WO2016157176A1 - Methods and systems for water recovery - Google Patents

Abstract

Disclosed are methods and systems for water recovery. The method comprises, inter alia, providing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes; extracting at least a portion of the wastewater stream with an extractant comprising an organic bi-directional solvent to form a water-depleted first aqueous solution and a water- enriched first organic phase; mixing the first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution; and fractionating the second organic phase into a stream enriched in the bi-directional solvent and a stream enriched in the hydrophobic solvent.

Description

METHODS AND SYSTEMS FOR WATER RECOVERY

This application claims priority from U.S. Patent Application No. 62/139,735, filed on March 29, 2015. The content of the above document is incorporated by reference as if fully set forth herein.

FIELD OF THE INVENTION

The invention relates, in some embodiments thereof, to the field of water treatment.

BACKGROUND OF THE INVENTION

Water, like many other natural resources, is present on earth in a finite amount. More than 95% of the water on Earth is present as brackish water or sea water containing a salt concentration which renders it unsuitable for many purposes.

It is estimated that more than two thirds of the remaining non-salty water is present as ice, primarily in polar caps and glaciers.

This means less than 1% of the water on earth is available as fresh water.

This small fraction of fresh water must sustain not only life, but industry. Although the demand for potable water increases with the world's population, direct consumption of water by man (i.e. drinking water) and indirect consumption by man (e.g. bathing, laundry, in sanitary installations) makes up a relatively small percentage of total water consumption in the world.

The bulk of total water consumption in the world is in industrial processes, including use as a cooling medium.

For example, The National Energy Board of Canada (2006) estimated that about 2 to 4.5 barrels of fresh water are used to produce a barrel of synthetic crude oil. Total water consumption for production of synthetic crude was projected to reach 529 million cubic meters/year. Wastewater from synthetic crude oil production is alkaline, and brackish.

Induced hydraulic fracturing (A.K.A. fracking) for production of natural gas and other petrochemicals from shale also consumes significant amounts of water. It is estimated that 20% to more than 40% of fracking water is recovered either as flow-back water or as produced water. In the state of Pennsylvania alone the amount of high-TDS (total dissolved solids) wastewater produced by fracking and needing disposal was projected to reach to 7300 million gallons per year in 2011 by the natural gas industry. Levels of salt in fracking water can be more than six times higher than in sea water.

SUMMARY OF THE INVENTION

A broad aspect of the invention relates, in some embodiments thereof, to treating a wastewater stream. According to an embodiment, the treating separates usable water from the wastewater.

According to an aspect of some embodiments of the present invention, there is provided a method comprising:

(a) providing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes

(b) extracting at least a portion of the wastewater stream with an extractant comprising an organic bi-directional solvent to form a water-depleted first aqueous solution and a water-enriched first organic phase;

(c) mixing the first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution, and

(d) fractionating the second organic phase into a stream enriched in the bidirectional solvent and a stream enriched in the hydrophobic solvent;

wherein water solubility in the bi-directional solvent is greater than water solubility in the hydrophobic solvent.

In some embodiments, the method further comprises the steps of: (e) reusing the stream enriched in the bi-directional solvent in the extracting, and (f) reusing the stream enriched in the hydrophobic solvent in the mixing.

In some embodiments, the fractionating comprises heating the separated second organic phase.

In some embodiments, the displaced aqueous solution comprises at least a portion of the bi-directional solvent.

In some embodiments, the method further comprises treatment of the displaced aqueous solution to form a separated water and a third organic phase. In some embodiments, the treatment include separation of at least part of the third organic phase by stripping.

In some embodiments, the treatment include separation of at least part of the third organic phase by hydrophobic solvent extracting.

In some embodiments, the method further comprises recycling at least a portion of the third organic phase to the separated second organic phase.

In some embodiments, the displaced aqueous solution comprises at least 60% of the water in the wastewater stream.

In some embodiments, the one or more crude-oil-associated hydrophobic solutes comprise at least one member of the group consisting of naphthenic acid, other organic acids comprising at least 5 carbon atoms, 1,4-dioxane, acetone, bromoform, dibenzo(a,h)anthracene, pyridine, phenols, oil, vegetable oil and synthetic oil.

In some embodiments, the second organic phase comprises at least 85% of the one or more crude-oil-associated hydrophobic solutes in the wastewater stream.

In some embodiments, the method comprises recycling at least 50% of water from the wastewater stream to an industrial process producing the wastewater stream.

In some embodiments, the wastewater stream is produced in an industrial process selected from the group consisting of recovering crude oil, processing crude oil, production of synthetic oil, processing synthetic oil, production of vegetable oil and processing vegetable oil.

In some embodiments, the wastewater stream is produced in an industrial process selected from the group consisting of: crude oil production from oil sand, steam-assisted gravity drainage (SAGD), induced hydraulic fracturing (fracking), petroleum industry processes, enhanced oil recovery (EOR), synthetic oil production and vegetable oil production.

In some embodiments, the wastewater stream comprises a blowdown of steam generation.

In some embodiments, the bi-directional solvent comprises one or more oxygen- comprising organic molecules with 3 to 6 carbon atoms.

In some embodiments, the bi-directional solvent comprise one or more members of the group consisting of alcohols, ketones, esters, phenols and organic acids. In some embodiments, the bi-directional solvent comprises one or more members of the group consisting of normal butanol, secondary butanol, isobutanol, tertiary butanol, normal pentanol, secondary pentanol, isopentanol and tert amyl alcohol.

In some embodiments, the bi-directional solvent is selected so that the ratio between the one or more hydrophilic solutes to the one or more crude-oil-associated hydrophobic solutes is at least three times greater in the water-depleted first aqueous solution compared with that in the wastewater stream.

In some embodiments, the method further comprises separating at least a portion of said one or more crude-oil-associated hydrophobic solutes from said second organic phase.

In some embodiments, the method further comprises separating at least a portion of the one or more crude-oil-associated hydrophobic solutes from the stream enriched in the bi-directional solvent. In some embodiments, the separating comprises evaporating.

In some embodiments, the hydrophobic solvent solubility in the bi-directional solvent is greater than water solubility in the bi-directional solvent at same temperature.

In some embodiments, the hydrophobic solvent is fully miscible with the bidirectional solvent at 25°C.

In some embodiments, the hydrophobic solvent comprises one or more hydrocarbons with 4 to 10 carbon atoms.

In some embodiments, the hydrophobic solvent comprises one or more members of the group consisting of hexane, cyclohexane, heptane, butane, pentane and cyclopentane.

In some embodiments, the method comprises conducting the extracting, or the mixing or both, in a counter current mode.

In some embodiments, the weight ratio between extractant and wastewater stream in the extracting is in the range between 2 and 20.

In some embodiments, the weight ratio between the hydrophobic solvent and the first organic phase in the mixing is in the range of between 0.1 and 2.

