CN114772826B - Reclaimed water recycling method - Google Patents
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- CN114772826B CN114772826B CN202210385633.3A CN202210385633A CN114772826B CN 114772826 B CN114772826 B CN 114772826B CN 202210385633 A CN202210385633 A CN 202210385633A CN 114772826 B CN114772826 B CN 114772826B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 242
- 238000004064 recycling Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000012266 salt solution Substances 0.000 claims abstract description 38
- 238000001728 nano-filtration Methods 0.000 claims abstract description 34
- 239000004902 Softening Agent Substances 0.000 claims abstract description 33
- 239000005708 Sodium hypochlorite Substances 0.000 claims abstract description 26
- 239000002253 acid Substances 0.000 claims abstract description 26
- 239000000243 solution Substances 0.000 claims abstract description 25
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000007800 oxidant agent Substances 0.000 claims abstract description 19
- 239000003513 alkali Substances 0.000 claims abstract description 18
- 230000001590 oxidative effect Effects 0.000 claims abstract description 17
- 238000001704 evaporation Methods 0.000 claims abstract description 13
- 230000001105 regulatory effect Effects 0.000 claims abstract description 9
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000000460 chlorine Substances 0.000 claims abstract description 6
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 6
- 239000012528 membrane Substances 0.000 claims description 123
- 238000001223 reverse osmosis Methods 0.000 claims description 106
- 239000000919 ceramic Substances 0.000 claims description 35
- 238000001471 micro-filtration Methods 0.000 claims description 35
- 238000006243 chemical reaction Methods 0.000 claims description 27
- 239000013535 sea water Substances 0.000 claims description 26
- 239000007788 liquid Substances 0.000 claims description 24
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 17
- 239000002131 composite material Substances 0.000 claims description 16
- 239000002101 nanobubble Substances 0.000 claims description 16
- 238000000926 separation method Methods 0.000 claims description 16
- 238000001914 filtration Methods 0.000 claims description 13
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 6
- 239000012141 concentrate Substances 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- 239000007921 spray Substances 0.000 claims description 4
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 3
- 239000000920 calcium hydroxide Substances 0.000 claims description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 claims description 3
- 238000007781 pre-processing Methods 0.000 claims description 3
- 239000011780 sodium chloride Substances 0.000 claims description 3
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 3
- 235000011152 sodium sulphate Nutrition 0.000 claims description 3
- 238000005292 vacuum distillation Methods 0.000 claims description 3
- 230000000717 retained effect Effects 0.000 claims 1
- 150000001875 compounds Chemical class 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 9
- 238000003860 storage Methods 0.000 description 9
- 230000008020 evaporation Effects 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 238000005868 electrolysis reaction Methods 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 239000010842 industrial wastewater Substances 0.000 description 4
- 241000894006 Bacteria Species 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 3
- 239000006004 Quartz sand Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 238000000151 deposition Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 229910001425 magnesium ion Inorganic materials 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000013618 particulate matter Substances 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000004659 sterilization and disinfection Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 208000028659 discharge Diseases 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- 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
- 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
- C25B1/14—Alkali metal compounds
-
- 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
- C25B1/24—Halogens or compounds thereof
- C25B1/26—Chlorine; Compounds thereof
-
- 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
- C25B1/50—Processes
-
- 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
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/048—Purification of waste water by 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
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
-
- 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
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
-
- 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
- C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
-
- 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
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
-
- 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
-
- 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
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/04—Disinfection
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/02—Specific form of oxidant
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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
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/06—Softening water by precipitation of the hardness using calcium compounds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Electrochemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Water Supply & Treatment (AREA)
- Environmental & Geological Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a reclaimed water recycling method, which belongs to the technical field of reclaimed water treatment, and comprises the steps of firstly pretreating reclaimed water, adding a compound strong oxidant and a softening agent, regulating the pH value of the reclaimed water to a first set value, concentrating and separating the treated reclaimed water, concentrating and separating the concentrated reclaimed water through nanofiltration to obtain a monovalent salt solution and a divalent salt solution, evaporating and concentrating the monovalent salt solution, electrolyzing the distilled concentrated solution to obtain sodium hypochlorite and chlorine, recycling the sodium hypochlorite as the compound strong oxidant, electrolyzing the divalent salt solution to obtain an acid liquor and an alkali liquor, recycling the acid liquor for concentrating and separating, and recycling the alkali liquor as the softening agent.
Description
Technical Field
The invention belongs to the technical field of reclaimed water treatment, and particularly relates to a reclaimed water recycling method.
Background
In China, the energy industries represented by coal-fired power generation, modern coal chemical industry and the like support national economy development, consume a large amount of water resources, and generate a large amount of industrial wastewater. In recent years, with increasing environmental protection efforts, how to safely and efficiently treat industrial wastewater becomes an important subject for the healthy development of related industries. Particularly in areas with shortage of water resources such as inner Mongolia, shaanxi, ningxia and Xinjiang and relatively fragile ecological environment, the zero discharge treatment of industrial wastewater becomes an urgent requirement.
