Self-control type food wastewater advanced treatment reactor based on algal membrane and use method of self-control type food wastewater advanced treatment reactor

Abstract

The invention discloses an algal membrane-based self-controlled food wastewater advanced treatment reactor and a use method, and relates to the field of food production wastewater treatment, and the algal membrane-based self-controlled food wastewater advanced treatment reactor comprises a water absorption room, a microalgae biological treatment unit, an ultrafiltration membrane separation unit, an effluent and biomass collection device and a computer control system. The secondary treatment effluent of the food processing wastewater flows into the water absorption chamber through the water inlet pipe, most of original suspended matters are removed through the ceramsite layer and the gravel layer, the effluent enters the microalgae biological treatment unit through the water absorption pipe, and main residual pollutants such as nitrogen, phosphorus and organic matters in the secondary treatment effluent of the production wastewater are removed in the microalgae biological treatment unit. Meanwhile, microalgae utilize nutrient substances in the wastewater to accumulate biomass, and after the microalgae biomass is accumulated to a certain level, algae liquid of the microalgae biological treatment unit enters the ultrafiltration membrane separation unit to separate the microalgae from the wastewater, so that the traditional MBR treatment process is optimized, the occupied space is reduced, and the wastewater treatment efficiency is improved. The method has a wide application prospect in deep treatment of food production wastewater.

Description

Technical Field

[0001] The present invention relates to an algae membrane-based self-controlled food wastewater deep treatment reactor and a use method, belonging to the field of deep treatment of industrial wastewater. Background Art

[0002] In recent years, with the rapid development of the food industry, more than two-thirds of freshwater resources have been used for food production, and in some countries, it has even reached 90%. The food industry is also considered one of the three major industrial water-consuming industries. At the same time, the discharge of production wastewater has increased, and the environmental pollution problem has become more serious. Usually, food wastewater contains a large amount of pollutants such as nitrogen and phosphorus. Discharge into the ocean or river will inevitably cause eutrophication of the water body, further leading to the deterioration of the water body and the reduction of aquatic biodiversity. At the same time, it may cause the spread of diseases such as thyroid cancer and methemoglobin.

[0003] For food industry wastewater, the existing treatment processes mostly rely on water treatment processes based on the activated sludge method, which uses the effects of microorganisms in the metabolic process to achieve wastewater treatment. The main disadvantages of biological methods are long treatment cycles and poor shock load resistance. The food industry is affected by the seasonality of raw material supply, large production cycle changes, and obvious changes in water quality and water quantity. Under conventional treatment processes, it is usually difficult to treat, the treatment effect is unstable and the cost is high. However, the carbon source, nitrogen source, phosphate and various trace minerals contained in food cooking wastewater are a free, low-cost and sustainable alternative culture medium that can be used to cultivate various algae. At present, some companies have proposed a continuous flow reactor that combines sewage treatment with microalgae cultivation. The pollutants removed in the sewage under conventional processes are further treated by microalgae. This method has many disadvantages. One is that for the food industry with large changes in water quality and water quantity and obvious production cycles, it is not easy to accurately control the continuous flow reactor and it is easily affected by factors such as flow rate; the second is that the mixing conditions of the reactor are required to be high, otherwise it will lead to uneven concentration and affect the reaction efficiency. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides an algae-based self-controlled food wastewater deep treatment reactor and a method of use. The reactor has a small footprint, is environmentally friendly and beautiful, is easy to operate, and has stable effluent quality.