According to an aspect of some embodiments of the present invention, there is provided a system comprising:

(a) a wastewater source producing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes; (b) an extractant source comprising an extractant including an organic bidirectional solvent;

(c) an extraction module in fluid communication with the extractant source and adapted to contact the extractant with at least a portion of the wastewater stream to form a water-depleted first aqueous solution and a water-enriched first organic phase;

(d) a mixing module adapted to receive the first organic phase and mixing the first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution;

(e) a fractionation module adapted to fractionate the second organic phase to a stream enriched in the hydrophobic solvent and a stream enriched in said bi-directional solvent;

(f) a pump adapted to route at least a portion of said stream enriched in said bidirectional solvent as recycled extractant to said extraction module, and

(g) a pump adapted to route at least a portion of the stream enriched in the hydrophobic solvent to the mixing module.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although suitable methods and materials are described below, methods and materials similar or equivalent to those described herein can be used in the practice of the present invention. In case of conflict, the patent specification, including definitions, will control. All materials, methods, and examples are illustrative only and are not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying figures. In the figures, identical and similar structures, elements or parts thereof that appear in more than one figure are generally labeled with the same or similar references in the figures in which they appear. Dimensions of components and features shown in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily to scale. The attached figures are: Fig. 1 is a schematic flow plan of a wastewater treatment process according to an exemplary embodiment of the invention depicting procedures and streams;

Fig. 2 is a schematic representation of a wastewater treatment system according to some exemplary embodiments of the invention.

DETAILED DESCRIPTION

Embodiments of the invention relate to methods and systems for treating wastewater and optionally for recovery of useable water as well as to various streams produced by the recovery process.

Specifically, some embodiments of the invention can be used to recover reusable water from wastewater produced in an industrial process.

The principles and operation of a methods and/or systems according to exemplary embodiments of the invention may be better understood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

In some exemplary embodiments of the invention, the wastewater stream is an effluent from an industrial process and the usable water is sufficiently pure to be re-used in the same industrial process.

Another aspect of some embodiments of the invention relates to recovery of usable water from the wastewater stream with no solids treatment, such as precipitation and/or crystallization of solutes.

One aspect of some embodiments of the invention relates to treatment of a wastewater stream containing one or more hydrophilic solutes and one or more hydrophobic solutes. In some exemplary embodiments of the invention, the hydrophobic solutes comprise crude-oil-associated hydrophobic solutes.

As used in this specification and the accompanying claims, the terms "wastewater stream" and "product process water" are interchangeable or the "wastewater stream" comprises "product process water". Hence, according to an embodiment, the wastewater stream comprises product process water mixed with another stream. According to an embodiment, the other stream comprises make-up water. According to a related embodiment, the make-up water comprises brackish water or sea water. In some embodiments, the term "make-up water" refers to brackish water or sea water that has been treated.

As used in this specification and the accompanying claims the term "crude-oil- associated" indicates materials present in crude oil (i.e. unrefined oil), materials produced during refining of crude oil or chemical conversion of crude oil, materials present in produced gas, materials produced during refining of produced gas or chemical conversion of produced gas. According to various exemplary embodiments of the invention, the term "crude oil" includes fossil oil and/or vegetable oil (e.g. Palm Oil Mill Effluent - POME). In some embodiments, crude-oil-associated hydrophobic solutes are present in the wastewater stream at concentrations of 10 PPM, 25 PPM, 50 PPM 100 PPM, 200 PPM, 300 PPM, 400 PPM or 500 PPM or intermediate or higher concentrations.

In some exemplary embodiments of the invention, there is provided method including: (a) providing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes; (b) extracting at least a portion of the wastewater stream with an extractant comprising an organic bi-directional solvent to form a water-depleted first aqueous solution and a water-enriched first organic phase; (c) mixing first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution; (d) fractionating second organic phase into a stream enriched in bi-directional solvent and a stream enriched in hydrophobic solvent. In some embodiments, the water solubility in the bi-directional solvent is greater than water solubility in the hydrophobic solvent.

Additionally, in some embodiments, the method further includes (e) reusing stream enriched in bi-directional solvent in the extracting; and (f) reusing stream enriched in hydrophobic solvent in the mixing.

According to an embodiment, the bi-directional solvent comprises one or more oxygen-comprising organic molecules. In some embodiments, the organic molecule comprises 3 to 6 carbon atoms.

In some embodiments, the organic molecule is or comprises, without limitation, one or more members of the group consisting of alcohols, ketones, esters, phenols and organic acids, substituted, or non-substituted. According to an embodiment, the bi- directional solvent include, but are not limited to, alcohols of 3 to 6 carbon atoms and/or ketones of 3 to 6 carbon atoms and/or esters of 3 to 6 carbon atoms and/or organic acids of 3 to 6 carbon atoms and/or amines. In some embodiments, the bi-directional solvent includes butanol. In some embodiments, butanol is the primary active component in a mixture of bi-directional solvents. In some embodiments, butanol serves as the sole active bi-directional solvent. Alternatively or additionally, in some embodiments one or more bidirectional solvents comprise one or more members of the group consisting of butanol, e.g., primary butanol, secondary butanol, isobutanol, tertiary butanol, normal pentanol, secondary pentanol, isopentanol and tert amyl alcohol. Alternatively or additionally, in some embodiments, one or more bi-directional solvents are provided as an extractant. Optionally, the extractant further includes components which are not bi-directional solvents. According to an embodiment, the extractant comprises water.

According to an embodiment the bi-directional solvent is selected so that the ratio between the one or more hydrophilic solutes to the one or more crude-oil-associated hydrophobic solutes is at least three times greater in the water-depleted first aqueous solution compared with that in the wastewater stream.

Examples of hydrophobic solvents include, but are not limited to, one or more members of the group consisting of hexane, cyclohexane, heptane, butane, pentane and cyclopentane.

Alternatively or additionally, in some embodiments, the fractionating comprises heating separated second organic phase.

Alternatively or additionally, in some embodiments the displaced aqueous solution comprises at least a portion of the bi-directional solvent.

Alternatively or additionally, in some embodiments, the method further comprises treatment of the displaced aqueous solution to form a separated water and a third organic phase.

Alternatively or additionally, in some embodiments the treatment includes separation of at least part of the third organic phase by stripping.

Alternatively or additionally, in some embodiments, the treatment includes separation of at least part of the third organic phase by hydrophobic solvent extracting. Alternatively or additionally, in some embodiments, the method further comprises recycling at least a portion of the third organic phase to the separated second organic phase. Alternatively or additionally, in some embodiments, the displaced aqueous solution comprises at least 60% of the water in wastewater stream.

Alternatively or additionally, in some embodiments, the one or more crude-oil- associated hydrophobic solutes comprise at least one member of the group consisting of other organic acids comprising at least 5 carbon atoms (e.g., naphthenic acid), 1,4- dioxane, acetone, bromoform, dibenzo(a,h)anthracene, pyridine, phenols, and oil, e.g., vegetable oil or Synthetic oil.

Alternatively or additionally, in some embodiments, the second organic phase comprises at least 85% of the one or more crude-oil-associated hydrophobic solutes in the wastewater stream.