At present, industrial wastewater is treated by a sewage plant to form reclaimed water, namely so-called reclaimed water, and the zero-emission treatment technology of the reclaimed water mostly adopts a multi-stage reverse osmosis membrane and evaporation concentration crystallization to produce high-purity salts, the salts are separated in a form of crystallization salts and temporarily stored in a warehouse to wait for treatment, and the evaporated condensate water is recycled or discharged after reaching the standard after biochemical treatment, so that reclaimed water recycling and zero emission are realized. Reasonable reuse of reclaimed water can reduce water environment pollution and relieve contradiction of shortage of water resources, and is an important measure for implementing sustainable development. However, due to the adoption of the evaporative crystallization system, the occupied area is large, the equipment investment and the operation cost are high, the process is complex, meanwhile, the temporarily stored waste salt belongs to dangerous waste, the zero-emission treatment technology only achieves zero emission of water, but a large amount of solid waste and dangerous waste are generated at the same time, so that the environmental pollution is serious, and the zero emission is not truly zero emission.
Disclosure of Invention
In order to solve the above problems, a method for recycling reclaimed water has been proposed.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the reclaimed water recycling method comprises the following steps:
step S100, preprocessing reclaimed water, adding a composite strong oxidant and a softening agent, and adjusting the pH value of the reclaimed water to a first set value to obtain preprocessed reclaimed water;
step S200, concentrating and separating the pretreated reclaimed water, and enabling the concentrated produced water to enter a reclaimed water recycling pool for later use;
step S300, separating concentrated water through nanofiltration to obtain monovalent salt solution and divalent salt solution;
step S400, evaporating and concentrating monovalent salt solution, electrolyzing distilled concentrated solution to prepare sodium hypochlorite and chlorine, wherein the sodium hypochlorite can be recycled to be used as a composite strong oxidant, and the distilled solution enters a reclaimed water recycling tank and is recycled for standby;
and S500, electrolyzing the divalent salt solution to obtain an acid solution and an alkali solution, wherein the acid solution can be recycled for concentration and separation, and the alkali solution can be recycled for use as a softening agent.
The invention is further provided with: the composite strong oxidant is added to the first reaction tank, the reclaimed water reacts with the composite strong oxidant and stays for a first set time, the softening agent is added to the second reaction tank, and the reclaimed water reacts with the softening agent and stays for a second set time.
By adopting the technical scheme, the reclaimed water reacts with the composite strengthening agent, partial COD is oxidized, the COD value of the oxidized reclaimed water is reduced by 70-80% after the oxidized reclaimed water stays for the first set time, bacteria and microorganisms in the reclaimed water can be removed, and the pollution blocking probability of the subsequent concentration process is reduced.
And then, the reclaimed water reacts with the softening agent and stays for a second set time, so that calcium ions and magnesium ions in the reclaimed water fully react with the softening agent to form precipitate particles.
The invention is further provided with: the compound strong oxidant is sodium hypochlorite and ozone, and the softening agent is one or two or more of sodium hydroxide, calcium hydroxide and sodium carbonate.
The invention is further provided with: the backwater mixed with ozone is sprayed through the release nozzle at a higher pressure to form micro-nano bubbles, that is, the ozone is added into the first reaction tank in the form of micro-nano bubbles.
Through adopting above-mentioned technical scheme, micro-nano bubble evenly disperses in the first reaction tank, and micro-nano bubble rising speed reduces, and the solubility is higher in water, and dwell time is longer, can fully contact with the pollutant, improves the utilization ratio of ozone.
The invention is further provided with: and (3) on-line monitoring the hardness value and the alkalinity content of the reclaimed water, adding the softening agent, and stirring until the PH value of the reclaimed water in the second reaction tank is adjusted to 10.8, thereby effectively ensuring the low hardness of the effluent.
The invention is further provided with: the sodium hypochlorite and the softening agent are added through an agent adding pump, and the agent adding pump is matched with the frequency converter for use and is linked with the pH on-line detector to adjust the pH.
The invention is further provided with: the second reaction tank adopts a three-grid structure which is connected, and comprises a first grid, a second grid and a third grid, wherein the softening agent is respectively added into the first grid and the second grid, and the third grid is used as a buffer grid.
Through adopting above-mentioned technical scheme, first check with be furnished with the mixer in the second check and stir, make softening agent and return water intensive mixing and reaction, the third check is furnished with the mixer and stirs, prevents that the precipitate particulate matter that the reaction produced from depositing.
The invention is further provided with: the reclaimed water in the second reaction tank flows through the micro-filtration ceramic membrane through the booster pump for filtration treatment.
By adopting the technical scheme, the micro-filtration ceramic membrane is used for filtering and removing the precipitated particles, so that the purpose of removing the hardness in backwater is realized, a precipitation area and a quartz sand filter are not required to be arranged after pretreatment, the process route is shortened, the occupied area is saved, and the hardness of effluent is less than 10mg/L after the filtration of the micro-filtration ceramic membrane.
