CN112499863A - Method for resource comprehensive utilization of high-concentration wastewater and waste salt - Google Patents
Method for resource comprehensive utilization of high-concentration wastewater and waste salt Download PDFInfo
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- CN112499863A CN112499863A CN202011133077.8A CN202011133077A CN112499863A CN 112499863 A CN112499863 A CN 112499863A CN 202011133077 A CN202011133077 A CN 202011133077A CN 112499863 A CN112499863 A CN 112499863A
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- 150000003839 salts Chemical class 0.000 title claims abstract description 103
- 239000002699 waste material Substances 0.000 title claims abstract description 89
- 239000002351 wastewater Substances 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 132
- 229910001868 water Inorganic materials 0.000 claims abstract description 132
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 93
- 238000011282 treatment Methods 0.000 claims abstract description 61
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical class O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 54
- 238000000909 electrodialysis Methods 0.000 claims abstract description 48
- 238000001728 nano-filtration Methods 0.000 claims abstract description 44
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 43
- 239000011780 sodium chloride Substances 0.000 claims abstract description 40
- 239000012528 membrane Substances 0.000 claims abstract description 32
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 28
- 230000008569 process Effects 0.000 claims abstract description 27
- 238000004064 recycling Methods 0.000 claims abstract description 27
- 239000007787 solid Substances 0.000 claims abstract description 23
- 238000002425 crystallisation Methods 0.000 claims abstract description 17
- 230000008025 crystallization Effects 0.000 claims abstract description 17
- 238000000926 separation method Methods 0.000 claims abstract description 15
- 230000008014 freezing Effects 0.000 claims abstract description 11
- 238000007710 freezing Methods 0.000 claims abstract description 11
- 239000012267 brine Substances 0.000 claims description 52
- 229920006395 saturated elastomer Polymers 0.000 claims description 34
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 33
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 33
- 235000011152 sodium sulphate Nutrition 0.000 claims description 33
- 238000005086 pumping Methods 0.000 claims description 31
- 239000000243 solution Substances 0.000 claims description 31
- 239000002910 solid waste Substances 0.000 claims description 20
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- 239000000460 chlorine Substances 0.000 claims description 18
- 229910052801 chlorine Inorganic materials 0.000 claims description 18
- 239000012452 mother liquor Substances 0.000 claims description 17
- 238000003860 storage Methods 0.000 claims description 17
- 239000008234 soft water Substances 0.000 claims description 16
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims description 13
- 238000001704 evaporation Methods 0.000 claims description 13
- RSIJVJUOQBWMIM-UHFFFAOYSA-L sodium sulfate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[O-]S([O-])(=O)=O RSIJVJUOQBWMIM-UHFFFAOYSA-L 0.000 claims description 13
- 238000007599 discharging Methods 0.000 claims description 11
- 238000012545 processing Methods 0.000 claims description 11
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 10
- 238000003825 pressing Methods 0.000 claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 9
- 238000001556 precipitation Methods 0.000 claims description 9
- 230000008020 evaporation Effects 0.000 claims description 8
- 239000013505 freshwater Substances 0.000 claims description 7
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000005189 flocculation Methods 0.000 claims description 6
- 230000016615 flocculation Effects 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- 229910001424 calcium ion Inorganic materials 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- -1 sodium chloride form saturated brine Chemical class 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 4
- 238000007670 refining Methods 0.000 claims description 4
- 238000012546 transfer Methods 0.000 claims description 4
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 239000005416 organic matter Substances 0.000 abstract description 5
- 230000015572 biosynthetic process Effects 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 3
- 239000002920 hazardous waste Substances 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 abstract description 3
- 239000002253 acid Substances 0.000 description 9
- 238000009713 electroplating Methods 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000003513 alkali Substances 0.000 description 6
- 150000002500 ions Chemical class 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 238000004061 bleaching Methods 0.000 description 4
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000009292 forward osmosis Methods 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- POJAQDYLPYBBPG-UHFFFAOYSA-N 2-(2,4,7-trinitrofluoren-9-ylidene)propanedinitrile Chemical compound [O-][N+](=O)C1=CC([N+]([O-])=O)=C2C3=CC=C([N+](=O)[O-])C=C3C(=C(C#N)C#N)C2=C1 POJAQDYLPYBBPG-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000005708 Sodium hypochlorite Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000002440 industrial waste Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 238000007781 pre-processing Methods 0.000 description 2
- 238000009287 sand filtration Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000007646 directional migration Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- 238000011034 membrane dialysis Methods 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 231100000243 mutagenic effect Toxicity 0.000 description 1
- 230000003505 mutagenic effect Effects 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000012465 retentate Substances 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 231100000378 teratogenic Toxicity 0.000 description 1
- 230000003390 teratogenic effect Effects 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/04—Chlorides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/14—Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/32—Hydrocarbons, e.g. oil
- C02F2101/322—Volatile compounds, e.g. benzene
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Electrochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Metallurgy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
The invention belongs to the technical field of environment-friendly wastewater and hazardous waste treatment, and particularly relates to a method for recycling and comprehensively utilizing high-concentration wastewater and waste salt. The invention combines and improves the processes of nanofiltration, electrodialysis, reverse osmosis, freezing crystallization, evaporative crystallization and bipolar membrane electrodialysis, solves the problems of low requirements on the sulfate radical and organic matter content of nanofiltration inlet water, low operating pressure, low recycling efficiency and the like, and simultaneously, by matching with the methods of electrodialysis concentration, reverse osmosis concentration and the like, the water yield of nanofiltration water production is greatly reduced, the concentration is improved, and the amount of solid sodium chloride required by the saturated brine formed by subsequent salt formation entering an electrolysis system is greatly reduced. The method has low cost, safety and no pollution, can realize the recycling of high-concentration wastewater and waste salt of waste, has good separation effect on the high-concentration wastewater and waste salt with specific compositions, has good application prospect from the perspective of dangerous waste recycling, and can realize zero emission of the high-concentration wastewater in a plant area.
