CN116835812A - A coking wastewater membrane filtration concentrate treatment system and method - Google Patents

Abstract

The invention discloses a coking wastewater membrane filtration concentrate treatment system, which includes a first adsorption device, a micro-electrolysis device, a Fenton device, a neutralization tank, a flocculation sedimentation tank, an electro-oxidation device, and a first hardness removal device, which are connected in sequence. A nanofiltration device, a second vacuum membrane distillation device, a low-temperature crystallizer, a second adsorption device, a second hardness removal device and a bipolar membrane electrodialysis device, and also includes a first vacuum membrane distillation device, a production pool, a crystallizer, and ferric acid Sodium preparation unit. Also disclosed is a membrane filtration concentrate treatment method for coking wastewater, which uses adsorption + micro-electrolysis + Fenton + electro-oxidation to remove organic matter in the concentrate, and uses nanofiltration + vacuum membrane distillation + bipolar membrane electrodialysis to process the concentrate. At the same time, the waste gas generated during the electro-oxidation treatment and the sludge generated during the micro-electrolysis + Fenton treatment are effectively utilized to prepare sodium ferrate solution to achieve a high recycling rate of coking wastewater.

Description

A coking wastewater membrane filtration concentrate treatment system and method

Technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to a coking wastewater membrane filtration concentrate treatment system, and also relates to a coking wastewater membrane filtration concentrate treatment method.

Background technique

Coking wastewater is a typical refractory organic wastewater with high toxicity and poor biodegradability. It is one of the difficult-to-treat wastewaters in the steel industry. At present, the treatment method commonly used by steel companies is biochemical treatment + nanofiltration + reverse osmosis process. During the treatment process, the membrane process will produce concentrated liquid.

At present, the recovery rate of membrane treatment of coking wastewater is generally about 70%, and the concentrated brine with a mass concentration of about 30% is mostly digested within the enterprise, and is mainly used for coal blending, slag washing, coke quenching, etc. In order to meet the requirements of energy conservation, emission reduction and water pollutant discharge standards, relevant enterprises need to improve wastewater treatment processes and adopt reduction measures.

When coking wastewater is used as slag flushing water, toxic and harmful substances volatilize under high temperature, causing air pollution. The effective treatment of concentrated liquid is an indispensable and important part of the entire treatment system, and it is also one of the bottlenecks in the current use of membrane treatment technology.

In the steel manufacturing process, only 30% to 50% of the energy is effectively utilized, and the remaining large amount of energy exists in the form of waste heat, with huge recovery potential. Achieving efficient recycling of waste heat resources and reducing energy costs of enterprises are major issues that steel companies need to consider in their research. For the treatment of high-salt wastewater, the traditional method is to first reduce and concentrate the wastewater, and then use the concentrated liquid to crystallize the salt through evaporation technology, and finally achieve desalination of the wastewater and recovery of salt resources. At present, the concentration methods that have been industrialized on a large scale mainly include thermal method and membrane separation method. The thermal method mainly uses heating to evaporate the water in high-salt wastewater to achieve concentration and volume reduction. This method usually uses water vapor as the heat source, so it consumes huge energy and has very high operating costs. Membrane distillation technology is a new separation technology that combines the traditional thermal evaporation process with membrane separation technology. Its principle is to prevent the waste liquid from penetrating the membrane pores in the form of liquid under the interception of the hydrophobic microporous membrane, and only the volatile components remain in the membrane. Driven by the vapor pressure difference on both sides of the membrane, it penetrates the membrane pores, and the non-volatile components are intercepted, finally achieving the separation and purification of the mixture, with high concentration multiples and low energy consumption (using a low-grade heat source of 30 to 70°C ) features.

A small number of coking enterprises evaporate and crystallize the membrane filtration concentrate of coking wastewater to obtain industrial water and mixed salt. The thermal salt separation crystallization process can recover 60 to 70% of sodium sulfate. The comprehensive recovery rate of crystallized salt products is 40 to 50%. The membrane method Salt separation crystallization can recover about 90% of sodium sulfate, and the comprehensive recovery rate of crystallized salt reaches about 80%. The current salt separation crystallization process still requires 15% of mixed salt to be processed. Since mixed salt contains impurities such as organic matter, it is hazardous waste and the disposal cost is high. It is of great significance to remove organic matter and other pollutants in coking wastewater, recycle the salt substances in it, and realize zero discharge technology of coking wastewater.

Contents of the invention

In order to overcome the shortcomings of the existing technology, the present invention provides a coking wastewater membrane filtration concentrate treatment system and method, which uses adsorption + micro-electrolysis + Fenton + electro-oxidation to remove organic matter in the concentrate, and adopts nanofiltration + vacuum membrane distillation. + Bipolar membrane electrodialysis utilizes the resources of the concentrated liquid, and at the same time effectively utilizes the waste gas generated during the electrooxidation treatment process and the sludge generated during the micro-electrolysis + Fenton treatment to prepare sodium ferrate solution, achieving zero discharge of coking wastewater.

In order to solve the above problems, the present invention provides the following solutions:

A coking wastewater membrane filtration concentrate treatment system, including a first adsorption device, the water outlet of the first adsorption device is connected to the micro-electrolysis water inlet pipe of the micro-electrolysis device, and the water outlet of the micro-electrolysis device is connected to the water inlet of the Fenton device. The water outlet of the Fenton device is connected to the water inlet of the neutralization tank, the water outlet of the neutralization tank is connected to the water inlet of the flocculation and sedimentation tank, the ferric hydroxide output of the flocculation and sedimentation tank is connected to the sodium ferrate preparation device, and the flocculation and sedimentation tank The water outlet of the electro-oxidation device is connected to the water inlet of the electro-oxidation device. The sodium hypochlorite outlet of the electro-oxidation device is connected to the sodium ferrate preparation device. The water outlet of the electro-oxidation device is connected to the water inlet of the first hard-removing device. The water outlet of the first hard-removing device is connected. The water inlet of the nanofiltration device, the nanofiltration water production port of the nanofiltration device are connected to the water inlet of the first vacuum membrane distillation device, the concentrated water outlet of the first vacuum membrane distillation device is connected to the crystallizer, and the mother liquor outlet of the crystallizer is connected to the water inlet of the first vacuum membrane distillation device. The water inlet of the first vacuum membrane distillation device is connected to the water inlet of the second adsorption device, the product water outlet of the first vacuum membrane distillation device is connected to the production pool, and the concentrated water port of the nanofiltration device is connected to the water inlet of the second vacuum membrane distillation device. connection, the produced water outlet of the second vacuum membrane distillation device is connected to the production pool, the concentrated water outlet of the second vacuum membrane distillation device is connected to the low-temperature crystallizer, and the mother liquor outlet of the low-temperature crystallizer is respectively connected to the inlet of the second vacuum membrane distillation device. The water inlet is connected to the water inlet of the second adsorption device, the water outlet of the second adsorption device is connected to the water inlet of the second hardness removal device, the water outlet of the second hardness removal device is connected to the water inlet of the bipolar membrane electrodialysis device, and the double The alkali solution outlet of the polar membrane electrodialysis device is respectively connected to the alkali solution dosing pipe of the neutralization tank, the alkali solution input port of the electro-oxidation device, the alkali solution dosing pipe of the first hardness removal device and the sodium ferrate preparation device. The acid outlet of the bipolar membrane electrodialysis device is connected to the acid dosing pipe of the microelectrolysis device, and the fresh water outlet of the bipolar membrane electrodialysis device is connected to the water inlet of the nanofiltration device.

As mentioned above, the first adsorption device includes a first adsorption device water inlet tank. The water inlet of the first adsorption device water inlet tank serves as the water inlet of the first adsorption device. The first adsorption device water inlet tank passes through the water inlet pump and the adsorption reaction pool. The first pool is connected. The bottom of the first pool of the adsorption reaction pool and the bottom of the second pool of the adsorption reaction pool are connected through a flow passage. Aeration pipes are installed at the bottoms of the first pool and the second pool of the adsorption reaction pool. The inlet of the pipe is connected to the first blower, the second pool of the adsorption reaction pool is connected to the water inlet of the filtering device through the first lifting pump, the concentrated water port of the filtering device is connected to the first pool of the adsorption reaction pool, and the product of the filtering device (5) The water inlet is connected to the first water production tank, the drainage outlet of the filtering device is connected to the external sludge dehydrator, and the water outlet of the first water production tank is the water outlet of the first adsorption device.

As mentioned above, the micro-electrolysis device includes a pipe mixer, one inlet of the pipe mixer is connected to the outlet of the micro-electrolysis water inlet pipe, the other inlet of the pipe mixer is connected to the acid dosing pipe, and the outlet of the pipe mixer is connected to the micro-electrolysis reactor water inlet pipe. The inlet of the micro-electrolysis reactor water inlet pipe extends to the lower part of the micro-electrolysis reactor. Multiple filler support layers are set up in the micro-electrolysis reactor. Block fillers are set on the filler support layer, and there are set bottoms of each filler support layer. Micro-electrolysis reactor aeration pipe, the bottom of the micro-electrolysis reactor is provided with a first baffle, the first baffle is located directly below the outlet of the water inlet pipe of the micro-electrolysis reactor, and is located on the side wall of the micro-electrolysis reactor corresponding to each filler support layer A micro-electrolysis reactor access port is provided. A first separator is provided above the uppermost packing support layer. A first overflow weir is provided above the first separator. The first overflow weir is located in the upper part of the micro-electrolysis reactor. The first overflow weir is connected to the water outlet pipe of the micro-electrolysis reactor, and the water outlet of the water outlet pipe of the micro-electrolysis reactor serves as the water outlet of the micro-electrolysis device.

As mentioned above, the Fenton device includes a Fenton reactor water inlet pipe. The water inlet of the Fenton reactor water inlet pipe serves as the water inlet of the Fenton reaction device and is connected to the water outlet of the microelectrolysis reactor water outlet pipe. The Fenton reactor water inlet pipe outlet extends To the lower part of the Fenton reactor, an aeration pipe and a second baffle are provided at the bottom of the Fenton reactor. The second baffle is located directly below the outlet of the water inlet pipe of the Fenton reactor, and the second overflow weir is located in the Fenton reactor. On the upper part of the reactor, the second separator is located below the second overflow weir. The second overflow weir is connected to the inlet of the outlet pipe of the Fenton reactor. The outlet of the outlet pipe of the Fenton reactor is the outlet of the Fenton device. The Fenton reactor The bottom is connected to the dosing pipe for hydrogen peroxide solution.

