ZA200600753B - System and method for treatment of acidic wastewater - Google Patents
System and method for treatment of acidic wastewater Download PDFInfo
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- ZA200600753B ZA200600753B ZA200600753A ZA200600753A ZA200600753B ZA 200600753 B ZA200600753 B ZA 200600753B ZA 200600753 A ZA200600753 A ZA 200600753A ZA 200600753 A ZA200600753 A ZA 200600753A ZA 200600753 B ZA200600753 B ZA 200600753B
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- wastewater
- reverse osmosis
- osmosis system
- prior
- silica
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- 239000002351 wastewater Substances 0.000 title claims description 223
- 238000000034 method Methods 0.000 title claims description 85
- 230000002378 acidificating effect Effects 0.000 title claims description 7
- 238000001223 reverse osmosis Methods 0.000 claims description 85
- 241000894007 species Species 0.000 claims description 82
- 238000000926 separation method Methods 0.000 claims description 74
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 64
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 52
- 230000015572 biosynthetic process Effects 0.000 claims description 47
- 239000002253 acid Substances 0.000 claims description 34
- 239000000377 silicon dioxide Substances 0.000 claims description 31
- 239000000356 contaminant Substances 0.000 claims description 30
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 28
- 229910019142 PO4 Inorganic materials 0.000 claims description 26
- 229910021529 ammonia Inorganic materials 0.000 claims description 26
- 235000021317 phosphate Nutrition 0.000 claims description 25
- -1 silicate ions Chemical class 0.000 claims description 23
- 241000195493 Cryptophyta Species 0.000 claims description 21
- 238000004065 wastewater treatment Methods 0.000 claims description 20
- 239000003513 alkali Substances 0.000 claims description 19
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 17
- 150000002222 fluorine compounds Chemical class 0.000 claims description 16
- 238000005189 flocculation Methods 0.000 claims description 13
- 239000005416 organic matter Substances 0.000 claims description 13
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 12
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 11
- 230000001737 promoting effect Effects 0.000 claims description 11
- 239000000440 bentonite Substances 0.000 claims description 10
- 229910000278 bentonite Inorganic materials 0.000 claims description 10
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 10
- 230000000536 complexating effect Effects 0.000 claims description 10
- 230000016615 flocculation Effects 0.000 claims description 10
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 9
- QAOWNCQODCNURD-UHFFFAOYSA-M bisulphate group Chemical group S([O-])(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 claims description 9
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 8
- 239000001506 calcium phosphate Substances 0.000 claims description 8
- 229910000389 calcium phosphate Inorganic materials 0.000 claims description 8
- 235000011010 calcium phosphates Nutrition 0.000 claims description 8
- 239000000460 chlorine Substances 0.000 claims description 8
- 229910052801 chlorine Inorganic materials 0.000 claims description 8
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000008394 flocculating agent Substances 0.000 claims description 6
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 5
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 4
- 239000006227 byproduct Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 230000002401 inhibitory effect Effects 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 150000002739 metals Chemical class 0.000 claims description 4
- 239000000701 coagulant Substances 0.000 claims description 3
- 239000000645 desinfectant Substances 0.000 claims description 3
- 239000008187 granular material Substances 0.000 claims description 3
- 150000003839 salts Chemical group 0.000 claims description 2
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims 6
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims 2
- 238000002347 injection Methods 0.000 claims 2
- 239000007924 injection Substances 0.000 claims 2
- 150000007513 acids Chemical class 0.000 claims 1
- 229910000019 calcium carbonate Inorganic materials 0.000 claims 1
- 239000010452 phosphate Substances 0.000 description 13
- 239000000463 material Substances 0.000 description 12
- 239000007787 solid Substances 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 10
- 230000001376 precipitating effect Effects 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical group F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 8
- 230000004907 flux Effects 0.000 description 8
- 238000010977 unit operation Methods 0.000 description 8
- 239000012528 membrane Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 239000012466 permeate Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 238000005345 coagulation Methods 0.000 description 4
- 230000015271 coagulation Effects 0.000 description 4
- 239000003456 ion exchange resin Substances 0.000 description 4
- 229920003303 ion-exchange polymer Polymers 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000010802 sludge Substances 0.000 description 3
- 235000011121 sodium hydroxide Nutrition 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 2
- 239000003830 anthracite Substances 0.000 description 2
- 125000002091 cationic group Chemical group 0.000 description 2
- 239000013626 chemical specie Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000002223 garnet Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 244000005700 microbiome Species 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 235000011118 potassium hydroxide Nutrition 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 101000760663 Hololena curta Mu-agatoxin-Hc1a Proteins 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910019093 NaOCl Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 229920006318 anionic polymer Polymers 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- VIJKGBZMANAGQI-UHFFFAOYSA-M benzyl(triethyl)azanium;hydrogen carbonate Chemical compound OC([O-])=O.CC[N+](CC)(CC)CC1=CC=CC=C1 VIJKGBZMANAGQI-UHFFFAOYSA-M 0.000 description 1
- JXRVKYBCWUJJBP-UHFFFAOYSA-L calcium;hydrogen sulfate Chemical compound [Ca+2].OS([O-])(=O)=O.OS([O-])(=O)=O JXRVKYBCWUJJBP-UHFFFAOYSA-L 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
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- 238000009296 electrodeionization Methods 0.000 description 1
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- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 230000035800 maturation Effects 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
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- 239000011368 organic material Substances 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
- Removal Of Specific Substances (AREA)
Description
- SYSTEM AND METHOD FOR TREATMENT OF ACIDIC WASTEWATER - CROSS REFERENCE TO RELATED APPLICATION
This application claims priority under 35 U.S.C. § 119(c) from the following U.S. ) provisional application: Application Serial No. 60/489,853 filed on July 24, 2003. That application is incorporated in its entirety by reference herein.