Alternatively or additionally, in some embodiments, the method includes recycling at least 50% of the water from the wastewater stream to an industrial process producing the wastewater stream.

Alternatively or additionally, in some embodiments, the wastewater stream is produced in an industrial process selected from the group consisting of, without limitation, recovering crude oil, processing crude oil, production of synthetic oil, processing synthetic oil, production of vegetable oil and processing vegetable oil

Alternatively or additionally, in some embodiments, the wastewater stream is produced in an industrial process selected from, without limitation, the group consisting of, crude oil production from oil sand, steam-assisted gravity drainage (SAGD), induced hydraulic fracturing (fracking), petroleum industry processes, enhanced oil recovery (EOR), synthetic oil production and vegetable oil production.

Alternatively or additionally, in some embodiments, the wastewater stream comprises a blowdown of steam generation.

Alternatively or additionally, in some embodiments, the method further comprises separating at least a portion of the one or more crude-oil-associated hydrophobic solutes from the second organic phase.

In some embodiments, the term "portion" refers to e.g., 0.01%, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 30%, 40% 50%, 60%, 70%, 80%, 90%, 95%, 99%, by weight, including any value and range therebetween.

Alternatively or additionally, in some embodiments, the method further comprises separating at least a portion of the one or more crude-oil-associated hydrophobic solutes from the stream enriched in bi-directional solvent. Alternatively or additionally, in some embodiments, the separating at least a portion of the one or more crude-oil-associated hydrophobic solutes comprises evaporating.

Alternatively or additionally, in some embodiments, the hydrophobic solvent solubility in the bi-directional solvent is greater than water solubility in the bi-directional solvent at the same temperature.

Alternatively or additionally, in some embodiments, the hydrophobic solvent is fully miscible with the bi-directional solvent at 25°C

By "fully miscible" it is meant that the liquids may mix with each other in any proportion.

Alternatively or additionally, in some embodiments, the hydrophobic solvent comprises one or more hydrocarbon having 4 to 10 carbon atoms. According to another embodiment, the hydrophobic solvent is characterized by a C:0 ratio of at least 2 times greater than that a ratio in the bi-directional solvent.

Alternatively or additionally, in some embodiments, the hydrophobic solvent comprises, without limitation, one or more members of the group consisting of hexane, cyclohexane, heptane, butane, pentane and cyclopentane.

Alternatively or additionally, in some embodiments, the extracting, or the mixing or both are conducted in a counter current mode.

Alternatively or additionally, in some embodiments, the weight ratio between extractant and wastewater stream in the extracting is in the range of between 2 and 20.

Alternatively or additionally, in some embodiments, the weight ratio between the hydrophobic solvent and the first organic phase in the mixing is in the range of between 0.1 and 2.

According to various exemplary embodiments of the invention, the extracting is conducted at conditions (e.g., temperature and pressure) wherein in the extractant and wastewater stream are liquids.

According to various exemplary embodiments of the invention, the mixing is conducted at conditions (e.g., temperature and pressure) wherein the hydrophobic solvent and the first organic phase are liquids.

According to various exemplary embodiments of the invention, the extracting is conducted at atmospheric pressure and at temperature higher than 1°C, 10°C, 20°C, 30°C or 40°C and lower than 99°C, 90°C, 80°C, 70°C or 60°C. According to various exemplary embodiments of the invention, the mixing is conducted at atmospheric pressure and at temperature higher than 1°C, 10°C, 20°C, 30°C or 40°C and lower than 99°C, 90°C, 80°C, 70°C or 60°C.

According to various exemplary embodiments of the invention, the extracting is conducted at temperature higher than 1°C, 10°C, 20°C, 30°C or 40°C and lower than 200°C, 180°C, 160°C, 140°C or 100°C.

According to various exemplary embodiments of the invention, the mixing is conducted at temperature higher than 1°C, 10°C, 20°C, 30°C or 40°C and lower than 200°C, 180°C, 160°C, 140°C or 100°C.

In some exemplary embodiments of the invention, there is provided a system including: (a) a wastewater source producing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes; (b) an extractant source comprising an extractant including an organic bi-directional solvent; (c) an extraction module in fluid communication with the extractant source and adapted to contact the extractant with at least a portion of the wastewater stream to form a water- depleted first aqueous solution and a water-enriched first organic phase; (d) a mixing module adapted to receive the first organic phase and mixing the first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution;

(e) a fractionation module adapted to fractionate the second organic phase to a stream enriched in the hydrophobic solvent and a stream enriched in the bi-directional solvent;

(f) a pump adapted to route at least a portion of the stream enriched in the bi-directional solvent as recycled extractant to the extraction module, and (g) a pump adapted to route at least a portion of the stream enriched in the hydrophobic solvent to the mixing module.

In some embodiments, the term "fluid communication" means fluidically interconnected, and refers to the existence of a continuous coherent flow path from one of the components of the system to the other if there is, or can be established, liquid and/or gas flow through and between the ports even if there exists a valve between the two conduits that can be closed, when desired, to impede fluid flow therebetween. Exemplary wastewater treatment processes overview

Reference is now made to Fig. 1 which is a schematic flow plan of a wastewater treatment process or methods according to an exemplary embodiments of the invention indicated generally as 100.

In the figure, a flow of organic phases is depicted by dashed arrows and a flow of aqueous solutions is depicted by solid arrows.

In the depicted exemplary embodiments, at least a portion of a wastewater stream containing one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes 106 is extracted 110 with an extractant 108 including a bi-directional solvent to form a water-depleted first aqueous solution 116 and a water-enriched first organic phase 118.

In the depicted exemplary embodiments, at least a fraction of the first organic phase 118 is mixed 120 with a hydrophobic solvent 138 to form a second organic phase 128 and a displaced aqueous solution 126.

In the depicted exemplary embodiments, the second organic phase 128 is fractionated 130 to form a stream enriched in the hydrophobic solvent 138 and a stream enriched in the bi-directional solvent 134.

In the depicted exemplary embodiments, the hydrophobic solvent 138 is recycled to mixing 120.

In the depicted exemplary embodiments, 100 the displaced aqueous solution 126 is treated 140 to form separated water 146 and a third organic phase 148.

In the depicted exemplary embodiments, bi-directional solvent in enriched stream 134 is recycled to extracting 110.

In the depicted exemplary embodiments, bi-directional solvent is recycled from the third organic phase 148 second organic phase 128.

In some exemplary embodiments of the invention, water partial vapor pressure at 50°C of the wastewater stream 106, the water-depleted first aqueous solution 116, the displaced aqueous solution 126 and the permeate 146 are PI, P2, P3 and P4, respectively; wherein P1>P2; and/or P2<P3 and/or P4>P3 and/or P2<P4.