[0005] Technical solution: To solve the above technical problems, the present invention provides an algae membrane-based self-controlled food wastewater deep treatment reactor, comprising a water absorption room, a control room and a pump room, a microalgae biological treatment unit, an ultrafiltration membrane separation unit, a microalgae collection box, a water outlet box and a computer control system, wherein the water absorption room is provided with a water inlet pipe and a liquid level sensor, a ceramsite layer and a gravel layer are provided below the water inlet pipe, the water absorption pipe bell mouth should be located below the designed minimum liquid level of the water absorption room, and a filter screen is provided at the front end of the water absorption pipe to prevent debris from entering the water pump; the control room and the pump room are designed in an integrated manner with the water absorption room, a valve is installed on the water absorption pipeline of the water pump, a check valve and a valve are installed on the water pressure pipeline of the water pump, a base is arranged under the water pump, and a lifting pump start-stop control device is installed on the water pump; the microalgae biological treatment unit is composed of a plurality of groups of airlift photobioreactors connected in parallel, the effluent from the secondary treatment of food wastewater is transported to a single airlift photobioreactor through the water pressure pipeline of the water pump, and the airlift photobioreactor is used for the airlift photobioreactor to start and stop the water. An aeration plate is installed at the bottom to connect the aeration pipe, and an air pump is used for aeration. A temperature sensor, an absorbance detection sensor and a heating device are installed inside. An air pump start-stop control device is installed on the air pump. Three LED light strips are arranged in the microalgae biological treatment unit, which can control the opening and closing and the intensity of light. The ultrafiltration membrane separation unit contains several groups of ultrafiltration membrane components. The algae liquid treated by the microalgae biological treatment unit is separated in the ultrafiltration membrane separation unit by the suction action of the water pump, wherein the outlet water enters the outlet water tank, and a liquid level sensor is arranged in the outlet water tank. The concentrated algae liquid enters the microalgae collection box, and a liquid level sensor is arranged in the microalgae collection box. A backwash pipe is also arranged on the outlet water tank and the ultrafiltration membrane separation unit. A set of water pumps is installed on the pipeline, and a water pump start-stop control device is arranged on the water pump. The computer control system is composed of the above-mentioned liquid level sensor, the water pump start-stop control device, the air pump start-stop control device and the computer, and the PLC control system is installed in the control room and the pump room.

[0006] On the basis of the above scheme, as a further preferred scheme, the airlift photobioreactor in the microalgae biological treatment unit stores common Chlorella at an inoculation concentration of 1.0 g / L when used for the first time, and each photobioreactor connected in parallel is provided with a temperature sensor, an absorbance detection sensor and a heating device, and a light intensity sensor is provided outside the photobioreactor.

[0007] On the basis of the above scheme, as a further preferred scheme, in order to maintain a high effluent quality and extend the service life of the ultrafiltration membrane assembly, the self-controlled food wastewater deep treatment reactor based on algae membrane can realize the backwashing process of the ultrafiltration membrane assembly.

[0008] On the basis of the above scheme, as a further preferred scheme, the LED light strip in the biological treatment unit can dynamically adjust the power through a PLC controller according to the ambient light intensity detected by the light intensity sensor, so as to achieve energy saving and the optimal treatment effect of wastewater and microalgae biomass production efficiency.

[0009] On the basis of the above scheme, as a further preferred scheme, the ceramsite layer in the water absorption room (1) is laid with a thickness of 200 mm, wherein the ceramsite particle size is 10-20 mm; the gravel layer is laid with a thickness of 200 mm, wherein the gravel particle size is 10-30 mm.

[0010] On the basis of the above scheme, as a further preferred scheme, the method for using the algae membrane-based self-controlled food wastewater deep treatment reactor includes the following specific steps: reactor sterilization, initial inoculation of Chlorella, deep treatment of secondary food wastewater treatment effluent, and ultrafiltration membrane backwashing.

[0011] The reactor sterilization includes sterilization of the water absorption room, the photobioreactor, the ultrafiltration membrane assembly and the reactor pipeline. During sterilization, a certain concentration of chlorine dioxide is added to the water absorption room, and it is transported to the remaining units of the reactor by a water absorption pump and maintained for a certain period of time to complete the sterilization. After the sterilization is completed, sterile water is added to the water absorption room instead of chlorine dioxide, and the water absorption pump is used to complete the cleaning of the residual chlorine dioxide in each unit and pipeline of the reactor.

[0012] The initial inoculation of the Chlorella should be performed after the sterilization operation of the reactor is completed, and the Chlorella with an initial concentration of 1.0 g / L should be added to the inoculation port on the top of the photobioreactor.