1. Field of the Invention
The present invention relates generally to treatment of acidic industrial wastewater and, more particularly, to minimizing precipitation in reverse osmosis systems utilized to treat wastewater. 2. Discussion of the Related Art : Wastewater associated with phosphate manufacturing operations is typically acidic "and typically has fluoride, ammonia, silica, sulfate, calcium, heavy metal and phosphate species. Various techniques have been utilized to reduce the level of such contaminants before wastewater can be discharged. For example, the double liming process, followed by air stripping, is a technique that is typically used. It utilizes lime addition in two stages, to promote precipitation of fluoride species and phosphate species, followed by high pH, air stripping to remove ammonia. In another technique, wastewater has been treated by techniques involving chemical precipitation followed by reverse osmosis. Like the double liming process, such techniques raise the pH of influent wastewater to promote precipitation and solids separation before the reverse osmosis step. The high chemical costs typically associated with raising the pH of the wastewater make such processes economically unattractive.
In accordance with one or more embodiments, the present invention provides a wastewater treatment System comprising an influent source comprising wastewater to be treated having a pH less than about 3.5, a first reverse osmosis system fluidly connected to the influent source, an alkali source disposed to introduce alkali downstream of the first reverse osmosis system, and a second reverse osmosis system fluidly connected downstream of the first reverse osmosis system and the alkali source.
; In accordance with one or more embodiments, the present invention provides a method of treating wastewater having a pH less than about 3.5. The method comprises steps of removing at least a portion of any contaminant from the wastewater in a first separation system, adjusting the pH of an effluent from the first separation system to at least about 6 or higher after removing at least a portion of any contaminant from the wastewater in the first separation system, and removing at least a portion of any contaminant from the wastewater in a second system after adjusting the pH of the effluent from the first separation system to at least about 6 or higher.
In accordance with one or more embodiments, the present invention provides a method of treating wastewater. The method comprises steps of inhibiting conditions in the wastewater that promote the formation of at least one of fluoride ions and silicate ions, removing any contaminant from the wastewater in a first separation system, promoting formation of at least one of the fluoride ions and silicate ions, and removing any contaminant from the wastewater to produce a treated effluent after promoting formation of at least one of the fluoride and silicate ions.
In accordance with one or more embodiments, the present invention provides a method of treating wastewater. The method comprises steps of maintaining an equilibrium condition for any precipitating contaminant in the wastewater, removing any one of phosphates, dissolved solids, ammonia, organic, and colloidal material from the wastewater, adjusting the equilibrium condition of at least one precipitating contaminant in the wastewater after removing any one of dissolved solids, ammonia, organic, and colloidal : material from the wastewater, and removing any residual fluoride, ammonia, or dissolved solid material from the wastewater to produce a treated effluent after adjusting the equilibrium condition of at least one precipitating contaminant in the wastewater.
The present invention provides a method of removing fluorides and silica from wastewater using a reverse osmosis system where the method reduces the potential for scaling in the reverse osmosis system. In the case of this aspect of the invention, the method entails promoting conditions in the wastewater that favor the formation of hydrofluorosilicic acid and directing the wastewater having the hydrofluorosilicic acid to the reverse osmosis - system. As the wastewater passes through the reverse osmosis system, fluorides and silica in or the form of the hydrofluorosilicic acid is removed from the wastewater. A second stage reverse osmosis System can be utilized to remove additional fluorides and silica. In this case, conditions are maintained in the wastewater effluent from the first reverse osmosis system that favors the formation of fluoride and silicate ions. Thus, additional fluorides and silica in the form of fluoride and silicate ions are removed as the wastewater passes through the second reverse osmosis system.
Further, the present invention entails removing algae from wastewater. In one particular embodiment, the wastewater is acidic. To remove algae from the wastewater, chlorine or a byproduct of chlorine is added to the wastewater to kill the algae. Further, ) bentonite is added and the algae, after being subjected to treatment with the chlorine or chlorine byproduct, is absorbed and or destabilized by the bentonite. Thereafter the algae can be removed by conventional process means.
In one particular embodiment of the present invention, the algae and/or suspended matter is removed through a ballasted flocculation separation system. In this process, the absorbed algae and bentonite form solids in the wastewater. In the ballasted flocculation process, a flocculant and insoluble granular material are added to the wastewater to form a flocculated mixture. The flocculated mixture form flocs, including the absorbed algae and bentonite, that settle from the wastewater.
Other advantages, novel features, and objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings, some of which are schematic and which are not intended to be drawn to scale. In the figures, each identical or nearly identical component that is illustrated ’ in various figures is represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.
Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a process flow diagram in accordance with one or more embodiments of the present invention showing a wastewater treatment system,
FIG. 2 is a schematic diagram of a ballasted separation system in accordance with one or more embodiments of the present invention;
FIG. 3 is a graph showing the equilibrium relative composition of sulfate and bisulfate species as a function of pH in accordance with one or more embodiments of the present invention;
i FIG. 4 is a graph showing the equilibrium relative composition of hydrofluoric acid and fluoride species as a function of pH in accordance with one or more embodiments of the present invention;
FIG. 5 is a graph showing the equilibrium relative composition of ammonium and . ammonia species as a function of pH; and
FIG. 6 is a graph showing the equilibrium relative composition of phosphoric acid and phosphate species as a function of pH.