Description
Technical Field
The invention belongs to the technical field of environment-friendly wastewater and hazardous waste treatment, and particularly relates to a method for recycling and comprehensively utilizing high-concentration wastewater and waste salt.
Background
In the electroplating processing industry, the sources of the electroplating wastewater are generally: (1) cleaning water for the plated part; (2) a waste plating solution; (3) other waste waters including flushing the floor of the shop, scrubbing the polar plates, aeration equipment condensation, and various bath liquids and drains that "run, spill, drip, leak" due to bath leakage or improper operation and management; (4) the equipment cools the water, and the cooling water is not polluted except for temperature rise in the using process. The quality and quantity of the electroplating wastewater are related to the process conditions, production load, operation management, water using mode and other factors of electroplating production. The electroplating wastewater has complex water quality and difficult control of components, contains heavy metal ions such as chromium, cadmium, nickel, copper, zinc, gold, silver and the like, cyanide and the like, and some of the heavy metal ions belong to highly toxic substances with carcinogenic, teratogenic and mutagenic properties. After a series of physicochemical treatments, neutralizing and discharging, adding a large amount of alkali or acid, and generating high-concentration salt-containing organic matter wastewater and a large amount of salt-containing sludge. The electroplating high-concentration wastewater cannot be directly discharged due to large salt content (1-10%) and high organic matter content (8000-10000 mg/L). Because the salt content in the high-concentration wastewater is too high, microorganisms cannot survive, and therefore organic matters and ammonia nitrogen total nitrogen in the high-concentration wastewater cannot be effectively treated. Therefore, most electroplating park sewage treatment plants adopt a method of 'multi-stage reverse osmosis membrane + evaporative concentration crystallization' to concentrate the wastewater to 7-8%, then use evaporation equipment to separate salt in the form of crystallized salt and temporarily store the salt in a warehouse for waiting treatment, and the evaporated condensate water is recycled or discharged after reaching the standard after biochemical treatment. However, this process is too costly to handle and the temporary storage of waste salts is hazardous, so the process is not destined to operate for long periods.
The problem of disposal of dangerous waste in the petroleum and chemical industry is the same as the problem of waste salt, and the industrial waste salt is mainly from a plurality of industries such as pesticide, pharmacy, fine chemical industry, printing and dyeing and the like. The mixed salt accounts for 80 percent, the recycling cost of the salt is high, and the separation difficulty of the mixed salt is large; the residual 20% of single salt has more impurities, contains toxic and harmful substances and is difficult to treat. The research foundation of the waste salt utilization and disposal technology is relatively weak at present. The types and contents of toxic and harmful substances and the types of inorganic salts contained in waste salt are generally greatly different according to different products. Therefore, a reasonable method for harmlessly utilizing waste salts must be determined on a case-by-case basis. At present, the disposal method of industrial waste salt (hazardous waste) is filling and incineration, and the cost of each ton is low, namely thousands of yuan, and the cost of each ton is more than ten thousand yuan.
And (3) nanofiltration salt separation: the rejection characteristic of the nanofiltration membrane is characterized by the rejection rate of standard sodium chloride, for example, the rejection rate of the nanofiltration membrane of a certain company to sodium sulfate is more than or equal to 98 percent, and the rejection rate to sodium chloride is about 30 percent. The high-salinity wastewater containing sodium chloride and sodium sulfate is filtered by a nanofiltration membrane, the obtained filtrate is concentrated and then evaporated and crystallized to obtain sodium chloride with qualified purity, the trapped fluid which does not permeate the nanofiltration membrane contains mixed salt of sodium chloride and sodium sulfate, the concentration of the evaporation end point is controlled to ensure that the qualified sodium sulfate is obtained by evaporation and crystallization, and the residual mother liquor is returned to a system to be mixed with the raw materials for continuous recycling (patent No. CN 201510375661.7). Or the method can be used for generating a small amount of miscellaneous salt by adopting a drying method, or other methods are used for further advanced treatment and resource utilization (patent No. CN 201510510673.6). The method can firstly concentrate the salt water to 3% -5% or 5% -7% by using common reverse osmosis or high-salt reverse osmosis before nanofiltration, and the concentration of permeate and retentate after the nanofiltration salt separation can adopt any one of multiple-effect evaporation, mechanical vapor recompression technology, electrodialysis membranes and forward osmosis.
