MVR concentrated solution treatment device

Abstract

The utility model discloses an MVR (mechanical vapor recompression) concentrated solution treatment device, which belongs to the field of wastewater treatment and comprises a first coagulating sedimentation device, a second persulfate advanced oxidation device, a second persulfate adding device for adding persulfate into the second persulfate adding device, a third biochemical treatment device, a fourth membrane treatment component and a fifth clear water tank. Wherein the MVR concentrated solution to be treated can be fed into the first coagulating sedimentation device. The first coagulating agent adding device is connected with the first coagulating sedimentation device, and the first coagulating agent adding device is used for adding a coagulating agent into the first coagulating sedimentation device, so that the MVR concentrated solution is flocculated and settled, and first coagulated sludge and first coagulated supernate are respectively obtained. The method can be suitable for MVR concentrated solution treatment scenes with different scales and treatment requirements, the wastewater treatment efficiency is improved, the treatment cost is reduced, efficient and stable treatment of wastewater can be achieved, and the method has high application value and wide popularization and application value.

Description

Technical Field

[0001] The utility model relates to the field of wastewater treatment, in particular to the field of MVR concentrated liquid treatment, and specifically to an MVR concentrated liquid treatment device. More specifically, the application provides a device for treating MVR concentrated liquid based on persulfate advanced oxidation, which can effectively improve the treatment effect and reduce the treatment cost. Background Art

[0002] In industrial production, a large amount of wastewater with extremely high salt content and COD is generated. MVR evaporation technology is often used in the treatment of such wastewater. MVR concentration technology is an evaporation concentration method widely used in the fields of chemical industry and environmental engineering. MVR concentrate is usually a by-product discharged from an evaporator or other concentration equipment, which contains a large amount of difficult-to-degrade organic matter, heavy metals and other pollutants, such as naphthalene, phenol, benzene, styrene, etc. In the MVR evaporation process, COD enrichment will inevitably occur. If the high COD concentrate formed after enrichment is not treated, it will seriously affect the evaporation efficiency.

[0003] At present, most MVR concentrates are either processed by outsourcing, or burned by diesel injection, or processed by deep concentration evaporators. However, there are great disadvantages in using diesel injection to burn MVR concentrates, as follows:

[0004] (1) Combustion consumes a lot of energy

[0005] During the evaporation process of MVR, 90% of the water will evaporate, and the remaining is the concentrate; for example, if 100 tons of water are processed every day, the remaining concentrate will reach 10 tons. Burning ten tons of organic matter (including a large amount of water) will consume a lot of diesel;

[0006] (2) Possibility of secondary pollution

[0007] After combustion, waste gas and a large amount of dioxins will be produced, requiring an additional waste gas treatment system, which will not only increase the owner's investment costs, but also add a new source of pollution.

[0008] At present, there are some similar waste liquid treatment technologies on the market, including Fenton technology and other Fenton-like advanced oxidation technologies, which mainly use Fenton reagents (usually a combination of hydrogen peroxide and iron salts) to trigger free radical reactions to degrade organic pollutants. When treating MVR concentrate, Fenton technology may cause metal precipitation, resulting in additional pollutants in the treated wastewater. At the same time, during the reaction, the pH value of the wastewater needs to be adjusted, which increases the complexity of the operation. The acidic conditions during the reaction and the subsequent alkali addition stage to adjust the pH will cause corrosion to the reactor, requiring the use of a reactor made of corrosion-resistant materials, which increases equipment costs and maintenance difficulties. In addition, the use of hydrogen peroxide and iron salts as reagents is relatively expensive.

[0009] For this reason, a new device is urgently needed to solve the above problems. Utility Model Content

[0010] One of the purposes of the present invention is to provide an MVR concentrated liquid processing device, comprising:

[0011] A first coagulation and sedimentation device connected to the MVR concentrate to be treated;

[0012] A first coagulant adding device, which is connected to the first coagulation sedimentation device and can add coagulant to the first coagulation sedimentation device to cause flocculation and sedimentation of the MVR concentrated liquid and obtain a first coagulation sludge and a first coagulation supernatant respectively;

[0013] A second persulfate adding device, which is connected to the second persulfate advanced oxidation device and can add persulfate into the second persulfate adding device;

