taken for pH measurement. Figure 22 shows the trend in change of pH over treatment time for titanium electrodes and, for comparison, the trend for graphite electrodes. Titanium and graphite electrodes showed completely different behavior when treating ORF water. There was no indication of several reactions at the electrode surface with titanium electrodes. On the other hand, pH trend with graphite electrodes does show several reactions, i.e. see minute 1-3, then minute 4-5, and finally more normal behavior after minute 5. During the tests with titanium electrodes, the surface of the +ve electrode became coated, and some suspended solids in the water after treatment were also observed.
Tests with voltage as a variable:
Identical tests with titanium electrodes were also carried out using graphite.
Figure 23 shows the curves for titanium at different voltages. The behavior is quite different for titanium, when compared to graphite. The curves show a solution with similar conductivity after 30 to 40 minutes of treatment, which is unusual, as voltage and amperage were both lower in the 10 V
test. This behavior might be caused by a coating on the surface of the titanium electrodes, which was observed. Some yellow to brown suspended solids were also observed in the treated water.
This might be due to formation of TiS on the surface of the electrodes.
Based on the results of these tests as set out above, operational parameters were selected for subsequent water treatment runs. It was initially assumed that the Miniflot runs would use 10 titanium electrodes, each 2mm thick. Due to the dimension of the reactor tank of the Miniflot the minimum electrode separation possible was 48 mm, which may result in reduced amperage during our tests. Tests were run without pH pre-adjustment, even in situations where the pH of the stored waters changed overtime. Tests could run at a flow rate of 601/h up to 2001/h. Most of the tests were conducted at lower flow rates. This meant that the specific amperage of low flow rate tests with titanium was comparable to higher flow rate tests with graphite. Lab tests indicated a relatively fast reaction and, hence, low residence time in the reactor was still sufficient.

Production of Fe2+ Solution:
A sufficient volume of Fe2+ solution was prepared for use in testing. This solution was to be injected into process waters pre-treated with either graphite or titanium electrodes, to induce flocking.
The Miniflot was used to generate a volume of Fe2+ solution in a similar setup as was used in previous examples, with BW used as carrier. The plant was operated in a closed loop for about four days using the following setup: Buffer volume ¨ feed pump pH pre-adjustment with dosing of HC1 - reactor ¨ overflow to drain ¨ connection drain to buffer tank.
At the end of each days' run, a sample was taken for lab analysis to test the concentration of dissolved iron in the solution. The pH in the pre-adjustment stage was set to 4, reactor outlet was about 5.8 to 6. Increase of Fe2+ concentration in BW over time is shown in Figure 24.
After completing the Fe2+ solution production run, the total volume of the system was drained, mixed and filled in a drum for storage. Characteristic and compositional data of the solution in storage is shown in Table 13.
Type of Water Diss. iron pH Conductivity mg/I mS/cm Fe' solution (BW 3,916 4.34 24.13 Carrier) (Table 13: Characteristic Data of Fe2+ Solution) Before using the concentrated Fe2+ solution, it was filtered. The quantity of suspended solids captured as filter sediment was not measured. Later analytics of the Fe2+
solution (carried out 7, 11 and 12 days after unfiltered storage) showed values for dissolved Fe2+
of 5,983, 6,020 and 6,100 mg/l. These may be equilibrium values based on the changing pH of stored unfiltered solution. The Fe' solution was used in most of the tests marked MGr and MTi below.
Test Runs on ORF using Miniflot Test runs with Miniflot were carried out in 3 steps. Some additional supplementary testing was undertaken between these three steps.

The first step involved the observation of flock formation with graphite electrodes, including the observation of flock behavior and precipitation after treatment only. In all cases flocks were observed with the graphite electrode tests. Concentration of Fe2+ injected after treatment was varied, and in addition to this, some tests were undertaken with the addition of polymer.
In the second step, a small quantity of H2S scavenger was also added, and results compared to runs without the use of this scavenger. The results were equally valid for graphite and for titanium electrodes. Studies to investigate the reaction velocity to destroy the organic complex were also performed.
In the third step, performance test runs with the Miniflot were performed. In these test runs, parameters were changed one by one and samples were taken for internal and external lab analysis to determine the level of reduction of silica, hardness, TOC, DOC and oil & grease after treatment. Tests performed with the Miniflot are summarized in Table 8 and Table 9 above.
Floc tests with graphite electrodes:
Initial tests were carried out with Fe2+ concentrations between 125 and 300 mg/I without addition of polymer and without H2S scavenger. At a concentration of 125 mg Fe2-71, no flocks were observed or precipitated, but the first precipitation was observed at 150 mg/l. Increased concentrations provided better flocculation, and at higher concentration flocks were seen to float, as they were large enough to adsorb micro bubbles of gas.
The sample with the addition of 150 mg Fe2 /I with and without polymer addition was compared. The polymer used was Bulab 590. Polymer addition was not optimized, but even still polymer addition was advantageous (better flocculation and separation).
Further flock tests at lower Fe2+ concentrations showed the process water turning black with extremely small flocks. This suggested the formation of FeS, before Fe(OH)2 can form.
(Solubility product for FeS is much lower than for Fe(OH)2). Use of H2S
scavenger, i.e. to remove the S2-' thereby reducing Fe2+ consumption, was therefore tested. These tests were mostly carried out using titanium electrodes in the Miniflot, but results were also confirmed using the lab unit with graphite electrodes.
Precipitation of Fe(OH)2 flocks, starting with a concentration of 25 mg/1 Fe2+
up to 175 mg/1 in incremental steps of 25 mg/1 was tested. After removal of sulfide (and removal of some mercaptans), flocculation and precipitation became easier and Fe2+ consumption was drastically reduced. Accordingly, results suggested that:
H2S scavenger combined with sulfide to form a fine yellow insoluble product, which may be taken out easily by Fe(OH)2 flocks.
Scavenger may be used where desirable, for example when economics of higher iron consumption versus amount of scavenger used is favorable.
The H2S scavenger used in these studies was called "StaSweet 6000" from CFR
Chemicals.
During tests, a concentration of 0.15 1/m3 was used.
.. Determination of reaction time:
Miniflot reactor was filled with ORF to the top. A simple system for taking samples out of the reactor was installed. Rectifier was turned on to 10 V and ran at 100 A and every minute a sample of 150 ml was taken out of the reactor for flocking tests. Fe2+
solution was added to the samples at constant concentration of 100 mg/1 Fe2+ and pH was adjusted to 9.5.
Good flocking, .. precipitation of flocks, and a clear supernatant was observed with all samples including the one taken after only one minute. Samples up to a reaction time of 5 min were tested and showed similar results. Results indicate that reaction time was short, i.e. less than one minute.
Floc tests with titanium electrodes:
Initial tests were carried out with the Miniflot, using titanium electrodes and ORF outlet water with Pe2+ concentrations between 125 and 300 mg/1 without the addition of either polymer or H2S scavenger. The Miniflot was drained in the third chamber for sampling and samples were then taken at the drain. These samples were treated at the laboratory bench as follows:
Using 5 to 7 single beakers, adding different amounts of Fe' solution for different iron concentrations, pH adjustment to 9.5 and observation for flocculation. In other tests, some polymer was also added, and/or some H2S scavenger.
Post treatment with titanium electrodes, iron concentrations of 75 to 200 mg/I
without the addition of polymer or H2S scavenger (and with pH adjustment) were compared with the same iron concentrations and conditions, but with the addition of a few drops of H2S scavenger.

