Organic wastewater treatment method and system

Abstract

An organic wastewater treatment method and system belong to the field of water treatment systems. The system comprises a coarse screen, a lifting pump station, a fine screen, an iron-carbon micro-electrolysis-ultrasonic reactor, a softening silicon removal tank, an osmotic pressure regulating tank, an SBR (sequencing batch reactor), an MBR (membrane bioreactor), a sterilization and disinfection device and a desalting device, the coarse grid, the lifting pump station, the fine grid, the iron-carbon micro-electrolysis-ultrasonic reactor, the softening silicon removal tank, the osmotic pressure regulating tank, the SBR, the MBR membrane-bioreactor, the sterilization and disinfection device and the desalting device are connected in sequence. According to the method, the iron-carbon micro-electrolysis-ultrasonic technology is used for pretreating the high-salt organic wastewater; after the organic matters are treated by the salt-tolerant microorganisms, the organic matters and salt ions are deeply treated by the sterilization and disinfection device and the desalting device, and the effluent reaches the reclaimed water reuse or discharge standard. A concentrated solution or produced water generated by the desalting device flows back to the osmotic pressure regulating tank, the salt-tolerant microorganisms which are cultured to be mature maintain the living salt concentration, and the stability of biological treatment is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of water treatment systems, and particularly relates to a method and system for treating organic wastewater. Background Art

[0002] High-salt organic wastewater is a type of industrial wastewater that not only has a high organic load (chemical oxygen demand COD > 2000 mg / L), but also has a high salinity (> 5000 mg / L). Currently, it is mostly generated in industries such as textile, food processing, petrochemical, pharmaceutical, papermaking, leather-making, and coal chemical industry. If directly discharged randomly, it will cause great harm to the environment. High-salt organic wastewater contains many refractory organic pollutants such as benzene and polycyclic aromatic hydrocarbons, and also contains a large amount of soluble organic salts. Its water quality is complex, highly toxic, harmful, and has poor biodegradability, which has become one of the urgent problems that many enterprises and factories need to solve.

[0003] When treating high-salt organic wastewater by the ordinary biological method, the effect is not good. On the one hand, the high-salt environment is extremely unfavorable to the growth of microorganisms. The high concentration of salt causes microbial cells to dehydrate, destroys their physiological balance, inhibits enzyme activity, seriously affects the metabolism and reproduction of microorganisms, changes the microbial community structure, and greatly reduces the treatment efficiency. On the other hand, the organic matter in high-salt organic wastewater becomes more difficult to degrade due to the salt effect. The interaction between the complex organic components and the high-salt environment increases the difficulty of biological treatment, making it difficult for ordinary biological flora to effectively remove the organic matter in such wastewater, which greatly limits its application in the field of high-salt organic wastewater treatment.

[0004] For high-salt organic wastewater, currently, advanced oxidation technology is mostly used to treat organic matter, and the operating cost is relatively high; due to the high content of high-molecular organic matter in high-salt organic wastewater, it is difficult to achieve effective removal simply by relying on biological organic matter. At the same time, ordinary wastewater microorganisms are difficult to adapt to the high-salt environment and are prone to microbial inactivation; when using the iron-carbon microelectrolysis technology as a pretreatment for organic wastewater, the surface of the iron-carbon filler is easily deposited by suspended impurities or other precipitates in the water, resulting in the blockage of the pores between the iron-carbon fillers, the phenomenon of caking, and the reduction of mass transfer efficiency and the deterioration of treatment effect. Summary of the Invention