In some exemplary embodiments of the invention, the wastewater stream 106 comprises one or more crude-oil-associated hydrophobic solutes. According to various embodiments of the invention, at least a portion of the one or more crude-oil-associated hydrophobic solutes 162 is separated from a portion of the extractant 108 (in the depicted exemplary embodiments, by distillation 160). According to an embodiment, separating hydrophobic solutes 162 is conducted prior to the fractionating 130 of the second organic phase 128 or simultaneously with it (not shown in the figure). In some embodiments, hydrophobic solutes 162 include organic acids (e.g. naphthenic acid).

In some exemplary embodiments of the invention, first aqueous solution 116 is substantially free of hydrophobic solutes other than the bi-directional solvent (e.g. crude- oil- associated hydrophobic solutes). These hydrophobic solutes (if present) tend to be extracted into the first organic phase 118.

As used herein, the term "substantially" refers to e.g., at least 70 %, at least 75%, at least 80 %, at least 75%, at least 80 %, at least 85%, at least 90 %, at least 95%, at least 99 %, or at least 99.9 %. Depicted exemplary embodiment 100 employs distillation 150 to separate bi-directional solvent 158 dissolved in first aqueous solution 116. In other exemplary embodiments of the invention, other separation methods are employed, e.g. salting out and/or using a hydrophobic solvent. The amount of bi-directional solvent 158 to be distilled is relatively small due to the low solubility of the solvent in the water- depleted first aqueous solution 116. In some embodiments, the bi-directional solvent 158 distills as an azeotrope with water. Optionally, water in solvent 158 contributes to an increased total water yield as extractant stream 108 is recycled.

In the depicted exemplary embodiments, distillation 150 also produces an impurities-enriched aqueous solution 156. According to an embodiment, the impurities- enriched solution is characterized by water partial vapor pressure at 50°C of P5 and P5 < PI. According to various embodiments, the impurities-enriched solution is disposed off as such or after further treatment. According to various embodiments, such further treatment comprises at least one of further concentration, precipitation of at least one component and addition of a chemical compound. According to various embodiments the flow rate of the wastewater is Fl, the flow rate of the impurities-enriched solution is F2 and F1/F2 is greater than 2, 4, 6, 8, 10 or intermediate of greater ratio.

In the depicted exemplary embodiments, enriched bi-directional solvent 134 (containing some water) is recycled to extractant stream 108 without further separation of water.

Displaced aqueous solution 126 is the primary product of method 100. In some exemplary embodiments of the invention, the amounts of bi-directional solvent and/or hydrophilic solutes and/or hydrophobic solutes in displaced aqueous solution 126 are sufficiently low to enable serve as feed water to an industrial process and/or agricultural irrigation water and/or potable water.

According to alternative embodiments, bi-directional solvent and/or hydrophilic solutes, and/or hydrophobic solutes is separated from the displaced aqueous solution 126, by one or more techniques selected from, but not limited to,, heating, evaporation, reverse osmosis, forward osmosis, electrodialysis and contacting with a solvent.

In some exemplary embodiments, separating water from the displaced aqueous solution 126 includes evaporating 140 the bi-directional solvent form a separated water 146 and a third organic phase 148.

In some exemplary embodiments, separating water from the displaced aqueous solution 126 includes connecting the displaced aqueous solution 126 with hydrophobic solvent to extract the bi-directional solvent and to form separated water 146 and a third organic phase 148.

According to some embodiments, displaced aqueous solution 126 includes a small fraction of the bi-directional solvent. The concentration of the bi-directional solvent in displaced aqueous solution 126 is a function of hydrophilic solutes (e.g. salts) concentration there. According to some embodiments the bi-directional solvent is at least partially removed from the displaced aqueous solution 126 prior to the contacting with the membrane e.g. by distillation. Alternatively or additionally, according to some embodiments, the bi-directional solvent is separated by contacting thereof with a membrane. According to an embodiment, the bi-directional solvent is rejected by the membrane and is retained in the retentate along with concentrated aqueous solution. According to an embodiment, the concentrated aqueous solution is of reduced volume and/or higher salt concentration compared to the displaced aqueous solution 126. As a result, the amount of bi-directional solvent dissolved in the concentrated aqueous solution is smaller than the amount dissolved in the displaced aqueous solution 126 and therefore a vast majority of the bi-directional solvent is rejected into a third organic phase 148, which is formed in the retentate.

In some embodiments, at least a portion of the third organic phase 148 is recycled as bi-directional solvent and combined with second organic phase 128 prior to fractionating 130 . According to various embodiments, the third organic phase 148 is combined with the enriched bi-directional solvent 134 or introduced separately to the extracting 110, e.g. at a point closer to the exit of the first aqueous solution 116. In some embodiments, the displaced aqueous solution 126 comprises at least 60%, 70%, 80%, 85%, 90% or at least 95% of the water in the wastewater stream 106.

According to various embodiments, the third organic phase 148 includes the bidirectional solvent and water. According to an embodiment, the third organic phase 148 is recycled as such to the fractionating 130.

According to various embodiments, water extraction (extracting 110) is selective to water over ions. Selectivity is particularly high compared to extraction of divalent ions, including ones contributing to hardness and scale.

According to some embodiments, wastewater stream 106 includes at least one multivalent ion and at least one monovalent ion at a multivalent to monovalent ratio Rl .In some embodiments, the first aqueous solution 116 includes at least one multivalent ion and at least one monovalent ion at a multivalent to monovalent ratio R2.

According to some embodiments, R2/R1 is in the range of between 0.75 and 1.25, between 0.8 and 1.2, between 0.85 and 1.15 or between 0.9 and 1.1. In some embodiments, R2/R1 is e.g., 0.75, 0.80, 0.85, 0.90, 0.95, 1, 1.05, 1.10, 1.15, 1.20, 1.25, including any value therebetween.

DEFINITIONS

As used in this specification and the accompanying claims the term "hydrophilic solute" indicates a solute with a log P < - 0.5. According to various exemplary embodiments of the invention the log P of the hydrophilic solute is -0.55; -0.6 -0.65; -0.7; -0.75; -0.8 or intermediate or lesser values. According to various exemplary embodiments of the invention, the term "hydrophilic solute" includes ionic compounds.

Hereinthroughout, P denotes partial vapor pressure.

As used in this specification and the accompanying claims the term "hydrophobic solute" indicates a solute with a log P > 0.0. According to various exemplary embodiments of the invention the log P of the hydrophobic solute is 0.1 ; 0.15; 0.2; 0.25; 0.3; 0.35 or intermediate or greater values. According to various exemplary embodiments of the invention, the term "hydrophobic solute" indicates organic compounds with C:0 atom ratio greater than 3.

As used in this specification and the accompanying claims the term "bi-directional solvent" indicates an organic solvent, or a mixture of two or more such solvents, which is characterized in that on equilibrating at 20°C with 5% (w/w) NaCl aqueous solution, solvent concentration in the aqueous phase is at least 1% and less than 50% (WAV) and water concentration in the solvent phase is at least 5% and less than 50% (W/W).

As used in this specification and the accompanying claims, the terms "distillation", "evaporation" and "stripping" are used interchangeably.