As mentioned above, the neutralization tank is connected to the outlet of the outlet pipe of the Fenton reactor. An aeration pipe is set at the bottom of the neutralization tank. The aeration pipe of the neutralization tank is connected to the second blower. The bottom of the neutralization tank and the bottom of the flocculation tank are connected through a flow passage. , the overflow channel serves as the water outlet of the neutralization tank and the water inlet of the flocculation sedimentation tank;

The flocculation and sedimentation tank includes a flocculation tank. The flocculation tank is equipped with a flocculation tank mixer. The flocculation tank is connected to a flocculant dosing pipe. The overflow port at the upper part of the flocculation tank is connected to the inlet of the sedimentation tank water inlet. The outlet of the water inlet pipe of the sedimentation tank extends to the sedimentation tank. In the middle of the tank, there is a sedimentation tank mud bucket at the bottom of the sedimentation tank. The sedimentation tank mud bucket is located below the outlet of the water inlet pipe of the sedimentation tank. The sedimentation tank mud bucket is connected to the inlet of the mud pump, and the outlet of the mud pump serves as a flocculation sedimentation The ferric hydroxide output port of the tank, the upper part of the sedimentation tank is equipped with a sedimentation tank outlet, and the sedimentation tank outlet serves as the water outlet of the flocculation sedimentation tank.

As mentioned above, the electro-oxidation device includes an electro-oxidation water inlet tank. The water inlet of the electro-oxidation water inlet tank serves as the water inlet of the electro-oxidation device. The top of the electro-oxidation water inlet tank is closed. The bottom of the electro-oxidation water inlet tank is provided with an aeration pipe. The aeration pipe of the oxidation water inlet tank is connected to the third blower, the inlet of the second exhaust fan is connected to the space above the liquid level in the electro-oxidation water inlet tank, and the outlet of the second exhaust fan is connected to the air inlet of the absorption tower. The inlet of the oxidation water inlet pump is connected to the water outlet of the electro-oxidation water inlet tank, the outlet of the electro-oxidation water inlet pump is connected to the inlet of the filter, the outlet of the filter is connected to the inlet of the electrolytic tank, and the air outlet of the electrolytic tank is connected to the electro-oxidation tank through the electrolytic tank exhaust pipe. The water inlet tank and the outlet of the electrolyzer exhaust pipe are located below the liquid level of the electrolytic tank. The electrolytic tank outlet is connected to the electrooxidation water production tank. The top of the electrooxidation water production tank is closed. The inlet of the first exhaust fan Connected to the space above the liquid level in the electrooxidation water production tank, the outlet of the first exhaust fan is connected to the air inlet of the absorption tower, and the bottom of the absorption tower is connected to the alkali liquid water tank. Multiple groups of alkali liquid water tanks are provided. When the alkali liquid water tank is empty The inlet of the alkali water tank serves as the alkali input port of the electro-oxidation device. When the alkali water tank is filled with sodium hydroxide solution, the inlet of the alkali water tank is disconnected from the alkali output port of the bipolar membrane electrodialysis device and the alkali water tank The outlet is connected to the inlet of the spray pump, the outlet of the spray pump is connected to the upper water inlet of the absorption tower, and the inlet of the alkali water tank is connected to the water outlet of the absorption tower. When the concentration of the sodium hypochlorite solution in the alkali water tank reaches the set value, the alkali water tank The outlet is the sodium hypochlorite water outlet of the electro-oxidation device, and the water outlet of the electro-oxidation water production tank is used as the water outlet of the electro-oxidation device.

As mentioned above, the first hardness removal device includes first reaction pools connected in sequence. The bottom of the first reaction pool and the bottom of the second reaction pool are connected through a flow passage. The upper part of the second reaction pool and the upper part of the third reaction pool are connected through an overflow channel. connection, the first reaction pool is equipped with a first mixer, the second reaction pool is equipped with a second mixer, and the third reaction pool is equipped with a third mixer. The water inlet of the first reaction pool is used as the water inlet of the first hardness removal device. The first reaction pool is equipped with There is an alkali solution dosing pipe, and the alkali solution dosing pipe of the first reaction tank serves as the alkali solution dosing pipe of the first hardness removal device. The second reaction tank is connected to the sodium carbonate dosing pipe, and the third reaction tank passes an ultrafiltration water inlet pump. Connect the inlet of the ultrafiltration membrane, the concentrated water outlet of the ultrafiltration membrane is connected to the third reaction tank, the water production port of the ultrafiltration membrane is connected to the second water production tank, and the second water production tank is connected to the resin tank of the first hard removal device through the second lifting pump. The resin tank of the hard device is filled with strong acidic cation exchange resin, and the outlet of the resin tank of the first hard device is used as the water outlet of the first hard device.

A coking wastewater membrane filtration concentrate treatment method, using a coking wastewater membrane filtration concentrate treatment system as described above, the characteristic steps include:

S1. First, remove most of the organic pollutants in the membrane filtration concentrate of coked wastewater through activated carbon in the first adsorption device; the effluent from the first adsorption device enters the micro-electrolysis device, and acid solution is added to adjust the pH of the incoming water of the micro-electrolysis device to 2~ 3. While further removing organic pollutants and color in wastewater, ferrous ions are generated. The produced water from the micro-electrolysis device enters the Fenton device. The Fenton device uses ferrous ions and hydrogen peroxide to further oxidize and remove organic pollutants and organic pollutants in the wastewater. Chroma, while producing ferric ions;

S2. The effluent from the Fenton device enters the neutralization tank. The alkaline solution is used to adjust the pH in the neutralization tank to 7-8. After adding flocculant to the flocculation tank, it precipitates in the sedimentation tank. The effluent from the sedimentation tank enters the electro-oxidation device and precipitates. The iron hydroxide precipitate in the pool enters the sodium ferrate preparation device;

S3. The electro-oxidation device removes ammonia nitrogen, COD and chroma from wastewater, and uses alkali solution to produce sodium hypochlorite solution. The sodium hypochlorite solution enters the sodium ferrate preparation device, and the electro-oxidation produced water enters the first hardness removal device; the first hardness removal device adopts Chemical precipitation and resin softening remove the hardness in the wastewater, and the effluent after the hardness removal enters the nanofiltration device;

S4. The produced water from the first hardness removal device is passed through the nanofiltration device to obtain nanofiltration produced water whose main component is sodium chloride. The nanofiltrated produced water enters the first vacuum membrane distillation device, and the concentrated water from the first vacuum membrane distillation device enters The crystallizer obtains sodium chloride crystals. A part of the mother liquor output from the crystallizer flows back to the first vacuum membrane distillation device. The other part of the mother liquor output from the crystallizer enters the second adsorption device. The product water from the first vacuum membrane distillation device enters the production pool, and the sodium chloride is collected. After the filtered concentrated water enters the second vacuum membrane distillation device and is further concentrated, the concentrated water from the second vacuum membrane distillation device enters the low-temperature crystallizer to obtain sodium sulfate decahydrate crystals. The product water from the second vacuum membrane distillation device enters the production pool for low-temperature crystallization. Most of the mother liquor from the low-temperature crystallizer flows back to the second vacuum membrane distillation device, and the remaining part of the mother liquor from the low-temperature crystallizer enters the second adsorption device;

S5. In the second adsorption device, granular activated carbon and macroporous adsorption resin are used to adsorb and remove organic matter in the mother liquor output from the low-temperature crystallizer. The effluent from the second adsorption device enters the second hardness removal device and uses resin softening to remove the hardness in the wastewater. The second The effluent from the hardness removal device enters the bipolar membrane electrodialysis device;

S6. The bipolar membrane electrodialysis device produces a mixed acid of hydrochloric acid and sulfuric acid and a sodium hydroxide solution. The mixed acid is reused in the microelectrolysis device. Part of the sodium hydroxide solution is used in the neutralization tank to adjust the pH, and part of it is used in the electrooxidation device. The alkali water tank absorbs the tail gas, and the remaining part is used in the sodium ferrate preparation device to prepare sodium ferrate solution with ferric hydroxide from the flocculation sedimentation tank and sodium hypochlorite from the electro-oxidation device.

As mentioned above, in step S3, multiple groups of alkali water tanks are set up. When the mass concentration of the sodium hypochlorite solution reaches 10% concentration, it is switched to the next group of alkali water tanks to continue running, and then transported to the sodium ferrate preparation device through a lift pump; the first remover The hard device resin tank is filled with strong acidic cation exchange resin to release hydrogen ions to adjust the pH of the wastewater; the mass concentration of the sodium hydroxide solution produced by bipolar membrane electrodialysis in step S6 is 8 to 10%, and the mixed acid is used for micro electrolysis Device pH adjustment, resin regeneration inside or outside the system, and membrane cleaning inside or outside the system.

As mentioned above, in step S4, the heat sources of the first vacuum membrane distillation device and the second vacuum membrane distillation device are waste heat from the steel plant, so that the operating temperature of the wastewater is 50 to 70°C.

Compared with the prior art, the beneficial effects of the present invention are as follows:

1. The present invention utilizes the pretreatment process of adsorption + micro-electrolysis + Fenton + electro-oxidation to effectively remove refractory organic matter and color in water. The acid and alkali used in the treatment come from the bipolar membrane electrodialysis device in this system. , the combined application of micro-electrolysis and Fenton can eliminate the need to add ferrous sulfate, thereby reducing the need for additional chemicals to increase the salt content in the wastewater, and effectively improving the water quality of the subsequent salt separation crystallization process. At the same time, chemical precipitation and resin dehardening are used to effectively remove the calcium and magnesium hardness in the concentrated solution, reduce impurities in the wastewater, and improve the purity of subsequent salt separation crystallization products.