[0014] A second persulfate advanced oxidation device is connected to the first coagulant adding device, and the first coagulation supernatant produced by the MVR concentrate can enter the second persulfate advanced oxidation device and undergo an advanced oxidation reaction under the action of persulfate to obtain a second oxidized fluid;

[0015] A third biochemical treatment device is connected to the second persulfate advanced oxidation device, and the second oxidized fluid in the second persulfate advanced oxidation device can enter the third biochemical treatment device for biochemical treatment and obtain a third biochemical fluid;

[0016] a fourth membrane treatment component, which is connected to the third biochemical treatment device and the third biochemical fluid in the third biochemical treatment device can enter the fourth membrane treatment component, and is used to perform ultrafiltration reverse osmosis treatment on the third biochemical fluid, and obtain fourth fresh water and fourth reverse osmosis liquid respectively;

[0017] The fifth clean water tank is connected to the fourth membrane treatment assembly and the fourth fresh water treated by the fourth membrane treatment assembly can enter the fifth clean water tank for storage.

[0018] It also includes a sludge dewatering device, which is connected to the first coagulation and sedimentation device, and the first coagulation sludge in the first coagulation and sedimentation device can enter the sludge dewatering device for dehydration treatment to obtain first dewatered sludge.

[0019] It also includes a first sludge storage device, the sludge dewatering device is connected to the first sludge storage device, and the first dewatered sludge in the sludge dewatering device can enter the first sludge storage device for storage.

[0020] The first coagulant adding device is a PAC and PAM adding device and the first coagulant adding device can add PAC and PAM into the first coagulation and sedimentation device.

[0021] It also includes a first solid-liquid separation device, the first coagulation and sedimentation device is connected to the first solid-liquid separation device, and the liquid in the first coagulation and sedimentation device can be separated into solid and liquid by the first solid-liquid separation device to obtain a first coagulated sludge and a first coagulated supernatant respectively, the first solid-liquid separation device is connected to the second persulfate advanced oxidation device, and the first coagulation supernatant separated by the first solid-liquid separation device can enter the second persulfate advanced oxidation device.

[0022] The persulfate added by the second persulfate adding device is sodium persulfate or potassium persulfate.

[0023] The third biochemical treatment device is an AO biochemical treatment device.

[0024] The AO biochemical treatment device contains biochemical sludge.

[0025] The fourth membrane treatment component includes a fourth MBR membrane reactor and a fourth RO membrane reactor. The third biochemical treatment device is connected to the fourth MBR membrane reactor and the third biochemical fluid can be filtered through the fourth MBR membrane reactor to obtain a fourth MBR filtrate. The fourth MBR membrane reactor is connected to the fourth RO membrane reactor and the fourth MBR filtrate treated by the fourth MBR membrane reactor can enter the fourth RO membrane reactor for reverse osmosis treatment to obtain fourth fresh water and fourth reverse osmosis liquid, respectively.

[0026] In summary, the present application provides an MVR concentrate treatment device, which is a device for treating MVR concentrate based on persulfate advanced oxidation technology, and is intended to solve the problems of poor treatment effect and high treatment cost of MVR concentrate in the prior art. The device mainly includes four parts: a first coagulation and sedimentation device, a second persulfate advanced oxidation device, a third biochemical treatment device, and a fourth membrane treatment component, and through the coordinated work of each part, efficient and environmentally friendly treatment of MVR concentrate is achieved. The device of the present application can achieve efficient and environmentally friendly treatment of MVR concentrate, reduce treatment costs, and improve effluent water quality through the organic combination of coagulation and sedimentation, persulfate advanced oxidation and membrane treatment devices, providing a new and effective solution for the field of industrial wastewater treatment.

[0027] Compared with the existing advanced oxidation treatment, especially Fenton treatment, the second persulfate advanced oxidation device used in this application has the following advantages:

[0028] (1) Fenton treatment usually operates under relatively low pH conditions (usually pH value is about 3), which requires acidification of wastewater, increasing treatment cost and complexity; the present application adopts persulfate advanced oxidation, which has a wider pH application range; specifically, the device can operate effectively in a wider pH range, and can even exert good oxidation effect under neutral or alkaline conditions, which greatly reduces the acid-base adjustment cost in the treatment process and improves the treatment efficiency;

