CA1174552A - Process for the production of a liquid agent for improving the quality of contaminated water - Google Patents

Abstract

ABSTRACT
A method of producing a liquid agent for improving the quality of contaminated water, particularly water in pools, natural bodies of water and waste waters. Comminuted rock-salt clay or a mixture thereof with rock-salt deads is introduced with agitation into an aqueous solution or suspension of an inorganic base. The resultant mixture is stirred for 2 to 5 and preferably 3 hours. The pH of the stirred mixture is adjusted to a value of between 7.5 and 10.5 and preferably between 9.5 and 10.5 by means of the addition of acid or alkali, and undissolved portions are removed from the solution.

Description

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The present invention relates to a method of producing a liquid agent for lmproving the quality of contaminated water~ particularly water in pools, natural bodies of water and waste waters.
Numerous agents are known for improving the quality of water such as water in swimming pools, ponds used for bathing and waste waters. These known agents not only require careful supervision and great care in use but also encounter objections since they frequently contain corrosive and poisonous chemicals which may lead to impairment of health when improper do~es are employed.
Austrian Patent 324,967 describes an agent for the purification of contaminated water based on an alkaline aqueous solution or suspension of inorganic salts. However, the patent contains no indication as to how such agent can be produced.
An ob~ect of the present disclosure is to provide a simple method of producing an agent of the aforementioned type for wide use but which is based on substances which occur in nature.
This result is achieved by introducing comminuted rock~salt clay or a mixture thereof wlth rock-salt deads into an aqueous solution or suspension of an inorganic base with agitation, stirring the resultant mixture for 2 to 5 and preferably 3 hours, thereupon adjusting the pH of the resultant solution to a value of between 7.5 and 10~5 if not already within that range, and pre~erably between 9.5 and 10.5, by addition of acid or alkali as required and s~paratln~ the ~olution from undi6solved components.
The method de~cribed not only makes use of cheap raw materLals but i~ alqo ex~remely simple. Thus the concentrations Oe the reactants (rock-salt clay and where appropriate rock-salt deads and the base) are not critical.
Simple preliminary tests are sufficient in order to determine the optimum quantitative proportions and minimum amounts. Since the agent is a solution, ~, ~.~7~

an accidental excess of one of the reactants is not disturbing since it simply remains unreacted in the residue.
An aqueous solution or suspension of a pH of more than lO and preferably more than 12 is preferable.
When starting with rock salt deads it is advisable to introduce solid materials (rock-salt clay, rock-salt deads or mixtures thereof) whose content of NaCl is between 20 and 80 wt% into the solution. sefore adjusting the pH
to a desired final value it is advisable to increase the content of NaCl in the solution to the desired value of 14 g of NaCl per liter of solution by the addition of ordinary salt and/or by adding ordinary salt in the form of an aqueous solution, for instance, untreated brine, of a concentration of preferably 28% NaCl.
The base used for the method described is not critical. Calcium oxide, calcium carbide and sodium hydroxide have been found to be particularly suitable.
The rock-salt clay used is a breccious mixture of clays, salt and gypsum such as is found in particular in the Salzkam~ergut region and in the Berchtesgaden Alps. Rock-salt deads are the residue obtained after the lesching of the salt, it differing from rock-salt clay essentially by the content of sodium chloride or the absence thereof.
A few analyses of two samples of rock-salt clay drill cuttings from deep drilling~ in the Salzberg Mountain at ~lallstatt are given next:

.-' SS~ , Sample 1: `
H20-soluble portion ~10 g of sample/500 ml distilled H20~ about 63%
consisting of:
% %
Ca++ 3.778 CaSO~12.833 Mg++ 0.244 MgC12 0-957 S04 9.477 Na2So40.623 Cl- 52.455 NaCl 84.725 K+ 0.386 KCl 0.736 H20-insoluble portion tlO g of sample/500 ml distilled H20) about 37%, consisting of:
%

CaO
MgO 9.325 so3 0.729 K20 12.494 Si2 49.740 Sesquioxides 27.215 Sample 2:

H20-insoluble portion (10 g of sample/500 ml distilled H20) about 33%, consisting oE:
% %
CA~+ 5.602 CaS0419.028 Mg~t~ 1.279 ~gC125.009 so4-- 15.101 ~a2SOI~ 2.476 Cl- 48.039 NaCl72.181 K+ 0.580 KCl1.106 i~ 7~52 H20-insoluble portion (10 g of sample/500 ml distilled H20) about 67%, consisting of:
%

CaO 0.736 MgO 7.939 3 0.986 K20 10.918 SiO2 51.160 Sesquioxides 27.810 The average composition (mean values of 14 analyses with alkali determination) of the Alpine salt clays contained in the rock-salt clay can be noted from Table 1.