Electrodialysis concentration: electrodialysis ionic membrane technology is a combination of ionic membrane dialysis diffusion and electrochemical processes. The homogeneous selective permeability ionic membrane is adopted, the directional migration of ions is realized under the normal temperature and the normal pressure under the driving of an external direct current electric field, and the separation efficiency, the concentration ratio and the current efficiency can reach higher levels. The salt-containing wastewater is concentrated to about 3% after being subjected to common reverse osmosis or the seawater reverse osmosis is concentrated to about 4% -5%, the total dissolved solids can be concentrated to more than 20% after being subjected to electrodialysis ion membrane/forward osmosis, the concentration multiple is 4 times of that of the traditional process, the water quantity entering crystallization and salt separation subsequently is greatly reduced, and the system energy consumption of zero emission of the coal chemical wastewater is greatly reduced. In the process, the electrodialysis membrane and the forward osmosis are promising high-concentration brine concentration technologies and can replace the mechanical steam recompression technology to a certain extent.
Bipolar membrane electrodialysis: for high-salt wastewater, the bipolar membrane technology can convert corresponding inorganic salts into acids and bases, such as: sodium sulfate waste water can be converted into sulfuric acid and sodium hydroxide; the sodium chloride wastewater can be converted into HCl and NaOH; the mixed salt wastewater can be converted into mixed acid and sodium hydroxide. The concentration of the effluent acid: the 0.5N-3N is adjustable, the 1N-2N is optimal in economy, and acids with strong oxidizability are excluded, and the concentration is limited. The alkali concentration of effluent water: the 0.5N-3N is adjustable, and the 1N-2N economy is optimal. However, the requirement for water inflow is high, the requirement for COD and the like is strict, the concentration of acid and alkali in effluent is low, and the investment and the operation cost of the membrane are slightly high.
The salt separation and concentration method has the characteristics of low cost, high safety coefficient, stable operation and the like, and is applied to industrial production of high-concentration wastewater and waste salt. However, the method is limited by the problems of overhigh system operation pressure, low recycling efficiency and the like caused by the brine concentration and the content of organic matters in the brine, and a complete continuous process for realizing the resource utilization and industrialization of high-concentration wastewater and waste salt is not available at present. Although the above 3 technical routes are different in every autumn, the wastewater needs to be pretreated to a certain extent and respectively reach a certain standard. The selection is determined according to the content and the characteristics of the wastewater. Whatever process route is used, the non-negligible and most critical issue is the handling of the mother liquor. Because the electroplating chemical wastewater contains higher organic matters, if the content of the organic matters is too high, the precipitation of salts can be influenced.
Disclosure of Invention
In view of the above, the invention provides a method for treating high-concentration wastewater and waste salt, which has a good separation effect on waste salt with a specific composition, and has a good application prospect in the aspect of dangerous waste recycling.
The method has low cost, safety and no pollution, can realize the recycling of high-concentration wastewater and waste salt of waste, has good separation effect on the high-concentration wastewater and waste salt with specific compositions, has good application prospect from the perspective of dangerous waste recycling, and can realize zero emission of the high-concentration wastewater in a plant area.
According to the invention, through reasonable process steps and actual reaction, the sodium chloride and the sodium sulfate in the high-concentration wastewater and the waste salt are effectively separated, recycled and reused, the waste of sodium salt resources is avoided, the problems of difficult treatment and high-cost discharge of the high-concentration wastewater and the waste salt are solved, zero emission and recycling comprehensive treatment and utilization of the high-concentration wastewater and the waste salt are realized, and the process is simple, low in cost and environment-friendly.