The invention is further provided with: the reclaimed water which permeates the micro-filtration ceramic membrane flows to a clear water outlet to form filtered clear liquid, the reclaimed water which is intercepted by the micro-filtration ceramic membrane flows to a concentration outlet to form filtered concentrated liquid, the concentration outlet is communicated with the water inlet end of the micro-filtration ceramic membrane through a circulation loop, and the clear water outlet and the concentration outlet form a cross-flow structure.
The invention is further provided with: the circulating pump with the flow being multiple times of the flow of the water inlet end of the micro-filtration ceramic membrane is arranged on the circulating loop, so that the water flow speed on the surface of the micro-filtration ceramic membrane is improved to be more than 5 m/s.
Through adopting above-mentioned technical scheme, improve the water velocity of flow on micro-filtration ceramic membrane surface through the circulating pump, carry out large-traffic, the quick washing to micro-filtration ceramic membrane surface, prevent that the precipitate particulate matter from piling up on micro-filtration ceramic membrane surface.
The invention is further provided with: the flow pipeline of the filtered clear liquid and the flow pipeline of the filtered concentrated liquid are respectively provided with an electromagnetic flowmeter and a regulating valve, the instantaneous flow and the accumulated flow are detected, the frequency of the circulating pump is regulated through a flow feedback signal, the flow pipeline of the filtered clear liquid is provided with an online hardness detector and a turbidity meter, and the frequency of the circulating pump is regulated through the feedback signal of the online hardness detector.
By adopting the technical scheme, the hardness of the filtered clear liquid can reach below 10ppm, and the turbidity is less than 1NTU.
The invention is further provided with: and (3) carrying out buffer treatment on the filtered clear liquid, adding acid liquor to adjust the pH value to a second set value to obtain pretreated reclaimed water, and staying for a third set time.
By adopting the technical scheme, the too high pH can influence the desalination performance of the brackish water reverse osmosis membrane and the seawater reverse osmosis membrane, the pH is adjusted to 9.5 by adding the acid liquor, the pH of reverse osmosis concentrated water is ensured to be lower than 11, the membrane performance is not influenced, the silicon in the water can be kept in a dissolved state, and the reverse osmosis membrane is not blocked due to scaling.
Meanwhile, the filtered clear liquid stays for a third set time, so that the effect of removing hardness is achieved, and the precipitation of calcium-magnesium slightly-soluble salts reaching saturated solubility in the reverse osmosis process is prevented, so that the reverse osmosis membrane is blocked.
The invention is further provided with: the pretreated reclaimed water sequentially flows through a brackish water reverse osmosis membrane and a seawater reverse osmosis membrane through a booster pump to carry out reverse osmosis treatment, so that concentration and separation are realized.
The invention is further provided with: the filtered clear liquid after buffer treatment enters the filter through the booster pump to be filtered, and then flows through the brackish water reverse osmosis membrane through the high-pressure pump, the brackish water reverse osmosis membrane adopts a multi-stage structure, the booster pump is arranged between the brackish water reverse osmosis membranes of two adjacent stages, the concentrated water of the front-stage brackish water reverse osmosis membrane is pressurized, and the running performance and the water yield of the rear-stage brackish water reverse osmosis membrane are ensured.
The invention is further provided with: the filtered clear liquid after the buffer treatment is concentrated by a brackish water reverse osmosis membrane for 3.5-4 times to form first-stage reverse osmosis produced water and first-stage reverse osmosis concentrated water, and the first-stage reverse osmosis produced water enters a reclaimed water recycling tank.
The invention is further provided with: the first-stage reverse osmosis concentrated water enters the filter through the booster pump to be filtered, and then flows through the seawater reverse osmosis membrane through the high-pressure pump, the seawater reverse osmosis membrane adopts a multi-stage structure, the booster pump is arranged between the seawater reverse osmosis membranes of two adjacent stages, the concentrated water of the pre-stage seawater reverse osmosis membrane is pressurized, and the running performance and the water yield of the post-stage seawater reverse osmosis membrane are ensured.
The invention is further provided with: the first-stage reverse osmosis concentrated water is concentrated by 2 times through a seawater reverse osmosis membrane to form second-stage reverse osmosis produced water and second-stage reverse osmosis concentrated water, and the second-stage reverse osmosis produced water enters a reclaimed water recycling pool.
The invention is further provided with: and recovering the high-pressure energy of the second-stage reverse osmosis concentrated water, so as to improve the pressure of the water inlet end of the seawater reverse osmosis membrane, reduce the energy consumption of the high-pressure pump and reduce the operation cost.
The invention is further provided with: the flow pipelines of the first-stage reverse osmosis water production, the first-stage reverse osmosis concentrated water, the second-stage reverse osmosis water production and the second-stage reverse osmosis concentrated water are respectively provided with an electromagnetic flowmeter, the instantaneous flow and the accumulated flow are detected, the frequency of the high-pressure pump is regulated through a flow feedback signal, and the water yield is ensured when the performance of the reverse osmosis membrane is changed.
The invention is further provided with: the flow pipelines of the first-stage reverse osmosis water production and the second-stage reverse osmosis water production are respectively provided with a conductivity meter, and the water quality is monitored in real time.
