Water treatment compositions and methods of use

Abstract

Methods for clarifying water, reducing turbidity of water, and removing phosphate from water include adding a water treatment composition having an aluminum-containing coagulant, and a natural non-charged polysaccharide, such as guar. The aluminum-containing compound can include polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate, or a combination thereof.

Claims

1. A composition consisting of the following components: polyaluminum chloride having a basicity greater than 65% and less than 70%; uncharged guar; and water, wherein a weight ratio of the polyaluminum chloride to the uncharged guar in the composition is between 10:1 and 100:1; said composition being capable of clarifying or reducing a turbidity of a turbid water when an effective amount of said composition is mixed therewith.

2. The composition of claim 1, wherein the weight ratio of the uncharged guar to the polyaluminum chloride is about 1:34.

3. The composition of claim 1, wherein the composition is made by a process comprising mixing the uncharged guar in a solid guar form and the polyaluminum chloride in a solid polyaluminum chloride form, and adding the water to the solid guar form and the solid polyaluminum chloride form.

4. A method for clarifying or reducing a turbidity of drill water, the method comprising: mixing a composition consisting of the following components: polyaluminum chloride having a basicity greater than 65% and less than 70%; and uncharged guar, wherein a weight ratio of the polyaluminum chloride to the uncharged guar in the composition is between 10:1 and 100:1; with the drill water; forming agglomerations in the drill water containing the composition that is mixed; and removing the agglomerations from the drill water, thereby clarifying or reducing the turbidity of the drill water.

5. The method of claim 4, comprising: mixing the uncharged guar in solid form and the polyaluminum chloride in solid form to form a solid mixture and adding water to said solid mixture.

6. A method for clarifying or reducing a turbidity of a process water comprising suspended materials from oil or gas drilling, hydraulic fracturing, or oil refinery operations, the method comprising: the step of forming a mixture comprising mixing a composition consisting of the following components: polyaluminum chloride having a basicity greater than 65% and less than 70%; and uncharged guar; and water, wherein a weight ratio of the polyaluminum chloride to the uncharged guar in the composition is between 10:1 and 100:1; with the process water from oil refinery operations containing suspended materials to form a mixed liquid; forming agglomerations in the mixed liquid; removing the agglomerations from the mixed liquid, thereby clarifying or reducing the turbidity of the process water.

Description

DESCRIPTION OF THE DRAWINGS

(1) The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying FIGURES:

(2) FIG. 1 is a graph illustrating results of turbidity reduction using guar and various samples of polyaluminum chloride; and

(3) FIG. 2 is a graph illustrating results of turbidity reduction using guar with polyaluminum chloride and guar with alum.

DETAILED DESCRIPTION

(4) Removal of suspended particulate or soluble matter in aqueous fluids can be accomplished by coagulation and flocculation followed by settling, skimming, filtration, centrifugation or any combination thereof. Coagulation often involves the use of multivalent inorganic metal salts such as aluminum sulfate (alum), aluminum chloride, polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, iron sulfate, or iron chloride.

(5) Flocculants such as chitosan or polyacrylamides have also been used separately or in combination with alum or polyaluminum chloride to treat water for reducing turbidity and/or removing suspended solid matter. Although the combination may offer improved coagulation, flocculation and floc size, the resulting floccules may still exhibit low shear strength and come apart when subjected to low to moderate pressure or agitation. Improved backwashing of filters containing flocculated insoluble materials that do not cling to the filter media but release easily from the filter media during backwashing cycles would be of significant value. The use of a natural non-charged polysaccharide, such as guar, in combination with an aluminum-containing coagulant, such as polyaluminum chloride or aluminum chlorohydrate or polyaluminum chlorohydrate or aluminum sulfate or sodium aluminate or polyaluminum sulfate or polyaluminum silicate chloride or polyaluminum silicate sulfate, or some combination thereof may allow for easy and more efficient backwashing. Other natural non-charged polysaccharides may include locust bean gum, starch, konjac, and cellulose.

(6) The water treatment composition used in the methods for clarifying water, reducing the turbidity of water, and removing phosphate from water includes an aluminum-containing coagulant or a combination of aluminum-containing coagulants, and a natural non-charged polysaccharide or combination of natural non-charged polysaccharides. Optionally, the water treatment composition may include water. The water treatment composition may be applied as a solution or in a dry solid form. The aluminum-containing coagulant, and the natural non-charged polysaccharide may be applied together in solution, or in dry solid form, or in a complexed form. The aluminum-containing coagulant, and the natural non-charged polysaccharide may be applied separately, each being in a solution or in a dry solid form. The aluminum-containing coagulants and the natural non-charged polysaccharides are described further below.