The technical scheme of the invention is as follows:
a method for resource comprehensive utilization of high-concentration wastewater and waste salt is characterized by comprising the following steps:
s1, pumping the high-concentration wastewater generated after treatment into a water storage tank, mixing the high-concentration wastewater with the electrolyzed light brine of the electrolytic cell, primarily removing TOC in the waste brine, fully reacting, pumping into a transfer tank for subsequent treatment, and treating the high-concentration wastewater into pretreated soft water after pretreatment;
s2, pumping the pretreated soft water into a DT nanofiltration system through a pump for salt separation treatment;
s3, pumping nanofiltration product water into a TOC treatment system, reducing the TOC of the nanofiltration product water entering the nanofiltration treatment system to 50-100mg/L, pumping into an activated carbon filter, further reducing the TOC to below 5mg/L, pumping into an electrodialysis device system for concentration, enabling concentrated sodium chloride solution after concentration to enter a salt dissolving pool to form saturated salt water with solid sodium chloride, enabling the saturated salt water to enter an electrolysis system, refining the saturated sodium chloride solution through a series of physicochemical treatments, and pumping into an electrolysis bath for electrolysis;
s4, the electrodialytic fresh water passes through the first reverse osmosis system, the first reverse osmosis produced water is discharged to a water storage device to be reused, and the first reverse osmosis concentrated water returns to the electrodialytic device for concentration;
s5, discharging nanofiltration concentrated water into a solid waste salinization pool to form saturated waste brine with solid waste salt, adding a small amount of water into the saturated waste brine, treating to remove most TOC in the solution, then, entering a crystallization kettle to exchange heat, freezing and cooling to 5 ℃ to precipitate high-purity sodium sulfate decahydrate (by utilizing the characteristic that the sodium sulfate is greatly changed along with the temperature), and using the sodium sulfate as a product or entering a bipolar membrane electrodialysis system to further process;
s6, further evaporating and concentrating the frozen mother liquor by using an MVR evaporator to obtain solid sodium chloride salt and evaporated mother liquor, dissolving the solid sodium chloride salt by using electrodialysis concentrated water, and then electrolyzing in the electrolytic cell in the step S3;
s7, returning the evaporation mother liquor to the solid waste salinization pool, preparing saturated waste salt water with nanofiltration concentrated water and solid waste salt, and performing circulating treatment according to the step S5;
s8, because the evaporated condensate water contains a small amount of ammonia nitrogen, total nitrogen and TOC, after being purified by the second reverse osmosis system, the second reverse osmosis produced water is discharged to a water storage device to be reused, the second reverse osmosis concentrated water is discharged to the S5 system, and saturated waste brine is diluted to an unsaturated state, so that sodium chloride is prevented from being separated out to form miscellaneous salts due to water absorption of sodium sulfate crystals during freezing crystallization.
Further, in the step S5, the high-purity sodium sulfate decahydrate is dissolved to form a 10-20% sodium sulfate solution, the sodium sulfate solution enters a bipolar membrane electrodialysis system for electrolysis, ions are transferred in the system by adding reverse osmosis produced water to form dilute diluted acid (1N-2N) for recycling in a plant, the sodium sulfate after being diluted by electrolysis is concentrated by an electrodialysis device and then returns to the bipolar membrane electrodialysis system for continuous electrolysis, and the electrodialysis fresh water about 8-12g/L of sodium sulfate is used for dissolving the sodium sulfate decahydrate.
The invention provides a process for continuously treating high-concentration wastewater and waste salt and combining various separation and concentration technologies to realize resource recycling of the waste salt, which combines and improves the processes of nanofiltration, electrodialysis, reverse osmosis, freezing crystallization, evaporative crystallization and bipolar membrane electrodialysis, solves the problems of low requirements on the sulfate radical and organic matter content of nanofiltration inlet water, low operating pressure (generally 2.5-3 MPa), low recycling efficiency (needing to dilute the wastewater with overhigh TDS) and the like, and greatly reduces the water yield and improves the concentration of nanofiltration water by matching with the methods of electrodialysis concentration, reverse osmosis concentration and the like, so that the amount of solid sodium chloride required by forming saturated salt water by subsequent salt into an electrolysis system is greatly reduced; mixing electrolytic light brine (about 200g/L NaCl and 8000mg/L residual chlorine) of the electrolytic cell, and primarily removing TOC in the waste brine to greatly reduce difficulty and cost for subsequently removing TOC; and (3) dissolving nanofiltration concentrated water and solid waste salt to a saturated state, feeding the saturated waste salt water into a crystallization kettle for heat exchange and freezing to separate out clean sodium sulfate decahydrate, and further processing the sodium sulfate decahydrate into dilute acid diluted alkali as a product or into a bipolar membrane electrodialysis system. And further evaporating and concentrating the frozen mother liquor by using an MVR evaporator to obtain solid sodium chloride and evaporated mother liquor, dissolving the solid sodium chloride serving as electrodialysis concentrated water, then feeding the dissolved solid sodium chloride into an electrolytic cell for electrolysis, returning the evaporated mother liquor into a waste salt pool, and preparing the dissolved solid sodium chloride, the nanofiltration concentrated water and the solid waste salt into saturated waste salt water for circulation. Realizes the continuous, low-cost and large-scale clean production of high-concentration waste brine and waste salt, and realizes the zero discharge of high-concentration waste water in a factory.
Further, in the step S3, the concentrated sodium chloride solution, i.e., the electrodialysis concentrated water, has a NaCl content of 14.5% to 20%.
Further, in step S3, the electrodialysis concentrated water and solid sodium chloride form saturated brine, which is pretreated and electrolyzed to form hydrogen, chlorine and 30-32% caustic soda liquid. The pretreatment comprises impurity removal, softening, ammonia nitrogen removal and the like, generated chlorine and liquid alkali are used as raw materials of bleaching water, hydrogen and chlorine are used as raw materials of hydrochloric acid, the chlorine and the chlorine are pumped into a storage tank to wait for external sales after reaction, part of electrolyzed light brine is directly pumped into a salt dissolving pool to circulate, and part of the electrolyzed light brine is pumped into a water storage tank to be mixed with waste brine after denitrification to carry out primary TOC removal according to the step S1.