Treatment of wastewater containing silica, calcium sulfate, calcium phosphate, calcium fluoride as well as any other species that can precipitate under neutral, or near neutral, pH conditions present scaling concerns. For example, reverse osmosis unit operations or systems develop scale when such wastewater is passed therethrough. Other potential fouling problems include those associated with soluble organic compounds as well as from organic materials. Consequently, such systems face significant operating costs such as, but not limited to, membrane cleaning and/or replacement and high chemical consumption. Accordingly, the present invention provides a system and a process for treating © wastewater that utilize chemical equilibrium properties in stages to produce an effluent suitable for discharge in regulated waterways. For example, the system and methods in accordance with the present invention can produce effluent, treated wastewater, having low concentrations of dissolved solids, fluoride, ammonia, phosphate, and sulfate species that can meet water discharge requirements. Thus, in accordance with one or more embodiments, the present invention provides a wastewater treatment system comprising an influent source comprising wastewater to be treated having a pH less than about 3.5, a first reverse osmosis system fluidly connected to the influent source, an alkali source disposed to introduce alkali downstream of the first reverse osmosis system, and a second reverse osmosis system fluidly connected downstream of the first reverse osmosis system and the alkali source. The wastewater treatment System can further comprise a clarifier fluidly connected between the influent source and the first reverse osmosis system. The wastewater treatment system can further comprise a multimedia or other type of filter fluidly connected between the influent source and the first reverse osmosis system. The wastewater treatment system can also further comprise an acid source disposed to add acid to the wastewater upstream of the first reverse osmosis system. The wastewater treatment system can also further comprise a mixed-bed polisher fluidly connected downstream of the second reverse 25 osmosis system.
In accordance with further embodiments, the present invention provides a method of treating wastewater having a pH less than about 3.5. The method can comprise steps of removing at oo least a portion of any undesirable species from the wastewater in a first separation system, adjusting the pH of an effluent from the first separation system to at least about 6 after removing at least a portion of any undesirable species from the wastewater in the first separation system, and removing at least a portion of any undesirable species from the wastewater in a second system after adjusting the pH of the effluent from the first separation system to at least about 6. The method can further comprise a step of clarifying the wastewater prior to performing the step of removing at least a portion of any undesirable species in the first separation unit operation. The method can further comprise a step of removing any organic matter from the wastewater prior to performing the step of removing at : least a portion of any undesirable species in the first separation system. The step of removing : any organic matter can comprise adding a disinfectant, a coagulant and a flocculating agent to the wastewater. The method can further comprise a step of removing any fine solids from the wastewater prior to performing the step of removing at least a portion of any undesirable species in the first separation system. The method can further comprise a step of adjusting a pH of the wastewater to about 3 prior to performing the step of removing at least a portion of undesirable species in the first separation system. The method can further comprise a step of reducing any one of ammonia and phosphate in treated wastewater from the second separation system to levels that comply with established EPA requirements.
In accordance with still further embodiments, the present invention provides a method of treating wastewater. The method can comprise steps of inhibiting conditions in the wastewater that promote the formation of at least one of fluoride ions and silicate ions, promoting conditions in the wastewater that form or maintain a complexing species of silica and fluoride, removing at least one undesirable species from the wastewater while promoting "condition that form or maintain a complexing species of silica and fluoride, adjusting the wastewater conditions to inhibit the formation of the complexing species after removing at least one undesirable species from the wastewater. The method can further comprise a step of removing at least a portion of any organic matter from the wastewater prior to removing any undesirable species from the wastewater in a first separation system.
In accordance with other embodiments, the present invention provides a method of treating wastewater. The method can comprise steps of maintaining an equilibrium condition for any precipitating species in the wastewater, removing any one of dissolved solids, ammonia, organic, and colloidal material from the wastewater, adjusting the equilibrium condition of at least one precipitating species in the wastewater after removing any one of dissolved solids, ammonia, organic, and colloidal material from the wastewater, and removing any residual fluoride, ammonia, or dissolved solid material from the wastewater to produce a treated effluent after adjusting the equilibrium condition of at least one precipitating species in the wastewater. The step of removing any one of dissolved solids, ammonia, organic, and colloidal material from the wastewater can be performed while maintaining an equilibrium condition for any precipitating species in the wastewater. In accordance with yet other embodiments, the present invention provides a method of treating wastewater. The method can comprise steps of promoting conditions in the wastewater to form or maintain a complexing species of silica and fluoride, removing at least one undesirable species from the wastewater while promoting conditions to form or maintain a complexing species of silica and fluoride, adjusting the conditions to inhibit the formation of the complexing species of silica and fluoride after removing at least one undesirable species "from the wastewater, and removing any residual undesirable species from the wastewater to ~~ produce a treated effluent after adjusting the conditions to inhibit the formation of the complexing species. In accordance with one or more embodiments of the present invention,
FIG. 1 shows a wastewater treatment system 10, which can comprise a first pretreatment system 12 fluidly, connected to a wastewater, influent, in wastewater source 14. Wastewater treatment system 10 can further comprise a second pretreatment system 16 fluidly connected to first pretreatment system 12. A first separation system 18 and a second separation system is typically fluidly connected downstream of first and/or second pretreatment systems 12 and 16. Treated wastewater, effluent, typically undergoes further treatment in final treatment system 22 prior to transfer to discharge 24.
Influent can be any source of wastewater suitable for treatment in accordance with the present invention. For example, a suitable influent wastewater can be wastewater accumulated having a relatively acidic pH such as those from phosphate manufacturing operations.