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It is advantageous to use rock-salt clay whose content of sodium ehloride amounts to 20 to 80% and preEerably is between 30 and 50~. It has been found particularly suitable for the content of sodium chloride to be about 40%.
If the eontent of sodium chloride in the available rock-salt clay is too high, it is possible to use a rock-salt elay whieh has been mixed with roek-salt deads. Roek-salt deads i9 the residue remaining upon the recovery of sodium ehloride by the leaehing proeess and has, for instance, the analysis of a roek-salt from the Rotsalz tred salt) Mountains of Hallstatt indicated in Table II.
Table II
Water soluble: 6.73% including 3.70% NaClX) Water insoluble: 93.27% (separated at 120C) Speeifie Gravity: 2.67 SiO2 4g.72%
A12o3 20.50%

Fe2o3 8.00%
CaO 0.91%
MgO 10.59%
K20 ) 4.50%
Na20~
C2 l.19%

S03 0.74~

~l20 3.84%
x) ean lnerease up to 15% (with 18% water-insoluble).

The ehemieal eomposition o~ roek-salt deads eorresponds to the ehemieal eompostion of the Alpine salt elays, as indieated in Table III below.

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Table III
Chemical composition of Alpine salt clays (in ranges) Illite Alpine salt clays SiO2 44-52.5% 42.5-53%
A1203 21.5-32.8% 17.4-23%
Fe203 ~ 2.3-6.2% 5.6-8%
FeO
MgO 1.3-3.9% 8.0-13/5%
CaO o.o-o.9% 0.3-2.3%
~a2o 0.1-0.9% 0.1-2.5%
K20 4.8-7.7% 2.8-5.1%
MnO 0-0.1%
i 2 0-0.7%
H20 8.5% 1.8-5.8%
The novel method is carried out as follows:
1. The base (quicklime, calcium carbide, caustic soda) is gradually introduced into water, the pH of the resultant solution or suspension should be more than 12.

2. Rock-salt clay is added, or instance in the form of drill cuttings, to this strongly a}lcaline solution. Rock-salt deads or ~ mixture thereo CAn al~o be u~ed with the drill cuttings. The amount added depends on the sodium chloride content o~ the solids, which content may be between 0%
(rock-salt deads) and 20-80% (rock-~alt clay). More rock-sslt clay can be u~ed the higher its NaCl content (the lower its ~ilicflte content).

3. The mixture obtained in this manner is stirred for about 2 to 4 hours in order to activate the clays.

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4. In order to improve the electrolytic properties, particularly when there using a high proportion of rock-salt deads (i.e. a low NaCl content of the solids introduced above in accordance with item 2), crude brine (28% NaCl) i8 added. About 2 to 20% NaCl should finally be present in the solution.

5. After continued stirring for one to three hours and if required also diluted with water - particularly if less water was originally used - the pH is brought to 9.0 to ll.0, and preferably 9.5 to 10.5, by addition of base or ~cid (for instance hydrochloric acid).