Further, in the step S1, the TOC concentration of the high concentration wastewater is less than or equal to 8000mg/L, and the electrolysis weak brine comprises 200g/L NaCl and 8000mg/L residual chlorine.
Further, in step S1, the pre-processing includes at least one of the following processing processes: softening treatment, flocculation precipitation, filter pressing and air floatation.
Further, in the step S1, the content of SS in the pretreated soft water is not more than 1mg/L, and the content of calcium and magnesium ions is not more than 20 mg/L.
Further, in step S2, the sodium sulfate concentration is 5% or less.
Further, in step S3, the TOC processing system includes at least one of the following processing systems: a Fenton treatment system, an ultraviolet/hydrogen peroxide method treatment system and an ozone method treatment system.
Further, in the step S3, before entering the electrolytic bath for electrolysis, a small amount of sodium hypochlorite is added to remove ammonia nitrogen.
Further, in the step S4, the first reverse osmosis concentrated water has a concentration equivalent to that of the concentrated sodium chloride solution in the step S3.
Further, in step S5, the solid waste salt is formed into saturated waste brine, and both sodium chloride and sodium sulfate are in a saturated state.
Further, in the step S5, the second reverse osmosis concentrated water may be used as the water added into the saturated waste brine.
Further, in step S5, the TOC removing process includes at least one of the following processes: flocculation precipitation, filter pressing, sand core filtration and air floatation.
The invention has the beneficial effects that:
the invention is a process for continuously treating high-concentration wastewater and waste salt and combining various separation and concentration technologies to realize the recycling of the waste salt, which combines and improves the processes of nanofiltration, electrodialysis, reverse osmosis, freezing crystallization, evaporative crystallization and bipolar membrane electrodialysis, solves the problems of low requirements on the sulfate radical and organic matter content of nanofiltration inlet water, lower operating pressure, low recycling efficiency and the like, and simultaneously combines the methods of electrodialysis concentration, reverse osmosis concentration and the like to greatly reduce the water yield and improve the concentration of the nanofiltration water product, so that the amount of solid sodium chloride required by the saturated brine formed by subsequent salt formation entering an electrolysis system is greatly reduced; in addition, the TOC in the waste brine is primarily reduced through the mixed treatment of the electrolyzed light brine (containing high residual chlorine) and the waste brine, so that the difficulty and the cost are reduced for reducing and removing the TOC by a subsequent advanced oxidation method, and the aim of zero emission in a plant area is fulfilled through the system.
Drawings
FIG. 1 is a process flow diagram of the process of the present invention;
FIG. 2 is a process flow diagram of a bipolar membrane electrodialysis system treatment of the present invention;
FIG. 3 is a process flow diagram of the electrolytic system treatment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
A method for resource comprehensive utilization of high-concentration wastewater and waste salt is characterized by comprising the following steps:
s1, pumping the high-concentration wastewater generated after treatment into a water storage tank, mixing the high-concentration wastewater with electrolytic light brine of an electrolytic tank at a mixing ratio of about 10:1, carrying out primary removal on TOC in the waste brine, simultaneously removing ammonia nitrogen in the waste brine by reacting with residual chlorine, pumping the wastewater into a transfer tank after full reaction for subsequent treatment, carrying out pretreatment, and then carrying out filter pressing on the wastewater after full reaction to obtain pretreated soft water, wherein the pretreated soft water comprises 40% ferric trichloride solution added with 0.5 kg/ton of waste brine, 0.1% PAM added with 0.002 kg/ton of waste brine and 1.5 kg/ton of sodium carbonate added with calcium and magnesium ions, and the ammonia nitrogen content is less than or equal to 1 mg/L;
s2, pumping the pretreated soft water into a DT nanofiltration system through a pump for salt separation treatment, wherein the water temperature is controlled at 25 ℃, the content of sodium sulfate in the pretreated soft water is 4 percent, the pressure of the wastewater to be treated is increased through a DTNF water inlet pump, a security filter is arranged behind the wastewater to prevent large-particle impurities from entering a membrane, the operating pressure is less than or equal to 60.0bar, and the filter element is replaced when the pressure difference between the water inlet end and the water outlet end of the filter exceeds 2.0 bar;
s3, pumping nanofiltration produced water into a TOC treatment system, and pumping the nanofiltration produced water into a TOC treatment system according to the mass concentration of hydrogen peroxide/TOC =2.5:1 and the molar concentration of Fe2+：H2O2Carrying out Fenton treatment for 1h in a feeding mode of 1:3, simultaneously providing 185nm ultraviolet strong irradiation, reducing the TOC entering nanofiltration water production through a nanofiltration membrane to 51mg/L, pumping into an activated carbon filter, further reducing the TOC to be below 5mg/L, pumping into an electrodialysis device system to be concentrated to 14.5%, concentrating concentrated sodium chloride solution with the TOC content being less than or equal to 10mg/L, entering into a salt dissolving pool to form saturated salt solution with solid sodium chloride, entering into an electrolysis system, refining the saturated sodium chloride solution through a series of physicochemical treatments, and pumping into an electrolysis bath for electrolysis;