2. The concentration process used in the process of the present invention combines nanofiltration, vacuum membrane distillation and crystallization processes, uses nanofiltration to separate salts from wastewater, and utilizes the selective interception characteristics of nanofiltration membranes for divalent salts to achieve a The separation of the valent salt sodium chloride and the divalent salt sodium sulfate in the liquid phase. Sodium chloride mainly enters the nanofiltration product water, while sodium sulfate is concentrated in the nanofiltration concentrated water. The nanofiltration product water and nanofiltration concentrated water are separated through After vacuum membrane distillation and concentration, sodium chloride and sodium sulfate are obtained by crystallization. The vacuum membrane distillation device uses the waste heat of the steel plant as a heat source, which can effectively reduce energy consumption, improve the heat energy utilization efficiency of the steel plant, and achieve the purpose of energy conservation and emission reduction. The recovery rate is high, the operating cost is low, the produced water quality is stable, the effluent water quality is stable and reaches the reuse water standard, and the comprehensive recovery rate of crystallized salt is high.

3. The remaining mixed salt after salt separation and crystallization is used to prepare mixed acid and sodium hydroxide solution through adsorption, hard removal and bipolar membrane electrodialysis to further improve the resource recovery rate of the concentrated solution. Mixed acid and sodium hydroxide solution It is used for internal consumption of the treatment system. The chlorine and iron sludge generated during the treatment process continue to be utilized as resources. Ferric hydroxide, sodium hypochlorite, and sodium hydroxide are used to synthesize sodium ferrate at low temperature. The obtained sodium ferrate solution can be used for Coking wastewater treatment. The present invention uses the bipolar membrane electrodialysis process for resource utilization of mixed salt, combines the iron sludge produced by the micro-electrolysis-Fenton process and the sodium hypochlorite solution produced by electro-oxidation to prepare a sodium ferrate solution with obvious economic benefits, and further improves the concentration The resource utilization rate of liquid can be achieved by using this technology to achieve zero discharge of concentrated liquid.

Description of the drawings

Figure 1 is a process flow diagram of a coking wastewater membrane filtration concentrate treatment system.

Figure 2 is a schematic structural diagram of the first adsorption device.

Figure 3 is a schematic structural diagram of the micro-electrolysis-Fenton reactor-neutralization tank-flocculation sedimentation tank device.

Figure 4 is a schematic structural diagram of the electro-oxidation device.

Figure 5 is a schematic structural diagram of the first hardware removal device.

In the picture: 1-the first adsorption device water inlet tank; 2-the water inlet pump; 3-the first blower; 4-adsorption reaction tank; 5-filtration device; 6-the first water production tank; 7-the first lifting pump; 10 - Micro electrolysis reactor; 11 - Micro electrolysis water inlet pipe; 12 - Acid dosing pipe; 13 - Pipe mixer; 14 - Micro electrolysis reactor water inlet pipe; 15 - First separator; 16 - First overflow weir; 17-micro-electrolysis reactor exhaust port; 18-micro-electrolysis reactor maintenance port; 19-micro-electrolysis reactor aeration pipe; 20-first baffle; 21-first air compressor; 22-first gas storage Tank; 23-packing support layer; 24-microelectrolysis reactor outlet pipe; 25-Fenton reactor water inlet pipe; 26-Fenton reactor; 27-second overflow weir; 28-Fenton reactor maintenance port; 29-The second air compressor; 30-The second gas storage tank; 31-The second baffle; 32-The second separator; 33-Fenton reactor outlet pipe; 34-The second blower; 35-Neutralization tank ; 36-flocculation tank; 37-sedimentation tank; 38-sludge discharge pump; 39-flocculation tank mixer; 40-sedimentation tank outlet; 41-electro-oxidation water inlet tank; 42-third blower; 43-electro-oxidation water inlet pump ; 44-filter; 45-electrolyzer; 46-power supply; 47-electrolyzer exhaust pipe; 48-electrooxidation water production tank; 49-first exhaust fan; 50-second exhaust fan; 51-absorption tower ; 52-alkali water tank; 53-spray pump; 61-first reaction tank; 62-second reaction tank; 63-third reaction tank; 64-ultrafiltration water inlet pump; 65-ultrafiltration membrane; 66-th One mixer; 67-the second mixer; 68-the third mixer; 69-the second water production tank; 70-the second lifting pump; 71-the first hard-removing device resin tank.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

In specific implementation, the process flow of the coking wastewater membrane filtration concentrate treatment system of the present invention is shown in Figure 1.

A membrane filtration concentrate treatment system for coking wastewater, including a first adsorption device, a micro-electrolysis device, a Fenton device, a neutralization tank 35, a flocculation sedimentation tank, an electro-oxidation device, a first hardness removal device, and a nanofiltration device connected in sequence , a second vacuum membrane distillation device, a low-temperature crystallizer, a second adsorption device, a second hardness removal device, a bipolar membrane electrodialysis device, and also includes a first vacuum membrane distillation device, a production pool, a crystallizer, and a sodium ferrate preparation device. .

The coking wastewater membrane filtration concentrate effluent is input to the water inlet of the first adsorption device. The water outlet of the first adsorption device is connected to the micro-electrolysis water inlet pipe 11 of the micro-electrolysis device. The water outlet of the micro-electrolysis device is connected to the water inlet of the Fenton device. , the water outlet of the Fenton device is connected to the water inlet of the neutralization tank 35, the water outlet of the neutralization tank 35 is connected to the water inlet of the flocculation sedimentation tank, the ferric hydroxide output port of the flocculation sedimentation tank is connected to the sodium ferrate preparation device, The water outlet of the flocculation sedimentation tank is connected to the water inlet of the electro-oxidation device, the sodium hypochlorite outlet of the electro-oxidation device is connected to the sodium ferrate preparation device, the water outlet of the electro-oxidation device is connected to the water inlet of the first hardness removal device, and the water inlet of the first hardness removal device is connected. The water outlet is connected to the water inlet of the nanofiltration device, the nanofiltration water production port of the nanofiltration device is connected to the water inlet of the first vacuum membrane distillation device, the concentrated water outlet of the first vacuum membrane distillation device is connected to the crystallizer, and the mother liquor outlet of the crystallizer The water inlet is connected to the water inlet of the first vacuum membrane distillation device and the water inlet of the second adsorption device respectively. The produced water outlet of the first vacuum membrane distillation device is connected to the production pool. The concentrated water inlet of the nanofiltration device is connected to the second vacuum membrane distillation device. The water inlet is connected, the product water outlet of the second vacuum membrane distillation device is connected to the production pool, the concentrated water port of the second vacuum membrane distillation device is connected to the low-temperature crystallizer, and the mother liquor outlet of the low-temperature crystallizer is connected to the second vacuum membrane distillation device respectively. The water inlet of the device is connected to the water inlet of the second adsorption device, the water outlet of the second adsorption device is connected to the water inlet of the second hardness removal device, and the water outlet of the second hardness removal device is connected to the water inlet of the bipolar membrane electrodialysis device. Connect, the alkali solution outlet of the bipolar membrane electrodialysis device to the alkali solution dosing pipe of the neutralization tank 35, the alkali solution input port of the electro-oxidation device, the alkali solution dosing pipe of the first hard removal device and sodium ferrate respectively. The preparation device is connected, the acid outlet of the bipolar membrane electrodialysis device is connected to the acid dosing pipe 12 of the microelectrolysis device, and the fresh water outlet of the bipolar membrane electrodialysis device is connected to the water inlet of the nanofiltration device.

As shown in Figure 2, the first adsorption device includes a first adsorption device water inlet tank 1, a water inlet pump 2, an adsorption reaction tank 4, a first lifting pump 7, a filter device 5 and a first water production tank 6 connected in sequence. The water inlet of the water inlet tank 1 of the first adsorption device serves as the water inlet of the first adsorption device. The water inlet of the water inlet pump 2 is connected to the water inlet tank 1 of the first adsorption device. The water outlet of the water inlet pump 2 is connected to the adsorption reaction pool 4. Specifically, the adsorption The reaction pool 4 is divided into a first pool and a second pool by a partition. There is a flow passage between the lower part of the partition and the bottom of the adsorption reaction pool 4. The bottom of the first pool and the bottom of the second pool of the adsorption reaction pool 4 pass through. The overflow channel is connected, and the adsorption reaction pool 4 is changed from the general complete mixing type to the partial push flow type, which can improve a certain removal efficiency. The outlet of the water inlet pump 2 is connected to the first pool of the adsorption reaction pool 4. The adsorption reaction pool Install aeration pipes at the bottom of the first pool and the second pool 4. The inlets of the aeration pipes of the first pool and the second pool are connected to the first blower 3. The aeration amount is 3 to 5L/(m ² according to the area of the liquid surface. ·s), the inlet of the first lifting pump 7 is connected to the second pool of the adsorption reaction tank 4, the outlet of the first lifting pump 7 is connected to the water inlet of the filtering device 5, and the concentrated water port of the filtering device 5 is connected to the first water tank of the adsorption reaction tank 4. There is a pool, and the water production port of the filtering device 5 is connected to the first water production tank 6; the filtering device 5 adopts a turntable filter, the turntable filter material is filter cloth, the filtration precision is 5μm, the operating pressure is 0.1~0.4Mpa, and the turntable speed is 60~ 300r/min, the drain outlet of the filter device 5 is connected to an external sludge dewatering machine. After the filter device 5 has been running for a period of time, cleaning and maintenance need to discharge a part of the effluent with activated carbon (sludge). It is discharged through the drain outlet, and the effluent discharged from the drain outlet enters. The sludge dewatering machine adopts a plate and frame filter press. The effluent after filtering returns to the first water production tank 6. The waste water in the first water production tank 6 is lifted to the micro-electrolysis device through a water pump. The first water production tank The water outlet of 6 is the water outlet of the first adsorption device, and the water outlet of the first water production tank 6 is connected with the inlet of the micro-electrolysis water inlet pipe 11. In the adsorption reaction pool 4 of the first adsorption device, activated carbon is used to remove most of the organic pollutants in the membrane filtration concentrate of coking wastewater.