6. After the settling of the undissolved portions (ti~e required:
5 to lO hours)~ the supernatant colorless, clear solution is poured off.
The agent prepared in accordance with this process has excellent properties and its use permits noticeable optimalization of the treatment and the quality of the water.
In order to test the possibilities of use in large bodies of water, four different types of water bodies with differing quantities of addition of agent were treated.
The following water bodies were chosen:
1. CoDmunity mechanical c1arification plant 2. Brewery (direct introduction) 3. ~isry (direct introduction) 4. 110spit~1 ~third ch~mber, chlorin~ted with about 0.2 mg/l chlorine) Properties examined:
a) ~edimentation time b) septlc tendency c) oxygen consumption d) oxidizability e) biological oxygen requirement It was detennined that the above were affected by use of the agent as follows:
a) shorter d) lower b) longer e) lower c) lower These results are undoubtedly due to the positive influence of the agent manufactured as here described and it is clear that advantages flow from the use of the agent in the field of water preparation and treatment. In the field of water treatment, a substantial improvement in the flocculation as a whole can be noted; together with this chlorine conten~ of pool water in public swimming pools requiring chlorine treatment can be reduced, while maintaining excellent quality of the water down to a value of about 50% of the quantity previously employed. This unquestionably represents a welcome step in the direction of low-chlorine and thus more pleasing pool waters.
In accordance with the invention there is provided the process of producing a liquid agent for improving the quality of contaminated water which comprises the steps of introducing a solid substance selected from comminuted rock-salt clay or a mixture thereof with rock-salt dead, with agitation into an aqueous solution or suspension of an inorganic base, stirring the resultant mixture for a period of from 2 to 5 hours, ad~u~ting the pH o~ the stirred mixture to a value o~ between 7.5 and 10.5 pH by addltlon of acid or alkali le the pH is not alr0ady within the a~orementioned range, and separating undissolved material from the resultant solution, such resultant solution comprising the liquld agent. The pH of the stirred mixture i9 preerably brought to the range of 9.5 to 10.5. The pH of the aqueous solution or suspension may be greater than 12. The solid substance may have s~;~

an NaCl content between 20 and 80 wt%. The stirred mixture may have its NaCl content increased to 14 g NaCl per liter by addition of sodium chloride, which may be added as an aqueous solution thereo~.
In order to test the effectiveness of the agent prepared in accordance with the process herein, the treatment of pool water with traditional agents and with the agent so produced was compared. The agent prepared in accordance with Example 1 was used, being referred to hereinbelow simply as the l'agent".
1.100 Preliminary Tests:
In order to check the effectiveness of the agent, examinations consisting of the following were carried out in the laboratory as basis for the subsequent tests:
1.110 Reduction in Iniurious Substances:
Fo~ this purpose a solution which contained defined amounts of phosphate and nitrate was treated with increasing quantities of the agent and the phosphate and nitrate contents in the filtrate determined, as compared with a control sample, after different times of reaction (at room temperature) and after fine filtration (Blauband) for the removal of the flocculant Eormed.
Ie was possible to establish that the content of phosphate and of nitrate in the filtered liquid was reduced by about 40% as compared with the test solution.
This efect is known as "refining" in water treatment, and can be explained that aR is known, hydrated oxide particles such as those of iron and/or al-aninum or, or instance, activated silica in Ereshly flocculated condition possess, a large energy-rich surface on whicb dissolved substance~
cfln be deposited by ~d~orption (adsorbates~.
~ comparable reduction of phosphate and nitrate could not be observed when using aluminum sulfate or iron chloride.

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1.120 Influence on Flocculation:
The agent ha3 inherent flocculating properties which however, in combination with a suitable flocculating agent, in this case with a so~called polyaluminum hydroxy chloride (PAC), shows a surprising improvement in the flocculation - beyond that of the aluminum hydroxy chloride.
Apart from the fact that the flocculation itself is substantially accelerated, coagulation appears to be even substantially more intense, even when only 0.3 ml/m3 is used.
As compared with this, co~nercial liquid flocculating agents having a base of PAC call for between 0~5 and 1.0 ml/m3 in their product litera~ure.
The agent is thus comparable in respect of its influence on flocculation, to a "synergistic intensifier" (activator, promoter). The residual amount of sodium chloride, which acts as electrolyte, is in this case certainly also of impo~tance particularly as the coagulation, and therefore the agglomerating of colloidal particles to form larger aggregates, can be noticeably activated, specifically upon the addition of an electrolyte.
2.000 Range of Use 2.100 Prerequisites The indoor pool selected for the testing purposes is owned by the Municipality and open to the public. It was opened for public use at Easter o~ 1974. It is located a few kilometers from the state capital city of Salzburg and is one of the mo~t popular within a wide nrea. This is due to the ea8e of ncceAsibility reaching it and because oE its good design, both wLth respect to the bath buildings nnd to the water treatment. It also enjoys very correct and meticulou~ maintenance and management.
2.110 Hydraulic Condit ons:

The ba~in made of stainless steel (V
2A) has dlmenslons of approximately 25 x 12 m with a sloping depth of approximately 0.9 to 1.8 m.

