Low-pressure ultrafiltration sewage treatment method and device based on bioelectrochemical enhancement and application

Abstract

The invention belongs to the technical field of wastewater treatment and recycling, and relates to a low-pressure ultrafiltration sewage treatment method and device based on bioelectrochemical enhancement and application. The treatment device consists of a water inlet tank, a constant water level water tank, a cathode, a resistor, a membrane assembly, a biological filter cake layer, a pre-filtering layer-anode, an ultrafiltration membrane, a water collecting device, a data acquisition module and a computer. The treatment device is used for treating effluent of a secondary sedimentation tank of a sewage plant and tail water of livestock and poultry breeding wastewater; on the basis of retaining nitrogen and phosphorus resources, deep removal of heavy metals and antibiotics is realized, propagation of resistance genes is inhibited, and safe reuse of nitrogen and phosphorus resources in effluent of sewage plants and tail water of livestock and poultry breeding wastewater can be realized. In the invention, low-pressure ultrafiltration adopts transmembrane pressure difference generated by gravitational potential energy to realize continuous flow filtration, coupled bioelectrochemistry utilizes electric energy generated by biodegradation of organic matters to realize reduction of heavy metals and deep removal of reinforced antibiotics, and the method has the advantages of greenness, low carbon and sustainability.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment and resource utilization, and specifically relates to a low-pressure ultrafiltration sewage treatment method and treatment device based on bioelectrochemical enhancement, as well as a method for deep treatment of sewage plant effluent and livestock and poultry breeding wastewater tail water. The treated water can retain nitrogen and phosphorus resources, has extremely low energy consumption, can effectively remove heavy metals, antibiotics and pathogens, and reduce the risk of resistance gene transmission, and can be used for agricultural irrigation. Background Art

[0002] The livestock and poultry farming industry and domestic sewage discharge a huge amount after treatment, but this type of wastewater is rich in nitrogen and phosphorus resources. If it can be re-irrigated into farmland after being treated to meet the standards, it can reduce the application of nitrogen and phosphorus fertilizers, and also meet the demand of "promoting the resource utilization of breeding waste."

[0003] Current processes such as anaerobic digestion and activated sludge process can effectively reduce conventional pollutants such as chemical oxygen demand (COD) and biological oxygen demand (BOD5), but the heavy metals and pathogens in the effluent are likely to exceed the limits of the Agricultural Irrigation Water Quality Standard. 2+ and Zn 2+ The rate of exceedance of standards reached 23.75%-73.9%, and 76.5% of effluents had excessive levels of E. coli. Furthermore, antibiotic concentrations in the effluent were high, with tetracyclines (TCs) reaching 388.02 μg / L and sulfonamides (SAs) reaching 21.24 μg / L. Furthermore, combined heavy metal-antibiotic pollution can enhance selective pressure, leading to an increased abundance of antibiotic resistance genes (ARGs). Direct reuse in agriculture can lead to contamination of the soil-crop system and pose public health risks.

[0004] Existing deep treatment technologies, such as constructed wetlands, can improve the removal rates of heavy metals and antibiotics, but the residual presence of pathogens such as fecal coliforms and the accumulation of ARGs are prominent issues. Membrane bioreactors can effectively remove pathogens through interception, but their high-pressure operation mode consumes a lot of energy and causes severe membrane fouling, which restricts their large-scale application. Furthermore, heavy metals in existing deep treatment technologies are primarily removed through adsorption and interception, without modifying the heavy metals themselves. The combined contamination of heavy metals and antibiotics increases selective pressure, leading to increased abundance of ARGs and heightened transmission risk.

[0005] Research has found that low-pressure ultrafiltration relies on microorganisms to achieve long-term flux stability. However, the accumulation of heavy metals and antibiotics in the biological filter cake layer can be toxic to the microorganisms, inhibiting their activity and exacerbating membrane fouling, thus affecting flux. Therefore, there is an urgent need to develop a new low-pressure ultrafiltration wastewater treatment device and method based on bioelectrochemical enhancement to effectively address these issues. Summary of the Invention

[0006] The purpose of the present invention is to provide a low-pressure ultrafiltration wastewater treatment method and treatment device coupled with a bioelectrochemical strategy. This treatment device and method are used to treat the effluent from the secondary sedimentation tank of a sewage treatment plant and the tailwater of livestock and poultry breeding wastewater. The treated water can be used for agricultural irrigation. This solves the problem of effectively removing heavy metals, antibiotics, and pathogens while preserving nitrogen and phosphorus resources in the water, reducing the risk of resistance gene transmission, and allowing the effluent from the secondary sedimentation tank of a sewage treatment plant and the tailwater of livestock and poultry breeding wastewater to be safely used in agriculture.