[0013] The deep treatment process of the secondary treatment effluent of food wastewater includes two processes: biological treatment based on Chlorella and ultrafiltration membrane treatment. The effluent of the secondary treatment of food wastewater enters the water absorption room through the water inlet pipe, and the liquid level sensor transmits the monitored liquid level height to the PLC controller. When its height reaches the preset value, the water absorption pump, the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor are opened by the PLC controller, so that the secondary effluent to be treated enters the biological treatment unit. After the secondary effluent enters the photobioreactor, the water absorption pump, the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor are closed by the PLC controller. At the same time, the temperature sensor, the absorbance detection sensor and the heating device in the photobioreactor start working, and according to the values ​​collected by the temperature sensor and the light intensity sensor, the LED light strip and the heating device in the photobioreactor are kept at a suitable working power through the PLC controller. When the absorbance of the microalgae monitored by the absorbance detection sensor reaches a predetermined value and there is no obvious change for two consecutive days, the biological treatment process of the sewage is completed. At this time, the water outlet valve of the photobioreactor and the suction water pump of the ultrafiltration membrane are opened through the PLC controller, and the separation of algae water and the further purification process of the secondary treatment water are completed in the ultrafiltration membrane separation unit. In this process, the water outlet of the photobioreactor should be set at a certain distance from its bottom. The remaining undischarged algae liquid serves as the basis for the next biological treatment. After the ultrafiltration membrane treatment process is completed, the water outlet valve of the photobioreactor and the suction water pump of the ultrafiltration membrane are closed through the PLC controller.

[0014] The backwashing process of the ultrafiltration membrane should be carried out after the sewage deep treatment process has been running for a certain period of time. In order to ensure the effluent quality of the ultrafiltration membrane and the algae-water separation efficiency, and to extend the service life of the ultrafiltration membrane assembly, the ultrafiltration membrane device should be backwashed. When backwashing the ultrafiltration membrane device, the backwashing water pump is turned on by the PLC controller, and the valve is opened and closed. If necessary, the ultrafiltration membrane assembly should also be alkaline washed to thoroughly remove the organic pollutants and inorganic salts accumulated on the membrane surface, so as to further improve the filtration performance and the service life of the membrane.

[0015] On the basis of the above scheme, as a further preferred scheme, the biological treatment unit of the algae-based self-controlled food wastewater deep treatment reactor is composed of multiple photobioreactors in parallel, and the inlet and outlet valves, temperature sensors, and absorbance detection sensors of each photobioreactor can be individually controlled by a PLC controller. When the liquid level in the water absorption room reaches a predetermined value, the water absorption pump, pipeline valves, and the water inlet valve of a single photobioreactor are opened at the same time. After the water intake is completed, the temperature sensor, absorbance detection sensor, heating device, etc. in the reactor are turned on by the PLC controller to monitor and adjust the reaction conditions in the reactor to achieve refined control of the biological treatment stage.

[0016] The reactor of the present invention aims to solve the problem of large fluctuations in the quality and quantity of food processing wastewater and the unstable treatment effect of traditional water treatment technology. It proposes an algae membrane-based self-controlled food wastewater deep treatment reactor to treat the effluent from the secondary treatment of the traditional process, further improve the effluent quality while harvesting microalgae biomass, which can generate additional economic benefits. Compared with the existing common continuous flow microalgae bioreactors, the advantage of the present invention is that the bioreactor adopts a multiple parallel mode and is controlled separately, which can flexibly control the reaction rate and gradually add reactants, making it more suitable for treating water bodies with large changes in water quality and quantity such as food processing wastewater.

[0017] Beneficial effects: The algae membrane-based self-controlled food wastewater deep treatment reactor and use method of the present invention have the following advantages:

[0018] 1. An algae membrane-based self-controlled food wastewater deep treatment reactor integrates a water absorption room, a control room and a pump room, a microalgae biological treatment unit, an ultrafiltration membrane separation unit, a microalgae collection box, a water outlet box and a computer control system. As a deep treatment process after the traditional process, it has the characteristics of short treatment cycle and good treatment effect, and can produce additional microalgae value-added products.

[0019] 2. The key operating parameters of an algae-based membrane-based self-controlled food wastewater deep treatment reactor, such as the light intensity of the LED lighting strip, light-dark cycle, biomass accumulation level in the microalgae biological treatment stage, aeration volume, and water pressure before the membrane of the ultrafiltration membrane separation unit, can be preliminarily determined by small-scale and pilot tests in the laboratory stage, and adjusted during operation according to the treatment effect.

[0020] 3. The whole process of an algae-based self-controlled food wastewater deep treatment reactor can be completed by a PLC controller. The water quality parameters and equipment status during the sewage treatment process can be grasped in real time on the computer, and the treatment system can be optimally controlled to ensure the effluent quality while keeping the entire system in an efficient and energy-saving state.