The first pretreatment system can comprise one or more unit operations that remove organic matter, such as algae as well as reduce the turbidity of the influent wastewater stream at its pH. A suitable pretreatment system can comprise a clarifier having ballasted flocculation subsystems. FIG. 2 shows one such exemplary unit having a coagulation stage, a maturation stage, a settling stage and a hydrocyclone. The clarifier 30 can utilize a disinfectant, such as sodium hypochlorite, to deactivate any microorganisms or organic matter in the wastewater stream; a coagulating agent, such as, but not limited to, bentonite,
“aluminum sulfate, and ferric chloride, to promote coagulation of deactivated matter; and a * flocculating agent such as, but not limited to, nonionic, cationic, anionic polymers or combinations thereof, to promote flocculation of the deactivated, coagulated matter. The clarifier can utilize microsand enhanced settling and hydrocyclone techniques to separate sludge or solids from the liquid-rich stream. Such systems preferably reduce the turbidity of "the wastewater stream to less than about 3 NTU.
The second pretreatment system comprises one or more unit operations that remove fine solids and/or improve the turbidity of the wastewater stream. A suitable system can comprise a multimedia filter utilizing any of anthracite, sand, and garnet. Such systems preferably reduce the turbidity of wastewater to less than about 2 NTU and reduce the SDI to less than about 4 to reduce the likelihood of downstream fouling.
The first and second separation systems remove contaminants or undesirable species from the wastewater to render it suitable for discharge into a body of water. As used herein the phrase suitable for discharge refers to treated wastewater having contaminant concentrations that meet or exceed United States EPA discharge requirements. For example, the first and second separation Systems can comprise one or more reverse osmogis devices “. suitable for service in conditions of the wastewater. Effluent treated wastewater typically a has contaminant concentrations as listed in Table 1. : Table 1. Effluent Quality Requirements (in mg/l). ms
Thus, in accordance with one or more embodiments of the present invention, first separation system 18 can comprise one or more reverse osmosis apparatus having separation membranes (not shown) suitable for service treatment of wastewater, such as brackish water, having a pH of less than about 3, and flux rates of about 6 to about 12 GFD because, it is believed, high flux rate greater than about 12 GFD can lead to fouling and flux rates less than about 6 GFD can lead to low permeate quality. Similarly, second separation system 20 : can comprise one OT More reverse OSMOSIS apparatus 20 having separation membranes (not shown) suitable for service treatment of wastewater, such as brackish water, having a pH of about 6 to about 7 and flux rates of about 15 to about 20 GFD. As with the reverse osmosis system of the first separation system, bigher flux rates can lead to unacceptable fouling whereas lower flux rates can lead to poor permeate quality. Any reverse osmosis apparatus may be utilized in the first or second separation system. Suitable examples include those : commercially available from United States Filter Corporation, Milton, Ontario, Canada.
Membranes suitable for service in the reverse osmosis apparatus in accordance with the present invention include FILMTEC BW30-365 membrane available from FilmTec, a subsidiary of The Dow™ Chemical Corporation, Midland, Michigan. The first separation system can be operated to treat wastewater having a pH of less than about 3.5 to promote the formation and/or removal of bisulfate species to inhibit the formation of sulfate species and reduce the scaling potential of calcium sulfate. The first separation system can also be operated to treat wastewater having a pH of less than about 3.5 to promote the formation and/or removal of hydrofluorosilicic species to reduce the scaling potential of silica and calcium fluoride or both. The first separation system can also be operated to treat wastewater having a pH of less than about 3.5 to promote the formation and/or removal of phosphoric acid species to reduce the scaling potential of calcium phosphate. The first separation system can also be operated to treat wastewater having a pH of less than about 3.5 to reduce the scaling potential of metals. The first separation system can also be operated to treat wastewater having a pH of less than about 3.5 to promote the formation and/or removal of ammonium species to improve the ammonia rejection rate. The second separation system can be operated to treat wastewater having a pH of about 6 to about 7 to promote the formation and/or removal of fluoride species to improve the removal of such species. The second separation system can be operated to treat wastewater having a pH of about 6 to about 7 to promote the formation and/or removal of silicate species to improve the removal of such species. The second separation system can be operated to treat wastewater having a pH of about 6 to about 7 to promote the formation and/or removal of phosphate species to improve the removal of such species. The second separation system can be operated to treat wastewater having a pH of about 6 to about 7 to promote the formation and/or removal of organic species to improve the removal of such species. Other techniques may be utilized in the first and second separation system to remove contaminants or otherwise undesirable species including, but not limited to, electrodialysis, electrodeionization, microfiltration, and evaporation/condensation. In some cases, the wastewater treatment system can further comprise an antiscalant and/or a flocculating agent source disposed to introduce an antiscalant and/or a flocculating agent into the wastewater upstream of the pretreatment system or either of the separation systems. Any suitable antiscalant can be used that inhibits the formation of scale in the various unit operations in accordance with the present invention.
The antiscalant can be used as recommended by respective manufacturers but are typically introduce at a concentration of about 3 to about 4 ppm. Final treatment system 22 can comprise one or more unit operations that further reduce any contaminant or undesirable species from the treated wastewater and make it suitable for discharge. For example, final treatment system 22 can comprise one or more mixed-bed polishers that reduce ammonia concentration to less than about 1 mg/1. The 15 mixed-bed typically can comprise one or more anionic and cationic ion exchange resins that attract and bind residual charged species in the treated wastewater. The ion exchange resin can be present in the mixed-bed in any suitable arrangement to further purify the treated wastewatex. Examples of suitable ion exchange resins include the DOWEX™ MARATHON resin family, available from The
Dow™ Chemical Corporation, Midland, Michigan, as well as the AMBERLITE™ resin family available from Robm and Haas Company, Philadelphia, Pennsylvania. Wastewater treatment system 10 typically further includes an acid source 26 and an alkali source 28.
Acid source 26 is typically connected to an inlet stream of first separation system 18 and alkali source 28 is typically connected to an inlet stream of second separation system 20. In such an arrangement, acid from acid source 26 can adjust one or more chemical properties of wastewater to be treated in first separation system 18. For example, the pH of wastewater to be treated in an inlet 30 of first separation system 18 can be adjusted to control and/or maintain the solubility or equilibrium of one or more chemical species including, for example, inhibiting formation of precipitating species by, for example, increasing the solubility of such species and/or promoting the formation of a complexing species comprising such otherwise precipitating species.