[0005] The object of the present invention is to solve the problem that the biological method has a poor treatment effect on refractory organic pollutants, and to provide an organic wastewater treatment method and system. Aiming at the limitation of the biological method in high-salt organic wastewater, the present invention adopts the cultivation and application of salt-tolerant microbial flora, overcomes the limitation of the biological method in treating refractory organic pollutants, and is equipped with a desalination device to remove the organic matter in the high-salt organic wastewater and reduce the salt ions in the wastewater, so that the effluent can meet the discharge standards or be recycled as reclaimed water. At the same time, the concentrated liquid or the produced water generated by the desalination device is returned to the front of the salt-tolerant microbial device to maintain the osmotic pressure suitable for the mature salt-tolerant microbial flora and the salt concentration of the wastewater, preventing water quality fluctuations caused by too high or too low salt concentrations.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] An organic wastewater treatment system, the system includes a coarse grid, a lift pump station, a fine grid, an iron-carbon microelectrolysis-ultrasonic reactor, a softening and silicon-removing tank, an osmotic pressure adjustment tank, an SBR reactor, an MBR membrane-bioreactor, a sterilization and disinfection device, and a desalination device;

[0008] The coarse grid, the lift pump station, the fine grid, the iron-carbon microelectrolysis-ultrasonic reactor, the softening and silicon-removing tank, the osmotic pressure adjustment tank, the SBR reactor, the MBR membrane-bioreactor, the sterilization and disinfection device, and the desalination device are connected in sequence.

[0009] Further, a TDS on-line analyzer is arranged in the osmotic pressure adjustment tank to detect the salt concentration of the wastewater in the tank and control the produced water and concentrated liquid outlet regulating valves of the desalination device. When the salt content is too low, the concentrated liquid outlet regulating valve of the desalination device is controlled to return to the osmotic pressure adjustment tank; when the salt content is too high, the produced water regulating valve of the desalination device is controlled to return to the osmotic pressure adjustment tank.

[0010] A method for treating organic wastewater by using the above system, the method is:

[0011] Step 1: The influent is treated by the coarse grid to remove larger suspended solids and impurities;

[0012] Step 2: The lift pump station is connected to the coarse grid to lift the wastewater;

[0013] Step 3: The fine grid is connected to the lift pump station to remove fine non-sticky fibrous and granular suspended solids;

[0014] Step 4: The iron-carbon microelectrolysis-ultrasonic reactor is connected to the fine grid. The iron-carbon microelectrolysis-ultrasonic reactor includes iron-carbon microelectrolysis filler, an aeration device, and an ultrasonic generator. The iron-carbon microelectrolysis filler is fixed inside the columnar reactor, with air holes arranged at the lower layer. The influent enters from the bottom and exits from the top. The ultrasonic generator applies ultrasonic waves to the bottom and the surrounding of the columnar reactor through an ultrasonic probe. The redox reaction of the iron-carbon microelectrolysis filler filled inside is used to break the bonds of long-chain and cyclic organic substances together, improving the biodegradability of the wastewater. At the same time, the ultrasonic technology treats organic substances through cavitation effect, thermal decomposition, and supercritical oxidation, synergistically enhancing the treatment effect. The ultrasonic technology can generate strong shear force and impact force in the liquid through ultrasonic vibration, preventing the surface of the filler from being blocked and passivated;

[0015] Step 5: The softening and silicon removal tank is connected to the iron-carbon microelectrolysis-ultrasonic reactor. By adding softening agents, silicon removal agents, and coagulants, the hardness ions and total silicon in the wastewater are removed to prevent the membrane of the subsequent desalination device from being fouled and blocked;

[0016] Step 6: The osmotic pressure adjustment tank is connected to the softening and silicon removal tank. The concentrated liquid or the produced water and the wastewater generated by the reflux desalination device are evenly mixed to maintain the osmotic pressure suitable for the mature salt-tolerant microbial flora and the salt concentration of the wastewater;

[0017] Step 7: The SBR reactor is connected to the osmotic pressure adjustment tank. Salt-tolerant microorganisms are cultured and domesticated to form a stable microbial flora in the SBR reactor. The microbial flora feeds on the organic substances in the wastewater. Through the metabolic activities of the microorganisms, the organic substances are decomposed into carbon dioxide, water, and the cell substances of the microorganisms themselves;