s4, pumping the electrodialytic fresh water into a first reverse osmosis system through a pump, controlling the water temperature below 40 ℃, controlling the operating pressure to be less than or equal to 75bar, controlling the maximum pressure difference to be not more than 0.7bar, discharging the first reverse osmosis produced water to a water storage device for reuse, and returning the first reverse osmosis concentrated water to the electrodialytic system for concentration;
s5, discharging nanofiltration concentrated water into a solid waste salinization pool to form saturated waste brine with the solid waste salt, adding a small amount of water into the saturated waste brine, adding 40% ferric trichloride solution of 0.5 kg/ton of waste brine and 0.1% PAM of 0.002 kg/ton of waste brine, adding sufficient bleaching water into filter liquor after filter pressing, removing most TOC in the solution through sand filtration treatment, entering a crystallization kettle for heat exchange, freezing and cooling to 5 ℃ to separate out high-purity sodium sulfate decahydrate (by utilizing the characteristic that the sodium sulfate has large temperature change along with the temperature), and using the sodium sulfate as a product or entering a bipolar membrane electrodialysis system for further processing;
s6, further evaporating and concentrating the frozen mother liquor by using an MVR evaporator, controlling the concentration degree to evaporate 70% of water to obtain solid sodium chloride salt and evaporated mother liquor, dissolving the solid sodium chloride salt by using electrodialysis concentrated water, and then electrolyzing in the electrolytic cell in the step S3;
s7, returning the evaporation mother liquor to the solid waste salinization pool, preparing saturated waste salt water with nanofiltration concentrated water and solid waste salt, and performing circulating treatment according to the step S5;
s8, purifying the evaporated condensate water by a second reverse osmosis system, controlling the operating water temperature to be 30 ℃, the operating pressure to be 40bar and the maximum pressure difference not to exceed 0.7bar, discharging the second reverse osmosis produced water to a water storage device for reuse, discharging the second reverse osmosis concentrated water to the S5 system, diluting the saturated waste brine to an unsaturated state, and avoiding sodium chloride precipitation and formation of miscellaneous salts due to water absorption of sodium sulfate crystals during freezing crystallization.
Example 2
S1, pumping the high-concentration wastewater generated after treatment into a water storage tank, mixing the high-concentration wastewater with electrolytic light brine of an electrolytic cell at a mixing ratio of about 10:1, carrying out primary removal on TOC in the waste brine, simultaneously removing ammonia nitrogen in the waste brine by reacting with residual chlorine, pumping the wastewater into a transfer tank after full reaction for subsequent treatment, carrying out pretreatment, and then carrying out filter pressing on the wastewater after full reaction to obtain pretreated soft water, wherein the pretreated soft water comprises 40% ferric trichloride solution added with 0.40 kg/ton of waste brine, 0.1% PAM added with 0.0015 kg/ton of waste brine and 1.0 kg/ton of sodium carbonate added with calcium magnesium ions and ammonia nitrogen, and the SS content of the pretreated soft water is less than or equal to 1mg/L, the calcium magnesium ions are less than or equal to 20mg/L, and the ammonia nitrogen is less than or equal to 1;
s2, pumping the pretreated soft water into a DT nanofiltration system through a pump for salt separation treatment, wherein the water temperature is controlled at 30 ℃, the content of sodium sulfate in the pretreated soft water is 5%, the pressure of the wastewater to be treated is increased through a DTNF water inlet pump, a security filter is arranged behind the wastewater to prevent large-particle impurities from entering a membrane, the operating pressure is less than or equal to 60.0bar, and the filter element is replaced when the pressure difference between the water inlet end and the water outlet end of the filter exceeds 2.0 bar;
s3, pumping nanofiltration produced water into a TOC treatment system, and pumping the nanofiltration produced water into a TOC treatment system according to the mass concentration of hydrogen peroxide/TOC =2.5:1 and the molar concentration of Fe2+：H2O2Performing Fenton treatment for 1h in a feeding mode of =1:3, simultaneously providing 185nm ultraviolet strong irradiation, reducing TOC (total organic carbon) entering nanofiltration water production through a nanofiltration membrane to 98mg/L, pumping into an activated carbon filter, and further reducing TOCPumping the solution to an electrodialysis device system to be concentrated to 19.8 percent when the concentration is lower than 5mg/L, enabling the concentrated sodium chloride solution after concentration to have a TOC content of less than or equal to 10mg/L, enabling the concentrated sodium chloride solution to enter a salt dissolving pool to form saturated salt solution with solid sodium chloride, enabling the saturated salt solution to enter an electrolysis system, refining the saturated sodium chloride solution through a series of physicochemical treatments, and pumping the refined saturated sodium chloride solution into an electrolysis bath for electrolysis;
s4, pumping the electrodialytic fresh water into a first reverse osmosis system through a pump, controlling the water temperature below 40 ℃, controlling the operating pressure to be less than or equal to 75bar, controlling the maximum pressure difference to be not more than 0.7bar, discharging the first reverse osmosis produced water to a water storage device for reuse, and returning the first reverse osmosis concentrated water to the electrodialytic system for concentration;