[0029] (2) The second persulfate advanced oxidation device of the present application has a higher oxidation capacity and a stronger organic matter removal effect; persulfate, as a free radical with extremely strong oxidation ability, can produce sulfate radicals (SO4·-), whose oxidation potential is higher than that of hydroxyl radicals (·OH), and can more effectively oxidize and decompose the difficult-to-degrade organic matter in the wastewater; compared with Fenton oxidation treatment, the present application can more thoroughly remove organic matter in the MVR concentrate and reduce the chemical oxygen demand (COD) and biological oxygen demand (BOD) in the effluent;

[0030] (3) Compared with Fenton advanced oxidation, etc., the sulfate radicals generated in the second persulfate advanced oxidation device used in the present application have higher reactivity and can react with organic matter more quickly, thereby achieving rapid degradation, making the advanced oxidation treatment process faster and the treatment time shorter, and also reducing the residence time of wastewater in the treatment facility, thereby improving the turnover rate of the treatment facility.

[0031] In this application, the second persulfate advanced oxidation device is the core treatment device, which cooperates with the first coagulation and sedimentation device, the third biochemical treatment device, and the fourth membrane treatment component to form a complete wastewater treatment system. The first coagulation and sedimentation device can remove suspended matter and colloidal substances in the wastewater, providing more favorable conditions for subsequent advanced oxidation and biochemical treatment; the third biochemical treatment device can utilize the metabolism of microorganisms to further degrade organic matter and reduce the burden of the fourth membrane treatment component; the fourth membrane treatment component can deeply purify the wastewater and realize the reuse of the wastewater.

[0032] Due to the adoption of the above scheme, this application has the following beneficial effects:

[0033] (1) In the present application, a first coagulation and sedimentation device is provided, which effectively removes suspended matter and colloidal particles in the MVR concentrate by coagulation and sedimentation, thereby creating good conditions for subsequent advanced oxidation treatment; at the same time, a second persulfate advanced oxidation device is provided in the device, which can achieve deep treatment of refractory organic matter and improve treatment efficiency;

[0034] (2) The device of the present application can effectively reduce the consumption of medicines and the use of energy, thereby reducing the processing cost;

[0035] (3) The device of the present application is provided with a fourth membrane treatment component, which can achieve fine filtration and separation, further remove impurities such as tiny particles, soluble organic matter and inorganic salts in the concentrate, improve the effluent quality, and ensure that the discharge meets environmental protection standards;

[0036] (4) Compared with the Fenton oxidation treatment in the prior art, the second persulfate advanced oxidation device of the present application has a wider pH application range, higher oxidation capacity, stronger organic matter removal effect, faster reaction rate, and shorter treatment time;

[0037] (5) The device of the present application is reasonably conceived and easy to operate. It can be applied to MVR concentrate treatment scenarios of different scales and treatment requirements, and has high application value and wide promotion and application value;

[0038] (6) Based on the synergistic effect of various parts, this application not only improves the treatment efficiency, but also reduces the treatment cost, and can also achieve efficient and stable treatment of wastewater;

[0039] (7) The device of the present application can achieve efficient and stable processing of MVR concentrate, providing a new and effective means for processing MVR concentrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the device in Example 1.

[0041] Markings in the figure: 1. The first coagulation and sedimentation device, 2. The second persulfate advanced oxidation device, 3. The third biochemical treatment device, 4. The fourth membrane treatment component, 5. The fifth clean water tank. DETAILED DESCRIPTION

[0042] The utility model is described in detail below in conjunction with the accompanying drawings.

[0043] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0044] Example 1

[0045] As mentioned above, in the prior art, the MVR concentrate is mainly treated by Fenton technology and other Fenton-like advanced oxidation technologies, which have corresponding defects. In contrast, the persulfate advanced oxidation technology has the advantages of higher efficiency, lower chemical reagent cost, more flexible operating conditions, etc.

[0046] For the purpose of this application, MVR concentrates usually contain organic pollutants, which may be difficult to degrade. Persulfate advanced oxidation technology can effectively degrade complex organic pollutants and improve the treatment efficiency of wastewater by producing highly active oxygen free radicals. Compared with some traditional chemical treatment methods, persulfate advanced oxidation technology reduces the need for additional chemical reagents during wastewater treatment, which helps to reduce operating costs and reduce the generation of secondary waste. In addition, compared with the metal precipitation that may be caused by some advanced oxidation technologies, persulfate advanced oxidation technology is more inclined to reduce the problem of metal precipitation and improve the quality of treated wastewater.