5~2 The surface therefore amounts to approximately 300 m2, the volu~e to approximately 400 m3.
The circulation performance is ensured by 3 parallel pumps which jointly pass 105 m3/h resulting in a total change cycle period of 4 hours.
Treated water enters along the length of the bath; removal is by an overflow gutter into an equalizing basin.
2.120 Water Treatment:
2.121 Process Span:
The water treatment process is divided into flocculation - filtra~ion - oxidation stage - and disinfection.
2.122 Flocculation:
Flocculation ls continuous, whereby the flocculating agent (firstly iron chloride, then aluminum sulphate, later poly-aluminum-hydroxychloride) are continuously metered in. At present the dosage quantity amounts to 1 ml PAC/m2 rotation.
2.123 Filtration:
A multiple-layer filter (quartz sand with hydro-anthracite -superimposed layer) i9 used. The diameter i8 2.0 m, the filtration surface is accordingly 3.1 m2. From this, using circulation performance of 105 m3/h, a rate of filtration of 34 m/hour i9 calculable, thus complying with the Pool Hygiene Law.
Back Elow cleaning of the filter i8 efEected automatically using a timed dieferential-pressure control, C
This con~i8t8 of an ozone sys~em, a reaction and dega~ification section and an activated-charcoal filtration zone.
The ozone capacity i8 stated to be lO0 g/hour or I g/m3 oE
circulated water. The reaction time of 1.7 minutes (in the degasification ., -- 11 ~

~'7~2 container) iB approximately in accord with present knowledge. The evolved ozone is passed oYer an ozone decomposer.
In the subsequent activated-charcoal filtration Sfilter area 2.5 m2, filtration rate 42 m/hour), the ozone still dissolved after the degasiiication stage is removed from the water.
2.125 _isinfection Disinfection i8 assured by addition of an aqueous chlorine-granulate solution. An organic chlorine substance (dichlorocyanurate) is used which, on exhaustion, is replaced by an inorganic compound (calcium hypochloride) to satisfy the requirements of the Pool Hygiene Law, in accordance with which dichlorisocyanurate i8 not permitted as the sol~ disinfectant for pool8 of a size of more than 130 m2.
Excess disinfectant i9 detected using the DPD method by which di~ferentiation into free chlorine and combi~ed chlorine is possible. A
colorimeter of suitable precision is used as the measurement instrument.
Measurements are carried out at least three times a day and entered in an operating data book.
~uring the course of the experiment the regular verifications carried out by the pool management were intensified or made more specific by suitable entries.
3.000 Procedure -~19~ i~., _ 110 Monitorin~:

To obtain the results of ~he individual measurements in reproducible ~on~, continuously operating instruments ~or free chlorine, pH and redox potential were installed. The ~est water for this was taken before the oxidation and chlorination steps.

The measurementg and entrieg of the pool management were expanded and ~l~ 7~S~i~

the data from the automatic measuring devices monitored by intensified control meas~rements.
In addition, samples were taken and subjected to more extensive examinations in which particular attention was paid to possible optimalization of the quality of the pool water and particularly a reduction in the amount of chlorine ~as a result of the use of the agent) while complying with the minimum and maximum values stipulated in the law.
3.111 Analytical Scope:
To assure a minimum quality (also governed by law) for pool water, etc., Austriao law requires a certain minimum number of chemical analyses, which must be carried out both by the management itself and by the government supervisory authority.
At a minimum pH, concentration of chlorine (free-active and bound-active by the DPD = diethyl-p.phenylenediamine method), content of oxidizable substances (KMnO4 consumption), redox potential, nitrate content and chloride content are concerned. The following values are permissible, with due consideration of the method of water treatment selected:
pH 7.0-8.3 chlorine, free 0.3 mg/L minimum chlorine, combined 0.5 mg/L maximum RMnO4 consumptio~ 3,0 mg/L maximum above filling water redox potential 650 mV minlmum nitrate 20 mg/L maximum above filling water chloride 100 mg/l, maximum above filling water From a bacteriological standpoint the number Oe aerobic colonies must not amount to more than 300 in 1 ml; ~scherichia coli must not be detectable in 100 ml, The examinations were directed at these requirements.