[0018] Step 8: The MBR membrane-bioreactor is connected to the SBR reactor. Through biodegradation and membrane separation technologies, the organic substances in the wastewater are deeply removed and the impurities in the wastewater are intercepted. Only water and small molecular substances in solution are allowed to pass through, thereby realizing solid-liquid separation and further removing the organic substances in the wastewater. The activated sludge in the MBR membrane-bioreactor comes from the mature microbial flora that has been domesticated and cultured in the front-end SBR reactor, and the sludge concentration is 5 - 15 g / L;

[0019] Step 9: The sterilization and disinfection device is connected to the MBR membrane-bioreactor. The sterilization and disinfection device is used to sterilize the remaining microorganisms in the wastewater to avoid the subsequent growth of microorganisms in the wastewater. The oxidants or ultraviolet rays generated by the sterilization and disinfection device react with the organic substances, further reducing the organic substances in the wastewater;

[0020] Step 10: Connect the desalination device to the sterilization and disinfection device to further reduce the residual organic matter in the wastewater and intercept the salt ions in the wastewater, so that the effluent meets the discharge or reuse standards. The concentrated liquid generated by the desalination device is centrally treated. When the salt concentration in the osmotic pressure adjustment tank is less than 2%, the reflux concentrated liquid is increased to the osmotic pressure adjustment tank to maintain the adapted salt concentration of the salt-tolerant microorganisms; when the salt concentration in the osmotic pressure adjustment tank is greater than 3%, the reflux effluent is reduced to the osmotic pressure adjustment tank to maintain the adapted salt concentration of the salt-tolerant microorganisms.

[0021] Further, in Step 4, the iron-carbon microelectrolysis filler is a spherical or oval filler sintered at high temperature, and its main components are composed of reduced iron powder, activated carbon powder and some additives, and its size is between 10-50 mm; the frequency of the ultrasonic generator is above 18 kHz; the aeration volume is 0.1-0.3 m 3 / (m 3 ·min).

[0022] Further, in Step 5, the softening and silicon removal tank is a high-density clarification tank or an integrated flocculation sedimentation tank; the softening agents are sodium carbonate (10-300 mg / L) and sodium hydroxide (10-500 mg / L); the silicon removal agents are one of magnesium oxide, magnesium chloride, magnesium sulfate, sodium metaaluminate, and aluminum chloride, and the dosage is 10-30 times the silicon dioxide content in the wastewater; the coagulant aid is PAM, and the dosage is 1-10 mg / L.

[0023] Further, in Step 7, the salt-tolerant microbial flora is domesticated and cultured inside the SBR reactor; the intermittent aeration method is adopted, the aeration volume is 2-4 mg / L; the hydraulic retention time is 6-12 h; the sedimentation period is 1-2 h; the drainage period is 0.5-1 h; the sludge age is 10-30 days.

[0024] Further, in Step 7, the method for culturing and propagating the salt-tolerant microbial flora in the SBR reactor is as follows:

[0025] (1) Take the sludge from the secondary sedimentation tank of the seaside sewage treatment plant and the bottom sediment of the ocean or estuary as the inoculated sludge to provide a suitable strain source for the cultivation of salt-tolerant microorganisms;

[0026] (2) Introduce the inoculated sludge and the wastewater with a salt content of 0.5%-1% into the reactor at a ratio of 1:3, and continuously carry out anaerobic aeration for 1-3 d under the condition of an aeration volume of 2-4 mg / L to restore the sludge activity;

[0027] (3) After the anaerobic aeration is completed, carry out intermittent aeration on the sludge and wastewater, the aeration volume is 2-4 mg / L, the hydraulic retention time is 6-12 h, the sedimentation period is 1-2 h, the drainage period is 0.5-1 h, and increase the sludge age of the sludge to 30-60 d;