[0047] By utilizing the strong oxidizing properties of persulfate, the concentration of organic pollutants in MVR concentrate can be efficiently degraded, metal precipitation can be reduced, and the complexity and cost of wastewater treatment can be reduced. However, the use of persulfate advanced oxidation technology alone is often costly, and the treatment effect may be affected by a variety of factors, which has certain limitations.

[0048] To this end, this embodiment provides an MVR concentrated liquid treatment device, which includes a first coagulation and sedimentation device, a second persulfate advanced oxidation device, a second persulfate adding device for adding persulfate to the second persulfate adding device, a third biochemical treatment device, a fourth membrane treatment component, and a fifth clean water tank. The MVR concentrated liquid to be treated can be sent to the first coagulation and sedimentation device. The first coagulant adding device is connected to the first coagulation and sedimentation device, and the first coagulant adding device is used to add a coagulant to the first coagulation and sedimentation device to cause flocculation and precipitation of the MVR concentrated liquid, and obtain a first coagulated sludge and a first coagulated supernatant respectively.

[0049] The first coagulation and sedimentation device is connected to the second persulfate advanced oxidation device, and the second persulfate addition device is connected to the second persulfate advanced oxidation device. The first coagulation supernatant produced by the MVR concentrate enters the second persulfate advanced oxidation device, and under the action of persulfate, an advanced oxidation reaction occurs, and a second oxidized fluid is obtained. The second persulfate advanced oxidation device is connected to the third biochemical treatment device, and the second oxidized fluid in the second persulfate advanced oxidation device can enter the third biochemical treatment device for biochemical treatment, and obtain a third biochemical fluid. The third biochemical treatment device is connected to the fourth membrane treatment component, and the third biochemical fluid in the third biochemical treatment device can enter the fourth membrane treatment component, which is used to perform ultrafiltration reverse osmosis treatment on the third biochemical fluid, and obtain fourth fresh water and fourth reverse osmosis liquid respectively. The fourth membrane treatment component is connected to the fifth clean water tank, and the fourth fresh water treated by the fourth membrane treatment component can enter the fifth clean water tank for storage, which can be discharged or reused.

[0050] Furthermore, it also includes a first solid-liquid separation device, the first coagulation and sedimentation device is connected to the first solid-liquid separation device, and the liquid in the first coagulation and sedimentation device can be separated into solid and liquid by the first solid-liquid separation device, and a first coagulation sludge and a first coagulation supernatant are obtained respectively; the first solid-liquid separation device is connected to the second persulfate advanced oxidation device, and the first coagulation supernatant separated by the first solid-liquid separation device can enter the second persulfate advanced oxidation device.

[0051] Furthermore, the first coagulant adding device is a PAC and PAM adding device, which is used to add PAC and PAM into the first coagulation and sedimentation device; the persulfate added by the second persulfate adding device is one or more of sodium persulfate and potassium persulfate; the third biochemical treatment device uses an AO biochemical treatment device, and the AO biochemical treatment device contains biochemical sludge. Preferably, the fourth membrane treatment component includes a fourth MBR membrane reactor and a fourth RO membrane reactor, the third biochemical treatment device is connected to the fourth MBR membrane reactor, and the fourth MBR membrane reactor is connected to the fourth RO membrane reactor. In this structure,

[0052] The third biochemical fluid is filtered through the fourth MBR membrane reactor to obtain a fourth MBR filtrate; the fourth MBR filtrate treated by the fourth MBR membrane reactor enters the fourth RO membrane reactor for reverse osmosis treatment to obtain fourth fresh water and fourth reverse osmosis liquid, respectively.

[0053] Furthermore, it also includes a sludge dewatering device and a first sludge storage device, wherein the sludge dewatering device is connected to the first coagulation and sedimentation device, and the sludge dewatering device is connected to the first sludge storage device. In this structure, the first coagulated sludge in the first coagulation and sedimentation device enters the sludge dewatering device, undergoes dehydration treatment, and obtains the first dewatered sludge; the first dewatered sludge in the sludge dewatering device enters the first sludge storage device for storage.

[0054] The processing flow of MVR concentrate is as follows.