By adopting the technical scheme, the brackish water reverse osmosis membrane and the seawater reverse osmosis membrane are combined, more than 85% of filtered clear liquid is recycled to the reclaimed water recycling pool, and the water quality of the reclaimed water recycling pool is far better than the ion index requirement in the standard of domestic drinking water.
The invention is further provided with: the second-stage reverse osmosis concentrated water enters the filter through the booster pump to be filtered, and then flows through the nanofiltration membrane through the high-pressure pump, the nanofiltration membrane adopts a multi-stage structure, the booster pump is arranged between the nanofiltration membranes of two adjacent stages, the concentrated water of the front-stage nanofiltration membrane is pressurized, and the running performance and the water yield of the rear-stage nanofiltration membrane are ensured.
The invention is further provided with: the second-stage reverse osmosis concentrated water is subjected to nanofiltration membrane nanofiltration separation to obtain a monovalent salt solution and a divalent salt solution, wherein the monovalent salt solution is mainly sodium chloride solution, and the divalent salt solution is mainly sodium sulfate solution.
The invention is further provided with: electromagnetic flow meters are arranged on the flow pipelines of the monovalent salt solution and the divalent salt solution, the instantaneous flow and the accumulated flow are detected, the frequency of the high-pressure pump is regulated through a flow feedback signal, and the water yield is ensured when the performance of the nanofiltration membrane is changed.
The invention is further provided with: and the flow pipelines of the monovalent salt solution and the divalent salt solution are respectively provided with a conductivity meter, so that the water quality is monitored in real time.
By adopting the technical scheme, the nanofiltration membrane is adopted to separate monovalent salt and divalent salt, so that the quality-separating recycling is realized.
The invention is further provided with: the monovalent salt solution is evaporated and concentrated in a low-temperature distillation mode, distilled distillate enters a reclaimed water recycling pool for recycling to enterprises, the concentration of the distilled concentrated solution reaches more than 26%, and the distilled concentrated solution is lifted to an ion membrane electrolytic tank through a booster pump for electrolysis to prepare sodium hypochlorite and chlorine.
By adopting the technical scheme, the evaporative crystallization treatment is not needed, the environment is prevented from being polluted, sodium hypochlorite can be recycled to be used as a composite strong oxidant, and meanwhile, the rest sodium hypochlorite can be used for disinfection and oxidation of enterprises.
The invention is further provided with: and lifting the bivalent salt solution to a bipolar membrane electrolytic cell through a booster pump to prepare acid liquor and alkali liquor.
By adopting the technical scheme, the acid liquor can be recycled for buffer treatment, the alkali liquor can be recycled as a softening agent, and the rest acid liquor and alkali liquor can be used for sales.
In summary, compared with the prior art, the invention has the following beneficial effects:
1. the pretreatment, concentration separation, nanofiltration separation, evaporation concentration and electrolysis processes are combined, and on the basis of realizing zero emission, the products of each link are reasonably treated and recycled, so that the aim of recycling reclaimed water is fulfilled.
2. The reclaimed water reacts with the compound strengthening agent firstly, the COD value of the reclaimed water is reduced by 70% -80% after oxidation, bacteria and microorganisms in the reclaimed water can be removed, the pollution blocking probability of the subsequent concentration process is reduced, and then the reclaimed water reacts with the softening agent, so that calcium ions and magnesium ions in the water fully react with the softening agent to form precipitate particles.
3. Ozone is added into water in the form of micro-nano bubbles, the rising speed of the micro-nano bubbles is reduced, the ozone can be fully contacted with pollutants, and the utilization rate of the ozone is improved.
4. Reclaimed water firstly passes through the microfiltration ceramic membrane, a precipitation area and a quartz sand filter are not required to be arranged after chemical reaction, the reclaimed water treatment flow is shortened, the reclaimed water treatment efficiency is improved, and meanwhile, the occupied area is saved.
5. The brackish water reverse osmosis membrane and the seawater reverse osmosis membrane are combined, so that more than 85% of reclaimed water is recovered and circulated to the reclaimed water recycling pool, the water inflow of nanofiltration separation is reduced, the treatment capacity of nanofiltration separation, evaporation concentration and electrolysis processes is reduced, and the treatment efficiency is improved.
6. And separating monovalent salt from divalent salt by adopting a nanofiltration salt separation mechanism, thereby realizing quality separation and recycling.
7. The evaporation and crystallization treatment is not needed, the environment is prevented from being polluted, the operation is convenient and fast, and the occupied area of the system is reduced.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of the structure of the pretreatment;
FIG. 3 is a schematic diagram of the structure of a brackish water reverse osmosis membrane and a seawater reverse osmosis membrane;
FIG. 4 is a schematic diagram of the structure of nanofiltration to separate salts, evaporation concentration and electrolysis treatment.
