High-salt food processing wastewater treatment system and method

Abstract

The invention discloses a high-salt food processing wastewater treatment system and method. The system comprises a grating tank, an adjusting homogenizing tank, an aeration activated sludge tank, a membrane bioreactor and a micro-nano aeration system, the membrane bioreactor is divided into a facultative tank and an immersed membrane filter tank, the facultative tank is located at the front end of the immersed membrane filter tank, and the facultative tank and the immersed membrane filter tank are connected through a pipeline; the immersed membrane filtration tank is provided with a membrane filtration assembly system, a sludge outlet and a water outlet; the grid tank is provided with a wastewater inlet, the grid tank, the adjusting and homogenizing tank and the aeration activated sludge tank are sequentially connected through pipelines, and a water outlet pipe of the aeration activated sludge tank is connected with the facultative tank. The system disclosed by the invention does not need to use efficient anaerobic process devices such as an IC tower and a UASB (Upflow Anaerobic Sludge Blanket); in addition, the system is short in technological process, high in efficiency, convenient to maintain and low in operation cost; the process can realize standard drainage, eliminate odor and consume excess sludge at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental pollution control, and specifically relates to a system and method for treating high-salt food processing wastewater. Background Art

[0002] Wastewater from pickled vegetable and kimchi factories is a common high-salt food processing wastewater, which mainly comes from the wastewater from the cleaning and pickling process of raw materials such as vegetable leaves, vegetable stems, and seasonings, as well as the cleaning water, disinfection water and other wastewater used in the production process. The main pollutants in the wastewater from pickled vegetable and kimchi factories are: 1) Organic matter: During the production process of pickled vegetable and kimchi factories, vegetables will release a large amount of organic matter, including protein, fat, carbohydrates, etc. during the cleaning and pickling process. These organic matter will consume oxygen, reduce the concentration of dissolved oxygen in the water, and cause harm to aquatic organisms. 2) Ammonia nitrogen: During the production process of pickled vegetable and kimchi factories, vegetables such as vegetable leaves and vegetable stems will release a large amount of ammonia nitrogen during the pickling process. Excessive ammonia nitrogen will cause serious harm to aquatic organisms and cause eutrophication of water bodies. 3) Total phosphorus: The chemicals and condiments used in the production process of pickled vegetable and kimchi factories contain a large amount of phosphorus. In addition, the vegetables themselves are also rich in phosphorus. The total phosphorus content in the wastewater is relatively high. If it is not treated and discharged directly, it will cause eutrophication of water bodies. 4) Other impurities: Wastewater also contains a small amount of suspended matter, sediment, impurities, etc., which need to be removed through pretreatment. If the above pollutants are not treated and directly discharged into the environment, it will cause great pollution to the surrounding environment and harm the surrounding ecology.

[0003] In the existing technology, for example: Yu Yubin, Lin Xing, Jia Yun. Engineering case of MBR process for treating typical mustard wastewater [J]. Environmental Science and Technology, 2019, 32(1): 40-43. The three-stage treatment process of improved regulating tank-hydrolysis acidification tank-A2 / 0-MBR membrane system was used to treat mustard wastewater from a certain industrial park, and the effluent was able to meet the GB18918-2002 Class A standard; Liu Jiangguo. Study on the treatment of mustard wastewater by coagulation-anaerobic-electrode SBBR method [D]. Chongqing: Southwest University, 2011. However, the traditional biological method disclosed in the above literature is not ideal for treating high-salt organic wastewater in the pickled vegetable industry, while the physical and chemical methods have high energy consumption and high operating costs. Summary of the invention

[0004] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a high-salt food processing wastewater treatment system with a short process flow, high efficiency and low operating energy consumption. Another object of the present invention is to provide a method for treating high-salt food processing wastewater.