[0055] (1) Coagulation and sedimentation

[0056] The MVR concentrate is first pre-treated by the first coagulation and sedimentation device, and the pH value is adjusted, and coagulants such as polyaluminium chloride and polyacrylamide are added to cause the suspended matter and colloidal particles in the MVR concentrate to condense and precipitate. The coagulated concentrate is separated into solid and liquid by the first solid-liquid separation device to remove most of the suspended matter and colloidal particles, creating good conditions for subsequent treatment. The coagulation and sedimentation process can not only reduce the turbidity of the wastewater, but also reduce COD. At the same time, the first coagulation sludge produced is discharged, and the first coagulation supernatant is sent to the second persulfate advanced oxidation device.

[0057] (2) Advanced oxidation

[0058] The first coagulation supernatant after coagulation and sedimentation treatment enters the second persulfate advanced oxidation device. The present application adds persulfate (such as sodium persulfate, potassium persulfate, etc.) as an oxidant, utilizes the strong oxidizing property of persulfate to oxidize and decompose the refractory organic matter in the concentrated solution, and obtains the second oxidized fluid.

[0059] (3) Biochemical treatment

[0060] In the second persulfate advanced oxidation device, the high molecular organic matter in the wastewater is decomposed into small molecular organic matter after persulfate oxidation treatment. Then, it flows into the third biochemical treatment device, which uses an AO biochemical treatment device (including an anaerobic tank and an aerobic tank). The anaerobic tank is used for further hydrolysis and acidification of organic matter, and the aerobic tank is used for further oxidation and degradation of organic matter. Through the action of microorganisms, it further removes organic matter in the concentrated liquid and obtains the third biochemical fluid.

[0061] (4) Membrane treatment

[0062] The third biochemical fluid treated by the third biochemical treatment device is sent to the fourth membrane treatment component. In the present application, the fourth membrane treatment component includes a fourth MBR membrane reactor and a fourth RO membrane reactor; it can further remove impurities such as tiny particles, soluble organic matter and inorganic salts in the concentrated liquid to improve the effluent water quality.

[0063] The device of the present application is used in a wastewater station of an oil and gas field in Sichuan. The COD, salinity and turbidity of the concentrate raw water produced by the MVR process of the wastewater station are extremely high. The specific water quality components are shown in Table 1 below.

[0064] Table 1 Water quality of raw water from MVR concentrate in an oil and gas field

[0065]

[0066]

[0067] In the first coagulation and sedimentation device, PAC and PAM are added through the first coagulant adding device to remove suspended solids in the concentrate. Among them, the PAM addition concentration is 10 mg / L, and the PAC addition concentration is 1000 mg / L. After the MVR concentrate to be treated is treated by the first coagulation and sedimentation device, the turbidity of the water body is significantly reduced, and the COD and SS are reduced by 24% and 93% respectively.

[0068] Table 2 Water quality of MVR concentrate from an oil and gas field after treatment by the first coagulation and sedimentation device

[0069] parameter pH Conductivity ms / cm COD mg / L SS mg / L Numeric 8.7 131 12752 420

[0070] The concentrated liquid treated by the first coagulation and sedimentation device enters the second persulfate advanced oxidation device for advanced oxidation. In a certain oil and gas field MVR waste liquid treatment system, by adding sodium persulfate as an oxidant for advanced oxidation reaction, the pH value of the water body is between 7-9 and the hydraulic retention time is 3-4 hours.

[0071] When the first coagulation supernatant enters the second persulfate advanced oxidation device, the water color quickly fades within the first hour, and after 4 hours, there is no obvious change in the water color in the second persulfate advanced oxidation device. After sodium sulfate advanced oxidation treatment, the water quality is shown in Table 3. In the second persulfate advanced oxidation device, COD in the water is removed in large quantities, with a removal rate of up to 97%; because most of the high molecular organic matter and difficult-to-degrade organic matter in the water are oxidized into small molecules and easily degradable organic matter, the turbidity of the water increases slightly, but it also provides favorable conditions for the next step of biochemical degradation.