In accordance with one or more embodiments of the present invention, an acid can be introduced into inlet 30 and mixed with wastewater to be treated to promote, maintain, or otherwise alter equilibrium conditions to inhibit the formation of any sulfate (SOs) species and/or favor the formation of any bisulfate (HSO4) species. As shown in FIG. 3, the equilibrium relative composition of sulfate and bisulfate species varies as a function of pH.
Lower pH conditions can promote the formation of bisulfate species whereas higher pH conditions can promote the formation of sulfate species. Thus, controlling the pH can affect the availability of sulfate species that typically have a tendency to precipitate in the separation systems of the present invention.
In other embodiments, acid addition can be utilized to promote, maintain or otherwise . alter equilibrium conditions to promote the formation of hydrofluorosilicic acid and/or inhibit ’ precipitation of silica and fluoride species. As shown in FIG. 4, the equilibrium relative composition of hydrofluoric acid and fluoride species varies as a function of pH. Lower pH conditions can promote the formation of hydrofluoric acid species whereas higher pH conditions can promote the formation of fluoride species. Thus, controlling the pH can affect the availability of hydrofluoric acid species, which, in turn, can affect the formation of hydrofluorosilicic species and reduce the availability of precipitating silica or silicate species.
In still other embodiments, acid addition can be utilized to promote, maintain, or otherwise alter equilibrium conditions to promote the solubility phosphate species such as, but not limited to, calcium phosphate. For example, the pH of wastewater to be introduced in inlet 30 of first separation system 18 can be maintained or adjusted to below about 3, typically to below about 2.8, and in some cases to below about 2.5, and in yet other cases to about 2.
Any acid can be used in accordance with the present invention that serves to lower or maintain the pH of a stream to the desired pH range. Suitable examples include hydrochloric acid and sulfuric acid or mixtures thereof. The selection of the particular acid will depend on several factors, including but not limited to, availability and cost as well as other disposal considerations. For example, hydrochloric acid may be preferable over sulfuric acid to avoid any concentration increases of the sulfate species.
Likewise, an alkali from alkali source 28 can be utilized to adjust one or more chemical properties of wastewater to be treated in second separation system 20. As with acid addition, alkali addition can be advantageously utilized to control and/or maintain the solubility or equilibrium of one or more chemical species. For example, the pH of wastewater treated from first separation system 18 can be adjusted to promote the formation of silicate or fluoride species, or both, to facilitate removal thereof from the wastewater stream in second separation system 20. Similarly, the pH can be adjusted to favor the formation of phosphate and ammonia species to facilitate removal thereof from the wastewater stream in second separation system 20. Thus, in accordance with one or more embodiments of the present invention, the pH of wastewater in an inlet 32 of second separation system 20 can be raised to at least about 6, in some cases to at least about 6.5, and in still other cases to between about 6 and about 7. The pH increase can also facilitate the formation of organic salt and their removal thereof in second separation system 20 to improve the TOC quality of the effluent. As shown in FIG. 5, the equilibrium relative composition of ammonium and ammonia species varies as a function of pH. Lower pH conditions can "promote the formation of ammonia species, which can promote removal thereof in the first separation system. In addition, as shown in FIG. 6, the equilibrium relative composition of phosphoric acid and phosphate species varies as a function of pH. pH conditions can be controlled to promote the formation of HPO, species, which can promote removal thereof in ~ the second separation system. Any alkali can be used in accordance with the present invention that serves to raise the pH of a stream to the desired pH range. Examples suitable for use as alkali include caustic soda or sodium hydroxide, caustic potash or potassium hydroxide. Preferably, the acid and the alkali comprise species that are suitable for discharge to a body of water. As used herein the terms contaminants and undesirable species refer to species in the wastewater or treated wastewater that have a defined concentration limit.
Contaminants include, for example, calcium, magnesium, sodium, potassium, aluminum, barium, ammonium, bicarbonate, sulfate, chloride, phosphate, nitrate, fluoride, silica, iron, and manganese comprising species. As used herein, the term organic matter can include ; bacteria, microorganisms, algae as well as suspended solids comprising such matter. Also as used herein, the term deactivating refers to rendering organic matter suitable for coagulation and/or flocculation. The function and advantage of these and other embodiments of the present invention will be more fully understood from the example below. The following example is intended to illustrate the benefits of the present invention, but do not exemplify the full scope of the invention.
This example shows the operation of a wastewater treatment system in accordance with one or more embodiments of the present invention. In particular, the wastewater treatment system 10, schematically shown in FIG. 1, bad pretreatment systems 14 and 16 comprised of a clarifier and a multimedia filter, respectively. The wastewater treatment system further included a first separation system 18 comprised of a first reverse osmosis apparatus and a second separation system 20 comprised of a second reverse osmosis apparatus. The treatment system also included final treatment system 22 comprised of a mixed-bed polisher.
The clarifier comprised of an ACTIFLO® treatment system, available from OTV SA, and utilized NaOCl to deactivate, at least partially, any organic matter. The clarifier also utilized bentonite to promote coagulation of the deactivated organic matter at about 80 to about 250 mg/1, depending on the amount necessary to coagulate the organic matter. A nonionic polymeric agent, P1142 high molecular weight polymer from Betz Dearborn,
Downers Grove, Illinois, was also utilized in the clarifier to promote flocculation of the coagulated, deactivated organic matter. The flocculating agent was introduced at a concentration of about 1 mg/1. Effluent from the clarifier had a turbidity of less than about 3
NTU. Sludge and other semisolid waste from the clarifier was returned to the accumulation pond or otherwise disposed.