As shown in Figure 3, the micro-electrolysis device includes a micro-electrolysis reactor 10, a micro-electrolysis water inlet pipe 11, an acid dosing pipe 12, a pipe mixer 13, a micro-electrolysis reactor water inlet pipe 14, and a micro-electrolysis reactor exhaust port. 17. The first separator 15, the first overflow weir 16, the micro-electrolysis reactor maintenance port 18, the micro-electrolysis reactor aeration pipe 19, the first baffle 20, the first air compressor 21, and the first gas storage tank 22. Filler support layer 23 and micro-electrolysis reactor outlet pipe 24. One inlet of the pipe mixer 13 is connected to the outlet of the micro-electrolysis water inlet pipe 11, the other inlet of the pipe mixer 13 is connected to the acid dosing pipe 12, and the outlet of the pipe mixer 13 is connected to the inlet of the micro-electrolysis reactor water inlet pipe 14. The outlet of the reactor water inlet pipe 14 extends to the lower part of the micro-electrolysis reactor 10. A plurality of filler support layers 23 are provided from top to bottom in the micro-electrolysis reactor 10. Each filler support layer 23 is provided with filler, and each filler support Micro-electrolysis reactor aeration pipes 19 are provided below the layer 23, and a first baffle 20 is provided at the bottom of the micro-electrolysis reactor 10. The first baffle 20 is located directly below the bottom outlet of the micro-electrolysis reactor water inlet pipe 14. The baffle 20 is tapered, and the first baffle 20 can form a cyclonic flow out of the water inlet pipe 14 of the micro-electrolysis reactor. Micro-electrolysis reactor maintenance is provided on the side wall of the micro-electrolysis reactor 10 corresponding to each filler support layer 23. Port 18, each micro-electrolysis reactor aeration pipe 19 is connected to the outlet of the first gas storage tank 22, the inlet of the first gas storage tank 22 is connected to the first air compressor 21, and the first gas storage tank 22 is provided above the uppermost filler support layer 23. The separator 15 is provided with a first overflow weir 16 above the first separator 15. The first overflow weir 16 is located in the upper part of the micro-electrolysis reactor 10. The first overflow weir 16 is connected to the micro-electrolysis reactor water outlet pipe 24. , the water outlet of the micro-electrolysis reactor outlet pipe 24 is used as the water outlet of the micro-electrolysis device; the micro-electrolysis reactor 10 uses high-temperature sintered iron-carbon filler, and the filler provided on the filler support layer 23 is in the shape of a block with a diameter of 3 to 5 cm. Add from the access port 18 of the micro-electrolysis reactor, and use the compressed air provided by the first air compressor 21 and the first gas storage tank 22 to aerate and wash the surface of the filler, thereby stirring the filler, improving the mass transfer effect, and the pressure of the compressed air is 0.4~0.7Mpa; the top separator 15 adopts a two-layer triangular plate, and an exhaust pipe is arranged on the top of the triangular plate. Each exhaust pipe is gathered into a first exhaust main pipe extending above the liquid level. The first exhaust main pipe is connected to the micro-electrolysis reaction The exhaust port 17 of the reactor; the hydraulic retention time of the micro-electrolysis reactor 10 is 2 to 4 hours. The organic pollutants and chromaticity in the wastewater are further removed in the micro-electrolysis reactor 10, and a large amount of ferrous ions are generated at the same time, and then the water produced from the micro-electrolysis reactor 10 enters the Fenton device.

The Fenton device includes a Fenton reactor water inlet pipe 25, a Fenton reactor 26, a second overflow weir 27, a Fenton reactor maintenance port 28, a second air compressor 29, a second gas storage tank 30, The second baffle 31, the second separator 32 and the Fenton reactor outlet pipe 33. The top water inlet of the Fenton reactor water inlet pipe 25 serves as the water inlet of the Fenton reaction device and is connected to the water outlet of the microelectrolysis reactor water outlet pipe 24 through a water pipeline. The bottom water outlet of the Fenton reactor water inlet pipe 25 extends to the Fenton reactor. 26, an aeration pipe and a second baffle 31 are provided at the bottom of the Fenton reactor 26. The second baffle 31 is located directly below the bottom outlet of the Fenton reactor water inlet pipe 25. The aeration tube of the Fenton reactor 26 The gas pipe is connected to the outlet of the second gas storage tank 30, the inlet of the second gas storage tank 30 is connected to the second air compressor 29, the second overflow weir 27 is located at the upper part of the Fenton reactor 26, and the second separator 32 is located at the top of the Fenton reactor 26. Below the second overflow weir 27, the second overflow weir 27 is connected to the inlet of the Fenton reactor outlet pipe 33, and the outlet of the Fenton reactor outlet pipe 33 is the outlet of the Fenton device; the separator 32 is composed of two layers of triangular plates. An exhaust pipe is arranged on the top of the triangular plate, and each exhaust pipe is gathered into a second exhaust main pipe, which is connected above the liquid level and connected to the Fenton reactor gas outlet provided on the top of the Fenton reactor 26; the lower part of the side wall of the Fenton reactor 26 A Fenton reactor inspection port 28 is provided for inspecting the interior of the Fenton reactor 26; the bottom of the Fenton reactor 26 is connected to a dosing pipe, and the dosing pipe is used to add hydrogen peroxide solution. The exposure of the Fenton reactor 26 is The gas volume is calculated based on the liquid surface area, and the value range is 0.6~3L/( ^m2 ·s), and the aeration pressure is 0.3~0.4Mpa; the hydraulic retention time of the Fenton reactor 26 is 1~2 hours;

The neutralization tank 35 is connected to the outlet of the Fenton reactor outlet pipe 33. The neutralization tank 35 is provided with an alkali solution dosing pipe. The alkali solution dosing pipe of the neutralization tank 35 is connected to the alkali solution output port of the bipolar membrane electrodialysis. An aeration pipe is provided at the bottom of the neutralization tank 35. The aeration volume of the neutralization tank 35 is calculated based on the liquid surface area and is 3-5L/( ^m2 ·s). The aeration pipe of the neutralization tank 35 is connected to the second blower 34. The bottom of the neutralization tank 35 and the bottom of the flocculation tank 36 are connected through a flow passage, which serves as the water outlet of the neutralization tank 35 and the water inlet of the flocculation tank 36 (that is, the water inlet of the flocculation sedimentation tank).

The flocculation and sedimentation tank includes a flocculation tank 36 and a sedimentation tank 37. The flocculation tank 36 is equipped with a flocculation tank mixer 39. The flocculation tank 36 is connected to a flocculant dosing pipe, and the overflow port at the upper part of the flocculation tank 36 is connected to the inlet of the water inlet of the sedimentation tank 37. , the water inlet pipe outlet of the sedimentation tank 37 extends to the middle of the sedimentation tank 37, and a sedimentation tank mud bucket is provided at the bottom of the sedimentation tank 37. The sedimentation tank mud bucket is located below the water inlet pipe outlet of the sedimentation tank 37, and the inlet of the mud discharge pump 38 It is connected to the mud hopper of the sedimentation tank. The outlet of the sludge pump 38 serves as the ferric hydroxide output port of the flocculation sedimentation tank and is connected to the sodium ferrate preparation device. The water outlet 40 of the sedimentation tank is located at the upper part of the sedimentation tank 37. The water outlet 40 of the sedimentation tank serves as the flocculation sedimentation tank. The water outlet of the tank is connected to the water inlet of the electro-oxidation device; specifically, the hydraulic retention time of the neutralization tank 35 is 15 to 30 minutes, the hydraulic retention time of the flocculation tank 36 is 5 to 10 minutes, and the hydraulic retention time of the sedimentation tank 37 is 2 Hour;

As shown in Figure 4, the electro-oxidation device includes an electro-oxidation water inlet tank 41, a third blower 42, an electro-oxidation water inlet pump 43, a filter 44, an electrolytic tank 45, a power supply 46, an electrolytic tank exhaust pipe 47, and an electro-oxidation tank. The produced water tank 48, the first exhaust fan 49, the second exhaust fan 50, the absorption tower 51, the alkali liquid water tank 52 and the spray pump 53. The water inlet of the electro-oxidation water inlet tank 41 serves as the water inlet of the electro-oxidation device. The top of the electro-oxidation water inlet tank 41 is closed. An aeration pipe is provided at the bottom of the electro-oxidation water inlet tank 41. The aeration pipe of the electro-oxidation water inlet tank 41 is connected The inlets of the third blower 42 and the second exhaust fan 50 are connected to the space above the liquid level in the electro-oxidation water inlet tank 41 through a gas pipeline. The outlet of the second exhaust fan 50 is connected to the air inlet of the absorption tower 51. The electro-oxidation inlet The inlet of the water pump 43 is connected to the water outlet of the electro-oxidation water inlet tank 41, the outlet of the electro-oxidation water inlet pump 43 is connected to the inlet of the filter 44, the outlet of the filter 44 is connected to the inlet of the electrolytic tank 45, and the air outlet of the electrolytic tank 45 is discharged through the electrolytic tank. The air pipe 47 is connected to the electro-oxidation water inlet tank 41 and the air outlet of the electrolytic cell exhaust pipe 47 is located below the liquid level of the electro-oxidation water inlet tank 41. The water outlet of the electrolytic cell 45 is connected to the electro-oxidation water production tank 48. The electro-oxidation water production tank 48 The top of the electrolyzer 45 is closed, and each electrolytic cell 45 is powered by a power supply 46. The inlet of the first exhaust fan 49 is connected to the space above the liquid level in the electrooxidation water production tank 48 through a gas pipeline, and the outlet of the first exhaust fan 49 is connected to The air inlet of the absorption tower 51, the bottom of the absorption tower 51 is connected to the alkali liquid water tank 52, the alkali liquid water tank 52 is provided with multiple groups, when the alkali liquid water tank 52 is empty, the entrance of the alkali liquid water tank 52 serves as the alkali liquid input port of the electro-oxidation device With the alkali solution output port of the bipolar membrane electrodialysis device, after the sodium hydroxide solution is loaded, the inlet of the alkali solution water tank 52 is disconnected from the alkali solution output port of the bipolar membrane electrodialysis device and sprayed with the outlet of the alkali solution water tank 52 The inlet of the spray pump 53 is connected to absorb chlorine, and the outlet of the spray pump 53 is connected to the upper water inlet of the absorption tower 51. At this time, the inlet of the alkali liquid tank 52 is connected to the lower outlet of the absorption tower 51 to collect the generated sodium hypochlorite solution; when The sodium hypochlorite solution produced by the alkali water tank 52 absorbing chlorine reaches the set concentration. The water outlet of the alkali water tank 52 containing the sodium hypochlorite solution with the set concentration is the sodium hypochlorite outlet of the electro-oxidation device. At this time, the next set of sodium hypochlorite solution is switched to the next one. The alkali water tank 52 is connected to the inlet of the spray pump 53 to continue operating the absorption tower 51, and the alkali water tank 52 containing the sodium hypochlorite solution is connected to an external lift pump to send the sodium hypochlorite solution to the sodium ferrate preparation device; the outlet of the electrooxidation water production tank 48 The water inlet serves as the water outlet of the electro-oxidation device. The electro-oxidation water inlet tank 41 and the electro-oxidation water production tank 48 are stirred by micropore aeration, and the second exhaust fan 50 and the first exhaust fan 49 are used to suck the water generated in the electro-oxidation water inlet tank 41 and the electro-oxidation water production tank 48 respectively. chlorine gas, and transport the chlorine gas to the absorption tower 51. In the absorption tower 51, alkali liquid is used to absorb the chlorine gas to obtain a sodium hypochlorite solution; the electrode plate of the electrolytic cell 45 adopts a porous electrode plate with a pore diameter of 20 to 50 μm and an electrode plate thickness of 3 to 5 mm. , the direction of the water flow in the electrolytic tank 45 is perpendicular to the electrode plates, the wastewater passes through each electrode plate in turn, the anode plates and the cathode plates are arranged alternately, the distance between the electrode plates is 1~2cm, and the current density of the electrolytic tank 45 is 600~800A/m ² .