3.200 Test Variants:
In order to test the optimum manner of adding the agent, different variants were selected in preliminary tests and attention also paid to the amount added.
Manner and quality of addition of the agent were selected as follows:
l.) intermittently a) every second day10 L
b) once a day 5 L
c) twice a day 5 L
2.) continuously in parallel with the flocculating agent.
It was found that doses introduced clo~er together in time had a more definite effect than doses separated by wider intervals.
This finding led to continuous dosing in parallel with the flocculating agent, from which the latter quantity could be reduced by more than 50% down to 0.4 ml/~3. A dose of 0.6 ml of agent per m3 of circulating water proved optimum.
With a daily circulation of 2400 m3 an addition of about 1.0 L of polyaluminum chloride (PAC) and 1.5 L of agent was used therefore.
4.000 Evaluation 4.100 Analytical Value8:
The values indicated under 3.111, "Analytical Scope"~ were u~ied and the ineluence o~ the a~ent then evalunted~
~: The pH before the ~tart of the experiment was in the range oE
between 7.2 nnd 7.4. It did not ~o~e beyond thi~ rang¢ dur;ng the course of the te~ts.
Prior to the tests with the agent the ~7~SiS~

proportion of free active chlorine was maintained, at at least 0.4 to 0.6 ~g/L. Thus it was possible to achieve and maintain a redox potential of about 700 (680 to 710 ~V).
With the continuo~s addition of 0.6 ml of agent in parallel with 0.4 ml of PAC per m3 it wag poggible to raise the redox potential from about 700 to 750 mV within one day. This resulted in a reduction in the chlorine addition in the final analysis of more than 50% of the quantity originally necessary, namely to such an amount as still assured the maintaining of the required redox potential. It wa3 thus possible with a content of 0.20 to 0.25 mg of free chlorine to maintain a redox potential of 710 mV, even in relative peak loads in the evening hours.
Chlorine, combined: The content of combined chlorine was already low in this pool. During the experiments combined chlorine could be found only in very slight amounts, -- in no case more than 0.1 mg/Liter.
KMnO4consumption: Before carrying out the experiments this was between 3 and 4 mg/~ absolute and thus les3 than that of the filling w~ter.
Even with the reduction of the addi~ion of chlorine to 0.2 mg/L no change beyond 4 mg/L occurred and it continued to be between 3 and 4 mg/L.
Redox ~otential: As already described under "Chlorine, free, active"
it was possible, with the use of the agent and despite a reduction in the dose oP chlorine by more than 50% to a~sure a redox potential of 700 to 710 mV.
For ~urther in~onmation Hee urther nbove under "Chlorine".
Nitrate: The ~itrate content wa~ in all case~ below 20 mg/L
(11-19 mg/L) and thu~ within the requirements of "20 mgtL below that oE the ~ill water" which contained 6 to ll~ mg/L.
Chloride: The value oE the ill watar (5 to 11 mg/L) may not be exceeded by more than 100 mgiL in accordance with the regulations of the Pool Hygiene Law. The amounts found during the geries o experiments were between ~7~;5;~

120 and 135 mg/L, whereby the maximum value i9 ~ slightly) exceede~.
The (preliminary) bacteriological examinations effected by the pool management staff showed excellent results even with only 0.2 mg/L of chlorine and a load about 50% greater than the rated load (88 persons as compared with 60). The largest number of aerobic colonies was 20/ml. Escherichia coli, not to be detectable in 100 ml, were not observed in any instance.
Additional chemicals, disinfectants, etc., other than those mentioned were not required during the entire time of the experiment.
The effectiveness of the agent prepared in accordance with the present disclosure was next evaluated for use in an open body of utility-water. The agent prepared in accordance with ExampIe 1 was used in this test also.
The open body of water concerned is an artificially formed pond which lies in the center of a loosely built-up week-end colony at Lassee in Lower Austria.
The dimensions of "Pond VII," as it i9 known locally, were about 300 x 60 m, with a maximum depth of about 3m; the volume is thus about S0,000 m3. No artificially formed inlets are present; no sewage or other waste waters flow into it from the adjoining dwellings.
The banks and floor of the pond are not artificially compacted but the retaining walls for rno~t of the lots of land are, however, ;n the vicinity o~ the bank. The wflter level i3 somewhat below the adjoining plots. The pond i~ ~tocked with iish and it is used for swimming at appropriate times.
During the latter years there has been an increasing impairment in the quality of the water, expressed primarily by turbidity, reduction oE the depth of view to about 30-40 cm and exces3ive growth of algae (primarily on the rock~ in the region Oe the bank) and, at times, an unpleasant odor.
The pond wa~ first of all treated by ~praying 1000 L of agent over the surface of the water using a pressure noz~le. This process was repeated after 3 weeks with 500 L of agent. The amount of agent used was thus about 1500 L for 50,000 m3, resulting in an amount of 30 mg/L.
The following chemical and physical parameters were considered for judging the effectiveness: temperature, pH, depth of view, total hardness, carbonate hardness, non-carbonate hardness, potassium-permanganate consumption (oxidizability), chloride, nitrate, nitrite, phosphate (total), sulfate, ammonium, iron, and oxygen content and con8umption (in individual cases). In individual cases the number of colonies in 1 ml, also coliform bacteria and Escherichia coli in 100 ml were determined.
sample taken before the first treatment (A) showed the following characteristics for the organic and nutrient load.
KMnO4 consumption 19 mg/L
nitrate NO3 41 mg/L
phosphate (P-total) 31 mg/L
ammonium NH3 0.05 mg/L
depth of view 40 cm After the first spraying (B), samples were again taken and examined at intervals of 3 hours, 4 days (C), 3 weeks (D~ and 6 weeks (E).
A B C D E
KMnO4 Con8umption mg/L 19 15 13 11 10 Nitrate N~3 mg/L 41 27 20 13 14 Pho~phate P (totAl) mg/L 31 27 25 18 19 Ammonium NH3 mg/L 0.05 0.05 0.05 0-05 Depth of view cm 40 40 80 110 120 Oxygen 2 mg/L 10.5 Oxygen consumption mg/L 0.8 Oxygen saturation mg/L 9.1 ~ 17 -~7'~S5~