(7) Aluminum-Containing Coagulants

(8) The aluminum-containing coagulants are readily commercially available. The aluminum-containing compounds may be applied as aqueous solutions or in a dry (solid) powder or granular form. The following may be used singly or in combination: polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate.

(9) Aluminum sulfate has the formula, Al.sub.2(SO.sub.4).sub.3.Math.xH.sub.2O, wherein X is reported to be 13, 14, 15, 16, 17, or 18, or a combination. Solutions can be defined by the aluminum content or expressed in terms of equivalent alumina Al.sub.2O.sub.3.

(10) Polyaluminum chloride may have the formula Al.sub.m(OH).sub.nCl.sub.(3m-n), wherein 0<n3m, and m1. See U.S. Pat. No. 7,846,318, incorporated herein expressly by reference. The species can form polymers in water. The ph correlates to the formula n/(3m). The higher the basicity of a coagulant, the lower the alkalinity consumption and, therefore, the less the pH of the water is reduced. Basicity can range from about 15% to about 83% w/w in commercially available polyaluminum chlorides. Basicity can be low, medium, or high basicity. Basicity can range from about 10% to about 83%, and any range derivable therebetween, such as between any range beginning from 10%, 20%, 30%, 40%, 50%, 60%, or 70%, and ending at 20%, 30%, 40%, 50%, 60%, 70, or 80%.

(11) Some polyaluminum chlorides may have sulfate. In the literature, these compounds are also sometimes referred to as polyaluminum chlorides, and sometimes as polyaluminum chorosulfates. The formula of some polyaluminum chlorides (polyaluminum chorosulfates) may be Al.sub.nOH.sub.m(SO.sub.4).sub.kCl.sub.(3n-m-k). Sulfate can range about 2% to 3% by weight.

(12) Aluminum chlorohydrate is the name of the polyaluminum chloride where n=2, and m=5. Aluminum chlorohydrate may have the formula Al.sub.2Cl(OH).sub.5, which has a basicity of about 83%.

(13) Suitable aluminum-containing coagulants are available from Kemira Chemicals, Inc. under the designation PAX.

(14) Polysaccharides

(15) The polysaccharide(s) that comprise the water treatment composition can include combinations of the following natural non-derivatized polysaccharides: galactomannans; glucomannans; -D glucans; xyloglucans; arabinoxylans; inulins; linear polysaccharides of alternating -(1-3)- and -(1-4) galactopyranose units; linear polysaccharides of glycosidically linked units of -D-glucopyranose; linear polysaccharides of glycosidically linked units of -D-glucopyranose; heteropolymers of glycosidically linked units of both -(1-4)-2-acetamido-2-deoxy-D-glucopyranose and -(1-4)-2-amino-2-deoxy-D-glucopyranose. Representative examples, although not exhaustive, include guar and locust bean gums, gum arabic, gum tragacanth, starches (branched and linear), agars, carrageenans, pectins, xanthan, konjac, cellulose, chitin, and chitosan.

(16) A natural non-charged polysaccharide includes guar. Guar (guar gum) is a straight chain galactomannan with galactose on every other mannose unit. Beta 1-4 glycosidic linkages couple the mannose units and the galactose side chains are linked by alpha 1-6. A suitable guar gum for use is available from Univar, Inc. Other natural non-charged polysaccharides may include locust bean gum, starch, konjac, and cellulose.

(17) Some embodiments of a method for clarifying water or removing phosphate from water include the steps: adding an aluminum-containing coagulant selected from polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate or a combination thereof, and a synergistic amount of a natural, non-charged polysaccharide to water containing matter; forming agglomerations in the water comprising the matter, the aluminum-containing compound, and the polysaccharide; and removing the agglomerations from the water to remove the matter from the water.

(18) In some embodiments, the natural, non-charged polysaccharide is guar.

(19) In some embodiments, adding the aluminum-containing coagulant and polysaccharide comprises adding a solution of aluminum-containing coagulant and guar.

(20) In some embodiments, adding the aluminum-containing coagulant and polysaccharide comprises adding solid forms of aluminum-containing coagulant and guar.

(21) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight polyaluminum chloride.

(22) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight aluminum chlorohydrate.

(23) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight polyaluminum chlorohydrate.

(24) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight aluminum sulfate.

(25) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight sodium aluminate.

(26) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight polyaluminum sulfate.

(27) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight polyaluminum silicate chloride.

(28) In some embodiments, the aluminum-containing coagulant is substantially 100% by weight polyaluminum silicate sulfate.