s5, discharging nanofiltration concentrated water into a solid waste salinization pool to form saturated waste brine with the solid waste salt, adding a small amount of water into the saturated waste brine, adding 40% ferric trichloride solution of 0.40 kg/ton of waste brine and 0.1% PAM of 0.0015 kg/ton of waste brine, adding sufficient bleaching water into filter liquor after filter pressing, removing most TOC in the solution through sand filtration treatment, entering a crystallization kettle for heat exchange, freezing and cooling to 5 ℃ to separate out high-purity sodium sulfate decahydrate (by utilizing the characteristic that the sodium sulfate has large temperature change along with the temperature), and using the sodium sulfate as a product or entering a bipolar membrane electrodialysis system for further processing;
s6, further evaporating and concentrating the frozen mother liquor by using an MVR evaporator, controlling the concentration degree to evaporate 70% of water to obtain solid sodium chloride salt and evaporated mother liquor, dissolving the solid sodium chloride salt by using electrodialysis concentrated water, and then electrolyzing in the electrolytic cell in the step S3;
s7, returning the evaporation mother liquor to the solid waste salinization pool, preparing saturated waste salt water with nanofiltration concentrated water and solid waste salt, and performing circulating treatment according to the step S5;
s8, purifying the evaporated condensate water by a second reverse osmosis system, controlling the operating water temperature to be 30 ℃, the operating pressure to be 40bar and the maximum pressure difference not to exceed 0.7bar, discharging the second reverse osmosis produced water to a water storage device for reuse, discharging the second reverse osmosis concentrated water to the S5 system, diluting the saturated waste brine to an unsaturated state, and avoiding sodium chloride precipitation and formation of miscellaneous salts due to water absorption of sodium sulfate crystals during freezing crystallization.
Further, in the step S5, the high-purity sodium sulfate decahydrate is dissolved to form a 10% sodium sulfate solution, the 10% sodium sulfate solution enters a bipolar membrane electrodialysis system for electrolysis, ions are transferred in the system to form dilute diluted acid (1N-2N) for recycling in a plant area by adding second reverse osmosis produced water, the sodium sulfate after being diluted by electrolysis is concentrated by an electrodialysis device and then returns to the bipolar membrane electrodialysis system for continuous electrolysis, and the electrodialysis fresh water at the place is used for dissolving the sodium sulfate decahydrate, wherein the concentration of the sodium sulfate is about 8-12 g/L.
Further, in the step S3, the concentrated sodium chloride solution, i.e., the electrodialysis concentrated water, has a NaCl content of 14.5% to 20%.
Further, in step S3, the electrodialysis concentrated water and solid sodium chloride form saturated brine, which is pretreated and electrolyzed to form hydrogen, chlorine and 30-32% caustic soda liquid. The pretreatment comprises impurity removal, softening, ammonia nitrogen removal and the like, wherein 30ppb of calcium and magnesium ions, 500ppb or less of Sr, 1ppm or less of iodine, 100ppb or less of aluminum ions and the like are controlled, the generated chlorine and liquid alkali are used as raw materials of bleaching water, hydrogen and chlorine are used as raw materials of hydrochloric acid, the chlorine and chlorine are pumped into a storage tank to wait for external sales after reaction, part of electrolyzed light brine is directly pumped into a salt dissolving tank for circulation, and the other part of electrolyzed light brine is pumped into a water storage tank to be mixed with waste brine after denitrification to primarily reduce TOC and ammonia nitrogen in the water according to the step S1.
Further, in the step S1, the TOC concentration of the high concentration wastewater is less than or equal to 8000mg/L, and the electrolysis weak brine comprises 200g/L NaCl and 8000mg/L residual chlorine.
Further, in step S1, the pre-processing includes at least one of the following processing processes: softening treatment, flocculation precipitation, filter pressing and air floatation.
Further, in the step S1, the content of SS in the pretreated soft water is not more than 1mg/L, and the content of calcium and magnesium ions is not more than 20 mg/L.
Further, in step S2, the sodium sulfate concentration is 5% or less.
Further, in step S3, the TOC processing system includes at least one of the following processing systems: a Fenton treatment system, an ultraviolet/hydrogen peroxide method treatment system and an ozone method treatment system.
Further, in the step S3, before entering the electrolytic bath for electrolysis, a small amount of sodium hypochlorite is added to remove ammonia nitrogen.
Further, in the step S4, the first reverse osmosis concentrated water has a concentration equivalent to that of the concentrated sodium chloride solution in the step S3.
Further, in step S5, the solid waste salt is formed into saturated waste brine, and both sodium chloride and sodium sulfate are in a saturated state.
Further, in the step S5, the second reverse osmosis concentrated water may be used as the water added into the saturated waste brine.
Further, in step S5, the TOC removing process includes at least one of the following processes: flocculation precipitation, filter pressing, sand core filtration and air floatation.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be implemented by any prior art in the field.