Better flocculation and separation was observed with the scavenger, but flocs were observed in both conditions.
In general, it was observed that after treating ORF outlet water in the reactor with graphite or titanium electrodes, and with the addition of Fe" solution, good flocking was observed in all cases. Sedimentation of flocks was also always very good.
Flock Tests Using Standard FeSO4 Solution Traditional electro-flotation is based on an electro-chemical reaction that makes use of electrons supplied by sacrificial metal electrodes. It also involves reactions associated with the dissolution of these electrodes. In a standard electro-flotation reactor, iron is normally the sacrificial or consumed electrode material used.
In the present tests, non-sacrificial (non-consumptive) graphite and titanium electrodes and electrolysis were used to supply the feed water with electrons, to destroy inhibitory compound(s) which have now been discovered to prevent the formation of Fe(OH)2 flocks.
The actual reactive material, a concentrated Fe" solution, was then produced by electrolytic dissolution in a side reaction using the Miniflot EF reactor. After a pre-treatment of the feed water with graphite or titanium electrodes to destroy the inhibitory compound(s), the pre-treated feed water was dosed with the Fe' concentrate and flocking was observed. Previous examples described above used Fe" solutions prepared by electrolytic dissolution. The following studies sought to determine whether commercially available Fe' solutions could instead be used, such as those prepared by dissolving iron salts.
Studies were performed in which the iron ion-enriched aqueous solution was prepared by alternative methods. Specifically, pre-made iron ion-enriched aqueous solutions made by dissolution of iron salts in water were tested, which did not require use of electro-flocculation, and instead utilize the iron ion-enriched aqueous solution as a straightforward chemical reagent or additive that can be slipstreamed into the produced water.
To investigate this, an FeSO4 solution was prepared with a concentration of 5g Fell using commercially available chemicals, and used for direct injection in place of electrolytically produced Fe"- (i.e. FeCl2) solution. FeSO4 was chosen, as it is used in modern waste water treatment systems as flocculant and to remove phosphate out of biological waste water. It is a by-product of titanium production, and is widely available at reasonable cost, both as a solution or also as solid salt.
flocculation tests with ORF outlet water pre-treated with graphite or titanium electrodes showed the same flocking behavior when injected with the FeSO4 solution as when injected with Fe2+ solution produced electrolytically in the Miniflot. The treatment results were similar and within the range of tolerance. No difference could be observed or measured using Fe2+
solution produced by electrolytic dissolution of iron to form a FeCl2 solution or by using a FeSat solution prepared by dissolving FeSO4 salt.
Tests described above examined treatment of ORF outlet water as the contaminated water.
Testing of three other contaminated water samples, namely two different Skim Tank Water (STW) samples and a second ORF outlet water, was also performed. In general, the behavior of these three process waters was almost identical to the behavior observed with ORF outlet water above. Flocking was about the same and all treatment standards were met.
Use of Polymer and H2S Scavenger Some of the above testing included the addition of polymer and H2S scavenger with the injection of Fe2+ solution after pre-treatment with either graphite or titanium electrodes. The following observations on the effect of adding polymer and H2S scavenger were made:
to 30 mg/I Fe2+ was sufficient to eliminate sulfide present in the water.
Black insoluble FeS was formed in the process.
20 An additional 25 to 50 mg/1 Fe2+ was sufficient to separate hardness and silica by reaction with Fe' or by absorption in the formed Fe(OH)2. Green flocks were formed and they exhibited good settling behavior.
With the addition of a small quantity of polymer during flock formation, it was observed that flocks tended to be bigger and that they tended to settle easier. Polymer Bulab 5901 25 was used in these studies. Although polymer use was not optimized, the amount applied was about 0.1%. The application of H2S scavenger reduced the amount of Fe2+
solution suitable for treatment drastically by about 25 ¨30 mg/l. H25 scavenger was added prior to the water treatment process directly into the feed stream. The scavenger reacted with the sulfide to form an insoluble organic product, which was then separated in the flocking step without difficulty or any additional step. Type and amount of scavenger was not optimized. In these tests, a product called "StaSweet 6000" supplied by CFR
Chemicals Inc. was used. The concentration used was 0.15 1 scavenger/m3.
Analytical Results Behavior of two ORF outlet waters and two STW waters was very similar and independent of the type of electrode used in pre-treatment. Final treatment results were also very similar.
Treatment results were the same for tests run with the Miniflot and the lab test unit.
Collected analytical data is shown in Table 14, Table 15, Table 16, and Table 17 below.
test-nr. Polymer I12S results scaveng.
Fe conc. In lab Ca Mg hardn. Silica TOC DOC
o+g di ss. Fe test mg/I mg/I mg/I mg/I mg/I mg/I mg/1 ing/1 mg/I
I_Gr 8 no no 100 4.4; <2.0; 11; 9.6 8.8;
3.04 0.49 25 LGr9 no no 100 <3,0; <2.0; <5.0; 5.9;
2,43 0.22 6.99 35 LGrIO no no 100 3.9; <2.0; 9.7; 15*
*silica in feed 150 mg/i 3.27 0.33 9.54 LGr11.1 yes yes 25 2.02; 0.37; 6.59; 85;
<3.0 <2.0 40.5 82 LGr11.2 yes yes 50 7.3; 3.4; 33; 52;
6.24 2.92 27.61 SO
LGr11.3 yes yes 75 5.71; 2.83; 25.9; 31 60;
6.8 3.3 53 (Table 14: Analytical Results for Lab Unit, Graphite Electrodes) test-nr.Polyinel 112.5 Fe conc. In results scaveng lab test Ca Mg hardn. Silica TOC
DOC (Hz ,diss. Fe mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I
LTI 1 no no 100 2.29 0.77 6.8 <1 (Table 15: Analytical Results for Lab Unit, Titanium Electrodes) Test-nr.Polymel H2S Lab Results scaveng conditions Fe conc. Ca Mg hardn. Silica TOC
DOC ois diss. Fe mg/I mg/I mg/I nigil rndi MGr 1 no no - -MGr 2 no no 250 1.01 0.13 3.06 40 MGr 3 no no 125 - -MGr 4 no no 150 2.29 0.27 6.83 <1 MGr 5 no no 150 3 0.29 8.69 <30 MGr 6 MGr 7 yes no 100 14.5; 0.535;
38.4; <1, 30 300.4; 243.4 16_5; 1.3 10.8 0.29 28.4 280.9 12.0 MGr 8 yes no 130 5.0; 0.4; 14.1;
10,0; 294.4; 254.2; 14.4; 0.35 4.1 0.55 12 9,3 230 230 13 MGr 9 yes yes 100 MGr 10 yes yes 130 2.9; 0.14; 7.8; 45;
7.2 <2.0 19 35 (Table 116: Analytical Results for Miniflot, Graphite Electrodes) Test-nrPolymet I-12S Lab Results scaveng Conditions Fe conc. Ca Mg hardn. Silica TOC DOC
ol-g mgil rne mg/I nigji rngil mg/I
MTi 1 yes no 150 0.94; 0.27; 3.46; 12;
<3.0 <2.0 <0.5 20 MTi 2.1 yes no 50 0.22; <d-l; a54; 40;
<3.0 <2.0 <0.5 40 Mit 2.2 yes no 100 0.31; 0.17; 1.48; 25;
<3.0 <2.0 <0.50 20 MTi 3.1 yes yes 50 0.26; 0.2; 1.48; 14;
<3.0 <2.0 <0.50 20 MTi 3.2 yes yes 100 2.83; 0.37; .. 8.6; .. 5.7;
<3.0 <2.0 <0.5 0 MTi 4.1 yes yes 130 2.18; 0.22; 6.33; 15;
<3.0 <2.0 <0.50 13 MTi 4.2 yes yes 130 2.36; 0.16; 6.55; 1.9;
<3.0 <2.0 <0.50 10 Mu i 5 yes no 100 3.33; a 33; 9.69; 20;
4.1 <2.0 10 20 MTi 6.1 yes yes 50 4.22; 0.43; 12.33; 70;
4.7 <2.0 12 65 Mu i 6.2 yes yes 100 4.12; a 44; 12.11; 45;
4.9 <2.0 12 39 MTi 7.1 yes no 50 3.67; 0.46; 11.04; 80; .. 387.1 303.6 15.28 4 <2.0 10 73 Mit 7.2 yes no 100 2.91; 0.28; 8.43; 50, 3.8 <2.0 9.6 46 (Table 17: Analytical Results for Miniflot, Titanium Electrodes) These data show, that independent of any geometric or material factors, treatment targets were met in nearly all cases.
Hardness:
Hardness is caused by the presence of calcium and magnesium ions, and the calculated combined hardness value is represented as carbonate. Target is 15 mg/l. Figure 25 shows data measured during testing, independent of the type of electrode used in pre-treatment, i.e.
whether graphite or titanium. In almost all cases the target was met.

Figure 25 shows consistent and near constant values for magnesium content, and a variable and changing concentrations of calcium. Due to these high calcium values, high values for hardness were calculated. It was considered that this may be caused by some error in measurement, or by cross contamination with drinking water. Real values for calcium are expected to be around 2-3 mg/I with a total hardness of 7-8 mg/l. This higher than expected concentration of Ca measured may be a result of cross contamination from residual Ca(OH)2 in the Miniflot from earlier test, where we used lime slurry instead of NaOH
for pH adjustment.
Silica:
Target for active Silica is 50 mg/1. In general, this target was met with average values for silica of about 18 ¨ 20 mg/I. Only two tests using titanium electrodes, in combination with higher flow rate, showed values higher than 50 mg/1¨ see Figure 26.
Summary Experiments herein tested whether a pre-treatment of main stream SAGD process contaminated water by electrolytic reduction using non-consumptive electrodes made of graphite or titanium could destroy inhibitory compound(s), and then permit use of a side-stream of Fe2+ solution by direct injection for flocking.
Non-consumable electrodes made of graphite or titanium were used. Two sources for Fe2+ for flocking purposes were also used, the first being a Fe2+ solution produced by electrolytic dissolution of iron and the second by using a Fe(H)504 solution created by dissolving a commercially available chemical reagent in water. In all cases, whether with the lab test unit or the Miniflot, whether with graphite or with titanium electrodes, good flocking was observed after the addition of Fe2+ solution from either source and after adjustment of the pH to 9.5.
Precipitation time of flocks could be reduced further by adding a small amount of polymer.
Reaction time to destroy inhibitory compound(s) which otherwise prevented the formation of Fe(OH)2 flocks was very short, i.e. within 1 minute with graphite, approximately 2 minutes with titanium electrodes. This means that an electrolytic reactor using these non-consumable electrodes may have a relatively small reaction volume, i.e. 5 to 10 m3 for an industrial size of plant, and still can pre-treat a relatively large volume, i.e. 200m3/hr, for example. Electrical power consumption may be less than 1/10 of the power consumption required for standard electro-flotation.
Both types of electrodes (graphite and titanium) performed the task of electrolytic reduction of the above-mentioned inhibitory compound(s). Graphite as an inert, but conductive material, showed absolutely no side reaction, no corrosion, no coating etc. After the tests the electrodes looked brand new. Electric behavior of the electrodes was constant over the testing cycle period. Other advantages of graphite over titanium included lower material costs, faster reaction time, which for graphite was less than one minute, or half of the reaction time with titanium. An additional advantage was the simple and easier machining and fabrication of this material.
Titanium, or more specifically, the alloy which was used, did not perform as well as graphite, but was certainly still functional. One relative disadvantage was the observed corrosion and pitting on the surface of titanium electrodes. In addition, a coating was observed on some electrodes, as well as electrical behavior that was not as constant or stable as observed with graphite under the conditions tested.
The physical-chemical behavior of Fe2+ ions was independent of the type of "production" of the iron solution. The solubility curves of Fe(OH)2 as a function of the pH
value are based on the Fe2+ concentration, and no changes were observed whether the iron solution was produced electrolytically or as by-product in other metal production, for example.
Readily available Fe(II)SO4 is used in waste water plants as a reagent to remove phosphate, as fertilizer, and as reduction agent in the cement industry. It is called iron vitriol or green salt. The sulfate anion does not change the process water composition, as sulfate is already found in the process water.
This product is available as crystalline salt or as solution in concentrations up to several hundred g/1. Different Fe concentrations generally did not affect the flocking mechanism.
The ability of a commercially available H2S scavenger to reduce Fe2+
consumption was also tested (i.e. when dosing Fe2+ solution, initially FeS is formed, if sulfide or mercaptans are present in the water to be treated). H2S scavengers are organic chemicals that can react quickly with sulfides and mercaptans and form an insoluble compound. It was hypothesized that this could then reduce the amount of Fe2+ needed for flocking and for treatment.
Studies confirmed that H25 scavenger did indeed work under these process conditions, and that iron consumption was reduced to about half of the amount needed without the use of a scavenger.