[0007] The purpose of the present invention is achieved through the following technical solutions: A low-pressure ultrafiltration wastewater treatment method based on bioelectrochemical enhancement comprises the following steps: A. The water in the water inlet tank 1 enters the constant water level tank 2; B. The float valve and water level sensor of the constant water level tank 2 control the liquid level difference between the liquid level of the constant water level tank 2 and the ultrafiltration membrane 8 to maintain 0.2-1.0 bar; C. After inoculation, the pre-filtration layer-anode 7 is laid on the ultrafiltration membrane 8. The biological filter cake layer 6 formed thereon removes organic matter and antibiotics through biological action; the biological filter cake layer 6, the pre-filtration layer-anode 7 and the ultrafiltration membrane 8 adsorb and retain heavy metals, pathogens and other substances; D. Microorganisms in the biological filter cake layer 6 can generate electrons by degrading organic matter and antibiotics, which are transmitted to the cathode 3 through the external circuit. Heavy metals are further removed by reduction at the cathode 3. E. Since heavy metals are effectively removed at the cathode 3 and antibiotics are enhancedly removed at the pre-filtration layer-anode 7, the accumulation of heavy metals and antibiotics in the biological filter cake layer 6 is reduced, thereby reducing the heavy metal-antibiotic selective pressure and reducing the generation of ARGs and the risk of ARGs transmission; F. The water in the constant water level tank 2 flows out after passing through the biological filter cake layer 6, the pre-filtration layer-anode 7, and the ultrafiltration membrane 8, and is collected in the water collection device 9.

[0008] A low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement, comprising a water inlet tank 1, a constant water level tank 2, a cathode 3, a resistor 4, a membrane assembly 5, a biological filter cake layer 6, a pre-filtration layer-anode 7, an ultrafiltration membrane 8, a water collection device 9, a data acquisition module 10, and a computer 11; The water inlet tank 1 is filled with collected sewage from the secondary sedimentation tank of the sewage treatment plant and tail water from livestock and poultry breeding. The bottom of the water inlet tank 1 is connected to the constant water level tank 2 through a pipeline equipped with a stop valve. A cathode 3 is installed in the constant water level tank 2, and the cathode 3 is connected to the pre-filtration layer-anode 7 in the membrane assembly 5 through a resistor 4 through a connecting wire. The bottom of the constant water level tank 2 is connected to the top of the membrane assembly 5 through a connecting pipeline, and a stop valve is installed on the connecting pipeline. The pre-filtration layer-anode 7 is directly laid on the ultrafiltration membrane 8, and a biological filter cake layer 6 is provided above the pre-filtration layer-anode 7. The membrane assembly 5 is provided with an operating pressure of 0.2-1.0 bar by the water depth, and the transmembrane pressure difference is achieved by using the gravitational potential energy generated by the corresponding water head. For continuous flow filtration, the side of the membrane assembly 5 is connected to the water collection device 9 through a connecting pipe, and a shut-off valve is also installed on the connecting pipe; the data acquisition module 10 is used to measure the voltage across the resistor 4; the computer 11 is used to collect the voltage data collected by the data acquisition module 10 and monitor the bioelectrochemical performance in real time.

[0009] Furthermore, the constant water level tank 2 is provided with a float valve and a water level sensor, which can control the amount of water flowing from the water inlet tank 1 into the constant water level tank 2, so that the liquid level difference between the liquid surface of the constant water level tank 2 and the ultrafiltration membrane 8 remains constant.

[0010] Furthermore, the fixed position of the cathode 3 is just submerged by the liquid level in the constant water level tank 2 .

[0011] Furthermore, the cathode 3 is made of carbon-based materials, including carbon paper, carbon felt, carbon rod, carbon fiber sheet, carbon brush, carbon foam, graphite plate, graphite rod, graphite sheet, graphite cloth, graphite particles, activated carbon and reticulated glassy carbon.