The multimedia filter utilized media comprised of anthracite, sand and garnet to reduce the turbidity of the wastewater to less than about 2 NTU and to reduce the SDI to less than about 4.
The mixed-bed polisher utilized a mixed-bed of DOWEX™ MARATHON™ A and
DOWEX™ MARATHONT™ C ion exchange resins, each available from The Dow™
Chemical Corporation, Midland, Michigan. The mixed-bed polisher served to further control the concentration of NH; to below about 1 mg/1, to reduce the concentration of PO4 species to below about 0.5 mg/1.
The first reverse osmosis apparatus utilized FILMTEC™ BW30-365 membranes from
FilmTec Corporation, a subsidiary of The Dow™ Chemical Corporation, Midland, Michigan.
It was operated at an average flux rate of about 10 GFD at about 250-300 psig operating pressure. The second reverse osmosis apparatus also utilized FILMTEC™ BW30-365 membranes. It was operated at an average flux rate of about 18 GFD. If necessary, acid (hydrochloric acid) was added from an acid source to the influent wastewater stream before treatment in the first reverse osmosis apparatus to control the pH to below about 3. Alkali, sodium hydroxide, was added to the wastewater stream after the first reverse osmosis apparatus and before introduction into the second reverse osmosis apparatus to raise the pH to between about 6 and about 7. Influent wastewater was retrieved from an accumulation pond of a phosphate manufacturing facility. It typically had contaminant concentrations as listed in
Table 2. The pH of the wastewater influent into the first reverse osmosis apparatus was adjusted or maintained at between about 2 to 2.8 to maintain or promote the complexing of silica and fluoride to form hydrofluorosilicic acid species thereby reducing the scaling potential associated with silica and calcium fluoride. The pH conditions also served to shift equilibrium to favor the formation of phosphoric acid, calcium bisulfate and ammonium species and consequently reduced the scaling potential associated with calcium phosphate and calcium sulfate while promoting removal of ammonia. Table 2 lists the properties,
E including the contaminant concentrations, of the permeate stream from the first reverse osmosis apparatus (First Pass Permeate Composition). Table 2 also lists the properties and contaminant concentrations of the permeate stream from the second reverse 0Smosis apparatus (Second Pass Permeate Composition). The data show that the systems and techniques of the present invention can be used to treat wastewater and produce an effluent suitable for discharge that meets or exceeds EPA water discharge requirements. This example also illustrated the use of a wastewater treatment system that had lower costs relative to traditional systems while avoiding lime sludge and other pretreatment chemical disposal.
Table 2. Wastewater Composition (in mg/1 unless indicated). onstituent Influent First Pass Second Pass
EEE
Composition | Composition
Sa NO, IL pon | ___ow om)
EE I EL NL a I, NL
ER LL NE, B,
I NE
CL I WO BR
CT LW
CT I . RR al I I
CO I EE BC
EEO | Won ow
EN IL IR. BR
While several embodiments of the invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other systems and structures for performing the functions and/or obtaining the results or advantages described herein, and each of such variations or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art would readily appreciate that all parameters, dimensions, materials, and configurations described herein are exemplary and that actual parameters, dimensions, materials, and configurations depend upon specific applications for which the teachings of the present invention are used. Thus, the size and capacity of each of the unit operations would vary depending on several considerations specific to an installation. Further, the particular materials of construction of the vessels, pumps, and other components of the system of the present invention would be dependent also on particular, specific installation considerations but the selection, construction, and design of ‘ such components and systems would be within the scope of those skilled in the art. For example, those skilled in the art would recognize that stainless steel should be used as materials of construction of unit operations for service or applications where carbon steel would be unsuitable. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments of the invention described herein. It is, therefore, understood that the embodiments disclosed herein are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described.
The present invention is directed to each individual feature, system, material and/or method described herein. In addition, any combination of two or more such features, systems, materials and/or methods, if such features, systems, materials and/or methods are not mutually inconsistent, is included within the scope of the present invention. As used herein, all transitional phrases such as "comprising," "including," "having," "containing," "involving," and the like are open-ended, i.e. to mean including but not limited and only the transitional phrases "consisting of and "consisting essentially of shall be closed or semi-closed transitional phrases, respectively, as set forth in § 2111.03 of the United States
Patent Office Manual of Patent Examining Procedures.
Claims (21)
1. A method of removing contaminants from wastewater comprising:
a. directing the wastewater to a first reverse osmosis system and removing contaminants from the wastewater;
b. prior to directing the wastewater to the first reverse osmosis system, controlling the pH of the water such that the pH of the wastewater is maintained within a selected range;
c. directing the wastewater from the first reverse osmosis system to a second reverse osmosis System and removing contaminants from the wastewater; and d adjusting the pH upwardly after the wastewater has been subjected to treatment in the first reverse osmosis system and prior to treatment in the second reverse osmosis system.
2. The method of claim 1 including adjusting the pH of the wastewater to less than about
3.5 before the wastewater is directed through the first reverse osmosis system.
3. The method of claim 2 including adjusting the pH of the wastewater to at least about 6 or higher before the wastewater is directed through the second reverse osmosis system. 4, The method of claim 3 including maintaining the wastewater effluent from the first reverse osmosis System at about 6 or higher prior to the wastewater being directed through the second reverse osmosis system.