[0021] 4. An algae membrane-based self-controlled food wastewater deep treatment reactor uses multiple photobioreactors in parallel in the microalgae biological treatment unit and can be controlled individually, which is convenient for fine control of the deep treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the reactor;

[0023] Figure 2 for Figure 1 Schematic diagram of top view;

[0024] Figure 3 This is a top view of the suction room, pump room and control room;

[0025] Figure 4 It is a schematic diagram of the structure of a single photobioreactor;

[0026] Figure 5 This is a schematic diagram of the control process of the algae film reactor;

[0027] Figure 6 Schematic diagram of the closed-loop temperature control process of the algae film reactor.

[0028] Among them, 1-water absorption room, 2-control room and pump room, 3-microalgae biological treatment unit, 4-ultrafiltration membrane separation unit, 5-microalgae collection box, 6-water outlet box, 7-water inlet pipe, 8-water absorption pipe, 9-first valve, 10-first water pump, 11-check valve, 12-second valve, 13-air pump, 14-LED light strip, 15-aeration plate, 16-water outlet pipe, 17-aeration pipeline, 18-airlift photobioreactor, 19-fourth water pump, 20-ultrafiltration membrane assembly, 21- The third valve, 22-backwash water pump, 23-first liquid level sensor, 24-lifting pump start-stop control device, 25-air pump start-stop control device, 26-water pump start-stop control device, 27-third liquid level sensor, 28-second liquid level sensor, 29-water pump start-stop control device, 30-PLC control system, 31-concentrated algae liquid discharge pipe, 33-recycling pipe, 34-ceramsite layer, 35-gravel layer, 37-suction water pump, 39-fourth valve, 40-backwash water drain pipe. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] like Figures 1 to 6 As shown, the algae membrane-based self-controlled food wastewater deep treatment reactor of the present invention consists of six parts: 1. a water absorption room, 2. a control room and a pump room, 3. a microalgae biological treatment unit, 4. an ultrafiltration membrane separation unit, 5. a microalgae collection box, and 6. a water outlet tank.

[0031] The water suction room 1 is built together with the control room and the pump room 2. The water suction room is provided with a secondary water inlet and outlet pipe 7 for food wastewater, a water suction pipe 8, and a ceramsite layer 34 and a gravel layer 35 on the lower side of the water inlet pipe. A first liquid level sensor 23 is also installed in the water suction room 1. The secondary water outflow of food wastewater enters the water suction room through the water inlet pipe 7 and passes through the ceramsite layer 34 and the gravel layer 35, and then enters the next treatment unit through the water suction pipe 8. The bell mouth of the water suction pipe 8 should be located below the lowest liquid level set in the water suction room. The liquid level sensor transmits data information to the PLC controller. When the liquid level in the water suction room is higher than the predetermined value, the PLC controller 30 located in the control room and the pump room controls the first water pump 10 to automatically start working. The secondary treated water outflow of food wastewater enters the water suction room through the water inlet pipe 7 and passes through the ceramsite layer 34 and the gravel layer 35, and then enters the next treatment unit through the first water suction pump 10.

[0032] The control room and pump room 2 are built together with the water absorption room 1. The control room and pump room 2 are designed with two floors. Two first water pumps 10 are installed on the first floor, one for use and one for standby, which will automatically switch after a certain period of time or when one of them fails. In addition, a water absorption pipeline 8, valve 9, check valve 11, etc. for secondary treatment of food wastewater are installed. A PLC control system 30 is installed on the second floor to receive signals from various monitoring devices in the reactor, and the computer can be viewed by management personnel. In order to facilitate the maintenance of instruments and equipment, lifting equipment is also installed on the second floor, and the two floors are connected by stairs. A lifting pump monitoring device is installed on the water pump, which can monitor the operating status of the lifting pump 10 in real time.