[0072] Table 3 Water quality of MVR concentrate after advanced oxidation in an oil and gas field

[0073]

[0074] In this oil and gas field wastewater treatment project, the third biochemical treatment device uses an AO (anaerobic-aerobic) device. The small molecular organic matter in the water body after advanced oxidation treatment is further hydrolyzed and acidified, and then flows through the aerobic pool in the third biochemical treatment device to further oxidize and degrade the organic matter. In this oil and gas field wastewater treatment project, the water body after biochemical treatment is deeply filtered by combining MBR and RO; after the water body is treated by MBR, COD is reduced to 60mg / L, and ammonia nitrogen is reduced to 12mg / L. The effluent water quality meets the requirements of the Class III surface water standard of the "Surface Water Environmental Quality Standard" (GB3838-2002) and the standard limit of the centralized drinking water surface water source supplementary project in Table 2.

[0075] After the device of the present application was actually applied in a wastewater station of an oil and gas field in Sichuan, the COD removal rate of the MVR concentrate produced by the wastewater station was greater than 95%, and the stability of the effluent was tested through continuous operation; the test results show that the effluent quality of the device is stable, meeting the surface water Class III standard of the "Surface Water Environmental Quality Standard" (GB3838-2002) and the standard limit requirements of the supplementary items of centralized drinking water surface water sources in Table 2.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An MVR concentrated liquid treatment device, characterized in that: include: A first coagulation and sedimentation device connected to the MVR concentrate to be treated; A first coagulant adding device, which is connected to the first coagulation sedimentation device and can add coagulant to the first coagulation sedimentation device to cause flocculation and sedimentation of the MVR concentrated liquid and obtain a first coagulation sludge and a first coagulation supernatant respectively; A second persulfate adding device, which is connected to the second persulfate advanced oxidation device and can add persulfate into the second persulfate adding device; A second persulfate advanced oxidation device is connected to the first coagulant adding device, and the first coagulation supernatant produced by the MVR concentrate can enter the second persulfate advanced oxidation device and undergo an advanced oxidation reaction under the action of persulfate to obtain a second oxidized fluid; A third biochemical treatment device is connected to the second persulfate advanced oxidation device, and the second oxidized fluid in the second persulfate advanced oxidation device can enter the third biochemical treatment device for biochemical treatment and obtain a third biochemical fluid; a fourth membrane treatment component, which is connected to the third biochemical treatment device and the third biochemical fluid in the third biochemical treatment device can enter the fourth membrane treatment component, and is used to perform ultrafiltration reverse osmosis treatment on the third biochemical fluid, and obtain fourth fresh water and fourth reverse osmosis liquid respectively; The fifth clean water tank is connected to the fourth membrane treatment assembly and the fourth fresh water treated by the fourth membrane treatment assembly can enter the fifth clean water tank for storage.

2. The device according to claim 1, characterized in that: It also includes a sludge dewatering device, which is connected to the first coagulation and sedimentation device, and the first coagulation sludge in the first coagulation and sedimentation device can enter the sludge dewatering device for dehydration treatment to obtain first dewatered sludge.

3. The device according to claim 2, characterized in that: It also includes a first sludge storage device, the sludge dewatering device is connected to the first sludge storage device, and the first dewatered sludge in the sludge dewatering device can enter the first sludge storage device for storage.

4. The device according to claim 1, characterized in that: It also includes a first solid-liquid separation device, the first coagulation and sedimentation device is connected to the first solid-liquid separation device, and the liquid in the first coagulation and sedimentation device can be separated into solid and liquid by the first solid-liquid separation device to obtain a first coagulated sludge and a first coagulated supernatant respectively, the first solid-liquid separation device is connected to the second persulfate advanced oxidation device, and the first coagulation supernatant separated by the first solid-liquid separation device can enter the second persulfate advanced oxidation device.

5. The device according to claim 1, characterized in that: The third biochemical treatment device is an AO biochemical treatment device.

6. The device according to claim 5, characterized in that: The AO biochemical treatment device contains biochemical sludge.

7. The device according to any one of claims 1 to 6, characterized in that: The fourth membrane treatment component includes a fourth MBR membrane reactor and a fourth RO membrane reactor. The third biochemical treatment device is connected to the fourth MBR membrane reactor and the third biochemical fluid can be filtered through the fourth MBR membrane reactor to obtain a fourth MBR filtrate. The fourth MBR membrane reactor is connected to the fourth RO membrane reactor and the fourth MBR filtrate treated by the fourth MBR membrane reactor can enter the fourth RO membrane reactor for reverse osmosis treatment to obtain fourth fresh water and fourth reverse osmosis liquid, respectively.

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