(29) In some embodiments, the aluminum-containing coagulant comprises a solution of polyaluminum chloride and water.

(30) In some embodiments, the aluminum-containing coagulant comprises a solution of aluminum chlorohydrate and water.

(31) In some embodiments, the aluminum-containing coagulant comprises a solution of polyaluminum chlorohydrate and water.

(32) In some embodiments, the aluminum-containing coagulant comprises a solution of aluminum sulfate and water.

(33) In some embodiments, the aluminum-containing coagulant comprises a solution of sodium aluminate and water.

(34) In some embodiments, the aluminum-containing coagulant comprises a solution of polyaluminum sulfate and water.

(35) In some embodiments, the aluminum-containing coagulant comprises a solution of polyaluminum silicate chloride and water.

(36) In some embodiments, the aluminum-containing coagulant comprises a solution of polyaluminum silicate sulfate and water.

(37) In some embodiments, the aluminum-containing coagulant is a solution made with the compound having the formula Al.sub.m(OH).sub.nCl.sub.(3m-n), wherein 0<n3m, and m1.

(38) In some embodiments, the aluminum-containing coagulant is a solution made with the compound having the formula Al.sub.2(SO.sub.4).sub.3.Math.xH.sub.2O.

(39) In some embodiments, the aluminum-containing coagulant is a solution made with the compound having the formula Al.sub.2Cl(OH).sub.5.

(40) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant is about 1:34.

(41) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant is about 1:48.

(42) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant ranges from about 1:10 to about 1:100.

(43) In some embodiments, the aluminum-containing coagulant and the polysaccharide are added as a guar aluminum complex.

(44) In some embodiments, the guar aluminum complex is made by the process comprising adding solid guar to a solid aluminum-containing coagulant and adding water to the solid guar and aluminum-containing coagulant.

(45) In some embodiments, the aluminum-containing compound and polysaccharide are added together.

(46) In some embodiments, the aluminum-containing compound and polysaccharide are added separately.

(47) In some embodiments, the phosphate that is removed is orthophosphate.

(48) In some embodiments, the matter in the water includes microorganisms, bacteria, viruses, protozoans, Cryptosporidium oocysts, Giardia oocysts; proteins, oils, fats, algae, hydrocarbons, metal oxides, metal oxide hydroxides, insoluble starches; pharmaceuticals, nutraceuticals; fibers, polyaramids, dredging solids; suspended materials from mine tailings, graphite particles, carbon particles, suspended materials from oil or gas drilling or hydraulic fracturing; suspended matter in recreational or water derived from aquaculture operations or aquariums; suspended matter present in construction runoff; and suspended matter present in water from oil refinery operations.

(49) In some embodiments, the polysaccharide is a natural non-charged polysaccharide selected from locust bean gum, starch, konjac, or cellulose.

(50) Some embodiments of a method for clarifying water include the steps: adding an aluminum-containing coagulant selected from polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate or a combination thereof, and a synergistic amount of a natural, non-charged polysaccharide to water containing a phosphate compound; forming agglomerations in the water comprising the phosphate compound, the aluminum-containing coagulant, and the polysaccharide; and removing the agglomerations from the water to remove the phosphate compound from the water.

(51) In some embodiments, the phosphate compound is orthophosphate.

(52) In some embodiments, the polysaccharide is guar.

(53) In some embodiments, the aluminum-containing compound is polyaluminum chloride.

(54) In some embodiments, the aluminum-containing compound is aluminum chlorohydrate.

(55) In some embodiments, the aluminum-containing compound is polyaluminum chlorohydrate.

(56) In some embodiments, the aluminum-containing compound is aluminum sulfate.

(57) In some embodiments, the aluminum-containing compound is sodium aluminate.

(58) In some embodiments, the aluminum-containing compound is polyaluminum sulfate.

(59) In some embodiments, the aluminum-containing compound is polyaluminum silicate chloride.

(60) In some embodiments, the aluminum-containing compound is polyaluminum silicate sulfate.

(61) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant is about 1:34.

(62) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant is about 1:48.

(63) In some embodiments, the ratio of polysaccharide to aluminum-containing coagulant ranges from about 1:10 to about 1:100.

EXAMPLES

Example 1

(64) (Demonstration of Synergy of Guar and Aluminum Sulfate in Turbidity Reduction)

(65) 1. Fill four glass scintillation (glass) vials each with 20-ml of flow-back/produced water 2. Mark one as control, cap and set aside 3. Add one or two drops of 1% by weight guar solution to two of the three remaining vials, cap and shake. 4. Add 48% by weight aluminum sulfate/water solution using the equivalent number drops used in Step #3 to the third vial without guar and to one of the two vials treated with 1% guar solution, cap and shake. 5. Shake all four capped scintillation (glass) vials again and set aside at ambient T. 6. View flocculation and clarification performance.