In the accompanying drawings: 1-raw water tank, 2-ozone generator, 3-first reaction tank, 4-second reaction tank, 5-sodium hypochlorite adding port, 6-sodium hydroxide adding port, 7-sodium carbonate adding port, 8-microfiltration ceramic membrane, 9-buffer tank, 10-acid liquor adding port, 11-brackish water reverse osmosis membrane, 12-first concentrated water buffer tank, 13-seawater reverse osmosis membrane, 14-reclaimed water recycling tank, 15-second concentrated water buffer tank, 16-nanofiltration membrane, 17-evaporation concentration mechanism, 18-ion membrane electrolytic tank, 19-sodium hypochlorite storage tank, 20-bipolar membrane electrolytic tank, 21-acid liquor storage tank and 22-alkali liquor storage tank.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings, and based on the embodiments in the present application, other similar embodiments obtained by those skilled in the art without making creative efforts should fall within the scope of protection of the present application. In addition, directional words such as "upper", "lower", "left", "right", and the like, as used in the following embodiments are merely directions with reference to the drawings, and thus, the directional words used are intended to illustrate, not to limit, the invention.
Examples
As shown in fig. 1 to 4, the method for recycling reclaimed water comprises the following steps:
step S100, preprocessing reclaimed water, adding a composite strong oxidant and a softening agent, and adjusting the pH value of the reclaimed water to a first set value to obtain preprocessed reclaimed water;
step S200, concentrating and separating the pretreated reclaimed water, and enabling the concentrated produced water to enter a reclaimed water recycling pool for later use;
step S300, separating concentrated water through nanofiltration to obtain monovalent salt solution and divalent salt solution;
step S400, evaporating and concentrating monovalent salt solution, electrolyzing distilled concentrated solution to prepare sodium hypochlorite and chlorine, wherein the sodium hypochlorite can be recycled to be used as a composite strong oxidant, and the distilled solution enters a reclaimed water recycling tank and is recycled for standby;
and S500, electrolyzing the divalent salt solution to obtain an acid solution and an alkali solution, wherein the acid solution can be recycled for concentration and separation, and the alkali solution can be recycled for use as a softening agent.
Specifically, as shown in fig. 2, reclaimed water enters the raw water tank 1 for collection, the composite strong oxidant is added into the first reaction tank 3, the reclaimed water reacts with the composite strong oxidant and stays for a first set time, the softening agent is added into the second reaction tank 4, and the reclaimed water reacts with the softening agent and stays for a second set time.
The reclaimed water reacts with the compound strengthening agent, partial COD is oxidized, the COD value of the reclaimed water is reduced by 70-80% after the partial COD is stopped for 10-20min (namely, the first set time), bacteria and microorganisms in the reclaimed water can be removed, and the pollution blocking probability of the subsequent concentration process is reduced. And then, the reclaimed water reacts with the softening agent and stays for a second set time, so that calcium ions and magnesium ions in the reclaimed water fully react with the softening agent to form precipitate particles.
Specifically, the compound strong oxidant is sodium hypochlorite and ozone, and in this embodiment, a sodium hypochlorite adding port 5 and an ozone adding port are provided on the first reaction tank 3. The softening agent is one or two or more of sodium hydroxide, calcium hydroxide and sodium carbonate, and in this embodiment, a sodium hydroxide adding port 6 and a sodium carbonate adding port 7 are arranged on the second reaction tank 4.
The return water mixed with ozone is sprayed at a relatively high pressure through the release nozzle to form micro-nano bubbles, that is, the ozone is added into the first reaction tank 3 in the form of micro-nano bubbles. Micro-nano bubbles are uniformly dispersed in the first reaction tank 3, the rising speed of the micro-nano bubbles is reduced, the solubility in water is higher, the residence time is longer, the micro-nano bubbles can be fully contacted with pollutants, and the ozone utilization rate is improved.
The release spray head comprises a first generation plate and a second generation plate which are provided with pressure release holes, the first generation plate and the second generation plate are arranged at intervals to form pressure release spaces, the number of the pressure release holes on the first generation plate is smaller than that of the pressure release holes on the second generation plate, backwater mixed with ozone sequentially passes through the first generation plate and the second generation plate, passes through the pressure release holes in the first generation plate and then passes through the pressure release holes in the second generation plate, and pressure is released from a few holes to a plurality of holes so as to form micro-nano bubbles.
The release spray head further comprises a generation column, a plurality of spiral holes penetrating through the generation column in a spiral mode are formed in the generation column, the number of the spiral holes is smaller than that of the pressure release holes in the first generation plate, so that the water pressure of backwater mixed with ozone when the backwater passes through the spiral holes in the generation column is smaller than that of the backwater when the backwater passes through the pressure release holes in the first generation plate, namely, a pressure release process is increased, and therefore micro-nano bubbles can be formed more fully by the ozone.
Specifically, the hardness value and the alkalinity content of the reclaimed water are monitored on line, a softening agent is added and stirred until the PH value of the reclaimed water in the second reaction tank 4 is adjusted to 10.8 (a first preset value), so that the low hardness of the effluent is effectively ensured. The sodium hypochlorite and the softening agent are added through an agent adding pump, and the agent adding pump is matched with the frequency converter for use and is linked with the pH on-line detector to adjust the pH.