[0028] (4) The initial influent salinity of the wastewater is 0.5% - 1%, and then every 15 - 30 days, the salinity is increased by 0.5% - 1% until it reaches 3%; during the cultivation and domestication period, sodium acetate or glucose is added to supplement the carbon source, ammonium sulfate or ammonium chloride is added to supplement the nitrogen source, and potassium dihydrogen phosphate is added to supplement the phosphorus source to maintain BOD5:N:P = 100:5:1 in the wastewater;

[0029] (5) The COD in the reactor is detected once a day. When the COD removal rate remains stable at a certain value for more than one week and is above 70%; the sludge color presents a yellowish - brown color; sludge flocculent precipitation can be visually observed; the sludge volume index is 50 - 200 mL / g; it means that the activated sludge cultivation is successful, and then the sludge age of the SBR reactor is restored to 10 - 30 days.

[0030] Further, in step eight, the MBR membrane - bioreactor is a hollow - fiber ultrafiltration membrane or a flat - plate ultrafiltration membrane; the hydraulic retention time is 12 - 48 h; the sludge age is 15 - 60 days.

[0031] Further, in step nine, the sterilization and disinfection device is one of ozone sterilization and disinfection, chlorine dioxide sterilization and disinfection, sodium hypochlorite sterilization and disinfection, and ultraviolet sterilization and disinfection.

[0032] Further, in step ten, the desalination device is one or a combination of a nanofiltration device, a reverse osmosis device, and an electrodialysis device. When the cultivation and domestication of salt - tolerant microorganisms are mature, part of the concentrated liquid or the produced water generated by the desalination device is refluxed to the osmotic pressure adjustment pool to maintain the salt concentration of the wastewater between 2% and 3%; other concentrated liquids are centrally treated, and the produced water is discharged or reused as reclaimed water.

[0033] The beneficial effects of the present invention compared with the prior art are as follows:

[0034] 1. A method for biochemical combined treatment of high - salt organic wastewater is provided. Compared with advanced oxidation for treating organic matter, the biological method for treating organic matter has a lower cost and is more environmentally friendly;

[0035] 2. A cultivation method for the growth, development and reproduction of salt - tolerant microorganisms in an SBR reactor is provided, which is used to treat organic matter in high - salt organic wastewater;

[0036] 3. Through the interception effect and charge effect of the desalination device, the residual organic matter in the wastewater is further removed, so that the produced water meets the reuse or discharge standard; at the same time, the concentrated liquid or the produced water generated by the desalination device is refluxed to the front of the salt - tolerant microorganism device to maintain the osmotic pressure and wastewater salt concentration suitable for the mature salt - tolerant microorganism flora, preventing the influence of the fluctuation of the too - high or too - low influent salt concentration environment on the living environment of microorganisms and maintaining the activity of the microorganism flora;

[0037] 4. Using the iron-carbon microelectrolysis-ultrasound technology to pretreat high-salt organic wastewater, reducing the biological toxicity of the wastewater, improving the biodegradability of the wastewater, facilitating the subsequent biological treatment of organic wastewater, and enhancing the treatment effect of salt-tolerant microorganisms; the sterilization and disinfection device further removes the organic matter in the wastewater by reacting with the organic matter and microorganisms in the wastewater. Description of the Drawings

[0038] Figure 1 It is a flow chart of the treatment method of the present invention;

[0039] Figure 2 It is a schematic structural diagram of the iron-carbon microelectrolysis-ultrasound reactor of the present invention;

[0040] Figure 3 It is a step sequence diagram of the treatment method of the present invention. Detailed Embodiments

[0041] The technical solutions of the present invention will be further described below in conjunction with the drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0042] Example 1:

[0043] An organic wastewater treatment system, the system includes a coarse grille, a lift pump station, a fine grille, an iron-carbon microelectrolysis-ultrasound reactor, a softening and desilication tank, an osmotic pressure adjustment tank, an SBR reactor, an MBR membrane-bioreactor, a sterilization and disinfection device, and a desalination device;

[0044] The coarse grille, the lift pump station, the fine grille, the iron-carbon microelectrolysis-ultrasound reactor, the softening and desilication tank, the osmotic pressure adjustment tank, the SBR reactor, the MBR membrane-bioreactor, the sterilization and disinfection device, and the desalination device are connected in sequence.