[0033] The microalgae biological treatment unit 3 is composed of a plurality of groups of airlift photobioreactors 18 connected in parallel, and an LED light strip 14 and a light intensity detection sensor are installed outside the reactor. When the PLC controller detects that the liquid level in the water absorption room reaches a predetermined value, a first water pump 10 delivers the secondary treated effluent of the food wastewater stored in the water absorption room to a single airlift photobioreactor 18 at a certain flow rate. A heating device, a temperature sensor and an absorbance detection sensor are installed inside the reactor. An aeration plate 15 is installed at the bottom of the reactor 18 and connected to an aeration pipe 17. An air pump 13 is used for aeration to keep the microalgae in a suspended state in the photobioreactor 18 at all times, and the carbon dioxide consumed by the photosynthesis of the microalgae itself is supplemented to adjust the pH. An air pump monitoring device 25 is installed on the air pump 13. The outlet pipe 16 is connected to the bottom of all airlift photobioreactors 18, and a suction water pump 37 is used to suck the algae liquid of the microalgae biological treatment unit 3 to the ultrafiltration membrane separation unit 4. In the microalgae biological treatment unit 3, three LED light strips 14 are arranged, and the opening and closing cycles and light intensity can be controlled by the PLC control system 30 in the control room and the pump room 2.

[0034] The microalgae biological treatment unit 3 is connected to the ultrafiltration membrane separation unit 4 through a fourth water pump 19. The ultrafiltration membrane separation unit 4 has several groups of ultrafiltration membrane components 20. The algae liquid treated by the microalgae biological treatment unit 3 is sucked into the ultrafiltration membrane separation unit 4 by a suction water pump 37. Under the suction of the suction water pump 37, the algae-water separation process is realized by the interception effect of the ultrafiltration membrane component 20, wherein the effluent enters the outlet water tank 6, and the collected effluent can be used for factory reuse, discharge and ultrafiltration membrane backwashing. A liquid level sensor 28 is provided in the outlet water tank, and the concentrated algae liquid enters the microalgae collection box 5, which can be used to supplement the algae species in the photobioreactor 18 or process microalgae products. A third liquid level sensor 27 is provided in the microalgae collection box. Under actual operating conditions, in order to reduce the pollution of the ultrafiltration membrane component and extend the service life of the ultrafiltration membrane component. After 24 hours of operation, the ultrafiltration membrane assembly needs to be backwashed. The first water pump 10 and the third valve 21 are closed by the PLC controller, the valve is opened and the backwash pump 22 located on the pipeline from the ultrafiltration membrane assembly to the water outlet tank is turned on. At this time, the backwash water will enter the ultrafiltration membrane separation unit through the backwash pipe to complete the ultrafiltration membrane flushing process, and then flow out of the ultrafiltration membrane separation unit through the outlet pipe 40 to complete the backwash process.

[0035] The airlift photobioreactor 18 is provided with an absorbance detection sensor. When the PLC controller detects that the absorbance of microalgae in the photobioreactor undergoing sewage biological treatment is low, the management personnel will be reminded to replenish the microalgae species in the reactor. After the PLC controller detects that the absorbance of microalgae reaches a predetermined value and has no significant change for two consecutive days, the algae liquid in the photobioreactor will be separated by an ultrafiltration membrane.

[0036] The microalgae collection box contains a third liquid level sensor 27 and a water outlet pipe 31. When the computer detects that the liquid level is too high, the computer will remind the management personnel to recycle the collected algae liquid.

[0037] The computer control system is composed of the above-mentioned liquid level sensor, temperature sensor, light intensity sensor, absorbance detection sensor, heating device, valve, water pump start-stop control device, air pump start-stop control device 25 and PLC control system 30, and the PLC control system 30 is installed in the control room and the pump room.

[0038] The specific settings are based on actual construction requirements and are not specifically limited in this application.

[0039] Preferably, in order to further improve the removal efficiency of nitrogen, phosphorus and organic matter in wastewater by microalgae, when it is monitored that the concentration of microalgae in the photobioreactor is too low, it can be adjusted by supplementing algae species.

[0040] Furthermore, in order to better meet the growth environment requirements of microalgae in the process of treating the effluent from the secondary treatment of food wastewater, the microalgae species inoculated in the airlift photobioreactor can be pre-cultured in a laboratory environment under the water quality.

[0041] Furthermore, in order to better meet the growth environment requirements of microalgae in the process of treating the effluent from the secondary treatment of food wastewater, small-scale and pilot-scale experiments can be carried out in the laboratory using the same wastewater, and the reactor parameters can be optimized in the process.