As used in this specification and the accompanying claims, the terms "water- depleted" and "water-enriched" mean containing less water and more water, respectively, compared with the content prior to extracting, in terms of amount or flux or concentration.

As used in this specification and the accompanying claims, the terms "stream enriched in" mean a stream containing more of the subject matter, respectively, compared with the content of the subject matter prior to previous state, in terms of amount or flux or concentration. As used in this specification and the accompanying claims, the term "fractionating" means dividing a mixture (gas, solid, liquid, or suspension) into at least two fractions of different composition.

Various exemplary embodiments

According to various exemplary embodiments of the invention hydrophobic solutes 162, e.g. crude-oil-associated hydrophobic solutes, include naphthenic acid and/or other organic acids comprising at least 5 carbons, and/or 1,4-dioxane, and/or acetone, and/or bromoform, and/or dibenzo(a,h)anthracene, and/or pyridine, and/or phenols and/or oil (e.g. fossil oil, vegetable oil). According to some embodiments, in addition to soluble crude-oil-associated hydrophobic matter, the wastewater stream comprises suspended crude-oil-associated hydrophobic matter, so that the content of the crude-oil-associated hydrophobic matter in 106 is greater than saturation concentration.

According to some embodiments, one or more of the crude-oil-associated hydrophobic solutes is less volatile than water, and is difficult to separate from the wastewater stream 106 by known methods, such as evaporation. According to some embodiments of the present invention, such solutes are efficiently removed at low cost, optionally without their evaporation.

In some embodiments, second organic phase 128 includes at least 85%, at least 90%, at least 95%, at least 97.5% or at least 99% of the at least one of the one or more crude-oil-associated hydrophobic solutes present originally in the wastewater stream 106. Alternatively or additionally, in some embodiments, water-depleted first aqueous solution 116 includes at least 80%, at least 85%, at least 90%, at least 95%, at least 97.5% or at least 99% of the at least one of the one or more hydrophilic solutes in the wastewater stream 106 (i.e. in case of multiple hydrophilic solutes, this could be true for one of the solutes in some embodiments and more than one of them in other embodiments).

In some exemplary embodiments of the invention, the method includes recycling at least 50%, at least 55%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90% or at least 95% of water from the wastewater stream 106 to an industrial process producing the wastewater stream. According to some embodiments, the recycled water is derived from the displaced aqueous solution 126. According to other embodiments, the recycled water includes the separated water 146 from the displaced aqueous solution treating 140 and/or from the displaced aqueous solution 126. According to some embodiments, the industrial process generates different "product process water" streams and/or consumes water/aqueous solutions in multiple steps. According to some embodiments, the recycled water results from any stream and is used in any step. According to some embodiments, the recycled water is at high quality. According to some exemplary embodiments, the recycled water is at quality as required for steam production (including steam required for stripping solvent from exiting streams). Alternatively or additionally, according to some embodiments, the water derived from the displaced aqueous solution 126 and/or from separated water 146 has alternative outlets (e.g. irrigation, emission to rivers and sewage). As used herein, the term "high quality" for recycled water refers to water with hydrophilic solutes level lower than 0.5% and hydrophobic solutes level lower than 0.05%, by weight.

According to various exemplary embodiments of the invention the wastewater stream 106 is produced by an industrial process selected from the group consisting of, but are not limited to, induced hydraulic fracturing (fracking), Steam Assisted Gravity drainage (SAGD), crude oil production from oil sand, petroleum industry processing, enhanced oil recovery (EOR) and vegetable oil production. In some exemplary embodiments of the invention, wastewater stream 106 is produced by an industrial process selected from the group consisting of recovering crude oil, recovering gas, and processing crude oil.

In some exemplary embodiments of the invention, the method includes contacting crude oil with displaced aqueous solution 126 and/or separated water 146 to produce the wastewater stream 106.

In some exemplary embodiments of the invention, the ratio of at least one of the hydrophilic solutes to at least one of the crude-oil-associated hydrophobic solutes is at least ten times greater in the water-depleted first aqueous solution 116 than that in the wastewater stream 106. Alternatively or additionally, in some embodiments of the invention, the concentration of at least one of the one or more crude-oil-associated hydrophobic solutes in extractant 108 is at least three times greater than that in the wastewater stream 106.

In the depicted exemplary embodiment, separating at least a portion of the one or more crude-oil-associated hydrophobic solutes 162 from extractant 108 and/or from second organic phase 128 includes evaporation 160. In some exemplary embodiments of the invention, evaporation 160 includes distillation. According to some embodiments, the hydrophobic solute is more volatile than the bi-directional solvent. In that case, the solute is evaporated out. In other cases, the opposite is true and the bi-directional solvent is evaporated. In case there are hydrophobic solutes that are more volatile than the bidirectional solvent as well as ones that are less volatile, the former are evaporated first, followed by the bi-directional solvent. According to an embodiment, only a small fraction of the extractant 108 is treated for separation of the hydrophobic solutes 162, e.g. less than 20% of it, less than 15%, less than 10%, or less than 5%.

In some embodiments, the method includes conducting extractionl lO and/or mixing 120 in a counter current mode. According to some embodiments, the extracting 110 and/or mixing 120 is conducted in 1-20 stages, 3-15 stages, 4-12 stages or 5-10 stages.

Alternatively or additionally, in some embodiments of the method, the weight/weight ratio between the amount of bi-directional solvent in stream 108 and the amount of water in stream 106 is in a range between 2: 1 and 20: 1, between 3: 1 to 17: 1, between 6: 1 to 15:1, between 2: 1 and 12: 1, between 3: 1 and 11: 1, between 4: 1 and 10: 1 or in a range between 8: 1 to 12: 1. According to some embodiments, extracting 110 is conducted in a continuous mode and this ratio is between the contents of the fluxes of streams instead of the amounts.

In some embodiments, stream 106 contains suspended solids. These solids can include, but are not limited to sand or soil particles. According to various embodiments, these solids are removed prior to the extracting 110. According to various exemplary embodiments of the invention, solids are removed in a settling tank and/or via filtration and/or via centrifugation (e.g. a flow through centrifuge and/or a cyclonic separator). In some embodiments, removal of solids contributes to mechanical efficiency of the following process steps.

Alternatively or additionally, in some embodiments, stream 106 contains one or more dissolved surfactants (e.g. soaps and/or detergents). According to various embodiments, at least one of the one or more surfactants is removed from and/or inactivated in at least a portion of stream 106 prior to extracting 110. In some embodiments, a surfactant removal and/or inactivation module is positioned upstream of the extracting 110 to reduce activity of surfactants present in stream 106. According to various exemplary embodiments of the invention, the surfactant removal and/or inactivation module employs surface active material (e.g. activated charcoal) and/or pH adjustment and/or addition of multivalent ions.

In some exemplary embodiments of the invention, the surfactant removal and/or inactivation module contributes to the efficiency of separating the first aqueous solution 116 from the first organic phase 118 and/or to the efficiency of separating the displaced aqueous solution 126 and the second organic phase 128.