[0045] A TDS on-line analyzer is arranged in the osmotic pressure adjustment tank to detect the salt concentration of the wastewater in the tank and control the water production and concentrated liquid outlet regulating valves of the desalination device. When the salinity is too low, control the concentrated liquid outlet regulating valve of the desalination device to return to the osmotic pressure adjustment tank; when the salinity is too high, control the water production regulating valve of the desalination device to return to the osmotic pressure adjustment tank.

[0046] Example 2:

[0047] A method for treating organic wastewater using the system described in Example 1, the method is:

[0048] Step 1: The influent water is treated by the coarse grille to remove larger suspended solids and impurities;

[0049] Step 2: The lift pump station is connected to the coarse grille to lift the wastewater;

[0050] Step 3: Connect the fine grille to the lift pump station, which is used to remove fine non-sticky fibrous and granular suspended solids.

[0051] Step 4: Connect the iron-carbon microelectrolysis-ultrasonic reactor to the fine grille. The iron-carbon microelectrolysis-ultrasonic reactor includes iron-carbon microelectrolysis fillers, an aeration device, and an ultrasonic generator. The iron-carbon microelectrolysis fillers are fixed inside the columnar reactor, with aeration holes arranged at the lower layer, and the influent enters from the bottom and exits from the top. The ultrasonic generator applies ultrasonic waves to the bottom and the surrounding of the columnar reactor through an ultrasonic probe. The redox reaction of the iron-carbon microelectrolysis fillers filled inside is used to break the bonds of long-chain and cyclic organic substances together, improving the biodegradability of the wastewater. At the same time, the ultrasonic technology treats organic substances through cavitation effect, thermal decomposition, and supercritical oxidation, synergistically enhancing the treatment effect. Through ultrasonic vibration, the ultrasonic technology can generate strong shear force and impact force in the liquid to prevent the surface of the fillers from being blocked and passivated. The iron-carbon microelectrolysis fillers are spherical or elliptical fillers sintered at high temperature, and the main components are composed of reduced iron powder, activated carbon powder, and some additives, with a size between 10 - 50 mm. The frequency of the ultrasonic generator is above 18 kHz, and the aeration volume is 0.1 - 0.3 m 3 / (m 3 ·min).

[0052] Step 5: Connect the softening and desilication tank to the iron-carbon microelectrolysis-ultrasonic reactor, and remove hardness ions and total silicon in the wastewater by adding softening agents, desilication agents, and coagulants. The softening and desilication tank is a high-density clarification tank. The softening agents are sodium carbonate (200 - 300 mg / L) and sodium hydroxide (450 - 500 mg / L). The desilication agent is magnesium oxide, and the dosage is 20 times the content of silicon dioxide in the wastewater. The coagulant is PAM, and the dosage is 2 - 6 mg / L.

[0053] Step 6: Connect the osmotic pressure adjustment tank to the softening and desilication tank, and uniformly mix the concentrated liquid or the produced water generated by the reflux desalination device with the wastewater to maintain the osmotic pressure suitable for the mature salt-tolerant microbial flora and the salt concentration of the wastewater.

[0054] Step 7: Connect the SBR reactor to the osmotic pressure adjustment tank, cultivate and domesticate salt-tolerant microorganisms to form a stable microbial flora in the SBR reactor. The microbial flora feeds on the organic substances in the wastewater. Through the metabolic activities of the microorganisms, the organic substances are decomposed into carbon dioxide, water, and the cell substances of the microorganisms themselves. The salt-tolerant microbial flora is domesticated and cultivated inside the SBR reactor. The intermittent aeration method is adopted, with an aeration volume of 2 - 4 mg / L, a hydraulic retention time of 8 - 10 h, a sedimentation period of 1 - 2 h, a drainage period of 0.5 - 1 h, and a sludge age of 20 - 30 days.