[0005] The purpose of the present invention is achieved through the following technical solutions: A high-salt food processing wastewater treatment system comprises a grid tank, a regulating and homogenizing tank, an aerated activated sludge tank, a membrane bioreactor and a micro-nano aeration system; the membrane bioreactor is divided into an anoxic tank and an immersed membrane filtration tank, the anoxic tank is located at the front end of the immersed membrane filtration tank, and the anoxic tank and the immersed membrane filtration tank are connected by a pipeline; the immersed membrane filtration tank is provided with a membrane filtration component system, a sludge outlet and a water outlet; The grid pool is provided with a wastewater inlet, the grid pool, the regulating and homogenizing pool and the aerated activated sludge pool are connected in sequence through pipelines, and the outlet pipe of the aerated activated sludge pool is connected to the anoxic pool; The outlet pipe of the anoxic tank is divided into two channels, one channel is connected to the submerged membrane filter tank, and the other channel is connected to the mixed liquor return pipe, and the outlet end of the mixed liquor return pipe is respectively connected to the regulating homogenization tank and the aerated activated sludge tank, so that part of the effluent of the anoxic tank flows back to the regulating homogenization tank and the aerated activated sludge tank; The sludge outlet of the submerged membrane filter tank is connected to the aerated activated sludge tank and the regulating and homogenizing tank respectively through a sludge return pipe, so that the sludge separated by the submerged membrane filter tank is returned to the regulating and homogenizing tank and the aerated activated sludge tank for decomposition and digestion; The micro-nano aeration system comprises a plurality of micro-nano jet aeration devices, a plurality of gas-liquid mixers, a water inlet pipe, an air pipe and a submersible pump. The micro-nano jet aeration devices are respectively installed in a regulating homogenization tank, an aerated activated sludge tank and an immersed membrane filtration tank. The number of the gas-liquid mixers is the same as the number of the micro-nano jet aeration devices. The submersible pump pumps water into the water inlet pipe, and the air introduced from the air pipe and the water introduced from the water inlet pipe are mixed by the gas-liquid mixer and then enter the micro-nano jet aeration devices respectively, so as to provide aeration for the regulating homogenization tank, the aerated activated sludge tank and the submerged membrane filtration tank.

[0006] Furthermore, J-shaped water distribution pipes are installed on both sides of the oxygen-conducting tank, and the installation height is 20-30 cm from the bottom of the tank; the water outlet of the J-shaped water distribution pipe adopts a trumpet-shaped mushroom-head shower-type water distributor; the oxygen-conducting tank adopts a middle water inlet, so that the J-shaped water distribution pipes on both sides of the tank body distribute water evenly; an overflow trough is provided at the tail end of the oxygen-conducting tank, and the wastewater treated in the oxygen-conducting tank overflows from the overflow trough to the outlet pipe and is divided into two parts, one part enters the submerged membrane filtration tank, and the other part flows back to the regulating homogenization tank and the aerated activated sludge tank.

[0007] Furthermore, the trumpet-shaped mushroom head shower type water distributor has evenly opened holes with a hole diameter of 2-4 mm; the overflow groove is designed in a 1 / 4 arc shape, which makes it more convenient for the water to overflow to the outlet pipe.

[0008] Furthermore, the membrane filtration component system uses a corrugated flat membrane as a filter membrane, which can be purchased directly from the market, is easy to install and disassemble, has a modular combination, is not easy to adhere to sludge and pollutants, and has good compatibility.

[0009] Furthermore, the salinity tolerance of the corrugated flat membrane is ≥10000 mg / L, and the membrane pore size is 0.1 μm~0.5 μm.

[0010] Furthermore, the submersible pump is a movable submersible pump.

[0011] Furthermore, the bubble particle size generated by aeration of the micro-nano jet aeration device is 60nm~200nm, and the air intake mode of the micro-nano jet aeration device is autonomous suction; the gas-liquid volume ratio of air and water mixed in the gas-liquid mixer is 1:2~4.

[0012] Furthermore, the micro-nano jet aeration device is installed at the upper end or the bottom of the homogenization tank, the aerated activated sludge tank, or the submerged membrane filtration tank, which can be flexibly selected; the micro-nano jet aeration device is suitable for installation in a water depth of 1 to 5 meters. It is preferably installed at the upper end for easy maintenance.