Exemplary wastewater compositions

In some exemplary embodiments of the invention, wastewater stream 106 contains at least 10,000 ppm; at least 20,000 ppm; at least 30,000 ppm or at least 40,000 ppm of total dissolved solids (TDS). In other exemplary embodiments of the invention, stream 106 contains less than 100,000 ppm, less than 90,000 ppm, less than 80,000 ppm, less than 70,000 ppm or less than 50,000 ppm of total dissolved solids (TDS).

In alternative exemplary embodiments of the invention, total dissolved solids (TDS) in the wastewater stream 106 is less than 10,000 ppm; less than 8,000 ppm; less than 6,000 ppm; less than 4,000 ppm or less than 2,000 ppm. Wastewater streams with these relatively low levels of TDS levels is produced, for example, in cooling towers and/or in the oil industry.

Alternatively or additionally, in some embodiments, the dissolved solids include barium and/or strontium and/or iron and/or other heavy metals and/or radioactive isotopes and/or cyanides and/or thiocyanates and/or salts of ammonia and/or sulfides and/or sulfates and/or calcium salts and/or silica.

Exemplary extraction conditions Various exemplary embodiments of the invention described herein relate to extraction (110) of water into an extractant comprising bi-directional solvent or displacement (120) of water from formed extract. According to various embodiments, at least one of such extraction and displacement is conducted by contacting in a multiple step, counter-current operation. According to various embodiments, such contacting is conducted in industrially used contactors, e.g. mixer- settlers, extraction columns, centrifugal contactors and raining-bucket contactor. According to an embodiment, the wastewater comprises suspended solids and/or solids are formed during the first contacting and the used contactor is designed to handle such solids.

Exemplary optional treatment of the first organic phase

In some exemplary embodiments of the invention, first organic phase 118 is treated prior to the mixing 120, e.g. by adding an organic solvent or contacting with an aqueous solution. According to another embodiment, first organic phase 118 comprises suspended solids and the treating prior to the mixing comprises separating such suspended solids, e.g. via extended settling or addition of a coagulant.

Exemplary solvent considerations

According to various exemplary embodiments of the invention, the bi-directional solvent employed in extractant stream 108 is selected based upon the total dissolved solids (TDS) content of stream 106 and/or the content of the hydrophobic solutes in stream 106 an/or the cost of available energy.

Exemplary advantages

A known method for treating wastewater streams involves evaporation of the water. Energy consumption is high due to the required input of latent heat. Major efforts are directed to developing alternatives based on membrane separation (e.g. Reverse Osmosis). Those require several pretreatments (e.g. filtration, adsorption, coagulation and softening) in order to protect the membrane. These pretreatments substantially increase the cost of the membranes-based separation.

One exemplary advantage of some embodiments of the invention is that water is separated by the extraction with a bi-directional solvent and recovered from the formed organic phase without the input of latent heat.

Alternatively or additionally, those portions of the process that optionally employ latent heat (e.g. distillations 150 or 160) are applied to smaller portions of the total mass in the system and directed to evaporation of solvents with relatively low latent heat, which results in significant energy savings.

Alternatively or additionally, exemplary method 100 achieves efficient separation of usable water (separated water 146 and/or displaced aqueous solution 126) from the wastewater (106), forming a reduced- volume, impurities-concentrated stream (impurities- enriched aqueous solution 156), thereby reducing the volume of wastewater to be disposed of.

Alternatively or additionally, exemplary method achieves 80%, 90%, 95%, 99%, 99.5% , 99.9% (or any parentage between them) separation of hydrophobic solutes 162, which can be used for energy and/or for more specific applications.

Alternatively or additionally, exemplary method 100 results in a high quality separated water 146 or displaced aqueous solution 126, which can be used e.g. for steam, at a relatively low costs compared to alternative treatments.

Alternatively or additionally, exemplary methods described herein are more suitable for use in handling hard water (at 106) than previously available alternatives.

Alternatively or additionally, exemplary method described herein contributes to a reduction in use of chemical reagents.

Alternatively or additionally, exemplary methods described herein contribute to reduction of Green House Gas (GHG) emission of steam boilers by feeding the steam boilers with higher quality water and thereby reducing the energy required to evaporate the water.

Alternatively or additionally, exemplary methods described herein are amenable to integration with other methods, e.g. gravity separation devices such as the API (American Petroleum Institute) oil-water separator.

Exemplary system

Reference is now made to Fig. 2 which is a schematic representation of a wastewater treatment system indicated generally as 200. In the figure, a flow of organic phases is depicted by dashed arrows, and a flow of aqueous solutions is depicted by solid arrows. Numbers which appear in Fig. 1 are used in Fig. 2 to indicate flows similar to those described above.

Depicted exemplary system 200 includes a water extraction module 210 adapted to contact an extractant comprising a bi-directional solvent 108 with at least a portion of a wastewater stream including one or more hydrophilic solutes and one or more crude- oil- associated hydrophobic solutes 106 to form a water-depleted first aqueous solution 116 and a water-enriched first organic phase 118.

In the depicted exemplary embodiment, system 200 includes a mixing module 220 adapted to mix the first organic phase 118 with a hydrophobic solvent 138, to form a second organic phase 128 and a displaced aqueous solution 126.

Depicted exemplary system 200 also includes a fractionating module 230 adapted to fractionate the second organic phase 128 to a stream enriched in hydrophobic solvent 138 and a stream enriched in bi-directional solvent 134.

In the depicted exemplary embodiment, system 200 includes recycling of stream enriched in hydrophobic solvent 138 to mixing module 220.

According to various embodiments of the invention, the extraction 110 at the extraction module 210 occurs at a first temperature (Tl) and the mixing 120 at the mixing module 220 occurs at a second temperature (T2). According to some embodiments T2 = Tl. According to other embodiments, T2 is lower than Tl. According to other embodiments, T2 is higher than Tl.

According to various embodiments of the invention, system 200 is configured to allow recycling of at least a portion of the stream enriched in bi-directional solvent 134 to the extraction module 210.

According to some embodiments of the invention, the system is characterized in that the displaced aqueous solution 126 includes bi-directional solvent.

According to some embodiments of the invention, displaced aqueous solution 126 further treated to form a separated water and a third organic phase. According to some embodiments of the invention, the displaced aqueous solution 126 treated by heating or by hydrophobic solvent extraction.

According to various embodiments of the invention, the third organic phase recycled to fractionating module 230.

According to various embodiments of the invention, system 200 is characterized in being portable. According to some embodiments, system 200 is mobile, moveable, and can be transported from one place to another (e.g. from one shale oil play to another). According to an embodiment, system 200 is skid mounted. Exemplary use scenario: Synthetic Crude Oil from Oil Sands

Production of a barrel of synthetic crude oil from oil sand requires about 2 to 4.5 barrels of fresh water as an input. In the conventional subterranean process, this water is applied as steam to oil sand in a well. In the Surface mining, the oil sand is removed from the well and then the water is applied.