[0012] Furthermore, the resistor 4 is a 100-1000 ohm resistor.

[0013] Furthermore, the biological filter cake layer 6 is composed of the initially inoculated organisms, the filtered, retained and proliferated organisms, and the substances retained by the pre-filtration layer-anode 7 .

[0014] Furthermore, the pre-filter layer-anode 7 is selected from one of carbon-based materials, precious metals, metal oxides, or a combination of carbon-based materials and precious metals, or a combination of carbon-based materials and metal oxides; the carbon-based materials include carbon paper, carbon felt, carbon rods, carbon fiber sheets, carbon brushes, carbon foam, graphite plates, graphite rods, graphite sheets, graphite cloth, graphite particles, activated carbon and reticulated glass carbon; the precious metals include Au and Pd; the metal oxides include MnO2, WO3 and TiO2.

[0015] Furthermore, the ultrafiltration membrane 8 is a flat ultrafiltration membrane or a hollow fiber membrane.

[0016] An application of a low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement is used to treat the effluent from the secondary sedimentation tank of a sewage treatment plant and the tail water of livestock and poultry breeding wastewater. The treated water can be used for agricultural irrigation.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention can achieve mineralization and removal of antibiotics, as well as adsorption and retention of heavy metals, through the biological filter cake layer on the pre-filtration layer-anode; the present invention reduces membrane contamination by pollutants and increases flux through the repulsive effect generated by the pre-filtration layer-anode by introducing bioelectrochemistry; the electrons generated by the pre-filtration layer-anode can achieve reduction of heavy metal ions at the cathode through an external circuit, thereby passivating the heavy metals and losing their toxicity; the introduction of bioelectrochemistry can also enhance the removal of antibiotics, reduce the heavy metal-antibiotic selectivity pressure, reduce the abundance of ARGs, and thus reduce their transmission risk; the ultrafiltration membrane of the present invention can retain pathogens and ARBs , reducing the spread of ARGs; achieving the deep removal of pollutants, reducing the risk of resistance gene transmission and membrane pollution control multi-effect enhancement; this method achieves the deep removal of heavy metals and antibiotics on the basis of retaining nitrogen and phosphorus resources, and inhibits the spread of resistance genes, which can realize the safe reuse of nitrogen and phosphorus resources in sewage treatment plant effluent and livestock and poultry breeding wastewater tail water; in this method, low-pressure ultrafiltration uses the transmembrane pressure difference generated by gravitational potential energy to achieve continuous flow filtration, and the coupled bioelectrochemistry uses the electrical energy generated by biodegradation of organic matter to achieve heavy metal reduction and enhance the deep removal of antibiotics. The method has the advantages of being green, low-carbon and sustainable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic structural diagram of a low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to the present invention; Figure 2 Schematic diagram of chemical oxygen demand (COD) concentration changes over time; Figure 3 Schematic diagram of total nitrogen (TN) concentration changes over time; Figure 4 Schematic diagram of total phosphorus (TP) concentration changes over time; Figure 5 Schematic diagram of copper (Cu) concentration changing with time; Figure 6 Schematic diagram of the change of tetracycline concentration over time; Figure 7 Schematic diagram of the relative abundance of tetracycline resistance genes (ARGs) on days 30 and 60; Figure 8 Schematic diagram of flux changes from 0 to 60 days.

[0020] In the figure, 1. Water inlet tank 2. Constant water level tank 3. Cathode 4. Resistor 5. Membrane assembly 6. Biological filter cake layer 7. Pre-filtration layer - anode 8. Ultrafiltration membrane 9. Water collection device 10. Data acquisition module 11. Computer. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0022] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are used only to distinguish the description and should not be understood as indicating or implying relative importance.

[0023] The present invention introduces bioelectrochemical strategy into low-pressure ultrafiltration system to construct a sewage treatment device with integrated "pre-filtration layer-anode". Figure 1 As shown, the low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement of the present invention is composed of a water inlet tank 1, a constant water level tank 2, a cathode 3, a resistor 4, a membrane assembly 5, a biological filter cake layer 6, a pre-filtration layer-anode 7, an ultrafiltration membrane 8, a water collection device 9, a data acquisition module 10 and a computer 11.