As shown in Figure 5, the first hardness removal device includes a first reaction tank 61, a second reaction tank 62, a third reaction tank 63, an ultrafiltration water inlet pump 64, an ultrafiltration membrane 65, and a second water production tank that are connected in sequence. 69. The second lifting pump 70 and the resin tank 71 of the first hard removal device. Among them, the bottom of the first reaction pool 61 and the bottom of the second reaction pool 62 are connected through a flow channel, the upper part of the second reaction pool 62 and the upper part of the third reaction pool 63 are connected through an overflow channel, and the first reaction pool 61 is equipped with a first mixer. 66. The second reaction tank 62 is equipped with a second mixer 67, and the third reaction tank 63 is equipped with a third mixer 68. The water outlet of the electrooxidation water production tank 48 is connected to the water inlet of the first reaction tank 61, and the water inlet of the first reaction tank 61 serves as The water inlet of the first hardness removal device, the first reaction tank 61 is provided with an alkali solution dosing pipe, and the alkali solution dosing pipe of the first reaction tank 61 serves as the alkali solution dosing pipe of the first hardness removal device and is connected to the bipolar membrane electrode. The alkali output port of the dialysis device, the second reaction tank 62 is connected to the sodium carbonate dosing pipe, the inlet of the ultrafiltration water inlet pump 64 is connected to the third reaction tank 63, the outlet of the ultrafiltration water inlet pump 64 is connected to the inlet of the ultrafiltration membrane 65, and the ultrafiltration water inlet pump 64 is connected to the inlet of the ultrafiltration membrane 65. The concentrated water outlet of the membrane 65 is connected to the third reaction tank 63, the water production port of the ultrafiltration membrane 65 is connected to the second water production tank 69, the inlet of the second lift pump 70 is connected to the second water production tank 69, and the outlet of the second lift pump 70 is connected to the first water removal tank. The resin tank 71 of the hard device, the outlet of the resin tank 71 of the first hard device is used as the water outlet of the first hard device; the ultrafiltration membrane 65 of the first hard device is a tubular ultrafiltration membrane, and the filtration precision is 50nm. The hard-removal device resin tank 71 uses strong acidic cation exchange resin; during the operation of the ultrafiltration membrane 65, a part of the concentrated water needs to be discharged, and the discharged concentrated water enters the external sludge dehydrator. The sludge dehydrator uses a plate and frame filter press, and passes through the plate. The effluent after filtering by the frame filter press returns to the second water production tank 69; when the resin in the resin tank 71 of the first hardness removal device needs to be regenerated during use, the mixed acid produced by the bipolar membrane electrodialysis device is used for regeneration.

After the hardness is removed by the first hardness removal device, the calcium and magnesium hardness concentration is low. However, after the wastewater is concentrated by the second vacuum membrane distillation device, the calcium and magnesium hardness concentration increases. Therefore, it is necessary to use the resin of the second hardness removal device to reduce the calcium and magnesium hardness. The concentration of magnesium hardness ensures the quality of the incoming water for bipolar membrane electrodialysis. In this embodiment, the second hardness removal device has the same structure as the first hardness removal device.

Example 2

In specific implementation, the process flow of a coking wastewater membrane filtration concentrate treatment method of the present invention is shown in Figure 1.

A coking wastewater membrane filtration concentrate treatment method, utilizing a coking wastewater membrane filtration concentrate treatment system described in Embodiment 1, includes the following steps:

S1. Remove organic pollutants and color from the membrane filtration concentrate of coking wastewater. First, most of the organic pollutants in the membrane filtration concentrate of coked wastewater are removed through activated carbon in the first adsorption device; the effluent from the first adsorption device enters the micro-electrolysis device, and the mixed acid solution from the bipolar membrane electrodialysis is added to adjust the micro-electrolysis device The pH of the incoming water is 2 to 3, which further removes organic pollutants and color in the wastewater while producing ferrous ions. The produced water from the micro-electrolysis device enters the Fenton device. The Fenton device uses ferrous ions and hydrogen peroxide to further oxidize and remove the wastewater. organic pollutants and chroma in the air, and at the same time produce ferric ions. The specific process is as follows:

The coking wastewater membrane filtration concentrate is first stored in the concentrate pool, and then sent to the first adsorption device inlet tank 1 through a lifting pump, and then sent to the adsorption reaction tank 4 through the inlet pump 2, where it is put into the adsorption reaction tank 4. Add a powdered activated carbon solution with a mass concentration of 5 to 10%, and use the powdered activated carbon to remove most of the organic pollutants in the wastewater. The wastewater in the adsorption reaction tank 4 is sent to the filtering device 5 through the first lift pump 7 and filtered in the filtering device 5 To realize the separation of powdered activated carbon, part of the separated concentrated water flows back to the adsorption reaction tank 4, and part of it is discharged to the external powdered activated carbon dehydration device (such as the plate and frame filter press in this embodiment) during maintenance and cleaning. The liquid flows to the first water production tank 6, and the wastewater in the first water production tank 6 is lifted to the micro-electrolysis device through a water pump;

The wastewater in the first produced water tank 6 enters the pipe mixer 13 from the micro-electrolysis water inlet pipe 11. At the same time, an acid solution is added from the acid dosing pipe 12 to the pipe mixer 13. The acid solution comes from the mixed acid of bipolar membrane electrodialysis. Solution (HCl solution and H ₂ SO ₄ solution) output port, the micro-electrolysis reactor 10 is equipped with a pH meter to control the pH of the inlet water of the micro-electrolysis reactor 10 to be 2 to 3, and the micro-electrolysis reactor 10 is filled with iron-carbon filler. The iron-carbon micro-electrolysis reaction is used to further remove organic pollutants and chromaticity in the wastewater, and at the same time a large amount of ferrous ions are produced, and the water produced from the micro-electrolysis reactor 10 enters the Fenton reactor 26;

The Fenton reactor 26 uses ferrous ions and the hydrogen peroxide solution added in the dosing pipe at the bottom of the Fenton reactor 26 to further oxidize and remove organic pollutants and color in the wastewater, and at the same time generates a large amount of ferric ions;

Both the micro-electrolysis reactor 10 and the Fenton reactor 26 use air compressors for aeration and stirring. The air inlet pressure of the micro-electrolysis reactor 10 is 0.4-0.7Mpa, and the aeration pressure of the Fenton reactor 26 is 0.3-0.4Mpa;

S2. Remove iron ions. The effluent from the Fenton device enters the neutralization tank 35. The alkali solution from the bipolar membrane electrodialysis device is used to adjust the pH in the neutralization tank 35 to 7-8. After adding flocculant in the flocculation tank 36, the process is carried out in the sedimentation tank 37. Precipitation, the water out of the sedimentation tank 37 enters the electro-oxidation device, and the iron hydroxide precipitate in the sedimentation tank 37 enters the sodium ferrate preparation device:

The effluent of the Fenton device enters the neutralization tank 35 from the Fenton reactor outlet pipe 33, and an alkali solution is added to the neutralization tank 35. The alkali solution comes from the alkali solution output port of the bipolar membrane electrodialysis, and the neutralization tank 35 is adjusted. The pH of the wastewater is 7 to 8. The second blower 34 is used in the neutralization tank 35 for aeration and stirring to continue oxidizing the unoxidized ferrous iron into trivalent iron. Then the effluent from the neutralization tank 35 is adjusted to overflow to the flocculation tank. 36;

Add flocculant to the flocculation tank 36 (the flocculant is anionic polyacrylamide PAM with a mass concentration of 0.1 to 0.2%). After stirring with the flocculation tank mixer 39, the wastewater enters the sedimentation tank 37 from the water inlet pipe of the sedimentation tank. After sedimentation in the tank 37, the effluent from the sedimentation tank 37 enters the electro-oxidation device, and the iron hydroxide precipitation in the mud hopper of the sedimentation tank 37 is transported to the sodium ferrate preparation device using the mud discharge pump 38;