Claims (10)
1. A method for resource comprehensive utilization of high-concentration wastewater and waste salt is characterized by comprising the following steps:
s1, pumping the high-concentration wastewater generated after treatment into a water storage tank, mixing the high-concentration wastewater with the electrolyzed light brine of the electrolytic cell, primarily removing TOC in the waste brine, fully reacting, pumping into a transfer tank for subsequent treatment, and treating the high-concentration wastewater into pretreated soft water after pretreatment;
s2, pumping the pretreated soft water into a DT nanofiltration system through a pump for salt separation treatment;
s3, pumping nanofiltration product water into a TOC treatment system, reducing the TOC of the nanofiltration product water entering the nanofiltration treatment system to 50-100mg/L, pumping into an activated carbon filter, further reducing the TOC to below 5mg/L, pumping into an electrodialysis device system for concentration, enabling concentrated sodium chloride solution after concentration to enter a salt dissolving pool to form saturated salt water with solid sodium chloride, enabling the saturated salt water to enter an electrolysis system, refining the saturated sodium chloride solution through a series of physicochemical treatments, and pumping into an electrolysis bath for electrolysis;
s4, the electrodialytic fresh water passes through the first reverse osmosis system, the first reverse osmosis produced water is discharged to a water storage device to be reused, and the first reverse osmosis concentrated water returns to the electrodialytic device for concentration;
s5, discharging nanofiltration concentrated water into a solid waste salinization pool to form saturated waste brine with solid waste salt, adding a small amount of water into the saturated waste brine, treating to remove most TOC in the solution, entering a crystallization kettle for heat exchange, freezing and cooling to 5 ℃ to precipitate high-purity sodium sulfate decahydrate, and using the sodium sulfate decahydrate as a product or entering a bipolar membrane electrodialysis system for further processing;
s6, further evaporating and concentrating the frozen mother liquor by using an MVR evaporator to obtain solid sodium chloride salt and evaporated mother liquor, dissolving the solid sodium chloride salt by using electrodialysis concentrated water, and then electrolyzing in the electrolytic cell in the step S3;
s7, returning the evaporation mother liquor to the solid waste salinization pool, preparing saturated waste salt water with nanofiltration concentrated water and solid waste salt, and performing circulating treatment according to the step S5;
s8, because the evaporated condensate water contains a small amount of ammonia nitrogen, total nitrogen and TOC, after being purified by the second reverse osmosis system, the second reverse osmosis produced water is discharged to a water storage device for reuse, and the second reverse osmosis concentrated water is discharged to the S5 system, so that the saturated waste brine is diluted to an unsaturated state.
2. The method for recycling high concentration wastewater and waste salt resources comprehensively according to claim 1, wherein in step S5, high purity sodium sulfate decahydrate is dissolved to form 10-20% sodium sulfate solution, which enters into bipolar membrane electrodialysis system for electrolysis, water is generated by adding reverse osmosis, the diluted sodium sulfate is concentrated by electrodialysis equipment, and then returned to bipolar membrane electrodialysis system for electrolysis, where about 8-12g/L sodium sulfate in electrodialysis fresh water is used for dissolving sodium sulfate decahydrate.
3. The method for recycling and comprehensively utilizing high-concentration wastewater and waste salt as claimed in claim 1, wherein in the step S3, the content of NaCl in the concentrated sodium chloride solution, namely the electrodialysis concentrated water, is 14.5% -20%.
4. The method for recycling high concentration wastewater and waste salt as claimed in claim 3, wherein in step S3, the electrodialysis concentrated water and solid sodium chloride form saturated brine, which is pretreated and electrolyzed to form hydrogen, chlorine and 30-32% caustic soda liquid.
5. The method for recycling high concentration wastewater and waste salt as claimed in claim 1, wherein in step S1, the TOC concentration of the high concentration wastewater is less than or equal to 8000mg/L, and the electrolyzed light salt water comprises 200g/L NaCl and 8000mg/L residual chlorine.
6. The method for recycling and comprehensively utilizing high-concentration wastewater and waste salt according to claim 1, wherein in the step S1, the pretreatment comprises at least one of the following treatment processes: softening treatment, flocculation precipitation, filter pressing and air floatation; in the pretreated soft water, the SS content is less than or equal to 1mg/L, and the calcium and magnesium ions are less than or equal to 20 mg/L.
7. The method for recycling high-concentration wastewater and waste salt as claimed in claim 1, wherein in step S2, the concentration of sodium sulfate is not more than 5%.
8. The method for recycling and comprehensively utilizing high-concentration wastewater and waste salt according to claim 1, wherein in the step S3, the TOC treatment system comprises at least one of the following treatment systems: a Fenton treatment system, an ultraviolet/hydrogen peroxide method treatment system and an ozone method treatment system.
9. The method for recycling high concentration wastewater and waste salt as claimed in claim 1, wherein in step S5, the second reverse osmosis concentrated water can be used as the water added to the saturated waste brine.
10. The method for recycling and comprehensively utilizing high-concentration wastewater and waste salt according to claim 1, wherein in the step S5, the TOC removal treatment comprises at least one treatment process selected from the group consisting of: flocculation precipitation, filter pressing, sand core filtration and air floatation.
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