In the Steam Assisted Gravity Drainage (S AGD) process two horizontal wells are drilled in the oil sands, one at the bottom of the formation and another about 5 meters above it. These wells are typically drilled in groups of central pads and can extend for miles in all directions. In each well pair, steam is injected into the upper well, the heat melts the bitumen, which allows it to flow into the lower well, where it is pumped to the surface.

The steam for the SAGD process can be generated by a once-through steam generator (OTSG). The feed for the OTSG can comprise produced water and optionally also make-up water. The OTSG generate a high quality steam for the well injection and a boiler blowdown (BBD) stream that may contain dissolve solids. That BBD stream requires treatment. The produced Synthetic Crude Oil contains water (produced water), which is separated during the processing of the Synthetic Crude Oil. Separated water is recycled to the steam generator.

During the Synthetic Crude Oil production, a portion of the injected steam remains in the ground formation and does not return as produced water. In order to retain the amount of steam required for the Synthetic Crude Oil production, make-up water is used in addition to the recycled separated produce water.

Make-up water is provided from natural sources, such as rivers or underground wells. In some cases, the make-up water contains inorganic salts (hydrophilic solutes).

Typically, removal of the hydrophilic solutes and hydrophobic solutes prior to the OTSG decreases the content of those solutes in the blowdown water.

In some exemplary embodiments of the invention, produced water (with or without mixing with make-up water) and blowdown water are the wastewater streams produced during production of synthetic crude oil.

Referring again to Figs. 1 and 2: in some exemplary embodiments of the invention, production of synthetic crude oil serves as industrial process and wastewater produced during production of synthetic crude oil serves as wastewater stream 106. During wastewater treatment process 100, the bulk of the hydrophilic solute is separated from the bulk of the water in the wastewater stream and is concentrated in the first aqueous solution 116. According to some embodiments, it is removed from the system as impurities-enriched aqueous solution 156 as described in details hereinabove.

The hydrophobic solutes are selectively and efficiently extracted into the first organic phase 118 in the extracting 110. The hydrophobic solutes remain practically fully in the extractant during the mixing, i.e. in the second organic phase 128. In the depicted exemplary embodiment of Figs. 1, a fraction of the hydrophobic solutes arrives at evaporation 160 and is at least partially removed from the system at 162. Separated water (depicted as displaced aqueous solution 126 or separated water 146) becomes feed process water to the industrial process and can be used as part of input water for a subsequent round of production of synthetic crude oil, e.g. of the feed water to the OTSG.

General:

It is expected that during the life of this patent many additional industrial processes and/or desalination techniques will be developed and the scope of the invention is intended to include all such new technologies a priori.

As used herein the term "about" refers to ± 10 %.

As used herein, the terms "comprising" and "including" or grammatical variants thereof are to be taken as specifying inclusion of the stated features, integers, actions or components without precluding the addition of one or more additional features, integers, actions, components or groups thereof. This term is broader than, and includes the terms "consisting of" and "consisting essentially of as defined by the Manual of Patent Examination Procedure of the United States Patent and Trademark Office.

The phrase "adapted to" as used in this specification and the accompanying claims imposes additional structural limitations on a previously recited component.

The term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of architecture and/or computer science.

Percentages (%) of chemicals and/or solutes are W/W (weight per weight) unless otherwise indicated. Percentages of solute in solvent (solute concentration) are W/W. In those cases where a portion of a solute precipitates or crystallizes, the weight of solid solute and dissolved solute are both considered in calculating the solute concentration. As used herein, "a proportion of, "a concentration of or "a ratio between" "hydrophobic solute", "one or more hydrophobic solute", "at least one of said one or more hydrophobic solute", "hydrophilic solute", "one or more hydrophilic solute", "at least one of said one or more hydrophilic solute", "monovalent", "at least one monovalent ion", "multivalent", "at least one multivalent ion" and similar phrases are to be taken as specifying a proportion of or a concentration of at least one solute/ion, or the ratio between concentration of a single solute/ion and the concentration of another single solute/ion.

Specifically, a variety of numerical indicators have been utilized. It should be understood that these numerical indicators could vary even further based upon a variety of engineering principles, materials, intended use and designs incorporated into the various embodiments of the invention. Additionally, components and/or actions ascribed to exemplary embodiments of the invention and depicted as a single unit may be divided into subunits. Conversely, components and/or actions ascribed to exemplary embodiments of the invention and depicted as sub-units/individual actions may be combined into a single unit/action with the described/depicted function.

Alternatively, or additionally, features used to describe a method can be used to characterize an apparatus and features used to describe an apparatus can be used to characterize a method.

It should be further understood that the individual features described hereinabove can be combined in all possible combinations and sub-combinations to produce additional embodiments of the invention. The examples given above are exemplary in nature and are not intended to limit the scope of the invention which is defined solely by the following claims.

Each recitation of an embodiment of the invention that includes a specific feature, part, component, module or process is an explicit statement that additional embodiments not including the recited feature, part, component, module or process exist.

Specifically, the invention has been described in the context of industrial processes and desalination but might also be used to reduce levels of radioisotopes in water.

All publications, references, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

The terms "include", and "have" and their conjugates as used herein mean "including but not necessarily limited to".

EXAMPLES

Reference is now made to the following example which, together with the above descriptions, illustrate some embodiments of the invention in a non-limiting fashion.

Example 1: Water extraction from a waste stream using recycled n-butanol extractant

A flowback waste stream (the wastewater stream) was extracted with recycled n- butanol extractant (the bidirectional solvent). The wastewater stream contained 3% total dissolved solutes (TDS), mainly salts (hydrophilic solutes), and about 200ppm crude-oil- associated hydrophobic solutes. The recycled n-butanol (Extractant) contained initially about 11.5% water. The bench scale extraction was conducted at 35oC and simulated counter-currently extraction of 8 stages. Water transferred from the wastewater stream to the Extractant. The extractant to aqueous feed (O/A) weight/weight ratio was 11. The formed organic phases and aqueous phases were analyzed to determine the time when their composition has reached a steady state. The steady state organic phase (Extract) and the steady state aqueous phase (Raffinate) were analyzed.

The TDS of the Raffinate was 12%. Its n-butanol concentration was 2.7% and the concentration of the organic matter there was less than 20ppm. The water content of the extract was 17%. These analyses indicate that about 75% of the water and essentially all the crude-oil-associated hydrophobic solutes initially present in the waste stream got extracted into the n-butanol. The formed Raffinate is the water-depleted first aqueous solution and the formed extract is the water-enriched first organic phase.

Examples 2-6: Water extraction from various wastewater stream using recycled n-butanol extractants

Additional wastewater streams of varying compositions were extracted with recycled n-butanol (extractants) of varying initial water content. The procedure was similar to that in Example 1 and the results are summarized in Table 1. Table 1

[1] Calculated as the fraction of water in the wastewater stream that got extracted into the Extract.

Examples 7-11: Water extraction from a waste stream using various recycled extractants Waste stream of various initial TDS were extracted with various recycled extractants. The procedure was similar to that in Example 1 and the results are summarized in Table 2.