[0013] Furthermore, the regulating homogenizing pool is a thin and long pool type, with a water depth of 3~4m, a length-to-width ratio of (6~12):2, a single pool body length L between 6m≤L≤12m, and a minimum width of 2m; the number of micro-nano jet aeration devices in the regulating homogenizing pool is set according to the pool capacity, and they are arranged at uniform intervals in the same direction as the water flow and installed on the same axis, installed in a single row or in parallel, with an installation spacing of 2m or 3m.

[0014] Furthermore, the aerated activated sludge tank is a long and narrow tank type, with a water depth of 1-5m, a length-to-width ratio of (6-12):2, a single tank body length L between 6m≤L≤12m, and a minimum width of 2m; the number of micro-nano jet aeration devices in the aerated activated sludge tank is set according to the tank capacity, and they are arranged at uniform intervals in the same direction as the water flow and installed on the same axis, installed in a single row or in parallel, with an installation spacing of 2m or 3m.

[0015] Furthermore, the number of micro-nano jet aeration devices installed in the regulating homogenization tank and the aerated activated sludge tank is more than two.

[0016] The present invention provides a method for treating high-salt food processing wastewater, comprising the following steps: (1) The high-salt food processing wastewater to be treated is pre-treated in a screen tank, and the wastewater after removing suspended matter and large particle impurities enters the regulating homogenization tank; (2) Pre-aerate the wastewater in the regulating homogenization tank through a micro-nano jet aeration device, and use the thrust force generated by aeration to stir the wastewater so that the wastewater is evenly mixed; (3) The wastewater homogenized in step (2) enters an aerated activated sludge tank for aerobic decomposition, wherein aerobic activated sludge is added to the aerated activated sludge tank; the wastewater is aerated by a micro-nano jet aeration device in the aerated activated sludge tank, and the thrust force generated by the aeration is used for stirring, so that the aerobic activated sludge and the wastewater are fully and evenly mixed and contacted, and the aerobic microorganisms in the aerobic activated sludge are used to decompose organic macromolecular compounds in the wastewater into small molecular substances; (4) The wastewater after aerobic treatment in the aerated activated sludge tank enters the facultative aerobic tank, where facultative aerobic bacteria are added. The facultative aerobic bacteria in the facultative aerobic tank can degrade the salinity of the wastewater by taking advantage of their aerobic and facultative properties, and adjust the Cl - 、SO4 2- 、Na + , Ca 2+ The concentration of plasma provides guarantee for subsequent membrane filtration; (5) After being treated in the aerobic tank, the wastewater is divided into two parts. One part is returned to the regulating homogenization tank and the aerated activated sludge tank; the other part enters the submerged membrane filtration tank, where a micro-nano jet aeration device is used for aeration and power supply, so that the wastewater passes through the membrane filtration component system, and the filter membrane is used to further decompose the organic matter in the wastewater and separate the sludge in the wastewater, so as to obtain effluent and sludge that meet the standards; The sludge is returned to the regulating homogenization tank and the aerated activated sludge tank for decomposition and digestion, and the effluent that meets the standards is directly discharged, thus achieving odorless and zero-residue sludge treatment of high-salt food processing wastewater.

[0017] Preferably, the dissolved oxygen content (DO value) of the homogenization tank is 1-3 mg / L, and the hydraulic retention time (HRT) is 8h-24h. This step utilizes aeration stirring to evenly mix the incoming water and achieve the effect of pre-aeration.

[0018] Preferably, the oxygen utilization rate of the regulating and homogenizing tank is ≥60%; and the oxygen utilization rate of the aerated activated sludge tank is ≥80%.

[0019] Preferably, the dissolved oxygen content (DO value) of the aerated activated sludge tank is 4-8 mg / L; the sludge concentration (MLSS) of the aerated activated sludge tank is controlled at 3000 mg / L-7000 mg / L, and the hydraulic retention time (HRT) is 12h-48h.

[0020] Preferably, the aerobic activated sludge is domesticated with food wastewater sludge of the same type as the wastewater to be treated, or municipal sludge plus aerobic engineered bacteria.