The above experiments successfully demonstrated that application of electrolysis (for example, electroreduction) using non-consumptive electrodes, followed by direct injection of Fe"
solution to induce flocculation, treated SAGD water to suitable standards.
Appropriate reductions in hardness and silica were obtained, and standards for reduction of suspended solids, oil and grease and reduction of TOC and DOC were also reached.
It was identified that an initial step of electroreduction could be performed on the produced water, which would destroy or inactivate the inhibiting contaminant(s) and restore flocculation-based contaminant removal. An initial electroreduction step may be introduced prior to injection of the iron ion-enriched solution (produced, in this example, from electro-flocculation at ambient temperature). A pH adjustment step may also be introduced following introduction of the iron ion-enriched aqueous solution, which further enhanced flocculation effectiveness.
Overall, these experiments demonstrated that electrolysis could be applied using non-consumptive electrodes, followed by direct injection of separately prepared Fe' solution, to induce flocculation and thereby treat contaminated water such as, for example, produced water from SAGD. Both graphite and titanium were used as non-consumptive electrode materials.
In general, both materials are chemically resistant and conductive. During tests, graphite performed better, as it showed no appreciable signs of corrosion or coating during process testing and no appreciable change in its behavior. In other tests, it was shown that, in addition to using Fe" solution made by electrolysis using the EF reactor (i.e. as per Example 1), Fe"
solutions available commercially, or produced by dissolving Fe' salts, could also be used.
EXAMPLE 4B ¨ Treating Produced Water at Elevated Temperature by Electroreduction, Followed by Injection of an Iron Ion-Enriched Aqueous Solution in a Modified Miniflot Tests were performed to further investigate the electroreduction and flocculating ion-enriched aqueous solution injection approaches set out in Example 4A at elevated temperatures. In particular, tests were performed at temperatures at or near about 80 C to further investigate the abrogation of contaminant inhibition by electroreduction and the treatment of SAGD
produced waters with flocculating ion-enriched aqueous solutions.
The tests used a modified Miniflot unit based on the one described in Example 4A. The modified Miniflot unit comprised four chambers. The first chamber (typically configured for a pH pre-adjustment) was configured for optional injection of an H2S scavenger.
The second chamber was configured as an electrolytic reactor in a similar manner to that described in Example 4A with a series of ten non-consumptive graphite electrodes. The third chamber was configured for injection of the Fe2+ solution in a similar manner to that described in Example 4A. The third chamber was also configured for pH adjustment and polymer injection. The fourth chamber was configured for sample collection. The tests involved treating the produced water in a process comprising the following steps: (i) optionally subjecting the produced water to an H2S scavenger; (ii) subjecting the produced water to reducing conditions induced through the graphite electrodes; (iii) introducing a flocculating ion-enriched aqueous solution, NaOH
(for pH adjustment), and a flocculation promoting polymer into the produced water; and (iv) removing flocks via manual filtration using fluted filter papers. In particular, the tests were completed as set out in Table 18.
Test-nr. Test water Flow rate H2S Fe - concentration scavenger l/h mg/I
M1 ORF out 150 no 150 M2 ORF out 100 no 150 M3 ORF out 100 no 300 M4 ORF out 100 no 250, 275, 300 M5 ORF out 60 no 275 M6 ORF out 100 yes 175, 200, 300 M7 ORF out 100 yes 100, 125, 150 M8/8a ORF out 100 no 150, 175, 200, 225, 250, 275, 300 M9 ORF out 100 no 175, 200, 225, 275 M10/10a ST Inlet 100 no 200, 225, 250, 275, 300, 325, 350, (Table 18: tests performed using the modified Miniflot unit ¨ "ORF out" refers to an oil removal filter outlet, and "ST Inlet" refers to a skim tank inlet) In the tests of Table 18, the graphite electrodes were operated at 100 A with voltages varying based on conductivity. In instances where an H2S scavenger was used, the scavenger was injected to provide a scavenger concentration of 100 ppm. The pH was adjusted to about 9.5 with NaOH. The polymer was injected to provide a polymer concentration of about 100 mg/l.
Analytical data from archetypal tests of Table 18 are provided in Table 19A
and Table 19B
and relevant trends are plotted in Figures 27-30.

Feed water nr. Test Fe Si02 Ca Mg hardness TSS 01W Fe Fe nr. conc.
total co II. react. ICP Hach mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I
1 M7 100 278 42,5 235,5 3,54 0,37 10,34 8 0,1 0,09 1,23 2 M7 125 278 42,5 235,5 3,54 0,37 10,34 8 0,1 0,09 1,23 3 M 125 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 4 M7 150 278 42,5 235,5 3,54 0,37 10,34 8 0,1 0,09 1,23 M 150 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 6 M 150 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 7 M 175 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 8 M 175 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 9 M9 175 344,5 72,5 272 3,78 0,39 11,1 11 - 1,77 M6 200 276 30 246 3,39 0,36 - 9,92 5 0,5 0,121 1,2 11 M8 200 276 - 283,5(?) 3,32 0,34 10 10 0,1 0,1 2 12 M9 200 344,5 72,5 272 3,78 0,39 11,1 11 - 1,77 13 M 200 323,4 74 249,4 4,14 0,53 12,53 149 98,2 0,09 2,67