Specifically, the second reaction tank 4 adopts a connected three-grid structure, which comprises a first grid, a second grid and a third grid, wherein the softening agent is respectively added into the first grid and the second grid, and the third grid is used as a buffer grid. The first grid and the second grid are internally provided with a stirrer for stirring, the reaction is carried out for 10-20min, the softening agent and the backwater are fully mixed and react, the third grid is provided with the stirrer for stirring for 20-30min, and the precipitation particles generated by the reaction are prevented from depositing.
The bottom of the first grid is communicated with the bottom of the second grid, and the top of the second grid is communicated with the third grid through an overflow port. The bottom of third check is equipped with the drain, the drain passes through pipeline and dredge pump intercommunication, and the dredge pump is mainly used for the clearance to fall the sediment particulate matter of deposit and remaining return water.
Specifically, as shown in fig. 2 and 3, the reclaimed water in the second reaction tank 4 flows through the micro-filtration ceramic membrane 8 through the booster pump for filtration treatment, and then flows through the brackish water reverse osmosis membrane 11 and the seawater reverse osmosis membrane 13 through the booster pump in sequence for reverse osmosis treatment, so that concentration and separation are realized.
The reclaimed water which permeates the micro-filtration ceramic membrane 8 flows to a clear water outlet to form filtered clear liquid, the reclaimed water which is intercepted by the micro-filtration ceramic membrane 8 flows to a concentration outlet to form filtered concentrated liquid, the concentration outlet is communicated with the water inlet end of the micro-filtration ceramic membrane through a circulation loop, and the clear water outlet and the concentration outlet form a cross-flow structure. The circulating loop is provided with a circulating pump with the flow being multiple times of the flow of the water inlet end of the micro-filtration ceramic membrane 8, the water inlet end of the micro-filtration ceramic membrane 8 is positioned at the bottom of the circulating pump, the clear water outlet is positioned at the top of the micro-filtration ceramic membrane 8, and the concentrated outlet is positioned at the side part of the micro-filtration ceramic membrane 8. Preferably, the flow rate of the circulating pump is 4-8 times of the flow rate of the water inlet end of the micro-filtration ceramic membrane 8, so that the water flow rate on the surface of the micro-filtration ceramic membrane 8 is increased to more than 5 m/s.
The micro-filtration ceramic membrane 8 is used for filtering and removing the precipitated particles, so that the purpose of removing the hardness in backwater is achieved, the micro-filtration ceramic membrane 8 is used for filtering, a precipitation area and a quartz sand filter are not required to be arranged, the process route is shortened, the occupied area is saved, and the hardness of the effluent is less than 10mg/L after the micro-filtration ceramic membrane 8 is used for filtering. Meanwhile, the circulating pump is used for improving the water flow rate on the surface of the micro-filtration ceramic membrane 8, and carrying out high-flow and rapid flushing on the surface of the micro-filtration ceramic membrane 8, so as to prevent deposition particles from accumulating on the surface of the micro-filtration ceramic membrane 8.
Specifically, all be equipped with electromagnetic flowmeter and governing valve on the flow pipeline of filtering clear liquid and filtering concentrate, detect instantaneous flow and cumulative flow, adjust circulating pump frequency through flow feedback signal, be equipped with online hardness detector and turbidity meter on the flow pipeline of filtering clear liquid, adjust circulating pump frequency through online hardness detector feedback signal. The hardness of the filtered clear liquid can reach below 10ppm, and the turbidity is less than 1NTU.
Specifically, the filtered clear liquid enters a buffer tank 9 for buffer treatment, acid liquor is added to adjust the pH value to a second set value, and the filtered clear liquid stays for a third set time, and in this embodiment, an acid liquor adding port 10 is arranged on the buffer tank 9. Too high pH can affect the desalination performance of the brackish water reverse osmosis membrane 11 and the seawater reverse osmosis membrane 13, and acid liquor is added to adjust the pH to 9.5 (namely a second set value), so that the pH of reverse osmosis concentrated water is ensured to be lower than 11, the membrane performance is not affected, silicon in the water can be kept in a dissolved state, and the reverse osmosis membrane is not blocked due to scaling. Meanwhile, the filtered clear liquid stays for 60-90min (namely, third set time), so that the effect of removing hardness is achieved, and the calcium-magnesium slightly-soluble salt is prevented from reaching saturated solubility precipitation in the reverse osmosis process, so that the reverse osmosis membrane is blocked.
Specifically, the filtered clear liquid after the buffer treatment enters the filter through the booster pump to be filtered, and then flows through the brackish water reverse osmosis membrane 11 through the high-pressure pump, the brackish water reverse osmosis membrane 11 adopts a multi-stage structure, the booster pump is arranged between the brackish water reverse osmosis membranes 11 of the adjacent two stages, the concentrated water of the brackish water reverse osmosis membrane 11 of the front stage is pressurized, and the running performance and the water yield of the brackish water reverse osmosis membrane 11 of the rear stage are ensured.
The filtered clear liquid after the buffer treatment is concentrated 3.5-4 times by a brackish water reverse osmosis membrane 11 to form primary reverse osmosis produced water and primary reverse osmosis concentrated water, and the primary reverse osmosis produced water enters a reclaimed water recycling tank 14.