5. The method of claim 1 wherein the wastewater to be treated includes fluorides, silica, phosphates, metals, calcium, and sulfates, and wherein the method entails controlling the pH of the wastewater prior to entry into the first reverse osmosis system so as to condition the wastewater to favor the formation of complexing species of silica and fluoride and which further favor the formation of bisulfates, thereby reducing the scaling potential in the first reverse osmosis system due to silica, calcium fluoride, calcium sulfate, calcium phosphate or " metals
6. The method of claim 5 wherein adjusting the pH of the wastewater effluent from the first reverse osmosis system upwardly forms conditions in the wastewater that favor the formation of fluoride and silicate ions or converts any weakly ionized acids into salt form.
7. The method of claim 6 wherein the wastewater being treated also includes ammonia, phosphates or metals and wherein controlling the pH of the wastewater prior to entry into the first reverse osmosis system conditions the wastewater to favor the formation of phosphoric acid and ammonium ions that reduce scaling potential in the first reverse osmosis system due to calcium phosphate and improves ammonia removal in the first reverse osmosis system; and wherein adjusting the pH upwardly of the wastewater effluent from the first reverse osmosis system conditions the wastewater to favor the formation of phosphate ions which contribute to the removal of phosphates in the second reverse osmosis system and further conditions the wastewater to generally increase the solubility of organics and thereby contributes to the removal of the organics in the second reverse osmosis system.
8. The method of claim 1 including prior to the first reverse osmosis system clarifying the wastewater by directing the wastewater through a ballasted flocculation system.
9. The method of claim 8 including directing the wastewater effluent from the ballasted flocculation system through a multimedia filter prior to the wastewater being directed to the first reverse osmosis system.
10. The method of claim 1 wherein the wastewater includes algae and wherein the method entails mixing chlorine or a chlorine byproduct with the wastewater to kill the algae, and mixing bentonite with the wastewater to absorb or destabilize the algae.
11. The method of claim 10 wherein the algae is removed in a ballasted flocculation system that is disposed upstream from the first reverse osmosis system.
12. The method of claim 1 wherein controlling the pH of the wastewater prior to entry into the first reverse osmosis system includes selectively adding an acid to the wastewater; and wherein adjusting the pH upwardly of the wastewater effluent from the first reverse osmosis system includes selectively adding an alkali to the wastewater.
13. A method of removing fluorides and silica from wastewater including at least one reverse 0Smosis system comprising: a maintaining the pH of the wastewater at less than about 3.5 prior to the wastewater being directed to the reverse osmosis system;
b. wherein maintaining the pH to less than about 3.5 causes at least some of the fluorides and silica to assume the form of hydrofluorosilicic acid; and
C. directing the wastewater having the hydrofluorosilicic acid through the reverse osmosis system where the fluorides and silicate in the form of the hydrofluorosilicic acid is removed.
14. The method of claim 13 including selectively adding an acid to the wastewater to maintain the pH at less than about 3.5.
15. The method of claim 14 wherein the wastewater includes calcium and the method includes reducing scaling in the reverse osmosis system by reducing the potential for the formation of calcium fluoride, calcium phosphate or calcium carbonate and further reducing scaling due to the scaling potential of silica.
16. The method of claim 15 including:
a. adjusting the pH of the wastewater effluent from the first reverse 0Smosis system upwardly and directing the wastewater with the upward adjusted pH to a second reverse osmosis system; and b. wherein the upwardly adjusted pH causes the fluorides and silica to assume the form of fluoride and silicate ions, which are removed from the wastewater in the second reverse osmosis System.
17. The method of claim 16 wherein controlling the pH levels of the wastewater prior to and after treatment in the first reverse osmosis system favors the formation of bisulfates, phosphoric acid and ammonium ions at the lower pH level; and wherein the higher pH levels favor the formation of phosphate ions and generally increases the solubility of some organics which contribute to the removal of phosphates and ammonia from the wastewater.
.
18. A method of removing algae from wastewater comprising:
a. adding chlorine or a chlorine byproduct to the wastewater and killing the algae;
: b. adding bentonite to the wastewater and utilizing the bentonite to absorb or destabilize the algae; and c. removing the algae from the wastewater.
19. The method of claim 18 including treating the wastewater with a ballasted flocculation process, and where in the absorbed algae and bentonite are removed from the wastewater by the ballasted flocculation process.
20. The method of claim 19 including mixing a flocculant and insoluble granular material with the wastewater to form a flocculated mixture such that flocs, including the absorbed algae and bentonite, form on the granular material and are settled from the wastewater. -
21. The method of claim 18 wherein the wastewater including the algae is acidic.
22. A method of removing contaminants such as fluorides, silica, sulfates, ammonia, and phosphates from wastewater having a pH less than about 3, comprising: a removing at least a portion of any contaminant from the wastewater in a first : separation system;
b. maintaining the pH of the wastewater at less than about 3 prior to being directed to the first separation system;
C. adjusting the pH of the effluent from the first separation system to at least about 6 or higher after at least a portion of any contaminant has been removed from the wastewater in the first separation system; and d removing at least a portion of any contaminant from the wastewater in a second separation system after adjusting the pH of the effluent from the first separation system to at least about 6.
23. The method of claim 22 further comprising a step of clarifying the wastewater prior to directing the wastewater to the first separation system.
24. The method of claim 23 including clarifying the wastewater in a ballasted flocculation system. 95 The method of claim 22 including removing organic matter from the wastewater prior to directing the wastewater to the first separation system.
26. The method of claim 25 including the step of removing organic matter by adding a disinfectant, a coagulant or a flocculating agent to the wastewater.
27. The method of claim 22 including converting fluorides and silica in the wastewater to hydrofluorosilicic acid prior to the wastewater being directed to the first separation system and removing fluorides and silica in the form of the hydrofluorosilicic acid by the first separation system.