[0055] The method for culturing and propagating salt-tolerant microbial flora in the SBR reactor is as follows:

[0056] (1) Take the sludge from the secondary sedimentation tank of a seaside sewage treatment plant as the inoculated sludge to provide a suitable strain source for the cultivation of salt-tolerant microorganisms;

[0057] (2) Import the inoculated sludge and the wastewater with a salt content of 0.5% - 1% into the reactor at a ratio of 1:3. Under the condition of an aeration rate of 3 - 4 mg / L, continuously carry out anaerobic aeration for 1 - 3 days to restore the sludge activity;

[0058] (3) After the anaerobic aeration ends, carry out intermittent aeration on the sludge and wastewater. The aeration rate is 2 - 4 mg / L, the hydraulic retention time is 6 - 12 h, the sedimentation period is 1 - 2 h, and the drainage period is 0.5 - 1 h to increase the sludge age of the sludge to 50 - 60 d;

[0059] (4) The initial influent salinity of the wastewater is 0.5% - 1%. Subsequently, every 15 - 25 days, increase the salt content by 0.5% - 1% until it reaches 3%. During the cultivation and domestication period, add sodium acetate or glucose to supplement the carbon source, add ammonium sulfate or ammonium chloride to supplement the nitrogen source, and add potassium dihydrogen phosphate to supplement the phosphorus source to maintain the BOD5:N:P in the wastewater at 100:5:1;

[0060] (5) Detect the COD in the reactor once a day. When the COD removal rate has been stable at a certain value for more than one week and is above 70%; the sludge color presents a yellowish-brown color; sludge flocculation precipitation can be visually observed; the sludge volume index is 50 - 200 mL / g; it means that the activated sludge cultivation is successful, and then the sludge age of the SBR reactor is restored to 10 - 30 d.

[0061] Step Eight: Connect the MBR membrane-bioreactor with the SBR reactor. Through biodegradation and membrane separation technologies, deeply remove the organic matter in the wastewater and intercept the impurities in the wastewater, allowing only water and small molecular substances in solution to pass through, thereby realizing solid-liquid separation and further removing the organic matter in the wastewater; the source of the activated sludge in the MBR membrane-bioreactor is the mature microbial flora domesticated and cultivated in the front-end SBR reactor, and the sludge concentration is 10 - 15 g / L; the MBR membrane-bioreactor is a hollow fiber ultrafiltration membrane or a flat ultrafiltration membrane; the hydraulic retention time is 36 - 48 h; the sludge age is 15 - 60 d.

[0062] Step Nine: Connect the ultraviolet disinfection device with the MBR membrane-bioreactor, and use the ultraviolet disinfection device to sterilize the remaining microorganisms in the wastewater to avoid subsequent microbial growth in the wastewater. Ultraviolet rays react with organic matter to further reduce the organic matter in the wastewater;

[0063] Step 10: The nanofiltration desalination device + the electrodialysis desalination device are connected to the sterilization and disinfection device to further reduce the residual organic matter in the wastewater and intercept the salt ions in the wastewater, so that the effluent meets the discharge or reuse standards, and the concentrated liquid generated by the desalination device is centrally treated. When the salt concentration in the osmotic pressure adjustment tank is too low, the refluxed concentrated liquid is increased to the salt concentration suitable for salt-tolerant microorganisms; when the salt concentration in the osmotic pressure adjustment tank is too high, the refluxed effluent is reduced to the salt concentration suitable for salt-tolerant microorganisms.