[0042] A method for using an algae membrane-based self-controlled food wastewater deep treatment reactor comprises the following steps:

[0043] (1) The reactor sterilization includes the sterilization of the water absorption room, the photobioreactor, the ultrafiltration membrane assembly and the reactor pipeline; during sterilization, a chlorine dioxide solution of a certain concentration is added to the water absorption room, and it is transported to the remaining units of the reactor by a water absorption pump and maintained for a certain period of time to complete the sterilization. After the sterilization is completed, sterile water is added to the water absorption room instead of chlorine dioxide, and the water absorption pump is used to clean the residual chlorine dioxide in each unit and pipeline of the reactor;

[0044] The initial inoculation of the Chlorella should be performed after the sterilization operation of the reactor is completed, and the Chlorella with an initial concentration of 1.0 g / L should be added to the inoculation port at the top of the photobioreactor;

[0045] The deep treatment process of the effluent from the secondary treatment of food wastewater includes two processes: biological treatment based on Chlorella and ultrafiltration membrane treatment. The effluent from the secondary treatment of food wastewater enters the water absorption room through the water inlet pipe, and the liquid level sensor transmits the monitored liquid level height to the PLC controller. When the height reaches the preset value, the water absorption pump, the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor are opened through the PLC controller, so that the secondary effluent to be treated enters the biological treatment unit. After the secondary effluent enters the photobioreactor, the water absorption pump, the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor are closed through the PLC controller. At the same time, the temperature sensor, absorbance detection sensor and heating device in the photobioreactor start working, and according to the values ​​collected by the temperature sensor and the light intensity sensor, the LED light strip and the heating device in the photobioreactor are kept at appropriate working power through the PLC controller; when the absorbance of the microalgae monitored by the absorbance detection sensor reaches a predetermined value and has no obvious change for two consecutive days, the biological treatment process of the sewage is completed; at this time, the water outlet valve of the photobioreactor and the suction water pump of the ultrafiltration membrane are turned on through the PLC controller, and the separation of algae water and the further purification process of the secondary treatment effluent are completed in the ultrafiltration membrane separation unit; in this process, the water outlet of the photobioreactor should be set at a certain distance from its bottom; the remaining algae liquid that has not been discharged is used as the basis for the next biological treatment. After the ultrafiltration membrane treatment process is completed, the water outlet valve of the photobioreactor and the suction water pump of the ultrafiltration membrane are closed through the PLC controller;

[0046] The backwashing process of the ultrafiltration membrane should be carried out after the sewage deep treatment process has been running for a certain period of time. In order to ensure the effluent quality of the ultrafiltration membrane and the algae-water separation efficiency, and to extend the service life of the ultrafiltration membrane assembly, the ultrafiltration membrane device should be backwashed. When backwashing the ultrafiltration membrane device, the backwashing water pump is turned on by the PLC controller, and the valve is opened and closed.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A self-controlled food wastewater deep treatment reactor based on algae membrane, characterized in that The invention comprises a water absorption room (1), a control room and a pump room (2), a microalgae biological treatment unit (3), an ultrafiltration membrane separation unit (4), a microalgae collection box (5), a water outlet box (6) and a PLC and computer control system (30); the water absorption room (1) is provided with a water inlet pipe (7) and a first liquid level sensor (23); a ceramsite layer (34) and a gravel layer (35) are provided below the water inlet pipe (7); a water absorption pipe (8) is located below the designed minimum liquid level of the water absorption room (1); a filter screen is provided at the front end of the water absorption pipe; the control room and the pump room (2) and the water absorption room (1) are integrated. The control room and the pump room (2) are provided with a first water pump (10), a first valve (9) is installed on the water suction pipe of the first water pump (10), a check valve (11) and a second valve (12) are installed on the pressure water pipe of the first water pump (10), and a lift pump start-stop control device (24) is installed on the first water pump (10); the microalgae biological treatment unit (3) includes an airlift photobioreactor (18), and the effluent from the secondary treatment of food production wastewater enters the microalgae biological treatment unit (3) through the water suction pipe (8) and is transported to the airlift photobioreactor ( 18), an aeration plate (15) is installed at the bottom of the airlift photobioreactor (18), the aeration plate (15) is connected to the air pump (13) through an aeration pipeline for aeration, an air pump start-stop control device (25) is installed on the air pump (13), the bottom of the airlift photobioreactor (18) is connected to a water outlet pipe (16), the water outlet pipe (16) is connected to an ultrafiltration membrane separation unit (4), and three LED light strips (14) are arranged in the microalgae biological treatment unit (3); the ultrafiltration membrane separation unit (4) has a plurality of groups of ultrafiltration membrane components (20), and the ultrafiltration membrane separation unit (25) is connected to the ultrafiltration membrane separation unit (4). The element (4) and the water outlet tank are provided with a suction water pump (37), and the algae-water separation process is realized through the interception effect of the ultrafiltration membrane assembly (20) under the suction action of the suction water pump (37), wherein the outlet water enters the water outlet tank (6), and a second liquid level sensor (28) is arranged in the water outlet tank, and the concentrated algae liquid enters the microalgae collection tank (5), and a third liquid level sensor (27) is arranged in the microalgae collection tank. A backwash pipe is also arranged between the water outlet tank and the ultrafiltration membrane separation unit, and a backwash water pump (22) is installed on the pipeline, and a water pump start-stop control device (29) is arranged on the backwash water pump (22).