(66) TABLE-US-00001 TABLE 3 Initial alum/guar jar test key and results CONTENTS TREATMENT 48% Alum 1% guar RESULTS Control NA NA No change 1 NA Yes No change 2 Yes Yes Floc/Cleared 3 Yes NA No change
Results:

(67) No observable flock or settling was observed in the produced water samples treated with alum alone or guar alone. There was significant settling observed in the sample treated with guar first followed by alum. There was no change in the untreated sample labeled control.

(68) Discussion:

(69) There appears to be a certain synergy present when alum and guar are used in combination. The sample treated with alum alone was unable to clear the sample and the same for the sample treated with guar alone. Only the sample containing both alum and guar produced a result.

Example 2

(70) (Demonstration of Synergy of Guar and Aluminum Sulfate in Phosphate Reduction)

(71) Procedure

(72) Orthophosphate-spiked water was prepared by adding 1.719 ml of phosphate standard solution (from PAS-STM-8039 02 of phosphate procedure) to 1 liter of deionized water. 100 ml of orthophosphate-spiked water was dispensed into plastic sample cups. 1. Aluminum sulfate (48% by weight aluminum sulfate hydrate, 52% by weight water was used neat (undiluted). 2. Hybrid EGuar aluminum complex created by mixing a solution of aluminum sulfate with solid water-soluble guar. The composition is approximately 24% (wt./wt.) alum and 0.5% (wt./wt.) guar (Univar guar gum 50). 3. 100 microliters of either Aluminum sulfate or Hybrid E was added to 100 ml of orthophosphate-spiked water which was mixed and allowed to sit for various time periods. Controls received 100 microliters of water alone. Following the various time periods, 12 ml of each treated water sample was filtered through a 0.45 micron filter, diluted 1:10 with deionized water and reacted with 1 powder pillow of HACH reagent PhosVer 3 and the phosphate concentration determined spectophotometrically using a HACH spectrophotometer. In other experiments, the phosphate concentration of the treated water was tested without filtration.
Results

(73) As shown in Table 1, Alum and Hybrid E reduced the phosphate concentration by 24% and 27% respectively compared to the non-treated control.

(74) TABLE-US-00002 TABLE 1 Phosphate concentration of filtered treated water following overnight incubation at room temperature Phosphate concentration in Phosphate treated water Concentration of corrected for 1:10 Treatment 1:10 dilution (ppm) dilution (ppm) Percent Removal Control 1.29 12.9 0% Alum neat 0.98 9.8 24% Hybrid E 0.94 9.4 27%

(75) 100 microliters of either Alum, or Hybrid E was added to 100 ml of orthophosphate-spiked water contained in a 100 ml graduated cylinder and mixed. After sitting undisturbed for two hours at RT (room temperature), water was sampled from the top (100-90 ml), middle (50-40 ml) or bottom (20-10 ml) portion of each graduated cylinder. Sampled water was diluted 1:10 with deionized water and tested without filtration spectrophotometrically for phosphate concentration using powder pillows of HACH PhosVer 3 reagent.

(76) Results are shown in table 2 below.

(77) TABLE-US-00003 TABLE 2 Phosphate concentration of treated water sampled at various levels in a graduated cylinder. Control phosphate water contained 10 ppm Top (100-90 ml) Middle (50-40 ml) Bottom (20-10 ml) Phosphate conc. Phosphate conc. Phosphate conc. Treatment (ppm) (ppm) (ppm) Alum 8.8 8.9 8.9 Hybrid E 8.1 8.3 8.0
Conclusion

(78) Hybrid E appeared to reduce orthophosphate concentrations similar to alum using about half the amount of alum.

Example 3

(79) (Testing of Various PACs with Guar)

(80) Product Testing Method:

(81) 1. 200 grams of Arizona Fine Dust ((PTI ID: 10943F) was mixed in 10 liters of DI H2O to prepare the Arizona test dust solution. 2. 1N HCl was added to the Arizona test dust solution to bring the pH to 7.2 from a pH of 9.4. 3. 500 mls of Arizona test dust solution was poured into separate 500 ml bottles and labeled respective to the guar/PAC formulation being added. 4. The respective guar/PAC formulation each containing a different PAC, was added to 500 ml of Arizona test dust solution to a final concentration of 50 ppm and mixed for approximately two minutes and then allowed to settle for ten minutes (the concentration of guar and aluminum was the same for each formulation. Following ten minutes of settling, turbidity was measured for each Arizona test dust solution that was treated with the respective guar/PAC formulation. Control non-treated Arizona test dust solution exhibited a turbidity of approximately 8000 NTU.