14 M 225 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 M 225 291,8 40,8 251 3,55 0,36 10,34 6 9,4 0,16 1,18 16 M9 225 344,5 72,5 272 3,78 0,39 11,1 11 - 1,77 17 M 225 323,4 74 249,4 4,14 0,53 12,53 149 98,2 0,09 2,67 18 M4 250 288 98 190 3,48 0,38 10,3 6,5 1,3 0,097 1,59 19 M8 250 276 - 283,5(?) 3,32 0,34 10 10 0,1 0,1 2 M8 250 276 - 283,5(?) 3,32 0,34 10 10 0,1 0,1 2 21 9 250 344,5 72,5 272 3,78 0,39 11,1 11 - 1,77 22 M 250 323,4 74 249,4 4,14 0,53 12,53 149 98,2 0,09 2,67 3,57 0,36 10,4 2068 495 0,126 0,67 24 M6 275 276 30 246 3,39 0,36 9,92 5 0,5 0,121 1,2 M8 275 276 - 283,5(?) 3,32 0,34 10 10 0,1 0,1 2 26 M9 275 344,5 72,5 272 3,78 0,39 11,1 11 - 1,77 27 M 275 324,9 255,5 4,14 0,53 12,53 149 376,5 0,089 -28 M3 300 307,4 57,4 250 3,57 0,36 10,42 2068 495 0,16 1,18 29 M6 300 276 30 246 3,39 0,36 9,92 5 0,5 0,121 1,2 M8 300 276 - 283,5(?) 3,32 0,34 10 10 0,1 0,1 2 31 M 300 324,9 69,4 255,5 4,14 0,53 12,53 149 376,5 0,089 -32 M 325 324,9 69,4 255,5 4,14 0,53 12,53 149 376,5 0,089 -33 M 350 324,9 69,4 255,5 4,14 0,53 12,53 149 376,5 0,089 -34 M 400 323,4 74 249,4 4,14 0,53 12,53 149 98,2 0,09 2,67 (Table 19A: analytical data from tests performed on untreated waters) Treated water nr. Test Fe S102 Ca mg Hard TSS 01W PH Fe Fe nr. conc. -ness out total co II. react total solu ble mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I mg/I
mg/I
1 M7 100 161 52,6 108,4 2,27 0,2 6,51 4 0 9,62 37,99 2,3 2 M7 125 139 81 58 2,33 0,22 6,71 18 0,1 9,74 36,12 4,3 3 M8a 125 140,1 29,4 110,7 2,58 0,25 7,49 16 0 9,63 27,52 0,65 4 M7 150 113 32 81 1,93 0,15 5,45 6 0,1 9,66 34 5,57 M8a 150 131,6 48,6 83,2 1,90 0,23 5,69 10 0 9,75 41,3 7,85 6 M8a 150 128,0 41,5 86,5 2,24 0,17 6,28 20 0 9,73 43,9 7,25 7 M8a 175 144,60 67,50 77,1 2,27 0,30 6,92 14 0 9,75 60,48 6,7 8 M8a 175 125,50 42,70 82,8 2,07 0,13 5,7 20 0 9,75 35,79 10,2 9 M9 175 132,30 58,50 73,8 1,75 0,22 5,26 18 0 9,78 43,54 2,84 M6 200 96,23 9,30 86,9 1,83 0,1 4,97 15 0 9,72 30,48 6,88 11 M8 200 131,2 77,0 54,2 2,71 0,23 7,72 22 0 9,12 80 0,65 12 M9 200 80,6 28,3 52,3 2,17 0,13 5,97 27 0 9,79 40,16 4,09 13 M10a 200 137,70 72,00 65,7 3,02 0,26 8,61 49 0 9,64 55,7 -14 M8a 225 67 10,9 56,1 1,33 0,07 4,13 6 0 9,71 9,13 2,48 M8a 225 83,95 25,5 58,5 2,12 0,12 5,78 6 0 9,7 32,5 6,1 16 M9 225 63,6 13,9 50,3 1,72 0,1 4,69 15 0 9,65 12,22 6,97 17 M10a 225 120,7 63,2 57,5 2,18 0,26 6,53 46 0 9,69 67,57 -18 M4 250 53,6 19 M8 250 72 29,5 42,5 1,97 0,12 5,41 8 0 9,66 43,3 2,1 M8 250 58 18,3 39,7 1,86 0,1 5,06 6 0 10,02 21,7 3,6 21 M9 250 71 27,9 43,1 1,19 0,15 3,6 12 0 10,08 19,08 2,81 22 M10a 250 70,9 23,6 47,3 1,95 0,11 5,33 16 0 9,77 22 1,1 23 M3 275 33,6 8,8 24,8 1,72 0,12 4,79 26 0 9,65 11,09 7,1 24 M6 275 49,1 7,6 41,5 2,36 0,01 6,26 5 0 9,84 7,9 2,62 25 M8 275 55,4 10,3 45,1 1,81 0,11 4,95 10 0 9,68 18,45 8,35 26 M9 275 48,1 13,1 35 2,21 0,14 6,07 8 0 9,73 14,85 3,19 27 M10 275 58,16 12,4 45,8 2,22 0,12 6,04 14 0 9,74 18,7 5,62 28 M3 300 12,4 -21,4(?) 1,875 0,109 5,13 2 0 9,7 2,07 2,96 29 M6 300 14,3 - 17,7(?) 1,87 0,13 5,23 1 0 9,72 1,02 0,04 30 M8 300 28,7 - 30,8(?) 2,04 0,09 5,54 12 0 9,65 2,98 0,72 - 31 M10 300 47,8 12,9 34,9 2,32 0,16 6,46 6 0 9,88 6,08 2,95 32 M10 325 29,3 31,70 1,05 0,08 2,94 7 4,3 9,82 5,4 1,17 - 33 M10 350 31,48 5,3 26,20 1,68 0,08 4,54 4 0 10,37 3,71 2,7 34 M 10a 400 23,6 23,5 0,11 0,73 0,11 3 1 3 0 10,33 7,02 1,16 (Table 19B: analytical data from tests performed on treated waters) Figures 27 and 28 provide information relating to silica content in the process waters from the tests. Figure 27 provides silica concentrations (reactive, colloidal, and total) for untreated process waters from the tests. As expected, total silica in feed water was measured at between 275 mg/I and about 350 mg/l. Figure 28 provides silica concentrations (reactive, colloidal, and total) for treated process waters from the tests as a function of Fe2+
concentration. In Figure 28, total silica concentration decreases with increased Fe2+ concentration, and crosses the typical 50 mg/1 threshold SAGD water processing at an Fe2+concentration of between about 280mg/1 and about 300 mg/1.
Figures 29 and 30 provide information relating to hardness content in the process waters from the tests. Figure 29 provides hardness concentrations (calculated, Ca2', and Mg2+) for untreated process waters from the tests. As expected, calculated hardness in feed water was measured at between 10 mg/1 and about 12 mg/l. Figure 30 provides hardness concentrations (calculated, Ca2 , and Mg2+) for treated process waters from the tests as a function of Fe2+ concentration.
In Figure 30, calculated hardness concentration decreases with increased Fe2 concentration and is reduced by about 50 % at an Fe2+ concentration of between about 280 mg/1 and about 320 mg,/1 (the concentration range correlated with silica concentrations approaching the typical 50 mg/1 threshold SAGD water processing in Figure 28).
In addition to the foregoing tests, a series of control tests were also completed. In particular, about 2.5 1 of untreated process water (i.e. process water not subjected reducing conditions) was removed from the Miniflot unit and divided into twelve aliquots. The various aliquots were treated with Fe2 solutions to provide concentrations ranging from about 150 mg/1 to about 1000 mg/1 (in increments of about 50 mg/1 and 100 mg/1) and then pH-adjusted to 9.5.
Qualitative observations from the control tests are set out in Table 20.
Fe conc. Observation mg/I
150 ¨ 400 complete black 450 very fine flocks 500 very fine flocks 550 some very small flocks 600 some very small flocks 650 flock and murky 700 flock and murky 800 almost clear phase with flocks 900 almost clear phase with flocks 1000 clear phase, flocks, filterable (Table 20: observations from control tests) The observations of Table 20 indicate that, in the absence of an electrolytic reduction step, it was not possible to treat process water to the required specifications without requiring uneconomical concentrations of Fe2+ concentrations.
In summary, the forgoing tests indicate that electrolysis (for example, electroreduction using non-consumptive electrodes), followed by direct injection of Fe2 , a polymer and a pH
adjusting agent, provided treated SAGD water to suitable standards.
Appropriate reductions in hardness and silica were obtained. Presently described water treatment processes may provide advantages over previous practices for SAGD process water treatment. By way of example, water treatment methods and systems as described herein may be compatible with high temperature operation which may provide for better energy efficiency and energy conservation.
In turn this may provide for lower total operating costs, may reduce amounts of sludge generated, may provide for overall process simplification, and/or may be compatible with existing process equipment for implementation.
EXAMPLE 5 ¨ Direct Injection Flocculation Treatment Pilot Plant Designs for Treatment of SAGD Process Water Design considerations for an embodiment of a direct injection flocculation treatment pilot plant for treatment of SAGD process water are described. The pilot plant embodiment is designed to treat up to 6m3/h SAGD process water under SAGD operating conditions, i.e.
design temperature of up to 170 C and design pressure of up to 1.450 kPa. It represents a scale-up factor of approximately 1:29 to 1:33 to a full commercial sized treatment train of between 175 to 200m3/h.
In this non-limiting system embodiment, the system provides for electrolytic reduction using non-consumable graphite electrodes; injection of concentrated Fe2+ solution (optionally also including the preparation or production of Fe2+ solution); polymer and H2S
scavenger injection;
and pH adjustment to permit the formation of Fe(OH)2 flocks. Initial electrolytic reduction is performed to destroy some inhibitory compound(s) which otherwise would interfere with the formation of Fe(OH)2 flocks. Flock containing contaminants are then separated from treated process water by a two stage IGF system.
In this embodiment, direct injection flocculation is used in the treatment of SAGD process water, and may operate under normal conditions found in SAGD, i.e. elevated temperature and pressure. With the ability to operate under these conditions, the creation of a heat sink is avoided during process water treatment. The maintenance of conditions of elevated temperature across the treatment platform may significantly improve the energy efficiency and overall economics of water treatment in SAGD.
Experiments have demonstrated that such methods and systems may be used to remove various contaminants in the process water to a high degree (i.e. Silica, hardness, suspended solids, oil and grease, etc.). Initial tests were carried out at room temperature and atmospheric pressure and at somewhat higher temperature, i.e. 60 C. In this example, a pilot plant is described which is designed to operate at both standard ambient operating conditions and at operating conditions that are normally found in SAGD.
The main process steps in this example are as follows:
Electrochemical reduction, Dosing of chemicals including flocculation, and separation of contaminants together with flocks in an IGF column.
Figure 40 depicts a general process description, and Figure 41 depicts a layout-general arrangement drawing of the designed pilot plant of this example. The pilot plant may be operated in parallel to current SAGD process water treatment. It may be operated at ambient conditions (i.e. atmospheric pressure and room temperature - approx. 20C), and up to more typical operating pressures and temperatures, as found in SAGD, i.e. 850 kPa and 140 C. Inlet and process outlet connections will operate under similar conditions. Process water will be pumped into the system using turbine pump P 01. Incoming process conditions will be measured by PIR 03, FIRCAL 01 and TIR 01. FIRC 01 will trigger the by-pass valve FCV 01, which allows for different flow rates through the plant.
In the first dosing step I-12S scavenger will be added according to a dosing rate established from previous tests. Dosing pump P 02 (flow rate adjustable via process control system (PCS)) pumps the chemical from the delivery and storage tote PT 02. PT 02 is installed in the spill containment pan PP 02 for safety reasons and will be equipped with the level switch LSAL 02, which triggers a low-level alarm and shuts down the dosing pump P 02 in case of empty container.
H2S scavenger will be dosed into the main process stream via injection valve CV 01 and mixed using the static mixer M 01. Process water with H2S scavenger will then enter the reduction stage with reaction tank T 01.
The reduction stage consists of the tank T 01 holding a set of internally installed graphite electrodes. The power supply for electro chemical reduction is applied in the process water between the electrodes. Temperature measurements will be taken at the inlet and outlet of tank T 01. The graphite electrodes will be powered via isolated copper bars inside the tank, which are also used as a support rack to keep the horizontally arranged electrodes in place. Positive and negative copper bars are fixed in the top of the rectangular flange via isolated feedthroughs.
The power supply is in the electrical room. DC current (10 V, 500 A) will be transferred to tank T 01 via insulated copper bus bars.
In total, 17 electrodes will be installed in the reduction tank T 01(9 cathodes, 8 anodes). Process water will flow inside the reaction tank T 01 and through the electrodes only.
Temperatures at in and outlet points will be measured using TIR 02 and TIR 03. Within PCS the temperature difference between these points will be measured and monitored at TDIAH 04.
For example, increasing temperature sets of an alarm indicating possible coating of the electrodes or other causes of decreased efficiency at the electrochemical reaction, resulting in increasing temperature due to heat input. To avoid critical buildup of heat in the system, DC supply R 01 will only deliver DC, when pump P 01 is working and flow rate within the process is higher than at a minimum value, measured with FIRCAL -01.
Within the power supply R 01 voltage and amperage will be monitored. Low values at EIAL
(V) and EIAL (A) will trigger an alarm, as no electrochemical reaction happens (caused by isolating problems or other problems).
Process water flows into next dosing station, where FeCl2 solution will be added using P 03.
Dosing pump P 03 (flow rate adjustable via PCS) pumps the chemical from the delivery and storage tote PT 03. PT 03 sits on a spill containment pan PP 03 for safety reasons and will be equipped with the level switch LSAL 03. This will trigger a low-level alarm and will shut down the dosing pump P 03 if the container is empty.
FeCl2 solution will be dosed into the main process stream via injection valve CV 02 and will be mixed with the static mixer M 02. Process water with FeCl2 solution will enter the third dosing station, where the pH in the process water is increased.
NaOH will be added using P 04. Dosing rate at dosing pump P 04 will be controlled at measurement point QICAL 01, which measures the pH value. Dosing pump P 04 pumps NaOH
from the delivery and storage tote PT 04. PT 04 sits on the spill containment pan PP 04 for safety reasons and will be equipped with the level switch LSAL 04. This switch will give a low-level alarm and will shut down dosing pump P 04 if the container is empty.
NaOH will be dosed into the main process stream via injection valve CV 03 and mixed with the static mixer M 03. PH adjusted process water flows through about 10 m piping for sufficient retention time to form Fe(OH)2 flocks, before it enters the last dosing station.
In the last dosing station polymer will be added to improve flocculation of the formed Fe(OH)2 flocks. Polymer solution will be added using P 04. Dosing pump P 04 (flow rate adjustable via PCS) pumps the chemical from the delivery and storage tote PT 04. PT 04 sits on the spill containment pan PP 05 for safety reasons and will be equipped with the level switch LSAL 04, which will trigger the low-level alarm LSAL 05 and will shut down dosing pump P 04 if the container is empty.
Polymer solution will be dosed into the main process stream via injection valve CV 04 and will be mixed with the static mixer M 04. Static mixer M 04 will be specially designed for polymer mixing. However, a rinsing device will be included in the design in case of plugging. When the pilot plant operation is stopped, the ball valves V 16 and V17 will be closed and the mixer M 04 can be rinsed with water via V 18 and 19.
.. For optimal flocculation, a retention time of 30 seconds may be provided by increasing the piping to a diameter of 200 mm for a length of about 1.6 m, prior to the process water entering the IGF column T 02 for flock and sludge separation.
The flock and sludge separation is based on the known IGF system including recycle pump and gas injection. Natural gas will be used for flotation.
Process water exits column T 02 via V 27 and measuring station QIR 02 (o+g) and flows back into main process stream. Flocks and sludge will exit the column T02 via V 28 and level control valve LCV 01 and will be added to process water stream to exit the pilot plant. Flow rate of the side stream is measured with FIR 02.
Basic layout and rough dimensions: Initial dimensions and the basic layout of the pilot plant are shown in Figure 41.
IGF Columns: The IGF set-up as shown in Figure 40 and Figure 41 is a representation of an IGF column for illustrative purposes only. By way of example, a 2 Stage IGF
may be used as an integrated component within the pilot plant and not as an add-on.
Figure 42 (A) depicts an embodiment of a reduction vessel, and Figure 42 (B) provides an embodiment of a reduction vessel specification example.
In certain embodiments, produced water may contain an oil component, and floc-rich coagulated oil may be separated from the water using, for example, a filter press. In other embodiments, particularly where scale-up is of interest, filter press-based floc removal may be substituted for, for example, floatation-based equipment such as induced static floatation (ISF), induced gas floatation (IGF), and compact floatation units (CFU) equipment (with either single or multiple stage floatation), for example. These systems may effectively deoil, and remove silica and hardness, from contaminated produced water, in a manner compatible with high temperature (up to 220 C, for example) and pressure. In certain embodiments, produced treated water stream may thus be directly used for steam generation, for example OTSGs, with minimal additional treatment and without excessive scaling.
EXAMPLE 6¨ Reduction and Oxidation of Naphthenic Acids/Naphthenates and Phenols in SAGD Process Water Methods and systems described herein include a pre-treatment step to destroy/inactivate/remove inhibitory compound(s) in contaminated water which would otherwise interfere with flocculation following addition of a flocculating ion-enriched aqueous solution. In this example, additional studies were performed to determine whether naphthenic acids and/or phenols could also be destroyed in the same pre-treatment step.
Electroreduction and Electro-chemical Oxidation (ECO) pre-treatment steps were both studied for ability to destroy naphthenic acids.
As described hereinbelow, while electroreduction pre-treatment was able to degrade naphthenic acids and phenols, the energy input required was not favourable. In contrast, ECO
showed effective removal of naphthenic acids. Of interest was the observed oxidation of naphthenic acids quickly, and at the early stage of oxidation of organics relative to the oxidation of total organics (TOC's). This supports an effective and efficient method to remove such fouling components from contaminated water such as, for example, SAGD process water prior to steam generation.
The problem of fouling, often seen in SAGD and other oil processing equipment that involves water and steam, has been linked to the formation of naphthenic salts (mainly with Ca2+) etc., and related to naphthenic acids and phenol(s) found in petroleum and in process water(s).
Naphthenic acids are believed to be more or less soluble in water, depending on their molecular weight and the pH of the water. It seems, that when pH is less than the 5-6 range, naphthenic acids are either soluble in water or form small droplets as emulsion in water.
In this range Ca2+
and Mg2+ are also soluble. In the range between pH 6-7, salt formation starts and emulsified drops go into solution as surface tension changes drastically. Naphthenic acids soluble in water are then able to form Canaphthenates. With pH >8, the Ca-naphthenates become insoluble and can cause problems, i.e. fouling. If the removal of naphthenic acids can be demonstrated using a pre-treatment step, this may offer yet another advantage to the presently described water treatment methods and systems.
Test procedure for reduction and oxidation tests ORF outlet water was used in these treatment studies. Table 21 shows physical and analytics data of the ORF outlet feed water, obtained for the water at time of collection and prior to use in experiments (columns 3 versus 4).
Fluid type ORF Outlet ORF Outlet Collection Point FC F701 MIT F701 Tote Sample ID 103350 Ce12027 Date Collected 201&04-18 2027-0/-24 Tate 1 pH was measured An fytics Data pH 7.3-7.4 during testing Conductivity mSicm 2.92 COD mg/I 2,350 TOC mg/I 740 250 04-0 mg/I 9.9 TSS mg/I 22 Difference attributed to lab Naphth.Acids mg/I 33 18 procedure Phenols 45 51 Hardness mg/I 8.1 Ca mg/I 3.2 Mg mg/I
Silica mg/I 130 Fe mg/I
H25 mei 9.7 2.4 Total OrgSulphur mg/I 8.7 2.2 (Table 21: ORF outlet water physical and analytical data) Reduction tests:
Approximately 201 of ORF outlet process water was prepared in a pail. A hose pump was used to pump the prepared process water into the bottom of the reactor. Overflow was collected for sampling. The lab reactor was equipped with 4 graphite electrodes (2 positive, 2 negative). To undertake tests at higher temperature, a small heat exchanger was assembled using copper tubing, installed in a bath of heated water. In this way, temperature could be increased in-line to about 50 C.