[0021] More preferably, the aerobic activated sludge acclimation method is carried out with reference to conventional methods in the art, wherein the main process parameters are as follows: aerobic activated sludge is added according to the sludge concentration MLSS ≥ 3000 mg / L; the water inlet is increased by 10% or 20% in steps, and the water is continuously inletted for 10 days or 5 days; the dissolved oxygen content (DO value) is 6 mg / L, and the mixed liquor is refluxed 100% to 200% to the regulating homogenization tank.

[0022] The aerobic engineering bacteria include at least one of Bacillus subtilis, Bacillus sphaericus, Bacillus licheniformis, etc. The dosage of aerobic engineering bacteria is 1 / 10,000 to 3 / 10,000 of the pool volume (g / m 3 ).

[0023] Preferably, the dissolved oxygen content (DO value) of the anoxic tank is 0.5-2 mg / L, the sludge concentration (MLSS) is controlled at 5000-7000 mg / L, and the hydraulic retention time (HRT) is 4h-8h.

[0024] Part of the wastewater treated by the mixed liquor in the aerobic tank directly enters the submerged membrane filtration tank, part of it flows back to the regulating homogenization tank with a return ratio of 100% to 300%, and part of it flows back to the aerated activated sludge tank with a return ratio of 100% to 200%.

[0025] Preferably, the anaerobic bacteria are salt-tolerant bacteria that are dominant in aerobic and anaerobic environments, such as halotolerant Bacillus. The dosage of the anaerobic bacteria is 1 / 10,000 to 5 / 10,000 of the capacity of the anaerobic tank (g / m 3 ).

[0026] Preferably, the COD of the wastewater to be treated is 3000 mg / L~20000 mg / L, and the salt content is 1%~2% (equivalent to 10000~20000 mg / L), and it is preferably wastewater from a pickled vegetable factory.

[0027] Preferably, the COD value of the effluent that meets the standards is ≤100 mg / L, and the chloride value is ≤600 mg / L.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The system of the present invention is an aerobic treatment process that is easy to operate throughout the entire process, and does not require the use of high-efficiency anaerobic process equipment, such as IC towers, UASB, etc.

[0029] 2. The system of the present invention adopts micro-nano jet aeration devices with large thrust for aeration in the homogenization tank, aerated activated sludge tank and submerged membrane filtration tank. The mud and water can be fully mixed through the aeration flow, and there is no need to set up a stirring device throughout the process. The separate aeration devices can also facilitate the control of dissolved oxygen (DO value).

[0030] 3. The system of the present invention sets an aerobic tank at the front end of the membrane bioreactor. The wastewater treated in the aerated activated sludge tank first enters the aerobic tank for treatment. No additional oxygen is supplied to this part (that is, no aeration device is installed in this part). The impact resistance of facultative anaerobic bacteria to load is utilized to effectively buffer water quality fluctuations; and part of the COD in the wastewater can be degraded, further stabilizing the sludge concentration and influent water quality of the membrane bioreactor.

[0031] 4. The system of the present invention has a short process flow, high efficiency, convenient maintenance and low operating cost; the process can achieve standard drainage, eliminate odor and absorb residual sludge at the same time.

[0032] 5. The system of the present invention is suitable for small-scale light food processing enterprises (wastewater output Q≤1000 m 3 / d). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the high-salt food processing wastewater treatment system of the present invention; 1-grid tank, 2-regulating homogenization tank, 3-aerated activated sludge tank, 4-membrane bioreactor, 4-A is an aerobic tank, 4-B is an immersed membrane filtration tank, 5-mixed liquor reflux pipeline, 6-sludge pipeline, 7-micro-nano jet aeration device, 8-gas-liquid mixer, 9-submersible pump.

[0034] Figure 2 It is a schematic diagram of the specific structure of the aeration tank in the high-salt food processing wastewater treatment system of the present invention; 4-1 is a water inlet pipe, 4-2 is a J-shaped water distribution pipe, 4-3 is a water outlet, 4-4 is an overflow trough, and 4-5 is a water outlet pipe. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not particularly noted, conventional techniques can be used.