For sample D (after three weeks) also determ;ned were:
number of colonies 875 coliform bacteria 212 Escherichia coli 86 From the results of ~hese analyses it can be seen that after the use of~the agent there was a noticeable improvement in the water quality.
Apart from the fact that, purely visually, a change in depth of view from 0.4 to 1.2 m was obtained, both the KMnO4 consumption and the phosphate and nitrate contents showed sub6tantial reduction. This can be explained in that these injur;ous substances are deposited or adsorbed on the flocculant fonmed, as has been desrribed above.
With the reduction in nutrient substances, the phosphates and/or nitrates corresponsible for eutrophication of the water, good prerequisites are created for preventing growth of algae, with the attendant inherent pheno~ena such as reduced depth of vision, etc. The fact that, certain significant chemical values change along with this cannot of course be seen by the naked eye but it does afford the analyst the po6sibility of a suitable technically directed evaluation.
` A few examples of the method of making the agent are given below:
Example 1: 0.6 kg of CaO (quicklimeS unslaked li~e) were added in a kettle to 390 liters of water over the course of one hour with agitation.

7 kg o drill cuttings (analysis sample 1) having an ~aCl content of 48~ were added. The mixture wa3 then 3tirred for three hours. After completion of the stirring, 406 literfl of crude brine (~8% NaCl) were added. The resultant ~nixture w~s again ~tirred Eor two hours. The p~l was then brought to the de3ired final value of 9.85. ~fter sedimentation of the undissolved portions ~or ~ period o~ 5 to 10 hour~ the solution was poured off.

The final product had the following properties:
Appearance: Colorless, clear liquid Odor: Odorless Taste: Salty~bitter Reaction: Akaline, pH 9.85 (undiluted) Density: 1.13 g/cm3 at 20C.
Example 2: 195 literg of water were introduced into a kettle. 0.6 kg of CaO (quicklime, unslaked lime) were added over the course of an hour with stirring. Thereupon, depending on the NaCl content, which in principle 0 iY inversely proportional to the silicate content, 2 to 7 kg of drill cuttings were added. If the NaCl content of the drill cuttings is 20%, 2 kg are added, if it is 80%, 7 kg of drill cuttings are added. After addition of 195 lite~s of water, the mixture thus obtained was again stirred for two hours. The pH
was brought to the desired final value of 9.5 to 10.5. (If this value is not ~eached it is established by the addition of quicklime or hydrochloric acid).
After settling of the insoluble portion for a period of about 5 to 10 hours -until the solution was clear - the solution was poured off.
Example 3: While retaining basically the same manner of operation as indicated In Example 2, the alkaline solution or suspension (water ~nd quicklime) was treated with 1 kg of rock-salt deads having an NaCl content of practically zero, in~tead of drill cuttings. After stirring, 406 L of crude brine containing 28 wt% NaCl were addèd, ollowed then by treatment in the manner indicated in Example 2.
Example 4: 417 liter~ of water were introduced into a kettle. After ~tarting the stirring apparfltuo, 1 kg of sodium hydrox;de and 15 kg o rock-salt dead~ were added, A mixin~ period o 3 hours duration Eollowed with a subsequent re~t time of twelve hours. 125 liter3 oE brine (28 wt%) Wfl8 then `