S3. Remove ammonia nitrogen, COD, color, and hardness from wastewater to produce sodium hypochlorite solution. The electrooxidation device removes ammonia nitrogen, COD and chroma from the wastewater, and at the same time uses the alkali solution from the bipolar membrane electrodialysis device to produce sodium hypochlorite solution. The sodium hypochlorite solution enters the sodium ferrate preparation device, and the electrooxidation produced water enters the first hardness removal device; The first hardness removal device uses chemical precipitation and resin softening to remove the hardness in the wastewater. The effluent after the hardness removal enters the nanofiltration device:

The effluent from the sedimentation tank 37 is first stored in the electro-oxidation water inlet tank 41, and is lifted to the electrolytic tank 45 using the electro-oxidation inlet pump 43. The electrolytic tank 45 is provided with a porous electrode plate with a thickness of 3 to 5 mm, and an anode plate and The cathode plates are alternately arranged, and the distance between the plates is 1 to 2 cm. The electrolytic tank 45 is connected to the power supply 46. The current density of the electrolytic tank 45 is 600 to 800A/m ² . When the wastewater passes through the porous electrode plate, it is oxidized to remove ammonia nitrogen, COD and chroma. , the tail gas generated during the oxidation process (mainly containing air, chlorine and a small amount of hydrogen) first enters the electro-oxidation water inlet tank 41 and is absorbed by the solution. The unabsorbed tail gas is sent to the absorption tower 51 using the second exhaust fan 50. At the same time, The produced water from the electro-oxidation device first enters the electro-oxidation water production tank 48, and then is transported to the first hardness removal device. Both the electro-oxidation water inlet tank 41 and the electro-oxidation water production tank 48 are aerated, stripped and stirred by the third blower 42. The tail gas in the oxidation water production tank 48 is sent to the absorption tower 51 using the first exhaust fan 49. The absorption tower 51 uses alkali spray to absorb chlorine and generate sodium hypochlorite solution. The alkali solution in the alkali water tank 52 comes from the bipolar membrane. The alkali solution and alkali liquid of the electrodialysis device are sent to the absorption tower 51 using the spray pump 53 . There are multiple groups of alkali water tanks 52. First, the empty alkali water tank 52 is connected to the alkali output port of the bipolar membrane electrodialysis device to collect the sodium hydroxide solution; then the alkali water tank 52 filled with sodium hydroxide solution is connected to the spray pump. 53 in order to absorb chlorine; when the sodium hypochlorite solution produced by a group of alkali liquid water tanks 52 absorbing chlorine reaches a mass concentration of 10%, switch to the next assembly of alkali liquid water tanks 52 with sodium hydroxide solution to connect the inlet of the spray pump 53 to continue. Run the absorption tower 51, and connect the alkali water tank 52 containing the sodium hypochlorite solution to an external lift pump to send the sodium hypochlorite solution to the sodium ferrate preparation device. In addition to the alkali solution utilizing bipolar membrane electrodialysis, the alkali solution water tank 52 can also be added The solid sodium hydroxide increases the concentration of the alkali solution, thereby improving the efficiency of chlorine absorption. The electro-oxidized water enters the first reaction pool 61 of the first hardness removal device. The tail gas after absorbing chlorine in the absorption tower 51 is mainly air and a small amount of hydrogen. From The exhaust port of the absorption tower 51 is discharged from the outside of the system;

Alkali solution is added to the first reaction tank 61, which comes from the alkaline output port of the bipolar membrane electrodialysis device. Sodium carbonate solution is added to the second reaction tank 62, and the wastewater in the third reaction tank 63 is ultrafiltrated. The inlet water pump 64 is sent to the ultrafiltration membrane 65 for filtration and separation. Part of the concentrated water generated by the ultrafiltration membrane 65 flows back to the third reaction tank 63, and part of it is discharged to the sludge dehydrator for dehydration treatment. The dehydrated clear liquid flows to the third reaction tank 63. In the secondary produced water tank 69, the produced water of the ultrafiltration membrane 65 enters the second produced water tank 69, and the waste water in the second produced water tank 69 is sent to the resin tank 71 of the first hardness removal device using the second lifting pump 70. The first hardness removal device The resin tank 71 is filled with a strong acidic cation exchange resin, which uses the resin to exchange calcium and magnesium ions in the wastewater and then releases hydrogen ions to adjust the pH of the wastewater. The water produced in the resin tank 71 of the first hard-removing device enters the water inlet tank of the nanofiltration device;

S4. Obtain sodium chloride crystals and sodium sulfate decahydrate crystals. The product water from the first hardness removal device is passed through the nanofiltration device to obtain nanofiltration product water whose main component is sodium chloride. The nanofiltration product water enters the first vacuum membrane distillation device, and the concentrated water from the first vacuum membrane distillation device enters the crystallizer. Sodium chloride crystals are obtained. A part of the mother liquor output from the crystallizer flows back to the first vacuum membrane distillation device. The other part of the mother liquor output from the crystallizer enters the second adsorption device. The product water from the first vacuum membrane distillation device enters the production pool, and the nanofiltration concentrates After the water enters the second vacuum membrane distillation device and is further concentrated, the concentrated water from the second vacuum membrane distillation device enters the low-temperature crystallizer to obtain sodium sulfate decahydrate crystals. The product water from the second vacuum membrane distillation device enters the production pool. The low-temperature crystallizer Most of the mother liquor flows back to the second vacuum membrane distillation device, and the remaining part of the mother liquor in the low-temperature crystallizer enters the second adsorption device:

The produced water from the first hardness removal device enters the nanofiltration device. The nanofiltration device separates the monovalent salts and divalent salts in the wastewater to obtain produced water and concentrated water. The main component of the nanofiltration produced water is sodium chloride. The nanofiltration product Water enters the first vacuum membrane distillation device. The first vacuum membrane distillation device uses the waste heat of the steel plant to heat the incoming water of the first vacuum membrane distillation device so that the temperature of the incoming water of the first vacuum membrane distillation device is controlled at 50 to 70°C. After heating The incoming water of the first vacuum membrane distillation device is separated to obtain concentrated water and water vapor. The water vapor of the first vacuum membrane distillation device is condensed to obtain product water. The concentrated water of the first vacuum membrane distillation device enters the crystallizer. Sodium chloride crystals are obtained. A part of the mother liquor output from the crystallizer is refluxed to the first vacuum membrane distillation device to continue concentration. The other part of the mother liquor output from the crystallizer enters the second adsorption device. The product water from the first vacuum membrane distillation enters the production pool, and the sodium chloride crystal is obtained. The concentrated water output from the filter device enters the second vacuum membrane distillation device. The second vacuum membrane distillation device also uses the waste heat of the steel plant to heat the inlet water temperature of the second vacuum membrane distillation device at 50-70°C. The output of the nanofiltration device The concentrated water is further concentrated by the second vacuum membrane distillation device and then enters the low-temperature crystallizer to obtain sodium sulfate decahydrate crystals. Most of the mother liquor output from the low-temperature crystallizer flows back to the second vacuum membrane distillation device, and the remaining part of the mother liquor enters the second adsorption device;

S5, remove organic matter and hardness in order. In the second adsorption device, granular activated carbon and macroporous adsorption resin are used to adsorb and remove organic matter in the mother liquor output from the low-temperature crystallizer; the effluent from the second adsorption device enters the second hardness removal device and resin softening is used to remove the effluent from the second adsorption device The hardness of the second hardness removal device enters the bipolar membrane electrodialysis device:

The second adsorption device includes a water inlet tank, a lift pump, an adsorption tank, and a resin tank. The second adsorption device uses granular activated carbon and resin adsorption. The mother liquor output from the low-temperature crystallizer first enters the water inlet tank of the second adsorption device, and uses the lift to Pump it into the adsorption tank. The adsorption tank is filled with granular activated carbon. The effluent from the adsorption tank enters the resin tank. The resin tank is filled with macroporous adsorption resin. The macroporous adsorption resin is a medium polar macroporous adsorption resin that contains ester groups. The adsorption resin uses multifunctional group methacrylate as a cross-linking agent. The surface has both hydrophobic and hydrophilic parts. The organic matter in the mother liquor is adsorbed and removed by the granular activated carbon and resin of the second adsorption device. The resin of the second adsorption device The tank structure is the same as that of the resin tank 71 of the first hard removal device but the type of resin filled is different (the resin tank 71 of the first hard removal device is filled with ion exchange resin, and the second adsorption device is filled with macroporous adsorption resin). Increasing resin Adsorption is to enhance the removal effect. Two-stage adsorption (activated carbon adsorption + resin adsorption) is used to improve the removal effect of organic matter. The bipolar membrane electrodialysis device has higher requirements for the water quality of the incoming water. The concentration of organic matter after step S1 is low, but After being concentrated by the second vacuum membrane distillation device and the low-temperature crystallizer, the organic matter concentration increases, so the organic matter concentration still needs to be further reduced in step S5.

The effluent of the second adsorption device enters the second hardness removal device. The resin tank of the second hardness removal device is filled with a strong acid cation exchange resin. The resin of the second hardness removal device is used to remove the hardness in the effluent of the second adsorption device. , the effluent from the second hardness removal device enters the bipolar membrane electrodialysis device;

S6. The bipolar membrane electrodialysis device prepares a mixed acid of hydrochloric acid and sulfuric acid and a sodium hydroxide solution. The mixed acid is reused in the micro-electrolysis device, part of the sodium hydroxide solution is used to adjust the pH of the neutralization tank 35, part is used in the alkali water tank 52 of the electro-oxidation device to absorb tail gas, and the remaining part is used in the sodium ferrate preparation device. Ferric hydroxide from the flocculation sedimentation tank and sodium hypochlorite from the electro-oxidation unit are used together to prepare the sodium ferrate solution:

In the bipolar membrane electrodialysis device, the sodium ions, sulfate ions and chloride ions in the wastewater are separated by the ion exchange membrane to obtain a mixed acid of hydrochloric acid and sulfuric acid and a sodium hydroxide solution. The mass concentration of the sodium hydroxide solution is 8 to 10 %, the mixed acid is used back for acid adjustment in the micro-electrolysis device, regeneration of the resin inside or outside the system, and membrane cleaning inside or outside the system. Part of the alkali solution is used in the neutralization tank 35 to adjust the pH and the alkali solution of the electro-oxidation device. The water tank 52 absorbs the exhaust gas; the other part is in the sodium ferrate preparation device. The ferric hydroxide is first washed and filtered, and then the sodium ferrate solution is prepared at low temperature using the sodium hydroxide solution, the washed ferric hydroxide and the sodium hypochlorite solution. The obtained Sodium ferrate solution is used in the treatment of coking wastewater or other wastewater and can be used as a strong oxidant and flocculant. The sodium chloride impurity contained in the sodium ferrate solution can be removed by recrystallization, thereby purifying the sodium ferrate solution.