Specifically, the first-stage reverse osmosis concentrated water enters the first concentrated water buffer tank 12 and enters the filter for filtering through the booster pump, and flows through the seawater reverse osmosis membrane 13 through the high-pressure pump, the seawater reverse osmosis membrane 13 adopts a multi-stage structure, the booster pump is arranged between the seawater reverse osmosis membranes 13 of two adjacent stages, the concentrated water of the seawater reverse osmosis membrane 13 of the front stage is pressurized, and the running performance and the water yield of the seawater reverse osmosis membrane 13 of the rear stage are ensured.
The first-stage reverse osmosis concentrated water is concentrated by 2 times through a seawater reverse osmosis membrane 13 to form second-stage reverse osmosis produced water and second-stage reverse osmosis concentrated water, and the second-stage reverse osmosis produced water enters a reclaimed water recycling tank 14. And meanwhile, the high-pressure energy of the second-stage reverse osmosis concentrated water is recovered and is used for improving the pressure of the water inlet end of the seawater reverse osmosis membrane, reducing the energy consumption of the high-pressure pump and reducing the operation cost.
Specifically, the flow pipelines of the first-stage reverse osmosis water production, the first-stage reverse osmosis concentrated water, the second-stage reverse osmosis water production and the second-stage reverse osmosis concentrated water are respectively provided with an electromagnetic flowmeter, the instantaneous flow and the accumulated flow are detected, the frequency of the high-pressure pump is regulated through a flow feedback signal, and the water production is ensured when the performance of the reverse osmosis membrane is changed. Meanwhile, the flow pipelines of the first-stage reverse osmosis water production and the second-stage reverse osmosis water production are respectively provided with a conductivity meter, and the water quality is monitored in real time.
The brackish water reverse osmosis membrane 11 and the seawater reverse osmosis membrane 13 are combined, more than 85% of filtered clear liquid is recycled to the reclaimed water recycling pool, and the water quality of the reclaimed water recycling pool 14 is far better than the ion index requirement in the standard of domestic drinking water.
Specifically, as shown in fig. 3 and fig. 4, the second-stage reverse osmosis concentrated water enters the second concentrated water buffer tank 15 and enters the filter for filtering through the booster pump, and then flows through the nanofiltration membrane 16 through the high-pressure pump, the nanofiltration membrane 16 adopts a multi-stage structure, the booster pump is arranged between the nanofiltration membranes 16 of two adjacent stages, the concentrated water of the nanofiltration membrane 16 of the front stage is pressurized, and the operation performance and the water yield of the nanofiltration membrane 16 of the rear stage are ensured.
The second-stage reverse osmosis concentrated water is subjected to nanofiltration separation by a nanofiltration membrane 16 to obtain a monovalent salt solution and a divalent salt solution, so that quality-separated recycling is realized. Wherein the monovalent salt solution is mainly sodium chloride solution, and the divalent salt solution is mainly sodium sulfate solution. Electromagnetic flow meters are arranged on the flow pipelines of the monovalent salt solution and the divalent salt solution, the instantaneous flow and the accumulated flow are detected, the frequency of the high-pressure pump is regulated through a flow feedback signal, and the water yield is ensured when the performance of the nanofiltration membrane is changed. Meanwhile, the flow pipelines of the monovalent salt solution and the divalent salt solution are respectively provided with a conductivity meter, so that the water quality is monitored in real time.
Specifically, the monovalent salt solution enters the evaporation and concentration mechanism 17 to be evaporated and concentrated in a low-temperature distillation mode, distilled distillate enters the reclaimed water recycling tank 14 to be recycled for enterprises, the concentration of the distilled concentrate reaches more than 26%, the distilled concentrate is lifted to the ion membrane electrolysis tank 18 through the booster pump to be electrolyzed to prepare sodium hypochlorite and chlorine, wherein the sodium hypochlorite is stored in the sodium hypochlorite storage tank 19, and the sodium hypochlorite storage tank 19 can be connected with the sodium hypochlorite adding port 5. The method does not need to carry out evaporation crystallization treatment, so that environmental pollution is avoided, sodium hypochlorite can be recycled to be used as a composite strong oxidant, and meanwhile, the rest sodium hypochlorite can be used for disinfection and oxidation of enterprises.
Specifically, the divalent salt solution is lifted to the bipolar membrane electrolytic tank 20 through the booster pump to prepare acid liquor and alkali liquor, the acid liquor is stored in the acid liquor storage tank 21, meanwhile, the acid liquor storage tank 21 can be connected with the acid liquor adding port 10 to recycle the acid liquor for buffer treatment, the alkali liquor is stored in the alkali liquor storage tank 22, meanwhile, the alkali liquor storage tank 22 can be connected with the sodium hydroxide adding port 6 to recycle the alkali liquor as a softening agent, and the rest of the acid liquor and the alkali liquor can be used for sales.
In summary, the pretreatment, concentration and separation, nanofiltration and separation, evaporation and concentration and electrolysis processes are combined, and on the basis of realizing zero emission, the products of each link are reasonably treated and recycled, so that the aim of recycling reclaimed water is fulfilled.