[0064] The method of Example 2 was used to treat a certain chemical wastewater. The water quality information of the chemical wastewater is shown in the following table, and the main water quality and treatment results are shown in the following table:

[0065]

[0066]

Claims

1. An organic wastewater treatment system, characterized in that: The system comprises a coarse grid, a lifting pump station, a fine grid, an iron-carbon micro-electrolysis-ultrasonic reactor, a softening and silicon removal tank, an osmotic pressure regulating tank, an SBR reactor, an MBR membrane-bioreactor, a sterilization and disinfection device, and a desalination device; The coarse grid, lifting pump station, fine grid, iron-carbon micro-electrolysis-ultrasonic reactor, softening and silicon removal tank, osmotic pressure regulating tank, SBR reactor, MBR membrane-bioreactor, sterilization and disinfection device, and desalination device are connected in sequence.

2. An organic wastewater treatment system according to claim 1, characterized in that: A TDS online analyzer is arranged in the osmotic pressure regulating pool to detect the salt concentration of the wastewater in the pool and control the water production and concentrate outlet regulating valves of the desalination device.

3. A method for treating organic wastewater using the system according to claim 1 or 2, characterized in that: The method is: Step 1: The incoming water is processed through a coarse screen to remove larger suspended solids and impurities; Step 2: The lifting pump station is connected to the coarse screen to lift the wastewater; Step 3: The fine screen is connected to the lifting pump station to remove fine non-sticky fibrous and granular suspended matter; Step 4: an iron-carbon micro-electrolysis-ultrasonic reactor is connected to a fine grid, wherein the iron-carbon micro-electrolysis-ultrasonic reactor comprises an iron-carbon micro-electrolysis filler, an aeration device and an ultrasonic generator; the iron-carbon micro-electrolysis filler is fixed inside the column reactor, aeration holes are arranged on the lower layer, water enters from the bottom and exits from the top, and the ultrasonic generator applies ultrasonic waves to the bottom and surroundings of the column reactor through an ultrasonic probe; Step 5: The softening and silicon removal tank is connected to the iron-carbon micro-electrolysis-ultrasonic reactor, and the hardness ions and total silicon in the wastewater are removed by adding softening agents, silicon removal agents and coagulants; Step 6: The osmotic pressure regulating tank is connected to the softening and desiliconizing tank, and the concentrate or produced water produced by the reflux desalination device is evenly mixed with the wastewater to maintain the osmotic pressure and wastewater salt concentration suitable for mature salt-tolerant microbial flora; Step 7: The SBR reactor is connected to the osmotic pressure regulating tank, and salt-tolerant microorganisms are cultivated and domesticated to form a stable microbial flora in the SBR reactor. The microbial flora feeds on organic matter in the wastewater; through the metabolic activities of the microorganisms, the organic matter is decomposed into carbon dioxide, water and the microorganisms' own cell substances; Step 8: The MBR membrane-bioreactor is connected to the SBR reactor. Through biodegradation and membrane separation technology, the organic matter in the wastewater is deeply removed and the impurities in the wastewater are intercepted. Only water and soluble small molecules are allowed to pass through, thereby achieving solid-liquid separation and further removing organic matter in the wastewater. The source of the activated sludge in the MBR membrane-bioreactor is the mature bacterial flora that has been domesticated and cultivated in the front-end SBR reactor, and the sludge concentration is 5-15g / L. Step 9: The sterilization and disinfection device is connected to the MBR membrane-bioreactor, and the residual microorganisms in the wastewater are sterilized by the sterilization and disinfection device to prevent the subsequent microbial growth in the wastewater; the oxidant or ultraviolet light generated by the sterilization and disinfection device reacts with the organic matter to further reduce the organic matter in the wastewater; Step 10: The desalination device is connected to the sterilization and disinfection device to further reduce the residual organic matter in the wastewater, intercept the salt ions in the wastewater, make the effluent meet the discharge or reuse standards, and the concentrated liquid produced by the desalination device is centrally treated; when the salt concentration in the osmotic pressure adjustment tank is less than 2%, the reflux concentrated liquid is increased to the osmotic pressure adjustment tank to maintain the adapted salt concentration of salt-tolerant microorganisms; when the salt concentration in the osmotic pressure adjustment tank is greater than 3%, the reflux water is reduced to the osmotic pressure adjustment tank to adapt to the salt concentration of salt-tolerant microorganisms.