The effect of the various treatment parameters on the following constituents was measured:
Naphthenic acids and phenols; hardness; Ca; Mg; total organic Sulphur; TOC;
DOC; TSS;
TDS; 0+G. Parameters that were varied during tests included: pH at treatment;
amperage;
voltage; temperature; retention time (flow rate, specific amperage, specific power).
Tests were performed at room temperature and at 50 C. About 200 1 process ORF
outlet water was transferred into an open barrel and pH-adjusted using HC1 for the tests at pH 5 and 7, and using NaOH for tests at pH 9. Mixing was done using a turbine pump installed in the barrel.
One barrel with pH-adjusted water provided enough water for about 9 runs.
After having used up the pH-adjusted water, a new batch was prepared in the same manner. pH
adjusted water was pumped using a hose pump with adjustable speed, so that the tests could be run at different flow rates. Test water entered the test reactor at the bottom and exited the reactor via overflow into a pail. All samples were taken out of this pail without further treatment.
The reactor was equipped with four graphite electrodes (dimensions: 11.5 x 12 cm, area 138 cm2). Distance between the electrodes was 2 cm. pH outlet and temperature differences between in and outlet of reactor were measured directly at time of testing.
Changes at the outlet pH during the test runs with process water at pH 7 and 9 were observed, so repeats of these runs later at higher temperatures were performed, but otherwise under the same conditions.
Oxidation tests:
Oxidation tests were undertaken by electro-chemical oxidation using a small lab ECU "beaker"
set-up. The ECO set-up utilized proprietary, specially coated ultra-high potential Boron Doped Diamond (UHP-BDD) electrodes that use Niobium or Tantalum as carrier material.
These electrodes permit the highest currently available electro-chemical potential to be applied to completely oxidize organics. Tests showed that this ECU can completely oxidize soluble organics to CO2 and water. The lowest TOC after ECU that we observed during qualitative testing was 2 mg/l. Initial ECU studies on TOC reduction included the following time study shown in Table 22:

time voltage amperage remarks min V A
0 9.10 10.2 foe m, chlo rine oda r 9.40 10.2 color turns dark 9.30 10.2 color turns lighter 9.10 10.2 color turns lighter 10.10 10.2 color turns lighter 9.50 10.2 color turns lighter 9.00 10.2 calor almost yellow 12.50 10.2 yellow SO 11.10 10.2 yellow, no foam 90 10.30 10.2 Color lighter 100 10.00 10.2 color hghter 110 9.60 10.2 color lighter /20 9.40 10.2 almost no color, Anne chbrine ado]
130 10.90 10.2 no chlorine, but some ozone odor 140 10.30 10.2 ozone odor 150 9.70 10.2 stop, take sample (Table 22: Extract of ECU testing protocol) A noteworthy observation was the presence of reaction stages based on the following characteristics:
5 foam production, chlorine odor;
no foam production, but change of color from dark-brown to yellow; and almost no color, no chlorine odor, but presence of ozone odor.
These reaction stages suggested that organics were not uniformly oxidized by ECU, but that different organics may be oxidized at different rates and at distinct stages.
Studies were thus 10 performed to determine whether naphthenic acids could be destroyed/oxidized at a faster rate than the overall reduction in organics by ECU, and at the initial stages of oxidation. Studies focused on measuring the concentration of naphthenic acids after different treatment times to see if a complete or partial oxidation of these compounds would be observed, and whether changes occur quickly or in a slow manner. Reaction temperature in the process water was

15 maintained to below 50 C. The first two runs were used to estimate the efficiency of the oxidation process relative to total energy input.