[0024] Among them, the water inlet tank 1 is filled with collected sewage from the secondary sedimentation tank of the sewage treatment plant and livestock and poultry breeding wastewater tail water. The bottom of the water inlet tank 1 is connected to the constant water level tank 2 through a pipeline equipped with a stop valve. The constant water level tank 2 is provided with a float valve or other liquid level sensor, which can control the amount of water flowing from the water inlet tank 1 into the constant water level tank 2, so that the liquid level difference between the liquid level of the constant water level tank 2 and the ultrafiltration membrane 8 can be kept constant (0.2-1.0 bar).

[0025] A cathode 3 is installed in the constant water level tank 2, and the fixed position of the cathode 3 is just submerged by the liquid level in the constant water level tank 2; the cathode 3 is connected to the pre-filtration layer-anode 7 in the membrane assembly 5 through a resistor 4 through a connecting wire to realize the coupling of bioelectrochemistry and low-pressure ultrafiltration system.

[0026] The cathode 3 is made of carbon-based materials, including carbon paper (CP), carbon felt (CF), carbon rod (CR), carbon fiber sheet (CS), carbon brush (CB), carbon foam (CFO), graphite plate (GP), graphite rod (GR), graphite sheet (GS), graphite cloth (GC), graphite particles (GG), activated carbon (AC) and reticulated glassy carbon (RGC).

[0027] The resistor 4 is a 100-1000 ohm resistor.

[0028] The constant water level tank 2 is equipped with a float valve and a water level sensor to control the liquid level to remain constant.

[0029] The bottom of the constant water level tank 2 is connected to the top of the membrane assembly 5 through a connecting pipeline, and a stop valve is installed on the connecting pipeline.

[0030] The pre-filtration layer-anode 7 is directly laid on the ultrafiltration membrane 8, and a biological filter cake layer 6 is provided above the pre-filtration layer-anode 7. The biological filter cake layer 6 is composed of the initial inoculated organisms, the filtered and retained and proliferated organisms, and the substances retained by the pre-filtration layer-anode 7.

[0031] The pre-filter layer-anode 7 is selected from a carbon-based material, a precious metal, a metal oxide, or a combination of a carbon-based material and a precious metal, or a combination of a carbon-based material and a metal oxide. The carbon-based material includes carbon paper (CP), carbon felt (CF), carbon rod (CR), carbon fiber sheet (CS), carbon brush (CB), carbon foam (CFO), graphite plate (GP), graphite rod (GR), graphite sheet (GS), graphite cloth (GC), graphite granules (GG), activated carbon (AC), and reticulated glassy carbon (RGC). The precious metals include Au and Pd. The metal oxides include MnO2, WO3, and TiO2.

[0032] The ultrafiltration membrane 8 is a flat ultrafiltration membrane or a hollow fiber membrane.

[0033] The membrane assembly 5 is provided with an operating pressure of 0.2-1.0 bar by the water depth, and the transmembrane pressure difference is achieved by using the gravitational potential energy generated by the corresponding water head, which is a continuous flow filtration. The side of the membrane assembly 5 is connected to the water collection device 9 through a connecting pipe, and a stop valve is also installed on the connecting pipe.

[0034] The data acquisition module 10 is used to measure the voltage across the resistor 4, that is, the voltage generated by the bioelectrochemical device. The computer 11 is used to collect the voltage data collected by the data acquisition module 10 and monitor the bioelectrochemical performance of the device in real time.

[0035] The present invention is based on a low-pressure ultrafiltration wastewater treatment method enhanced by bioelectrochemical technology, comprising the following steps: A. The water in the water inlet tank 1 enters the constant water level tank 2; B. The float valve and water level sensor of the constant water level tank 2 control the liquid level difference between the liquid level of the constant water level tank 2 and the ultrafiltration membrane 8 to maintain a constant level (0.2-1.0 bar); C. After inoculation, the pre-filtration layer-anode 7 is laid on the ultrafiltration membrane 8. The biological filter cake layer 6 formed thereon removes organic matter and antibiotics through biological action; the biological filter cake layer 6, the pre-filtration layer-anode 7 and the ultrafiltration membrane 8 adsorb and retain heavy metals, pathogens and other substances; D. Microorganisms in the biological filter cake layer 6 can generate electrons by degrading organic matter and antibiotics, which are transmitted to the cathode 3 through the external circuit. Heavy metals are further removed by reduction at the cathode 3. E. Since heavy metals are effectively removed at the cathode 3 and antibiotics are enhancedly removed at the pre-filtration layer-anode 7, the accumulation of heavy metals and antibiotics in the biological filter cake layer 6 is reduced, thereby reducing the heavy metal-antibiotic selective pressure and reducing the generation of ARGs and the risk of ARGs transmission; F. The water in the constant water level tank 2 flows out after passing through the biological filter cake layer 6, the pre-filtration layer-anode 7, and the ultrafiltration membrane 8, and is collected in the water collection device 9.