[0036] like Figure 1 As shown, the present invention provides a high-salt food processing wastewater treatment system, comprising a grille pool 1, a regulating and homogenizing pool 2, an aerated activated sludge pool 3, a membrane bioreactor 4 and a micro-nano aeration system; the membrane bioreactor 4 is divided into an aerobic pool 4-A and an immersed membrane filtration pool 4-B, and the aerobic pool 4-A and the immersed membrane filtration pool 4-B are connected by pipelines; the immersed membrane filtration pool 4-B is provided with a membrane filtration component system, a sludge outlet and a water outlet; the grille pool 1 is provided with a wastewater inlet, and the grille pool 1, the regulating and homogenizing pool 2 and the aerated activated sludge pool 3 are connected in sequence by pipelines; the outlet pipe of the aerated activated sludge pool 3 is connected to the aerobic pool 4-A; The outlet pipe of the anoxic tank 4-A is divided into two channels, one channel is connected to the submerged membrane filter tank 4-B, and the other channel is connected to the mixed liquor return pipe 5. The outlet end of the mixed liquor return pipe 5 is respectively connected to the regulating homogenization tank 2 and the aerated activated sludge tank 3, so that part of the effluent of the anoxic tank 4-A flows back to the regulating homogenization tank 2 and the aerated activated sludge tank 3; The sludge outlet of the submerged membrane filter tank 4-B is connected to the aerated activated sludge tank 3 and the regulating homogenization tank 2 respectively through the sludge return pipe 6, so that the sludge separated by the submerged membrane filter tank 4-B is returned to the regulating homogenization tank 2 and the aerated activated sludge tank 3 for decomposition and digestion; The micro-nano aeration system includes a plurality of micro-nano jet aeration devices 7, a plurality of gas-liquid mixers 8, a water inlet pipe, an air pipe and a submersible pump 9. The micro-nano jet aeration devices 7 are respectively installed in the regulating homogenization tank 2, the aerated activated sludge tank 3 and the submerged membrane filter tank 4-B. The number of the gas-liquid mixers 8 is the same as the number of the micro-nano jet aeration devices 7. The submersible pump 9 pumps water into the water inlet pipe, and the air introduced from the air pipe and the water introduced from the water inlet pipe are mixed by the gas-liquid mixer 8 and then enter the micro-nano jet aeration device 7 respectively, providing aeration for the regulating homogenization tank 2, the aerated activated sludge tank 3 and the submerged membrane filter tank 4-B.

[0037] The membrane filtration component system adopts a corrugated flat membrane as a filter membrane, the salinity tolerance of the corrugated flat membrane is ≥10000 mg / L, and the membrane pore size is 0.1μm~0.5μm; the submersible pump is a movable submersible pump.

[0038] like Figure 2 As shown, J-shaped water distribution pipes 4-2 are installed on both sides of the oxygen-conducting tank, and the installation height is 20~30cm from the bottom of the tank; the water outlet 4-3 of the J-shaped water distribution pipe adopts a trumpet-shaped mushroom-head shower-type water distributor; the oxygen-conducting tank adopts intermediate water inlet, and the water inlet pipe 4-1 is installed in the middle, so that the J-shaped water distribution pipes 4-2 on both sides of the tank body distribute water evenly; the tail end of the oxygen-conducting tank is provided with an overflow trough 4-4, and the wastewater treated in the oxygen-conducting tank overflows from the overflow trough 4-4 to the outlet pipe 4-5 and is divided into two parts, one part enters the submerged membrane filtration tank, and the other part flows back to the regulating homogenization tank and the aerated activated sludge tank. The trumpet-shaped mushroom-head shower-type water distributor has uniform openings with an aperture of 2~4mm; the overflow trough is designed in a 1 / 4 arc shape, which is more convenient for overflowing the outlet water to the outlet pipe.