Fe ³⁺ +3OH ^- →Fe(OH) ₃

2Fe(OH) ₃ +3NaClO+4NaOH→2Na ₂ FeO ₄ +3NaCl+5H ₂ O

Example 3

The coking wastewater membrane filtration concentrate of a steel plant in Hubei Province is selected as the treatment object of the present invention, and the above-mentioned Example 2 is implemented. The water quality of the coking wastewater membrane filtration concentrate: pH is 7.0~8.5, SS concentration is 20~70mg/L, conductivity The rate is 15500~18000μs/cm, the COD (chemical oxygen demand) concentration is 480~650mg/L, the TDS (total dissolved solids) concentration is 12800~15500mg/L, the ammonia nitrogen concentration is 35~60mg/L, sulfate The concentration is 5000~7000mg/L, the chloride ion concentration is 3500~5000mg/L, the Ca ²⁺ concentration is 260~280mg/L, and the Mg ²⁺ concentration is 80~100mg/L.

In step S1: after the coking wastewater membrane filtration concentrate is processed by the first adsorption device, the effluent COD is 150-170 mg/L, and the produced water from the first adsorption device enters the micro-electrolysis reactor 10 and the Fenton reactor 26 for processing;

In step S2: the COD of the effluent from the sedimentation tank 37 is 100-120 mg/L. After the effluent from the sedimentation tank 37 is treated by the electro-oxidation device, the COD of the effluent is less than 30 mg/L, and the ammonia nitrogen is less than 0.2 mg/L;

In step S3: the effluent of the electro-oxidation device undergoes chemical precipitation to remove hardness in the first hardness removal device. The hardness of the effluent of the ultrafiltration membrane 65 in the first hardness removal device is less than 20 mg/L. The resin of the first hardness removal device The hardness of the water from tank 71 is less than 5 mg/L,

In step S4: the effluent of the first hardness removal device is processed by the nanofiltration device, the nanofiltration water is concentrated by the first vacuum membrane distillation, and the concentrated water of the first vacuum membrane distillation is crystallized through the crystallizer to obtain sodium chloride. The water produced by membrane distillation enters the production tank for storage, and the water produced in the production tank reaches the reuse water standard; after the nanofiltration concentrated water is processed by the second vacuum membrane distillation device, it is crystallized in a low-temperature crystallizer to obtain sodium sulfate decahydrate.

In step S5: part of the mother liquor discharged from the low-temperature crystallizer flows back to the second vacuum membrane distillation device, and part enters the second adsorption device. The COD of the water effluent from the second adsorption device is less than 10 mg/L, and the effluent from the second adsorption device enters the second adsorption device. Hardness removal device, the outlet water hardness of the second hardness removal device is less than 5mg/L;

In step S6: the effluent from the second hardness removal device enters the bipolar membrane electrodialysis device to finally prepare a mixed acid of sulfuric acid solution and hydrochloric acid solution and a sodium hydroxide solution with a mass concentration of 8 to 10%; sodium ferrate preparation device The ferric hydroxide, sodium hydroxide and sodium hypochlorite produced by the system are used to prepare sodium ferrate solution at low temperature, and the sodium ferrate solution is used in the pretreatment of coking wastewater.

Through this process, the resource utilization rate of the coking wastewater membrane filtration concentrate reaches more than 95%, which reduces the operating cost of the treatment system and basically achieves zero discharge of the concentrate.

Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail, those of ordinary skill in the art will understand that the technical solutions of the present invention can be modified or modified. Equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A coking wastewater membrane filtration concentrate treatment system, including a first adsorption device, characterized in that the water outlet of the first adsorption device is connected to the micro-electrolysis water inlet pipe (11) of the micro-electrolysis device, and the water outlet of the micro-electrolysis device It is connected to the water inlet of the Fenton device, the water outlet of the Fenton device is connected to the water inlet of the neutralization tank (35), the water outlet of the neutralization tank (35) is connected to the water inlet of the flocculation sedimentation tank, and the hydrogen in the flocculation sedimentation tank The iron oxide output port is connected to the sodium ferrate preparation device, the water outlet of the flocculation sedimentation tank is connected to the water inlet of the electro-oxidation device, the sodium hypochlorite outlet of the electro-oxidation device is connected to the sodium ferrate preparation device, and the water outlet of the electro-oxidation device is connected to the first remover. The water inlet of the hard device, the water outlet of the first hard removal device are connected to the water inlet of the nanofiltration device, the nanofiltration water production port of the nanofiltration device is connected to the water inlet of the first vacuum membrane distillation device, and the concentrated water inlet of the first vacuum membrane distillation device is connected. The water outlet is connected to the crystallizer, the mother liquor outlet of the crystallizer is connected to the water inlet of the first vacuum membrane distillation device and the water inlet of the second adsorption device respectively, and the produced water outlet of the first vacuum membrane distillation device is connected to the production pool. The concentrated water port of the filter device is connected to the water inlet of the second vacuum membrane distillation device, the product water outlet of the second vacuum membrane distillation device is connected to the production pool, the concentrated water port of the second vacuum membrane distillation device is connected to the low-temperature crystallizer, and the low-temperature crystallizer The mother liquor outlet of the device is connected to the water inlet of the second vacuum membrane distillation device and the water inlet of the second adsorption device respectively. The water outlet of the second adsorption device is connected to the water inlet of the second hardness removal device. The second hardness removal device The water outlet is connected to the water inlet of the bipolar membrane electrodialysis device, and the alkali liquid outlet of the bipolar membrane electrodialysis device is respectively connected to the alkali liquid dosing pipe of the neutralization tank (35), the alkali liquid input port of the electrooxidation device, and the The alkali solution dosing pipe of the hardware removal device is connected to the sodium ferrate preparation device. The acid outlet of the bipolar membrane electrodialysis device is connected to the acid dosing pipe (12) of the microelectrolysis device. The bipolar membrane electrodialysis device The fresh water outlet is connected to the water inlet of the nanofiltration device. 2. A coking wastewater membrane filtration concentrate treatment system according to claim 1, characterized in that the first adsorption device includes a first adsorption device water inlet tank (1), and the first adsorption device water inlet tank (1) ) is used as the water inlet of the first adsorption device. The water inlet tank (1) of the first adsorption device is connected to the first pool of the adsorption reaction pool (4) through the water inlet pump (2). The third pool of the adsorption reaction pool (4) The bottom of the first pool and the bottom of the second pool of the adsorption reaction pool (4) are connected through a flow passage. The bottoms of the first pool and the second pool of the adsorption reaction pool (4) are both equipped with aeration pipes, and the inlets of the aeration pipes are connected. The first blower (3) and the second pool of the adsorption reaction pool (4) are connected to the water inlet of the filtering device (5) through the first lifting pump (7). The concentrated water port of the filtering device (5) is connected to the adsorption reaction pool (4). ), the water production port of the filtering device (5) is connected to the first water production tank (6), the drainage port of the filtering device (5) is connected to the external sludge dehydrator, and the water outlet of the first water production tank (6) is The water outlet of the first adsorption device. 3. A coking wastewater membrane filtration concentrate treatment system according to claim 2, characterized in that the micro-electrolysis device includes a pipeline mixer (13), and one inlet of the pipeline mixer (13) is connected to a micro-electrolysis water inlet pipe. The outlet of (11), the other inlet of the pipe mixer (13) is connected to the acid dosing pipe (12), the outlet of the pipe mixer (13) is connected to the inlet of the micro-electrolysis reactor water inlet pipe (14), the micro-electrolysis reactor The outlet of the water inlet pipe (14) extends to the lower part of the micro-electrolysis reactor (10). Multiple filler support layers (23) are provided in the micro-electrolysis reactor (10), and block fillers are provided on the filler support layers (23). A micro-electrolysis reactor aeration pipe (19) is provided below each filler support layer (23). A first baffle (20) is provided at the bottom of the micro-electrolysis reactor (10). The first baffle (20) is located at the bottom of the micro-electrolysis reactor (10). Directly below the outlet of the water inlet pipe (14) of the electrolysis reactor, a micro-electrolysis reactor access port (18) is provided on the side wall of the micro-electrolysis reactor (10) corresponding to each filler support layer (23). The uppermost filler support layer A first separator (15) is provided above the first separator (15), and a first overflow weir (16) is provided above the first separator (15). The first overflow weir (16) is located in the micro-electrolysis reactor (10) In the upper inner part, the first overflow weir (16) is connected to the micro-electrolysis reactor water outlet pipe (24), and the water outlet of the micro-electrolysis reactor water outlet pipe (24) serves as the water outlet of the micro-electrolysis device. 4. A coking wastewater membrane filtration concentrate treatment system according to claim 3, characterized in that the Fenton device includes a Fenton reactor water inlet pipe (25), and a Fenton reactor water inlet pipe (25) water inlet As the water inlet of the Fenton reaction device is connected to the water outlet of the microelectrolysis reactor water outlet pipe (24), the water outlet of the Fenton reactor water inlet pipe (25) extends to the lower part of the Fenton reactor (26), and the Fenton reactor (26) 26) An aeration pipe and a second baffle (31) are provided at the bottom. The second baffle (31) is located directly below the outlet of the Fenton reactor water inlet pipe (25), and the second overflow weir (27) is located at the Fenton reactor. In the upper part of the reactor (26), the second separator (32) is located below the second overflow weir (27). The second overflow weir (27) is connected to the inlet of the Fenton reactor outlet pipe (33). Fenton The outlet of the reactor water pipe (33) is the water outlet of the Fenton device, and the bottom of the Fenton reactor (26) is connected to a dosing pipe for the hydrogen peroxide solution. 5. A coking wastewater membrane filtration concentrate treatment system according to claim 4, characterized in that the neutralization tank (35) is connected to the outlet of the Fenton reactor outlet pipe (33), and the neutralization tank (35) An aeration pipe is arranged at the bottom, and the aeration pipe of the neutralization tank (35) is connected to the second blower (34). The bottom of the neutralization tank (35) and the bottom of the flocculation tank (36) are connected through a flow passage, and the flow passage serves as a neutralizer. The water outlet of the pool (35) and the water inlet of the flocculation sedimentation tank; The flocculation and sedimentation tank includes a flocculation tank (36). The flocculation tank (36) is equipped with a flocculation tank mixer (39). The flocculation tank (36) is connected to a flocculant dosing pipe, and has an overflow port and a sedimentation tank at the upper part of the flocculation tank (36). The inlet of the water inlet pipe of the pond (37) is connected, and the outlet of the water inlet pipe of the sedimentation tank (37) extends to the middle of the sedimentation tank (37). A sedimentation tank mud bucket is provided at the bottom of the sedimentation tank (37), and the sedimentation tank mud bucket is located in the sedimentation tank. Below the outlet of the water inlet pipe of (37), the mud hopper of the sedimentation tank is connected to the inlet of the mud pump (38). The outlet of the mud pump (38) serves as the iron hydroxide output port of the flocculation sedimentation tank. The upper part is provided with a sedimentation tank water outlet (40), and the sedimentation tank water outlet (40) serves as the water outlet of the flocculation sedimentation tank. 6. A coking wastewater membrane filtration concentrate treatment system according to claim 5, characterized in that the electro-oxidation device includes an electro-oxidation water inlet tank (41), and the water inlet of the electro-oxidation water inlet tank (41) serves as The water inlet of the electro-oxidation device, the top of the electro-oxidation water inlet tank (41) is closed, an aeration pipe is set at the bottom of the electro-oxidation water inlet tank (41), and the aeration pipe of the electro-oxidation water inlet tank (41) is connected to the third blower ( 42), the inlet of the second exhaust fan (50) is connected to the space above the liquid level in the electro-oxidation water inlet tank (41), and the outlet of the second exhaust fan (50) is connected to the air inlet of the absorption tower (51) , the inlet of the electro-oxidation water inlet pump (43) is connected to the water outlet of the electro-oxidation water inlet tank (41), the outlet of the electro-oxidation water inlet pump (43) is connected to the inlet of the filter (44), and the outlet of the filter (44) is connected to the electrolyzer The inlet of the tank (45) and the air outlet of the electrolytic tank (45) are connected to the electrooxidation water inlet tank (41) through the electrolytic tank exhaust pipe (47), and the air outlet of the electrolytic tank exhaust pipe (47) is located in the electrooxidation water inlet tank. (41) below the liquid surface, the water outlet of the electrolyzer (45) is connected to the electro-oxidation water production tank (48), the top of the electro-oxidation water production tank (48) is closed, and the inlet of the first exhaust fan (49) is connected to the electric oxidation water production tank (48). In the space above the liquid level in the oxidation water production tank (48), the outlet of the first exhaust fan (49) is connected to the air inlet of the absorption tower (51), and the bottom of the absorption tower (51) is connected to the alkali liquid tank (52). (52) multiple groups are provided. When the alkali liquid water tank (52) is empty, the entrance of the alkali liquid water tank (52) serves as the alkali liquid input port of the electro-oxidation device. When the alkali liquid water tank (52) is filled with sodium hydroxide solution The inlet of the alkali liquid water tank (52) is disconnected from the alkali liquid output port of the bipolar membrane electrodialysis device, and the outlet of the alkali liquid water tank (52) is connected to the inlet of the spray pump (53), and the outlet of the spray pump (53) Connect the upper water inlet of the absorption tower (51), and the inlet of the alkali liquid water tank (52) is connected with the water outlet of the absorption tower (51). When the concentration of the sodium hypochlorite solution in the alkali liquid water tank (52) reaches the set value, the alkali liquid water tank (52) ) is the sodium hypochlorite water outlet of the electro-oxidation device, and the water outlet of the electro-oxidation water production tank (48) is used as the water outlet of the electro-oxidation device. 7. A coking wastewater membrane filtration concentrate treatment system according to claim 6, characterized in that the first hardness removal device includes a first reaction tank (61) connected in sequence, and the bottom of the first reaction tank (61) It is connected to the bottom of the second reaction tank (62) through a flow channel, the upper part of the second reaction tank (62) and the upper part of the third reaction tank (63) are connected through an overflow channel, and the first reaction tank (61) is equipped with a first mixer. (66), the second reaction tank (62) is equipped with a second mixer (67), the third reaction tank (63) is equipped with a third mixer (68), and the water inlet of the first reaction tank (61) serves as the first hardness removal device. The water inlet, the first reaction tank (61) is provided with an alkali solution dosing pipe and the alkali solution dosing pipe of the first reaction tank (61) serves as the alkali solution dosing pipe of the first hard removal device, the second reaction tank (62 ) is connected to the sodium carbonate dosing pipe, the third reaction tank (63) is connected to the inlet of the ultrafiltration membrane (65) through the ultrafiltration water inlet pump (64), and the concentrated water outlet of the ultrafiltration membrane (65) is connected to the third reaction tank (63), The water production port of the ultrafiltration membrane (65) is connected to the second water production tank (69), and the second water production tank (69) is connected to the resin tank (71) of the first hardness removal device through the second lifting pump (70). The first hardness removal device resin The tank (71) is filled with strong acidic cation exchange resin, and the outlet of the resin tank (71) of the first hardness removal device serves as the water outlet of the first hardness removal device. 8. A coking wastewater membrane filtration concentrate treatment method, utilizing a coking wastewater membrane filtration concentrate treatment system according to claim 7, the characteristic steps of which include: S1. First, remove most of the organic pollutants in the membrane filtration concentrate of coked wastewater through activated carbon in the first adsorption device; the effluent from the first adsorption device enters the micro-electrolysis device, and acid solution is added to adjust the pH of the incoming water of the micro-electrolysis device to 2~ 3. While further removing organic pollutants and color in wastewater, ferrous ions are generated. The produced water from the micro-electrolysis device enters the Fenton device. The Fenton device uses ferrous ions and hydrogen peroxide to further oxidize and remove organic pollutants and organic pollutants in the wastewater. Chroma, while producing ferric ions; S2. The effluent from the Fenton device enters the neutralization tank (35), uses alkali solution to adjust the pH in the neutralization tank (35) to 7-8, adds flocculant to the flocculation tank (36), and then adds the flocculant to the sedimentation tank (37). Precipitation is carried out in the sedimentation tank (37), the water effluent from the sedimentation tank (37) enters the electro-oxidation device, and the iron hydroxide precipitate in the sedimentation tank (37) enters the sodium ferrate preparation device; S3. The electro-oxidation device removes ammonia nitrogen, COD and chroma from wastewater, and uses alkali solution to produce sodium hypochlorite solution. The sodium hypochlorite solution enters the sodium ferrate preparation device, and the electro-oxidation produced water enters the first hardness removal device; the first hardness removal device adopts Chemical precipitation and resin softening remove the hardness in the wastewater, and the effluent after the hardness removal enters the nanofiltration device; S4. The produced water from the first hardness removal device is passed through the nanofiltration device to obtain nanofiltration produced water whose main component is sodium chloride. The nanofiltrated produced water enters the first vacuum membrane distillation device, and the concentrated water from the first vacuum membrane distillation device enters The crystallizer obtains sodium chloride crystals. A part of the mother liquor output from the crystallizer flows back to the first vacuum membrane distillation device. The other part of the mother liquor output from the crystallizer enters the second adsorption device. The product water from the first vacuum membrane distillation device enters the production pool, and the sodium chloride is collected. After the filtered concentrated water enters the second vacuum membrane distillation device and is further concentrated, the concentrated water from the second vacuum membrane distillation device enters the low-temperature crystallizer to obtain sodium sulfate decahydrate crystals. The product water from the second vacuum membrane distillation device enters the production pool for low-temperature crystallization. Most of the mother liquor from the low-temperature crystallizer flows back to the second vacuum membrane distillation device, and the remaining part of the mother liquor from the low-temperature crystallizer enters the second adsorption device; S5. In the second adsorption device, granular activated carbon and macroporous adsorption resin are used to adsorb and remove organic matter in the mother liquor output from the low-temperature crystallizer. The effluent from the second adsorption device enters the second hardness removal device and uses resin softening to remove the hardness in the wastewater. The second The effluent from the hardness removal device enters the bipolar membrane electrodialysis device; S6. The bipolar membrane electrodialysis device produces a mixed acid of hydrochloric acid and sulfuric acid and a sodium hydroxide solution. The mixed acid is reused in the microelectrolysis device. Part of the sodium hydroxide solution is used in the neutralization tank (35) to adjust the pH, and part of it is used in the neutralization tank (35) to adjust the pH. The alkali water tank (52) of the electro-oxidation device absorbs the tail gas, and the remaining part is used in the sodium ferrate preparation device to prepare sodium ferrate solution with ferric hydroxide from the flocculation sedimentation tank and sodium hypochlorite from the electro-oxidation device. 9. A kind of coking wastewater membrane filtration concentrate treatment method according to claim 7, characterized in that: in the step S3, the alkali liquid water tank (52) is provided with multiple groups. When the mass concentration of the sodium hypochlorite solution reaches the set concentration concentration Then switch to the next group of alkali water tanks (52), and then transport it to the sodium ferrate preparation device through a lifting pump; the mass concentration of the sodium hydroxide solution prepared by bipolar membrane electrodialysis in step S6 is 8 to 10%, and the mixed acid It is used for pH adjustment of micro-electrolysis devices, regeneration of resin inside or outside the system, and membrane cleaning inside or outside the system. 10. A method for treating coking wastewater membrane filtration concentrate according to claim 7, characterized in that: the heat source of the first vacuum membrane distillation device and the second vacuum membrane distillation device in step S4 adopts the waste heat of the steel plant, Keep the wastewater operating temperature at 50 to 70°C.