Tests were carried out using a beaker which held the ECO electrode set. A
magnetic stirrer was used to mix the feed water and to push some of the feed water through the narrow space between the electrodes. During ECO tests, about 1 I of water was used for sampling purposes.
Atotal of five tests were undertaken, with reaction times of 20, 40, 60, 80 and 120 minutes. As reaction time increased, the formation of a precipitate was observed, which was believed to be , a "new' organic compound. At this point, the early formation of foam had stopped. Precipitate after 80 min of treatment formed a flock that could not be oxidized in further treatment, as only soluble organics are typically treated with this process. The formation of this "new" organic compound took place at the later stage of ECO treatment.
Analytical Results of Reduction Tests Table 23 shows analytical data for reduction test runs performed.
test data ' -- - analytical dat a test on. set voltage det. flow-mate. centric pat 00d. temp. COD '00C TOC dsg 050 fuel, plisen. fwd. Maid Cs Mg fe, re, 02133 HIS 1001 1,71 -wave-sag - tete ARV fla Off. filtered 120141 filleted attititit wok 5 S = 0 eted spec.
V A 7:0708 qn no ns so, -'3' 91,11 403/32 170 31372 313/1 993.11 mgAS 78811 762/1 17311 8980 177370 813,72 7881i 593,0 0147!
1.1<4 37<133)1 1300 740 43 45 .3.1 3-.7 !,?1,23 .. = = .. . = Me< sin 2130 1.31 = 240 ' 244 932 11 Ili 51 300 <60 130 1A 2.2 1.1.1 ' 0.0 . 015 5.02 = 200 7..20.3 30.00 5.06 1 130 240 8.8 20 15 49 8.1 cos 13.3 '2 906 140 005 001 1.0/ ; 0.0 : 9.35 sno 1.04 i bo.o 43.noo 5_02 04 210 HO 730 27 17 47 8.1 <0.4 32 .322 .05 140 1.2 1.1 12.3 :5,0 9..30 . 5.03 0.50 20.0,04700 5.02 2 210 240 81 14

16 48 11.0 <794 .3.1. '2 10.47 140 1.1 1.2 1.1.4 ' 5.0 20 300 0.2.9 : 130 1L562.13 4.28 23. .220 140 1.4 24 16 40 /5 .115 .11 . 2 10.6 130 1.2 1.1.1 I SA 13.50 830 . 2420 11.20.0 39340 ' 522. 90 1.421 177 52 24 17 45 6.9 521 3.0 .10 , <0.3 0.08 150 , 02 1.1.2 SA 130 8.0 LW i 60.03.9280 0,10 IS 130 240 5.1 0.4 17 42 S. 7 0200 15. 300 , Ø3 1.1 140 2.5 2.3 1.2<1.21323,0 9000.13) 40.02301240 5.532 LS 200 280 154 0 8 132 44 11 160 4.1 31.0 0.44 1.3 140 2.0 1.24 1 "3 1430 . 6200 029 i 15.0 7.024,30 .6.14, 46 140 250 01 34 14 18 0.32 9.22 14 .1.0 0.51 1.3 13203 2.2 21 10.1 4.0 id 20 1020 2.10 120.0 57320 .5.01 10 140 260 3.2 12 13, 41 80 5.64 16 710 <0.179 0.40 160 , 1.1 1<3 1.3.2 5.0 13 60 . 1320 1.00 . 6.3.0 97930 0.1.6 2.4 240 150 5.1 11 16 _ 42 8.5 11 3.5 31.0 0.30 0.91 140 151 1.3 1.3.3 = 5.0 13.60 10.20 00.50 = 30.05340.40 5.10 21 240 240 94 24 17 45 8.4 0.74 34 .10 03.8 1.3 140 2.4 2.2 1.1.4 '0.0 13.00 10.20 0.25 . 15.02.91140 520 55 , 2710 270 0.1 372 16 39 8.1 851 3.3 11.0 0..4 2,9 150 1.9 10 21.1 = 1.0 9.80 5.00 0.00 1120.0 110.00 244 0 230 234 III 2.5 18 718 5.3 8.58 3.1 '10 10.4 7251 120 2.4 2.2 11.1 7.0 9.00 5.00 1.00 . 00.0304500 6.69 ' 00 * 17.11 2221 ' 33 4 3.12 4 10 "48 " 0.4 ' 8 3.3 ' 3.4 '10 7331 "0048 "140 ' 2.0 ' 1:3 2.1.1 7.0 9.60 500 0.50 30.0 33371 5.27 1.5 - 2.,:., ' 2013 ' 0.0 r 6.5 - 10 - 41 ' 8.77 881 ' 3.4 .00 303 ..
0112 .. 1337 .= 11 ' 2.2 1.1.4 7.0 9.50 43301 0.25 15.0 1320130 7.04 0 2 ' 230 " 26,11 ' 9.2 ' 4.7 .. 17 ' 45 ' 22 4 9.02 ' 1.3 31.0 ... 059 ' 1.5 P. 110 ' 1.9 * 111 2.2.1 '7.0 12.00: 720' 200 120.0 22320 137 0 ,,, ' 240 '224 '8.0 ' s.s r lb r 45 " 8.1 "9.21 ' 13 .71.0 37130 .. 0678 1o77 p2.) . 20 22.? 10 12.20 3.23 1.00 60.0 646.110 733.
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182 ':10 r 0 91 110 11 ..= 7 (Table 23: Analytical Data for Reduction Test Runs) Analytical Results of ECO Tests Table 21 shows analytical data for reduction test runs performed.
AnAytical results from (CO tests lelectro chemical oxidation) heed at Data lime lume matto temp. ratter istripera, TOC DOC
011ograme 04006004 46e na6 vedwaiee reductlee cement swank a time lama= add TOC 6149100evit I WA C V A met pet 416/4 VaAfl.
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Off rata 24.04.2017 vote 250 242 9,9 111 51 WM, C0.1 24042017 OM 1 TO 25 11.4 _10 170 ..31. ad.
7,1 n.d, 1200 60,56 foam:, dJ= =
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ad 34 4.4 56/40 111,11 , eta KO. 3 20,31.7017 09135 1 fie 20 14,2.15,e 10 SS
11-Ø4 25212017 10A0 1 40 26 14,5=16A 10 47 FC0.5 75 64.2017 13,15 I 120 70 14.6.17.11 10 22 a *marks 1 'Aetna defecten Omit ..der tedetattper Afait, ed. 0011 409111104 (Table 21: Analytical Data for Oxidation Test Runs; commas are decimal points) Discussions In total, 46 single reduction tests were performed. At the completion of each test, water samples were taken for analysis. Specific attention was paid to the concentrations of naphthenic acids and phenols. In addition, the change in concentration of various other components was also tracked.
Components like TOC, DOC, oil and grease, silica, H2S and total organic S
showed no change when parameters during reduction tests were changed to optimize for degradation of naphthenic acids and/or phenols. These data support these components typically tending to react chemically with Fe' or to get absorbed by Fe(OH)2. They were not affected by electro-chemical reduction.
Analytical values observed related to naphthenic acids, phenols and total suspended solids (TSS) were assessed.
Removal of Naphthenic Acids - Reduction:
Electro-chemical reduction tests were conducted to measure the effect of parameters like pH, flow rate, temperature, voltage, amperage. This was done by taking one of these parameters as a constant, and testing the effect of the other parameters against this constant. The specific energy, measured in kWh/m3, was chosen as a measure of degradation of naphthenic acids or phenols. This main parameter involved the following single variables: Flow rate, retention time, power input (voltage and amperage). Furthermore, it implied an operating cost and it can be used to compare operating costs of electro-chemical reduction against other operating costs like electro-flotation, etc.
In general, a low rate of removal of naphthenic acids was observed during electro-chemical reduction tests. Figure 31 shows degradation (removal) of naphthenics at pH
values of 5, 7, and 9 (A-C, respectively). pH variation and treatment at room temperature were not material parameters for optimization of degradation of naphthenic acids. Basically, the slope of the degradation curve was almost independent of pH value. Degradation levels observed were generally poor under the conditions tested.
Another important operating parameter is temperature. As previously mentioned, most of the reduction tests were conducted at room temperature to establish general trends. Two runs were also conducted at higher temperature, i.e. 50 C, using a "heat exchanger" set-up. Figure 32 shows degradation of naphthenic acids at pH 7 at temperatures of 20 and 50 C;
and at pH 9 and at temperatures of 20 and 50 C (A and B, respectively). All other parameters were kept constant.
No clear differences in degradation of naphthenic acids by electro-chemical reduction were observed at either 20 or 50 C, nor at pH 7 or pH 9.
Figure 33 compares the degradation of naphthenic acids at room temperature and a pH of 7 with current, as conducted through graphite electrodes, used as a variable.
This figure shows an unusual behavior. All parameters were kept constant, with exception of current, which was changed (3 series) from 5 A, 8.3 A and finally to 10 A. The trend lines for 5 A and 8.3 A show a low level of degradation. At 10 A, no slope was seen for the trend line. The line is flat, indicating no degradation. Under these conditions the specific surface amperage is 24 mA/cm2, which may be too high for the requirement of the reduction reaction using this type of graphite electrode.
Overall, degradation of naphthenic acids by electro-chemical reduction was poor, and apparently independent of temperature, and of changes in pH under the conditions tested.
Removal of Phenols ¨ Reduction:
In addition to the tests for degradation of naphthenic acids by electro-chemical reduction, the behavior of phenols to electro-chemical reduction was also tested. Degradation of phenols is shown in Figure 34 at pH 5, 7, and 9 (A-C, respectively). Degradation rates for phenolics were somewhat higher than the degradation rates observed for naphthenic acids (at least at room temperature). However, operating costs were still high. The behavior at higher temperature (20 C instead of 50 C) was different from the behavior observed for naphthenic acids degradation. Figure 35 shows increasing degradation rates with increasing temperature for phenols (20 and 50 C at pH 7 in A, 20 and 50 C at pH 9 in B).
Electro-chemical reduction treatment for phenols show two different trend lines based on temperature for both pH 7 and for pH 9. This is quite different from the behavior observed for naphthenic acids. A basic projection of behavior to 80 C and 140 C would estimate a 50 %
degradation of phenols at 80 C with operating costs based on about 10 kWh/m3 and a further estimated 50 % degradation of phenols at 140 C with operating costs based on about 6 kWh/m3.
Figure 36 shows the influence of current in the degradation of phenols. The trend lines are according to normal standard and show behavior as expected.
Although the observed degradation of phenols was somewhat faster than the degradation of naphthenic acids, based on the amount of power required to achieve meaningful levels of reduction in naphthenic acid/phenol levels under the conditions tested, this approach was not favoured. As will be understood, an economical decision may influence applications where such treatment may be desired. In certain embodiments, such as where higher energy inputs are not cost prohibitive or otherwise undesirable, such reduction treatment may be employed.
Removal of Naphthenic Acids ¨ Oxidation (ECO):
Specially coated Niobium or Tantalum BDD electrodes may be used to oxidize all organic compounds to carbon dioxide and water and oxides of sulfur and phosphorus through a process called electro-chemical oxidation (ECO). In general, the speed and efficiency of this "ECO"-process is high, i.e. approaching 100% efficiency. Oxidation of organic matter occurs in steps, with some organics oxidized or destroyed immediately, and others in a second or third step or stage of oxidation. The electrodes are non-consumptive and permanent.