[0039] Example 1 This embodiment adopts Figure 1 and 2 The high-salt food processing wastewater treatment system shown in the figure treats a certain company's pickled vegetable wastewater, with a pickled vegetable wastewater output of 40m 3 / day, the water quality of pickled vegetable wastewater: COD is 4000mg / L~7000mg / L, BOD is 2500mg / L~3000mg / L.

[0040] In the system described in this embodiment, the regulating homogenization tank is a thin and long tank type, 2m wide × 6m long × 3m deep, and is equipped with 4 1.5kw and 3.6m suction capacity units. 3 / h micro-nano jet aeration device; the aerated activated sludge tank is a thin and long type, 2m wide × 8m long × 5m deep, with a tank capacity of 80 m 3 , equipped with 4 3.7kw, air intake volume of 15m 3 / h micro-nano jet aeration device; 70% of the bubbles generated by the micro-nano jet aeration device have a particle size of about 100 nm, and the gas-liquid volume ratio is 1:3.

[0041] The system debugging operation control parameters described in this embodiment are: the water inlet volume is increased by 10%, 30%, 50%, 70% and 100% of the total water inlet volume each time, and the water inlet volume is increased when the effluent COD meets the discharge requirements.

[0042] The pickled vegetable wastewater treatment process is as follows: (1) The pickled vegetable wastewater is pre-treated in a screen tank to remove suspended solids and large particle impurities before entering the regulating homogenization tank; (2) Pre-aerate the wastewater in the micro-nano jet aeration device of the homogenization tank, and use the thrust of the aeration to stir the wastewater so that the wastewater is evenly mixed; the dissolved oxygen content in the homogenization tank is 1-3 mg / L, and the hydraulic retention time is 8-16 h; (3) The wastewater homogenized in step (2) enters an aerated activated sludge tank for aerobic decomposition, wherein aerobic activated sludge is added to the aerated activated sludge tank; aeration is performed in the aerated activated sludge tank by a micro-nano jet aeration device, and aeration thrust is utilized to stir the aerobic activated sludge and the wastewater, so that the aerobic activated sludge and the wastewater are fully and evenly mixed and contacted, and aerobic microorganisms in the aerobic activated sludge are utilized to decompose organic macromolecular compounds in the wastewater into small molecular substances; the MLSS sludge concentration in the aerated activated sludge tank is controlled to be ≥3000 mg / L, the hydraulic retention time is 12-24 h, the dissolved oxygen content is 4-8 mg / L, and the sludge settling volume ratio is SV30≈30%; (4) The wastewater after aerobic treatment in the aerated activated sludge tank enters the facultative aerobic tank at the front end of the membrane bioreactor, where the facultative aerobic bacteria, Bacillus halodurans, has both aerobic and facultative aerobic advantages to degrade the salinity of the wastewater and adjust the ion concentration of the wastewater, providing a guarantee for subsequent membrane filtration; The dissolved oxygen content (DO value) of the anoxic tank is 0.5~2mg / L, the sludge concentration (MLSS) is controlled at 5000~7000mg / L; the hydraulic retention time (HRT) is 4h~8h; The dosage of the salt-tolerant Bacillus is 0.03% of the capacity of the aerobic tank (g / m 3 ); (5) After being treated in the aerobic tank, the wastewater is divided into two parts. One part is returned to the regulating homogenization tank (the return ratio is 100%~200%) and the aerated activated sludge tank (the return ratio is 200%); the other part enters the submerged membrane filter tank, where a micro-nano jet aeration device is used for aeration and power is provided to make the wastewater pass through the membrane filtration component system. The filter membrane is used to further decompose the organic matter in the wastewater and separate the sludge in the wastewater to obtain effluent and sludge. The COD of the effluent is 20~30mg / L and the BOD is 5mg / L. The sludge is returned to the regulating homogenization tank and the aerated activated sludge tank for decomposition and digestion. The effluent that meets the standards is directly discharged, realizing the odorless and residual sludge-free treatment of high-salt food processing wastewater. In the submerged membrane filtration tank, the dissolved oxygen content (DO value) is ≥2mg / L, and the sludge concentration (MLSS) is controlled at ≥3000mg / L.