[0036] The low-pressure ultrafiltration sewage treatment device and method based on bioelectrochemical enhancement of the present invention have the following advantages: 1. Pre-filtration layer - The anode is located at the deepest part of the water. The biological filter cake layer formed on it is in an anoxic / anaerobic state. The microorganisms in the biological filter cake layer, especially the electroactive microorganisms, use organic matter and antibiotics as electron donors to achieve mineralization and removal of antibiotics.

[0037] 2. The pre-filtration layer, the anode, formed from carbon-based materials, metal oxides, or a combination of both, can reduce direct blockage of membrane pores by metal contaminants, reducing membrane fouling and thus increasing flux. Furthermore, the electrostatic repulsion generated by the anode also reduces membrane fouling by contaminants, thereby increasing flux.

[0038] 3. The cathode is on the water surface and is in an aerobic state. The electrons generated by the anode can reduce heavy metal ions, thereby passivating heavy metals and losing their toxicity. For example, Cu 2+ Reduced to Cu, Cd 2+ Reduced to Cd, Se 4+ Reduced to Se, Cr 6+ Reduction to Cr 3+ .

[0039] 4. Due to the introduction of bioelectrochemistry, heavy metals are converted into other non-toxic valence states and removed by enhanced antibiotics, thereby reducing the heavy metal-antibiotic selective pressure, reducing the abundance of ARBs and ARBs, and thus reducing their transmission risk.

[0040] 5. Ultrafiltration membranes can intercept pathogens such as fecal coliforms and Ascaris eggs. They can also intercept ARBs and reduce the spread of ARBs and ARGs.

[0041] 6. Since the entire system has a low nitrogen and phosphorus removal efficiency, nitrogen and phosphorus resources are preserved. Furthermore, since the above process achieves deep removal of heavy metals and antibiotics and inhibits the spread of resistance genes, it can achieve safe reuse of nitrogen and phosphorus resources in sewage treatment plant effluent and livestock and poultry wastewater tailwater.

[0042] 7. Bioelectrochemistry uses biological methods to remove organic matter and antibiotics to generate electric current to achieve heavy metal reduction and enhance antibiotic removal. Low-pressure ultrafiltration uses the transmembrane pressure difference generated by the gravitational potential energy formed by water depth to achieve continuous flow filtration, both of which significantly save energy.

[0043] Example 1: A low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement consists of a water inlet tank 1, a constant water level tank 2, a cathode 3, a resistor 4, a membrane assembly 5, a biological filter cake layer 6, a pre-filtration layer-anode 7, an ultrafiltration membrane 8, a water collection device 9, a data acquisition module 10 and a computer 11.

[0044] The bottom of the water inlet tank 1 is connected to the constant water level tank 2 via a pipeline equipped with a shutoff valve. A cathode 3 is installed within the constant water level tank 2. The cathode 3 is a carbon brush connected in series via a titanium wire to a 1000-ohm resistor 4 and the pre-filter layer (anode 7) in the membrane assembly 5. A float valve is installed within the constant water level tank 2, and the bottom of the constant water level tank 2 is connected to the top of the membrane assembly 5 via a connecting pipeline equipped with a shutoff valve.

[0045] The pre-filtration layer - anode 7 is installed within the membrane assembly 5, above the ultrafiltration membrane 8, and is composed of carbon felt and MnO2. After inoculation and long-term filtration, the pre-filtration layer - anode 7 forms a biological filter cake layer 6 above it. The ultrafiltration membrane 8 utilizes a flat ultrafiltration membrane (UP150). The membrane assembly 5 operates at a transmembrane pressure differential of 0.007 MPa, achieved by a 70 cm liquid level difference between the constant water level tank 2 and the ultrafiltration membrane 8. The entire device provides continuous flow filtration.