Tests were carried out using an ECO lab unit set-up. Figure 37 shows the concentration of naphthenic acids and total organic carbon (TOC) versus treatment time. After 20 min of treatment naphthenic acids concentration was decreased from 18 to 7.1 mg/I, while general TOC concentration was reduced from 250 to 170 mg/l. This shows that naphthenic acids were oxidized faster than the overall mixture of organics in the feedwater.
Figure 38 shows that removal of naphthenic acids took place much faster than the total removal of organic carbon. At the point when approximately 50 % of naphthenic acids are removed, only 30 % of total organics are removed (based on 18 mg/1 naphthenic acids in feed and 250 mg/I TOC in feed). These values may be optimized using different geometries for electrodes.
Figure 37 shows the reduction in naphthenic acids and TOC over time using a small electrode package with a separation of 2 mm between electrodes. During the first run the temperature increase was measured in the beaker containing the process water and the electrodes. The beaker was not cooled. In subsequent tests, a water bath was used to cool down the beaker during treatment. Energy input is defined by voltage and amperage. Energy output can be measured by the temperature increase of the test water. Temperature increase can be caused by:
oxidation heat of organic matter through use of these electrodes, and heat from unused energy, used to generate radicals that are not used to oxidize organics.
It is estimated that the degradation of naphthenic acids in a properly designed ECO plant may even reach about 100% efficiency, or about 20 times faster than what was observed in these initial studies. Figure 39 shows estimated design values for an ECO plant. As shown, it is estimated that a reduction of naphthenic acids from 18 to about 3.4 mg/1 may take a residence time of about 2 min. The final content of TOC may be around 100 mg/1 at this point.
Discussions:
Lab tests with ECO have shown that electro-chemical oxidation was effective in removing naphthenic acids. It is also known that phenols are effectively and efficiently removed by ECO, and that the reaction time is as fast for phenols as for naphthenic acids, possibly even faster.
Of interest was an observed destruction of naphthenic acids at the initial stage of the oxidation process, especially when compared to the overall oxidation of TOC's. After 20 minutes of treatment, concentration of naphthenic acids was decreased from 18 to 7.1 mg/1, a reduction of 61%, while general TOC concentration was only reduced from 250 to 170 mg/1, a reduction of 32%. This supports that the destruction of naphthenic acids took place quickly and early in the oxidation reaction process.
Based on this, a rough calculation on the efficiency of ECO for the destruction of naphthenic acids in an industrial sized set-up was made. In certain embodiments, it may be possible to reduce naphthenic acid levels from about 18mg/1 untreated to about 3mg/1 with a plant residence time of about 2 minutes.
In certain embodiments, ECO may offer a beneficial additional finishing treatment step, after water treatment and before water is used in steam generation of SAGD, for example.
Results obtained further indicate that in certain embodiments, using ECO to provide oxidizing conditions to destroy flocculation inhibiting compound(s) in the contaminated water may additionally provide for removal of naphthenic acids/naphthenates and/or phenols, in addition to certain other organics when present in the contaminated water.
EXAMPLE 7 ¨Additional Water Treatment System Design Configurations Particular embodiments of methods and systems for treating contaminated water are described in this Example. The following exemplified water treatment system and method embodiments each include a reducing (chemical or electrical) or oxidizing (chemical or electrical) unit/step which subjects the contaminated water to reducing or oxidizing conditions; a separation unit/step for removing flocs/contaminant(s) from the contaminated water (in these examples, a filtration or floatation-based separation unit/step); and an input/step of introduction for a flocculating ion (in these examples, iron ions) into the contaminated water to cause flocculation. The exemplified system and method embodiments may optionally further include one or more inputs/addition steps for optionally inputting one or more of the following additional agents: an H2S scavenger; a pH adjustment agent; a chelant; a sulphite; and/or a polymer. These examples are intended for non-limiting purposes to illustrate that a wide variety of configurations and sequences of operations of systems and methods as described herein are contemplated, which may be employed depending on the particular application.
By way of example, a preferred exemplary process sequence for treating a contaminated water may include the following:
Reduction (Chemical or Electrical) ¨> H2S Scavenger (optional) ¨> Iron Rich Water ¨>
pH Adjustment (optional) --> Separation (optional) ¨> Chelant (optional) -->
Sulphite (optional) The present inventors have identified that flocks form particularly well when iron-rich water is added to the contaminated water at a suitable pH, such as a pH between about 7-11. It has further been identified that for treating contaminated water which contains, or which may contain, one or more flocculation inhibiting compound(s), a reduction or oxidation step may be performed prior to flocculation, so as to destroy/degrade/remove the flocculation inhibiting compound(s) (if present). As well, it has been observed that adding an H2S
scavenger prior to flocculation may be used to suppress the negative impact of sulfur on flocculation. A chelant may be used after flocculation and separation, so as to reduce scaling properties of the treated water without interfering with the flocculating ions used for flocculation/separation. Sulphite may be used to attack oxygen, and may be introduced at generally any suitable process stage.
The inventors have additionally identified that a one- or two-stage pH
adjustment may be performed to assist with flocculation and contaminant removal. By way of example, a pH
adjustment to a pH of about 7 to about 11 may be performed at generally any suitable stage prior to or during flocculation to assist with flocculation. Where a two-stage pH adjustment is used, the pH may be adjusted to a pH of about 2-4 to make silica in the contaminated water reactive at generally any suitable stage prior to flocculation, and the pH may then be adjusted to a pH of about 7 to about 10 prior to or during the flocculation step to promote flocculation and contaminant removal.
The inventors have further identified that where an oxidation step is used to destroy/degrade/remove flocculation inhibiting compound(s) from the contaminated water, such oxidation may additionally remove certain organics from the contaminated water.
Furthermore, where output treated water still contains at least some organics, a downstream oxidation step may be performed on the treated water to remove organics therefrom. In certain embodiments, an oxidation step may be used two or more times during water treatment, for example.
Based on these observations, and the studies described in detail throughout the present specification, additional examples of exemplary process sequences of methods and systems for treating a contaminated water as described herein may include one or more of the following:
= Reduction -->
Scavenger ¨> Iron Rich Water ---> pH Adjustment ¨> Separation ¨>
Chelant = Oxidation ¨> Scavenger ¨> Iron Rich Water ¨> pH Adjustment ¨> Separation ¨>
Chelant = Reduction pH Adjustment ¨> Scavenger ¨> Iron Rich Water ¨> Separation ¨>
Chelant = pH Adjustment --> Reduction ¨> Scavenger ¨> Iron Rich Water Separation Chelant = pH Adjustment --> Scavenger ¨> Reduction ¨> Iron Rich Water -->
Separation ¨>
Chelant = Reduction ¨> Scavenger ¨> Iron Rich Water ¨> pH Adjustment ¨> Separation ¨>
Oxidation ¨> Separation ¨> Chelant = Reduction ¨> Scavenger ¨> Iron Rich Water ¨> pH Adjustment ¨* Separation ¨>
Oxidation ¨> Chelant ¨> Separation = Oxidation ¨> Scavenger --> Iron Rich Water ¨> pH Adjustment ¨* Separation --->
Oxidation ¨> Chelant ¨> Separation = Oxidation ¨> pH Adjustment ¨> Scavenger ¨> Iron Rich Water ¨* Separation ¨>
Oxidation ¨> Chelant ¨> Separation = Iron Rich Water ¨* Scavenger ¨> Reduction ¨> pH Adjustment ¨> Separation ¨>
Chelant The person of skill in the art having regard to the teachings herein will understand that various other configurations may be possible, and may be employed to suit the particular application.
These examples are provided for illustrative purposes to demonstrate that a variety of configurations/sequences are contemplated herein.

One or more illustrative embodiments have been described by way of example. It will be understood to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.

Claims

WHAT IS CLAIMED IS:

1. A method for treating a contaminated water, said method comprising:
subjecting the contaminated water to reducing or oxidizing conditions;
introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water;
thereby producing a treated water.

2. The method according to claim 1, wherein the flocculating ion comprises iron, aluminum, or a combination thereof.

3. The method according to claim 1 or 2, wherein the step of subjecting the contaminated water to reducing or oxidizing conditions comprises a step of electroreduction.

4. The method according to claim 3, wherein the step of electroreduction uses one or more non-sacrificial electrodes.

5. The method according to claim 1 or 2, wherein the step of subjecting the contaminated water to reducing or oxidizing conditions comprises a step of electrooxidation.

6. The method according to claim 5, wherein the step of electrooxidation uses one or more non-sacrificial electrodes.

7. The method according to claim 1 or 2, wherein the step of subjecting the contaminated water to reducing conditions comprises a step of chemical reduction.

8. The method according to claim 7, wherein the step of chemical reduction uses a chemical reduction agent which is NaHSO3, Na2SO3, Na2S2O4, Na2S2O3, nascent hydrogen, or a combination thereof.

9. The method according to claim 1 or 2, wherein the step of subjecting the contaminated water to oxidizing conditions comprises a step of chemical oxidation.

10. The method according to claim 9, wherein the step of chemical oxidation uses a chemical oxidation agent which is H2O2, NaOCl, or a combination thereof.

11. The method according to any one of claims 1-10, wherein the flocculating ion-enriched aqueous solution comprises an aqueous solution of Fe2+ ions.

12. The method according to any one of claims 1-11, wherein the flocculating ion-enriched aqueous solution comprises a solution generated: by electro-flocculation using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in water; from a solution of iron vitriol;
or a combination thereof.

13. The method according to any one of claims 1-12, wherein the flocculating ion-enriched aqueous solution is introduced into the contaminated water as a slipstream.

14. The method according to any one of claims 1-13, wherein the introducing of the flocculating ion-enriched aqueous solution comprises: a step of pH adjustment to render silica or other ionic contaminants in the contaminated water reactive; a step of pH
adjustment to promote formation of the flocculating ion flocks; or a combination thereof.

15. he method according to claim 14, wherein the step of pH adjustment to render silica or other ionic contaminants in the contaminated water reactive comprises adjusting the pH to between about 2 and about 4.

16. The method according to claim 15, wherein the pH is adjusted using HCl, H2SO4, another acid, or a combination thereof

17. The method according to claim 14, wherein the step of pH adjustment to promote formation of the flocculating ion flocs comprises adjusting the pH to between about 7 and about 11.

18. The method according to claim 17, wherein the pH is adjusted using NaOH, steam blowdown, another base, or a combination thereof

19. The method according to any one of claims 1-18, which further comprises adding an H2S scavenger, a chelant, a polymer, a sulphite, or a combination thereof to the contaminated water during treatment.