[0043] The aerobic activated sludge acclimation method in this embodiment is carried out according to the conventional method in the art, wherein the main process parameters are as follows: municipal dewatered sludge (water content 80%) + aerobic engineering bacteria (Bacillus subtilis, Bacillus sphaericus and Bacillus licheniformis) are added according to the sludge concentration MLSS ≥ 3000 mg / L; the step water inlet is increased by 10%, and the water is continuously inletted for 10 days; the dissolved oxygen content is 6 mg / L, and the mixed solution is refluxed 200% to the regulating homogenization tank; the dosage of aerobic engineering bacteria is 0.02% of the tank volume (g / m 3 ).

[0044] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-salt food processing wastewater treatment system, characterized in that: It includes a grid tank, a regulating homogenization tank, an aerated activated sludge tank, a membrane bioreactor and a micro-nano aeration system; the membrane bioreactor is divided into an aerobic tank and an immersed membrane filtration tank, the aerobic tank is located at the front end of the immersed membrane filtration tank, and the aerobic tank and the immersed membrane filtration tank are connected by a pipeline; the immersed membrane filtration tank is provided with a membrane filtration component system, a sludge outlet and a water outlet; The grid pool is provided with a wastewater inlet, the grid pool, the regulating and homogenizing pool and the aerated activated sludge pool are connected in sequence through pipelines, and the outlet pipe of the aerated activated sludge pool is connected to the anoxic pool; The outlet pipe of the anoxic tank is divided into two channels, one channel is connected to the submerged membrane filter tank, and the other channel is connected to the mixed liquor return pipe, and the outlet end of the mixed liquor return pipe is respectively connected to the regulating homogenization tank and the aerated activated sludge tank, so that part of the effluent of the anoxic tank flows back to the regulating homogenization tank and the aerated activated sludge tank; The sludge outlet of the submerged membrane filter tank is connected to the aerated activated sludge tank and the regulating and homogenizing tank respectively through a sludge return pipe, so that the sludge separated by the submerged membrane filter tank is returned to the regulating and homogenizing tank and the aerated activated sludge tank for decomposition and digestion; The micro-nano aeration system comprises a plurality of micro-nano jet aeration devices, a plurality of gas-liquid mixers, a water inlet pipe, an air pipe and a submersible pump. The micro-nano jet aeration devices are respectively installed in a regulating homogenization tank, an aerated activated sludge tank and an immersed membrane filtration tank. The number of the gas-liquid mixers is the same as the number of the micro-nano jet aeration devices. The submersible pump pumps water into the water inlet pipe, and the air introduced from the air pipe and the water introduced from the water inlet pipe are mixed by the gas-liquid mixer and then enter the micro-nano jet aeration devices respectively, so as to provide aeration for the regulating homogenization tank, the aerated activated sludge tank and the submerged membrane filtration tank.

2. The high-salt food processing wastewater treatment system according to claim 1, characterized in that: J-shaped water distribution pipes are installed on both sides of the oxygen-conducting tank, and the installation height is 20-30 cm from the bottom of the tank; the water outlet of the J-shaped water distribution pipe adopts a trumpet-shaped mushroom-head shower-type water distributor; the oxygen-conducting tank adopts a middle water inlet, so that the J-shaped water distribution pipes on both sides of the tank body distribute water evenly; an overflow trough is arranged at the tail end of the oxygen-conducting tank, and the wastewater treated in the oxygen-conducting tank overflows from the overflow trough to the outlet pipe and is divided into two parts, one part enters the submerged membrane filtration tank, and the other part flows back to the regulating homogenization tank and the aerated activated sludge tank.

3. The high-salt food processing wastewater treatment system according to claim 2, characterized in that: The trumpet-shaped mushroom-head shower-type water distributor has evenly opened holes with a hole diameter of 2-4 mm; the overflow groove is designed in a 1 / 4 arc shape.