28. The method of claim 27 wherein the first separation system is a reverse osmosis system.
29. The method of claim 27 including removing sulfates from the wastewater by maintaining the pH of the wastewater to less than about 3 prior to the wastewater entering the first separation system such that the sulfates within the wastewater assume the form of bisulfates and thereby the formation of calcium sulfate is discouraged.
30. The method of claim 29 wherein by maintaining the pH of the wastewater at less than about 3 prior to entry into the first separation system, phosphates within the wastewater tend to assume the form of phosphoric acid and ammonia tends to assume the form of ammonium ions, and wherein the bisulfates, hydrofluorosilicic acid, phosphoric acid and ammonium ions can be efficiently removed in the first separation system.
31. The method of claim 30 wherein adjusting the pH to at least about 6 creates conditions in the wastewater that favor the fluorides and silica assuming the form of fluoride and silicate ions and further favors the phosphates assuming the form of phosphate ions and increases the solubility of organics within the wastewater, all of which contaminants would be subject to removal in the second separation system.
32. A method of treating wastewater and moving fluorides and silica from the wastewater, comprising:
a. inhibiting conditions in the wastewater that promote the formation of at least one of fluoride ions or silicate ions;
b. promoting conditions in the wastewater that favor the formation of hydrofluorosilicic acid;
Cc. removing fluorides and silica in the form of hydroftuorosilicic acid from the wastewater by directing the wastewater through a first separation system; d after the wastewater has been treated in the first separation system, promoting conditions that favor the formation of fluoride and silicate ions; and e. directing the wastewater, including the fluoride and silicate ions, through a second separation system and removing from the wastewater the fluoride and silicate ions.
33. The method of claim 32 wherein the first and second separation systems include first and second reverse osmosis systems.
34. The method of claim 32 wherein the conditions in the wastewater is controlled before ; and after the first reverse osmosis system by controlling the pH of the wastewater.
35. The method of claim 34 wherein the pH is controlled to less than about 3 prior to the wastewater entering the first reverse osmosis system; and wherein the pH of the wastewater effluent from the first reverse osmosis system is controlled to at least about 6 or higher.
36. The method of claim 33 wherein the wastewater includes the further contaminants of ammonia, phosphates and sulfates, and wherein by controlling the pH of the wastewater prior to entry into the first reverse osmosis system, the phosphates tend to assume phosphoric acid and thereby reduce the scaling potential due to calcium phosphate, and the ammonia tends to assume the form of ammonium ions which can be efficiently removed via the first reverse 08mMosis system.
37. The method of claim 36 wherein increasing the pH of the wastewater effluent from the first reverse osmosis system results in the phosphates assuming the form of phosphate ions and generally increases the solubility of organics within the wastewater, and wherein the phosphate ions and organics can be removed in the second reverse osmosis system.
38. A wastewater treatment system designed to remove contaminants such as fluorides, silica, phosphates, sulfates, ammonia and to remove such contaminants without generating scaling, the system comprising:
a. a first reverse osmosis system;
b. a second reverse osmosis system disposed downstream from the first reverse 0Smosis system,
C. an acid injection inlet disposed upstream from the first reverse osmosis system and adapted to be operatively connected to an acid source for selectively . injecting an acid into the wastewater prior to the wastewater reaching the first reverse osmosis system such that the pH of the wastewater entering the first reverse osmosis system can be controlled; and d. an alkali injection inlet disposed between the first and second reverse osmosis system and operatively connected to an alkali source for selectively injecting an alkali into the wastewater effluent from the first reverse osmosis system for controlling the pH of the wastewater prior the wastewater entering the second reverse osmosis system.
39. The wastewater treatment system of claim 38 further including a clarifier disposed upstream from the first reverse osmosis system.
40. The wastewater treatment system of claim 39 wherein the clarifier forms a part of a ballasted flocculation system.
41. The wastewater treatment system of claim 39 further including a multimedia disposed upstream from the first reverse osmosis system. 42, The wastewater treatment system of claim 38 further comprising a mixed-bed polisher disposed downstream from the second reverse osmosis system.
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US20110203929A1 (en) * | 2008-11-17 | 2011-08-25 | David Buckley | Recovery of lithium from aqueous solutions |
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US9840667B2 (en) * | 2013-04-25 | 2017-12-12 | Solvay Sa | Reverse osmosis for purifying mixtures of hydrofluoric acid and nitric acid |
CN106645290A (en) * | 2016-10-11 | 2017-05-10 | 广西大学 | System for pre-warning destabilization of microstickies by utilizing pH value change of white water |
CN108128933A (en) * | 2018-01-16 | 2018-06-08 | 四川大学 | Silicon-containing wastewater treatment technology in a kind of silicon process |
CN110304695A (en) * | 2019-06-28 | 2019-10-08 | 南方汇通股份有限公司 | A kind of reclaiming system and method for the high fluorine waste water of high phosphorus |
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US5766479A (en) * | 1995-08-07 | 1998-06-16 | Zenon Environmental Inc. | Production of high purity water using reverse osmosis |
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US6398965B1 (en) * | 1998-03-31 | 2002-06-04 | United States Filter Corporation | Water treatment system and process |
US6071413A (en) * | 1999-01-13 | 2000-06-06 | Texaco Inc. | Process for removing organic and inorganic contaminants from phenolic stripped sour water employing reverse omosis |
US6338803B1 (en) * | 1999-08-30 | 2002-01-15 | Koch Microelectronic Service Co., Inc. | Process for treating waste water containing hydrofluoric acid and mixed acid etchant waste |
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AU2002322559A1 (en) * | 2001-07-20 | 2003-03-03 | Microbar, Inc. | Reverse osmosis pretreatment using low pressure filtration |
US6758976B2 (en) * | 2001-10-25 | 2004-07-06 | Imc Global Operations Inc. | Simplified purification of phosphoric acid plant pond water |
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