2. The algae membrane-based self-controlled food wastewater deep treatment reactor according to claim 1, characterized in that: The airlift photobioreactor (18) in the microalgae biological treatment unit (3) stores 1.0 g / L of Chlorella at an inoculation concentration when used for the first time, and each of the photobioreactors connected in parallel is provided with a temperature sensor, an absorbance detection sensor and a heating device, and a light intensity sensor is provided outside the photobioreactor.

3. The algae membrane-based self-controlled food wastewater deep treatment reactor according to claim 1, characterized in that: The ceramsite layer (34) located in the water absorption room (1) has a laying thickness of 200 mm, wherein the ceramsite particle size is 10-20 mm; the gravel layer (35) has a laying thickness of 200 mm, wherein the gravel particle size is 10-30 mm.

4. The algae membrane-based self-controlled food wastewater deep treatment reactor according to claim 1, characterized in that: The microalgae biological treatment unit is composed of a plurality of groups of airlift photobioreactors connected in parallel, and the bottoms of the airlift photobioreactors are all connected to water outlet pipes.

5. A method for using an algae membrane-based self-controlled food wastewater deep treatment reactor as described in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Reactor sterilization: including sterilization of the water absorption room (1), the photobioreactor (18), the ultrafiltration membrane assembly (20) and the reactor pipeline. During sterilization, a chlorine dioxide solution of a certain concentration is added to the water absorption room (1), and is transported to the remaining units of the reactor by the first water pump (10) and maintained for a certain period of time to complete the sterilization. After the sterilization is completed, sterile water is added to the water absorption room instead of chlorine dioxide, and the first water pump is used to clean the residual chlorine dioxide in each unit and pipeline of the reactor; S2: adding Chlorella with an initial concentration of 1.0 g / L to the inoculation port at the top of the photobioreactor (18); S3: The effluent from the secondary treatment of food wastewater enters the water absorption room through the water inlet pipe. The first liquid level sensor (23) transmits the monitored liquid level height to the lift pump start-stop control device (24). When the liquid level reaches a preset value, the lift pump start-stop control device (24) opens the first water pump (10), the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor (18), so that the secondary effluent to be treated enters the biological treatment unit. After the secondary effluent enters the photobioreactor, the first water pump (10) is closed by the lift pump start-stop control device (24). ), the pipeline solenoid valve and the water inlet valve of the corresponding single photobioreactor (18), at the same time, the temperature sensor, absorbance detection sensor and heating device in the photobioreactor start to work, and according to the values ​​collected by the temperature sensor and the light intensity sensor, the LED light strip (14) and the heating device in the photobioreactor (18) are kept at appropriate working power through the PLC control system 30; when the absorbance of the microalgae monitored by the absorbance detection sensor reaches a predetermined value and there is no obvious change for two consecutive days, the biological treatment process of the sewage is completed; At this time, the water outlet valve of the photobioreactor (18) and the suction water pump (37) of the ultrafiltration membrane are opened through the PLC controller, and the separation of algae water and the further purification process of the secondary treatment effluent are completed in the ultrafiltration membrane separation unit (4); in this process, the water outlet of the photobioreactor should be set at a certain distance from its bottom; the remaining undischarged algae liquid is used as the basis for the next biological treatment. After the ultrafiltration membrane treatment process is completed, the water outlet valve of the photobioreactor (18) and the suction water pump (37) of the ultrafiltration membrane are closed through the PLC controller; S4: After the sewage deep treatment process has been running for a certain period of time, the backwash water pump (22) is turned on through the PLC controller (30), the fourth valve (39) is opened and the third valve (21) is closed.

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