4. The high-salt food processing wastewater treatment system according to claim 1, characterized in that: The bubble particle size generated by the micro-nano jet aeration device is 60nm~200nm, and the air intake mode of the micro-nano jet aeration device is autonomous suction; the gas-liquid volume ratio of air and water mixed in the gas-liquid mixer is 1:2~4; The membrane filtration component system uses a corrugated flat membrane as a filter membrane; The salinity tolerance of the corrugated flat membrane is ≥10000 mg / L, and the membrane pore size is 0.1 μm~0.5 μm.

5. The high-salt food processing wastewater treatment system according to claim 1, characterized in that: The regulating homogenizing pool is a thin and long pool type, with a water depth of 3-4m, a length-to-width ratio of (6-12):2, a single pool body length L between 6m≤L≤12m, and a minimum width of 2m; The aerated activated sludge tank is a long and narrow tank type, with a water depth of 1-5m, a length-to-width ratio of (6-12):2, a single tank body length L between 6m≤L≤12m, and a minimum width of 2m.

6. A method for treating high-salt food processing wastewater based on the system according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) The high-salt food processing wastewater to be treated is pre-treated in a screen tank, and the wastewater after removing suspended matter and large particle impurities enters the regulating homogenization tank; (2) Pre-aerate the wastewater in the regulating homogenization tank through a micro-nano jet aeration device, and use the thrust force generated by aeration to stir the wastewater so that the wastewater is evenly mixed; (3) The wastewater homogenized in step (2) enters an aerated activated sludge tank for aerobic decomposition, wherein aerobic activated sludge is added to the aerated activated sludge tank; the wastewater is aerated by a micro-nano jet aeration device in the aerated activated sludge tank, and the thrust force generated by the aeration is used for stirring, so that the aerobic activated sludge and the wastewater are fully and evenly mixed and contacted, and the aerobic microorganisms in the aerobic activated sludge are used to decompose organic macromolecular compounds in the wastewater into small molecular substances; (4) The wastewater after aerobic treatment in the aerated activated sludge tank enters the facultative aerobic tank, where facultative aerobic bacteria are added. The facultative aerobic bacteria in the facultative aerobic tank take advantage of their aerobic and facultative properties to degrade the salinity of the wastewater and adjust the concentration of ions in the wastewater. (5) After being treated in the aerobic tank, the wastewater is divided into two parts. One part is returned to the regulating homogenization tank and the aerated activated sludge tank; the other part enters the submerged membrane filtration tank, where a micro-nano jet aeration device is used for aeration and power supply, so that the wastewater passes through the membrane filtration component system, and the filter membrane is used to further decompose the organic matter in the wastewater and separate the sludge in the wastewater, so as to obtain effluent and sludge that meet the standards; The sludge is returned to the regulating homogenization tank and the aerated activated sludge tank for decomposition and digestion, and the effluent that meets the standards is directly discharged, thus achieving odorless and zero-residue sludge treatment of high-salt food processing wastewater.

7. The method according to claim 6, characterized in that The dissolved oxygen content of the regulating homogenization tank is 1-3 mg / L, and the hydraulic retention time is 8h-24h.

8. The method according to claim 6, characterized in that The dissolved oxygen content of the aerated activated sludge tank is 4-8 mg / L, the sludge concentration is controlled at 3000 mg / L-7000 mg / L, and the hydraulic retention time is 12h-48h.

9. The method according to claim 6, characterized in that The dissolved oxygen content of the anoxic tank is 0.5-2 mg / L, the sludge concentration is controlled at 5000-7000 mg / L, and the hydraulic retention time is 4-8 hours; Part of the wastewater treated by the mixed liquor in the aerobic tank directly enters the submerged membrane filtration tank, part of it flows back to the regulating homogenization tank with a return ratio of 100% to 300%, and part of it flows back to the aerated activated sludge tank with a return ratio of 100% to 200%.

10. The method according to claim 6, characterized in that The COD of the wastewater to be treated is 3000mg / L~20000mg / L, and the salt content is 1%~2%; The COD value of the effluent that meets the standards is ≤100mg / L, and the chloride value is ≤600mg / L.

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