4. The method for treating organic wastewater according to claim 3, characterized in that: In step 4, the iron-carbon micro-electrolysis filler is a spherical or elliptical filler sintered at high temperature, and its main components are reduced iron powder, activated carbon powder and some additives, and its size is between 10-50 mm; the frequency of the ultrasonic generator is above 18 kHz; the aeration volume is 0.1-0.3 m 3 / (m 3 ·min).

5. The method for treating organic wastewater according to claim 3, characterized in that: In step five, the softening and silicon removal tank is a high-density clarification tank or an integrated flocculation sedimentation tank; the softening agent is sodium carbonate (10-300 mg / L) and sodium hydroxide (10-500 mg / L); the silicon removal agent is one of magnesium oxide, magnesium chloride, magnesium sulfate, sodium aluminate, and aluminum chloride, and the dosage is 10-30 times the silicon dioxide content in the wastewater; the coagulant aid is PAM, and the dosage is 1-10 mg / L.

6. The method for treating organic wastewater according to claim 3, characterized in that: In step seven, salt-tolerant microbial flora are domesticated and cultured inside the SBR reactor; intermittent aeration is adopted with an aeration volume of 2-4 mg / L; hydraulic retention time is 6-12 h; sedimentation period is 1-2 h; drainage period is 0.5-1 h; and sludge age is 10-30 days.

7. The method for treating organic wastewater according to claim 3, characterized in that: In step 7, the culture and propagation method of the salt-tolerant microbial flora in the SBR reactor is as follows: (1) Take the sludge from the secondary sedimentation tank of a seaside sewage treatment plant, the bottom mud of the ocean or estuary as inoculated sludge to provide a suitable source of bacteria for the cultivation of salt-tolerant microorganisms; (2) Introducing the inoculated sludge and wastewater with a salt content of 0.5% to 1% into the reactor at a ratio of 1:3, and continuously aerating for 1 to 3 days at an aeration rate of 2 to 4 mg / L to restore the sludge activity; (3) After the aeration is completed, the sludge and wastewater are intermittently aerated, with an aeration rate of 2-4 mg / L, a hydraulic retention time of 6-12 hours, a sedimentation period of 1-2 hours, and a drainage period of 0.5-1 hour, to increase the sludge age to 30-60 days; (4) The initial salinity of the wastewater inlet is 0.5% to 1%, and then the salinity is increased by 0.5% to 1% every 15-30 days until it reaches 3%; during the culture and acclimatization period, sodium acetate or glucose is added to supplement the carbon source, ammonium sulfate or ammonium chloride is added to supplement the nitrogen source, and potassium dihydrogen phosphate is added to supplement the phosphorus source to maintain the BOD5:N:P in the wastewater = 100:5:1; (5) The COD in the reactor is tested once a day. When the COD removal rate is stable at a certain value and is above 70% for more than one week, the sludge color is yellow-brown, the flocculent precipitate of sludge is visible to the naked eye, and the sludge volume index is between 50-200 mL / g, it means that the activated sludge is successfully cultivated, and then the sludge age of the SBR reactor is restored to 10-30 days.

8. The method for treating organic wastewater according to claim 3, characterized in that: In step eight, the MBR membrane-bioreactor is a hollow fiber ultrafiltration membrane or a flat ultrafiltration membrane; the hydraulic retention time is 12-48 hours; and the sludge age is 15-60 days.

9. The method for treating organic wastewater according to claim 3, characterized in that: In step nine, the sterilization and disinfection device is one of ozone sterilization and disinfection, chlorine dioxide sterilization and disinfection, sodium hypochlorite sterilization and disinfection, and ultraviolet sterilization and disinfection.

10. The method for treating organic wastewater according to claim 3, characterized in that: In step ten, the desalination device is a nanofiltration device, a reverse osmosis device, an electrodialysis device, or a combination of multiple devices.

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