The foregoing detailed description of the invention has been presented for purposes of illustration and description, but is not intended to limit the scope of the invention, i.e., the invention is not limited to the details shown and described.
Claims (5)
1. The reclaimed water recycling method is characterized by comprising the following steps of:
step S100, preprocessing reclaimed water, adding a composite strong oxidant and a softening agent, and regulating the pH value of the reclaimed water to a first set value to obtain preprocessed reclaimed water, wherein the composite strong oxidant is sodium hypochlorite and ozone, and the ozone is added into a first reaction tank in a micro-nano bubble mode;
the method comprises the steps that backwater mixed with ozone is sprayed to form micro-nano bubbles through a release spray head at a higher pressure, the release spray head comprises a first generation plate and a second generation plate which are provided with pressure release holes, the first generation plate and the second generation plate are arranged at intervals to form pressure release spaces, the number of the pressure release holes on the first generation plate is smaller than that of the pressure release holes on the second generation plate, backwater mixed with ozone sequentially passes through the first generation plate and the second generation plate, passes through the pressure release holes in the first generation plate and then passes through the pressure release holes in the second generation plate, and pressure is released from a few holes to a plurality of holes so as to form micro-nano bubbles;
step 200, the pretreated reclaimed water sequentially flows through a brackish water reverse osmosis membrane and a seawater reverse osmosis membrane through a booster pump to realize concentration and separation, the pretreated reclaimed water is concentrated 3.5-4 times through the brackish water reverse osmosis membrane to form primary reverse osmosis produced water and primary reverse osmosis concentrated water, the primary reverse osmosis concentrated water is concentrated 2 times through the seawater reverse osmosis membrane to form secondary reverse osmosis produced water and secondary reverse osmosis concentrated water, the primary reverse osmosis produced water and the secondary reverse osmosis produced water both enter a reclaimed water recycling tank, the high pressure energy of the secondary reverse osmosis concentrated water is recycled, the high pressure energy is used for improving the pressure of the water inlet end of the seawater reverse osmosis membrane, the energy consumption of the high pressure pump is reduced, the running cost is reduced, the secondary reverse osmosis concentrated water enters a filter through the booster pump to be filtered, and then flows through a nanofiltration membrane through the high pressure pump, the nanofiltration membrane adopts a multi-stage structure, the booster pump is arranged between the nanofiltration membranes of two adjacent stages, the concentrated water of the front nanofiltration membrane is pressurized, and the running performance and the water yield of the rear nanofiltration membrane are guaranteed;
step S300, performing nanofiltration separation on the second-stage reverse osmosis concentrated water through a nanofiltration membrane to obtain a monovalent salt solution and a divalent salt solution, wherein the monovalent salt solution is mainly sodium chloride solution, and the divalent salt solution is mainly sodium sulfate solution;
step S400, evaporating and concentrating monovalent salt solution in a low-temperature distillation mode, enabling distilled distillate to enter a reclaimed water recycling pool, enabling the concentration of the distilled concentrate to reach more than 26%, lifting the distilled concentrate to an ion membrane electrolytic tank through a booster pump, and electrolyzing to prepare sodium hypochlorite and chlorine, wherein part of the sodium hypochlorite is recycled to be used as a composite strong oxidant;
and S500, lifting the divalent salt solution to a bipolar membrane electrolytic tank through a booster pump to prepare acid liquor and alkali liquor, wherein part of the acid liquor is recycled for buffer treatment, and part of the alkali liquor is recycled as a softening agent.
2. The method for recycling reclaimed water according to claim 1, wherein in step S100, the composite strong oxidizer is added to the first reaction tank, reclaimed water reacts with the composite strong oxidizer and stays for a first set time, the softening agent is added to the second reaction tank, the pH of reclaimed water is adjusted to the first set value, and reclaimed water reacts with the softening agent and stays for a second set time.
3. The method for recycling reclaimed water according to claim 2, wherein the softening agent is one or a combination of two or more of sodium hydroxide, calcium hydroxide and sodium carbonate.
4. The recycling method of reclaimed water according to claim 3, wherein reclaimed water flows through a micro-filtration ceramic membrane through a second reaction tank for filtration treatment, the reclaimed water which passes through the micro-filtration ceramic membrane flows to a clear water outlet to form filtered clear liquid, reclaimed water which is trapped by the micro-filtration ceramic membrane flows to a concentration outlet to form filtered concentrate, the concentration outlet is communicated with the water inlet end of the micro-filtration ceramic membrane through a circulation loop, and the circulation loop is provided with a circulation pump with the flow rate which is multiple times that of the water inlet end of the micro-filtration ceramic membrane, so that the water flow rate on the surface of the micro-filtration ceramic membrane is increased to more than 5 m/s.
5. The method for recycling reclaimed water according to claim 4, wherein the filtered clear liquid is subjected to buffer treatment, and the pH is adjusted to a second set value by adding an acid solution to obtain pretreated reclaimed water, and the pretreated reclaimed water is retained for a third set time.
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