Table 2

[1] Calculated as the fraction of water in the wastewater stream that got extracted into the

Extract.

Example 12: mixing of extract formed in Example 1 with a hydrophobic solvent The Extract formed in Experiment 1 was mixed with recycled (regenerated) hexane. The bench scale mixing was conducted at 30°C. The hydrophobic solvent to Extract weight/weight ratio was 0.2. As a result of the mixing, water was rejected from the Extract to form a displaced aqueous solution. The formed organic phase and aqueous solution were analyzed to determine the time when their composition has reached a steady state. The steady state organic phase and the steady state aqueous phase were analyzed. The water content of the formed organic phase was 11.5% The water extracted from the wastewater stream into the extract in Example 1, was rejected from the extract during the mixing to form the displaced aqueous solution, and to regenerate the extractant of Example 1.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

Claims

CLAIMS:

1. A method comprising:

(a) providing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes;

(b) extracting at least a portion of said wastewater stream with an extractant comprising an organic bi-directional solvent to form a water-depleted first aqueous solution and a water-enriched first organic phase;

(c) mixing said first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution;

and

(d) fractionating said second organic phase into a stream enriched in said bidirectional solvent and a stream enriched in said hydrophobic solvent;

wherein, water solubility in said bi-directional solvent is greater than water solubility in said hydrophobic solvent.

2. A method according to claim 1, further comprising

(e) reusing said stream enriched in said bi-directional solvent in said extracting; and

(f) reusing said stream enriched in said hydrophobic solvent in said mixing.

3. A method according to any one of claims 1 and 2, wherein said fractionating comprises heating said separated second organic phase.

4. A method according to any one of claims 1 to 3, wherein said displaced aqueous solution comprises at least a portion of said bi-directional solvent.

5. A method according to claim 4, further comprising treatment of said displaced aqueous solution to form a separated water and a third organic phase.

6. A method according to claim 5, wherein said treatment include separation of at least part of said third organic phase by stripping.

7. A method according to claim 5, wherein said treatment include separation of at least part of said third organic phase by hydrophobic solvent extracting.

8. A method according to any one of claims 5 to 7, further comprising recycling at least a portion of said third organic phase to said separated second organic phase.

9. A method according to any one of claims 1 to 8, wherein said displaced aqueous solution comprises at least 60% of the water in said wastewater stream.

10. A method according to any one of claims 1 to 9, wherein said one or more crude- oil- associated hydrophobic solutes comprise at least one member of the group consisting of naphthenic acid, other organic acids comprising at least 5 carbon atoms, 1,4-dioxane, acetone, bromoform, dibenzo(a,h)anthracene, pyridine, phenols, oil, vegetable oil and synthetic oil

11. A method according to any one of claims 1 to 10, wherein said second organic phase comprises at least 85% of said one or more crude-oil-associated hydrophobic solutes in said wastewater stream.

12. A method according to any one of claims 1 to 11, comprising recycling at least 50% of water from said wastewater stream to an industrial process producing said wastewater stream.

13. A method according to any one of claims 1 to 12, wherein said wastewater stream is produced in an industrial process selected from the group consisting of recovering crude oil, processing crude oil, production of synthetic oil, processing synthetic oil, production of vegetable oil and processing vegetable oil.

14. A method according to any one of claims 1 to 13, wherein said wastewater stream is produced in an industrial process selected from the group consisting of crude oil production from oil sand, steam-assisted gravity drainage (SAGD), induced hydraulic fracturing (tracking), petroleum industry processes, enhanced oil recovery (EOR), synthetic oil production and vegetable oil production.

15. A method according to any one of claims 1 to 14, wherein said wastewater stream comprises a blowdown of steam generation.

16. A method according to any one of claims 1 to 15, wherein said bi-directional solvent comprises one or more oxygen-comprising organic molecules with 3 to 6 carbon atoms.

17. A method according to claim 16, wherein said bi-directional solvent comprise one or more members of the group consisting of alcohols, ketones, esters, phenols and organic acids.

18. A method according to claim 17, wherein said bi-directional solvent comprises one or more members of the group consisting of normal butanol, secondary butanol, isobutanol, tertiary butanol, normal pentanol, secondary pentanol, isopentanol, and tert amyl alcohol.

19. A method according to any one of claims 1 to 18, wherein the bi-directional solvent is selected so that the ratio between said one or more hydrophilic solutes to said one or more crude-oil-associated hydrophobic solutes is at least three times greater in said water-depleted first aqueous solution compared with that in said wastewater stream.

20. A method according to any one of claims 1 to 19, further comprising separating at least a portion of said one or more crude-oil-associated hydrophobic solutes from said second organic phase.

21. A method according to any one of claims 1 to 20, further comprising separating at least a portion of said one or more crude-oil-associated hydrophobic solutes from said stream enriched in said bi-directional solvent.

22. A method according to claims 20 or claim 21, wherein said separating at least a portion of said one or more crude-oil-associated hydrophobic solutes comprises evaporating.

23. A method according to any one of claims 1 to 22, wherein said hydrophobic solvent solubility in said bi-directional solvent is greater than water solubility in said bidirectional solvent at same temperature.

24. A method according to claim 23, wherein said hydrophobic solvent is fully miscible with said bi-directional solvent at 25°C.

25. A method according to any one of claims 1 to 24, wherein said hydrophobic solvent comprises one or more hydrocarbons with 4 to 10 carbon atoms

26. A method according to claim 25, wherein said hydrophobic solvent comprises one or more members of the group consisting of hexane, cyclohexane, heptane, butane, pentane and cyclopentane.

27. A method according to any one of claims 1 to 26, comprising conducting said extracting, or said mixing or both in a counter current mode.

28. A method according to any one of claims 1 to 27, wherein the weight ratio between extractant and wastewater stream in said extracting is in the range between 2 and 20.

29. A method according to any one of claims 1 to 28, wherein the weight ratio between said hydrophobic solvent and said first organic phase in said mixing is in the range between 0.1 and 2.

30. A system comprising:

(a) a wastewater source producing a wastewater stream comprising one or more hydrophilic solutes and one or more crude-oil-associated hydrophobic solutes;

(b) an extractant source comprising an extractant including an organic bidirectional solvent; (c) an extraction module in fluid communication with said extractant source and adapted to contact said extractant with at least a portion of said wastewater stream to form a water-depleted first aqueous solution and a water-enriched first organic phase;

(d) a mixing module adapted to receive said first organic phase and mixing said first organic phase with a hydrophobic solvent, to form a second organic phase and a displaced aqueous solution;

(e) a fractionation module adapted to fractionate said second organic phase to a stream enriched in said hydrophobic solvent and a stream enriched in said bi-directional solvent;

(f) a pump adapted to route at least a portion of said stream enriched in said bidirectional solvent as recycled extractant to said extraction module, and

(g) a pump adapted to route at least a portion of said stream enriched in said hydrophobic solvent to said mixing module.