20. The method according to any one of claims 1-19, wherein the flocculating ion flocs are separated using filtration or flotation.

21. The method according to any one of claims 1-20, wherein the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.

22. The method according to claim 21, wherein the contaminated water is maintained at or above about 80 °C during treatment.

23. The method according to claim 22, wherein the contaminated water is maintained at or above about 100 °C during treatment.

24. The method according to any one of claims 1-23, wherein the contaminated water is a produced water.

25. The method according to claim 24, wherein the produced water is a produced water from a SAGD operation.

26. The method according to any one of claims 1-25, wherein the one or more contaminants removed from the contaminated water comprise calcium, magnesium, silica, an organic contaminant, or a combination thereof.

27. The method of any one of claims 1-26, further comprising a step of subjecting the treated water to an electrochemical oxidation treatment or a chemical oxidation treatment to render organics in the treated water insoluble, and separating the organics from the treated water.

28. A method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam, water, or a combination thereof into the subterranean reservoir;

producing a produced water and a hydrocarbon to the surface;
treating at least a portion of the produced water using a method according to any one of claims 1-27 thereby generating a treated water stream; and using the treated water stream to provide steam, water, or a combination thereof for re-injection into the subterranean reservoir to produce more hydrocarbons to the surface.

29. A method for producing hydrocarbons from a subterranean reservoir, said method comprising:
injecting steam into the subterranean reservoir via an injection well;
producing a produced water stream and a hydrocarbon stream to the surface via a production well, or producing a mixed produced water and hydrocarbon emulsion stream from the subterranean reservoir via a production well and separating the mixed produced water and hydrocarbon emulsion stream into a produced water stream and a hydrocarbon stream;
treating at least a portion of the produced water stream using a method according to any one of claims 1-27, thereby generating a treated water stream; and using the treated water stream to provide steam for re-injection into the subterranean reservoir via the same or a different injection well to produce more hydrocarbons to the surface.

30. A system for treating contaminated water, the system comprising:
an input for a contaminated water;
a reducing or oxidizing unit configured to receive the contaminated water from the input and generate reducing or oxidizing conditions in the contaminated water;
a separation unit downstream of the reducing or oxidizing unit and in fluid communication therewith, the separation unit configured to receive the contaminated water from the reducing or oxidizing unit and remove flocculating ion flocks with captured contaminant from the contaminated water;
an input for a flocculating ion-enriched aqueous solution, the input configured for introducing the flocculating ion-enriched aqueous solution into the contaminated water upstream of the separation unit, at the separation unit, or a combination thereof; and an output for outputting a treated water from the separation unit.

31. The system according to claim 30, wherein the flocculating ion comprises iron, aluminum, or a combination thereof.

32. The system according to claim 30 or 31, wherein the reducing or oxidizing unit comprises an electroreduction apparatus for generating reducing conditions in the contaminated water.

33. The system according to claim 32, wherein the electroreduction apparatus comprises one or more non-sacrificial electrodes.

34. The system according to claim 32, wherein the electroreduction apparatus comprises an input for introducing a chemical reductant for generating reducing conditions in the contaminated water.

35. They system according to claim 34, wherein the chemical reductant is NaHSO3, Na2SO3, Na2S2O4, Na2S2O3, nascent hydrogen, or a combination thereof.

36. The system according to claim 30 or 31, wherein the reducing or oxidizing unit comprises an electrooxidation apparatus for generating oxidizing conditions in the contaminated water.

37. The system according to claim 36, wherein the electrooxidation apparatus comprises one or more non-sacrificial electrodes.

38. The system according to claim 36, wherein the electrooxidation apparatus comprises an input for introducing a chemical oxidant for generating oxidizing conditions in the contaminated water.

39. The system according to claim 38, wherein the chemical oxidant is H2O2, NaOCl, or a combination thereof

40. The system according to any one of claims 30-39, wherein the flocculating ion-enriched aqueous solution comprises an aqueous solution of Fe2+ ions.

41. The system according to any one of claims 30-40, wherein the flocculating ion-enriched aqueous solution comprises a solution generated: by electro-flocculation using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in water; from a solution of iron vitriol;
or a combination thereof.

42. The system according to any one of claims 30-41, wherein the input for the flocculating ion-enriched aqueous solution comprises a slipstream line.

43. The system according to any one of claims 30-42, which further comprises at least one input for a pH adjustment agent for: adjusting pH to render silica or other ionic contaminants in the contaminated water reactive; adjusting pH to promote formation of the flocculating ion flocks; or a combination thereof

44. The system according to claim 43, wherein the adjusting the pH to render silica or other ionic contaminants in the contaminated water reactive comprises adjusting the pH to between about 2 to about 4.

45. The system according to claim 44, wherein the pH adjustment agent comprises HCl, H2SO4, another acid, or a combination thereof

46. The system according to claim 43, wherein the adjusting the pH to promote formation of the flocculating ion flocks comprises adjusting the pH to a range between about 7 and about 11.

47. The system according to claim 46, wherein the pH adjustment agent comprises NaOH, steam blowdown, another base, or a combination thereof.

48. The system according to any one of claims 30-47, which further comprises one or more inputs configured for introducing an H2S scavenger, a chelant, a polymer, a sulphite, or a combination thereof to the contaminated water.

49. The system according to any one of claims 30-48, wherein the separation unit comprises a filtration apparatus or a flotation apparatus for separating flocculating ion flocs from the contaminated water.

50. The system according to any one of claims 30-49, which is configured to maintain the contaminated water at high temperature throughout treatment, thereby generating the treated water at high temperature.

51. The system according to claim 50, which is configured to maintain the contaminated water at or above about 80°C during treatment.

52. The system according to claim 50, which is configured to maintain the contaminated water at or above about 100°C during treatment.

53. The system according to any one of claims 30-52, wherein the contaminated water comprises a produced water.

54. The system according to claim 53, wherein the produced water is a produced water from a SAGD operation.

55. The system according to any one of claims 30-54, wherein the one or more contaminants removed from the contaminated water by the system comprise calcium, magnesium, silica, an organic contaminant, or a combination thereof.

56. The system according to any one of claims 30-55, further comprising:
downstream electrochemical oxidation unit which is configured to receive the treated water output from the separation unit and to subject the treated water to an electrochemical oxidation treatment to render organics in the treated water insoluble; and a downstream organics separation unit for removing insoluble organics from the treated water.

57. The system according to any one of claims 30-55, further comprising:

a downstream chemical oxidation unit which is configured to receive the treated water output from the separation unit and to subject the treated water to a chemical oxidation treatment to rendering organics in the treated water insoluble; and a downstream organics separation unit for removing insoluble organics from the treated water.

58. A system for producing hydrocarbons from a subterranean reservoir, the system comprising:
a wellbore system comprising at least one well contacting the subterranean reservoir, wherein the wellbore system is configured for injecting steam, water, or a combination thereof into the subterranean reservoir and for producing a produced water and a hydrocarbon to the surface; and a system for treating contaminated water as defined in any one of claims 30-57, wherein the system for treating contaminated water is configured: (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the wellbore system or to a different wellbore system for re-injection into the subterranean reservoir.

59. A system for producing hydrocarbons from a subterranean reservoir, the system comprising:
an injection well and a production well contacting the subterranean reservoir, wherein the injection well is configured for injecting steam into the subterranean reservoir, and wherein the production well is configured for producing a produced water stream and a hydrocarbon stream, or a mixed produced water and hydrocarbon emulsion stream, to the surface; and a system for treating contaminated water as defined in any one of claims 30-57, wherein the system for treating contaminated water is configured: (i) to receive at least a portion of the produced water from the subterranean reservoir at the input for the contaminated water, (ii) to treat the produced water, and (iii) to return treated water from the output to the same, or a different, injection well for re-injection into the subterranean reservoir.

60. The system of claim 59, wherein the injection well and the production well are a SAGD
well pair.

61. A method for treating a contaminated water, said method comprising:
introducing a flocculating ion-enriched aqueous solution into the contaminated water; and removing at least some of at least one contaminant from the contaminated water by ion flocculation, whereby the contaminant is captured with flocculating ion flocks which are then separated from the contaminated water;
thereby producing a treated water.

62. The method according to claim 61, wherein the flocculating ion-enriched aqueous solution is introduced into the contaminated water as a side-stream or a slip-stream.

63. The method according to claim 61 or 62, wherein the flocculating ion-enriched aqueous solution is generated: by electro-flocculation of a carrier water using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in a carrier water; from a solution of iron vitriol; or a combination thereof.

64. The method according to any one of claims 61-63, wherein the ion flocculation comprises adjusting the pH to render silica or other ionic contaminants in the contaminated water reactive.

65. The method according to any one of claims 61-63, wherein the ion flocculation comprises adjusting the pH to promote formation of the flocculating ion flocks.

66. The method according to any one of claims 61-65, wherein the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.

67. A system for treating contaminated water, the system comprising:

an input for a contaminated water;
a separation unit configured to receive the contaminated water and remove flocculating ion flocks with captured contaminant from the contaminated water;
an input for a flocculating ion-enriched aqueous solution, the input configured for introducing the flocculating ion-enriched aqueous solution into the contaminated water upstream of the separation unit, at the separation unit, or a combination thereof; and an output for outputting a treated water from the separation unit.

68. The system according to claim 67, wherein the input for the flocculating ion-enriched aqueous solution is a side-stream or a slip-stream.

69. The system according to claim 67 or 68, wherein the flocculating ion-enriched aqueous solution is generated: by electro-flocculation of a carrier water using a sacrificial iron electrode, a sacrificial aluminum electrode, or a combination thereof; by dissolving an iron salt, an aluminum salt, or a combination thereof in a carrier water; from a solution of iron vitriol; or a combination thereof.

70. The system according to claim 67 or 68, wherein the flocculating ion comprises iron, aluminum, or a combination thereof.

71. The system according to any one of claims 67-70, which further comprises at least one input for a pH adjustment agent for: adjusting pH to render silica or other ionic contaminants in the contaminated water reactive; adjusting pH to promote formation of the flocculating ion flocks; or a combination thereof.

72. The system according to any one of claims 67-71, wherein the contaminated water is maintained at high temperature throughout treatment, thereby generating the treated water at high temperature.