(82) The results shown in FIG. 1 clearly demonstrate that formulation 29-RT exhibiting a basicity of 70% performed significantly better at reducing turbidity compared the formulations 28RT and 30RT that exhibited a basicity of 75% and 51% respectively. Values represent the average of five replicates.

(83) Description of the Samples:

(84) 240-48-28-RT

(85) 0.5 grams of guar (Univar, Lot #10202008) was added to 17.22 grams of Grade 28 PAC and stored as powder at room temperature on Dec. 20, 2012. After 4 weeks on 02/06/13, 82.28 grams of DI water was added, and mixed for about 2 hours. The solution was then held and stored as liquid for 27 days then tested. Grade 28 PAC has a basicity of 75% and an Al.sub.2O.sub.3 content of 30.2%.

(86) 240-48-29-RT

(87) 0.5 grams of guar was added to 16.99 grams of Grade 29 PAC and stored as powder at room temperature on Dec. 20, 2012. After 4 weeks on Feb. 6, 2013, 82.51 grams of DI water was added, and mixed for about 2 hours. The solution was then held and stored as liquid for 27 days then tested. Grade 29 PAC has a basicity of 70% and an Al.sub.2O.sub.3 content of 30.6%.

(88) 240-48-30-RT Liquid

(89) 0.5 grams of guar was added to 16.99 grams of Grade 30 PAC and stored as powder at room temperature on Dec. 20, 2012. After 4 weeks on Feb. 6, 2013, 82.51 grams of DI water was added, and mixed for about 2 hours. The solution was then held and stored as liquid for 27 days then tested. Grade 30 PAC has a basicity of 51% and an Al.sub.2O.sub.3 content of 30.6%.

(90) Results

(91) FIG. 1 is an illustration of graph showing the results. Turbidity is reported in NTU. The sample 29@RT was the most effective in reducing turbidity. At 50 ppm, 29 @RT reduced turbidity to approximately 100 NTU, compared to approximately 300 NTU by 28@RT, and approximately 700 NTU by 30@RT.

Example 4

(92) A sample of frac pit water (sometimes referred to as drill water) from Bear Creek Services (Contly 27-H #1 34-H #1). The amount dosed was added to 20 ml of sample, mixed, and then rested for 5 minutes before the turbidity was measured. The results are in the Table 3 below:

(93) TABLE-US-00004 20 ml sample Control 1% Guar PAX-XL6 213-133-B Amount dosed 0 25 mg 25 mg 50 mg NTU (5 min) 740 760 860 320

(94) Formula 213-133-B is 50% by weight Kemira PAX-XL6 poly aluminum chloride (basicity 55%, Al.sub.2O.sub.3 10.3%, Al 5.31%, Sulfate 2.5%), 50% by weight 1% guar solution in water (Univar 45 Guar). To make the product, the PAC is slowly added to guar solution while mixing, to get a uniform solution.

Example 5

(95) (Testing of Guar/PAC vs. Guar/Alum)

(96) Product Testing Method

(97) 1. 200 grams of Arizona Fine Dust ((PTI ID: 10943F) was mixed in 10 liters of DI H2O to prepare the Arizona test dust solution. 2. 1N HCl was added to the Arizona test dust solution to bring the pH to 7.2 from a pH of 9.4. 3. 500 mls of Arizona test dust solution was poured into separate 500 ml bottles. 4. The guar/PAC formulation and the guar/alum formulation was each added to separate 500 ml aliquots of Arizona test dust solution to a final concentration of 50 ppm and then mixed for approximately two minutes and then allowed to settle for ten minutes. The P-50 formulation is 50% by weight Kemira PAX-XL8 polyaluminum chloride (basicity 70%, Al.sub.2O.sub.3 10%, Al 5.5%) and 50% by weight 1% guar solution in water. The A48 formulation is the same as Hybrid E described earlier). Following ten minutes of settling, turbidity was measured for each Arizona test dust solution that was treated with the respective guar/PAC formulation. Control non-treated Arizona test dust solution exhibited a turbidity of approximately 8000 NTU.

(98) The results are shown in FIG. 2, wherein the values represent the average of five replicates. The results clearly demonstrate that the P-50 formulation performed significantly better at reducing turbidity compared to the A48 (Hybrid E) formulation. Compare approximately 180 NTU to 1000 NTU.

(99) While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.