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added and a further 1100 liters of water introduced. The mixture was stirred for a half hour period and then allowed to stand for 5 to 10 hours (until the solution cleared). The pH was then brought into the range of 9.5 to 11.0 as in Example 2 above. The resultant solution was decanted.

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TABLE I
Designation of Group of the Black Salt Clays Group of the Green to Grey Salt Clays rock Black an- ¦ Black Greenish- Green Greyish- Grey Salt Clay hydrous l Black green Hallthein salt clays lSrol Hallein A1203 15.8017.50 18.85 20.21 22.20 16.75 19.80 SiO2 45.2443.20 ~6.00 49.20 50.3~ 61.65 52.86 MgO+CaO 16.2815.60 12.16 10.80 9.36 7.82 10.10 (KNa)~ 3.124.48 5.19 4.01 ~.41 3.14 4.04 Fe23+Fe 5.607.00 7.20 7.33 8.53 5.81 5.96 Total 86.0487.78 89.40 91.55 94.84 95.17 93.36 Mineral Conponents (Mean Values) Alumina-alkali silicates 42.3649.01 56.65 60.60 60.73 47~93 55.94 Mg-hydrosilicate16.70 17.80 17.49 16.70 17.65 14.98 18.50 Quartz 14.989.62 7.77 8.29 10.3g 29.12 14.01 Anhydrite 16.164.82 1.94 1.28 0.94 1.24 1.36 Celcite _ __ _ 0.75 0.92 _ Dolomite _ 0.82 0.29 0.40 _ _ Magnesite 4.2010.93 7.06 5.17 0.95 __ 3.62 Total of the Fe-oxldes and secood~ry components 5.607.00 8.81 7.56 8.69 5.81 6.57 _ _ __ __ __ ___. __ __ Totsl 100.00 100.00 100.00 100.00 100.13 Speclic Gravlty 2.77 2.75 2.74 2.73 2.77 2.78 2.75

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. The process of producing a liquid agent for improving the quality of contaminated water which comprises the steps of introducing a solid substance, selected from comminuted rock-salt clay or a mixture thereof with rock-salt deads, with agitation into an aqueous solution or suspension of an inorganic base, stirring the resultant mixture for a period of from 2 to 5 hours, adjusting the pH of the stirred mixture to a value of between 7.5 and 10.5 pH by addition of acid or alkali if the pH is not already within that range, and separating undissolved material from the resultant solution, such resultant solution comprising the liquid agent.

2. A process is defined in claim 1, the stirring step being effected for about 3 hours.

3. A process as defined in claim 1, the pH of the stirred mixture being adjusted to the range of 9.5 to 10.5.

4. A process as defined in Claim 1, the aqueous solution or suspension having a pH of more than 10.

5. A process as defined in claim 4, the pH of the aqueous solution or suspension being greater than 12.

6. A process as defined in Claim 1, the solid substance having a NaCl content between 20 and 80 wt%.

7. A process as defined in Claim 1, characterized including the step before the adjustment of the pH to the desired final value of increasing the sodium chloride content of said stirred mixture to 14 g NaCl per liter of solution by addition of sodium chloride.

8. A process as defined in Claim 7, the sodium chloride being added as an aqueous solution.

9. A process as defined in claim 8, the sodium chloride solution comprising brine of 28 wt% sodium chloride.

10. A process as defined in Claim 7, comprising the further step of adding water to the mixture after the step increasing the NaCl content and thereupon stirring the mixture from one to four hours.

11. A process as defined in Claim 1, the quantity of solid substance added to the alkaline solution being based on the sodium chloride content of said solids, said quantity comprising 1 kg of solids having a sodium chloride content of 0% to 7 kg of solids having a sodium chloride content of 80%, for every 180 to 200 liters of alkaline aqueous solution, or suspension.

12. A liquid agent for improving the quality of contaminated water when produced by the process of Claim 1.