[0046] The membrane assembly 5 is laterally connected to the water collection device 9 via a connecting pipe equipped with a shut-off valve. The data acquisition module 10 is used to measure the voltage of the resistor 4, i.e., the voltage generated by the bioelectrochemical process of the device. The computer 11 and the data acquisition module 10 are capable of receiving and processing the voltage data collected by the data acquisition module 10.

[0047] Example 2: A low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement consists of a water inlet tank 1, a constant water level tank 2, a cathode 3, a resistor 4, a membrane assembly 5, a biological filter cake layer 6, a pre-filtration layer-anode 7, an ultrafiltration membrane 8, a water collection device 9, a data acquisition module 10 and a computer 11.

[0048] The bottom of the water inlet tank 1 is connected to the constant water level tank 2 via a pipeline equipped with a shutoff valve. A cathode 3 is installed within the constant water level tank 2. The cathode 3 is a carbon rod, connected in series via a titanium wire to a 100-ohm resistor 4 and the pre-filtration layer (anode 7) in the membrane assembly 5. A float valve is installed within the constant water level tank 2, and the bottom of the constant water level tank 2 is connected to the top of the membrane assembly 5 via a connecting pipeline equipped with a shutoff valve.

[0049] The pre-filtration layer - anode 7 is installed within the membrane assembly 5, above the ultrafiltration membrane 8, and is composed of carbon felt and AC. The pre-filtration layer - anode 7 undergoes inoculation and long-term filtration, forming a biological filter cake layer 6 above it. The ultrafiltration membrane 8 utilizes a flat ultrafiltration membrane (UP100). The membrane assembly 5 achieves a transmembrane pressure differential of 0.01 MPa, generated by a 100 cm liquid level difference between the constant water tank 2 and the ultrafiltration membrane, as its operating pressure. The entire device provides continuous flow filtration.

[0050] The membrane assembly 5 is laterally connected to the water collection device 9 via a connecting pipe equipped with a shut-off valve. The data acquisition module 10 is used to measure the voltage of the resistor 4, i.e., the voltage generated by the bioelectrochemical process of the device. The computer 11 and the data acquisition module 10 are capable of receiving and processing the voltage data collected by the data acquisition module 10.

[0051] Example 3: A low-pressure ultrafiltration wastewater treatment method based on bioelectrochemical enhancement comprises the following steps: A. The water in the water inlet tank 1 enters the constant water level tank 2; B. The level difference between the liquid level of the constant water level tank 2 and the ultrafiltration membrane 8 is controlled by a float valve and a water level sensor to maintain 0.2-1.0 bar; C. After inoculation, the pre-filtration layer-anode 7 is laid on the ultrafiltration membrane 8. The biological filter cake layer 6 formed thereon removes organic matter and antibiotics through biological action; the biological filter cake layer 6, the pre-filtration layer-anode 7 and the ultrafiltration membrane 8 adsorb and retain heavy metals, pathogens and other substances; D. Microorganisms in the biological filter cake layer 6 can generate electrons by degrading organic matter and antibiotics, which are transmitted to the cathode 3 through the external circuit. Heavy metals are further removed by reduction at the cathode 3. E. Since heavy metals are effectively removed at the cathode 3 and antibiotics are enhancedly removed at the pre-filtration layer-anode 7, the accumulation of heavy metals and antibiotics in the biological filter cake layer 6 is reduced, thereby reducing the heavy metal-antibiotic selective pressure, reducing the generation of ARGs, and reducing the risk of ARGs transmission; F. The water in the constant water level tank 2 flows out after passing through the biological filter cake layer 6, the pre-filtration layer-anode 7, and the ultrafiltration membrane 8, and is collected in the water collection device 9.

[0052] Example 4: The treatment device in Example 1 was used to treat the effluent from the secondary sedimentation tank of a sewage treatment plant in Jilin. The water quality was as follows: COD value was 25-34 mg / L, ammonia nitrogen concentration was 5.3-8.9 mg / L, TN concentration was 17.6-23.5 mg / L, TP concentration was 0.7-0.9 mg / L, Cu 2+ The concentration is 0.4-0.9mg / L, and the tetracycline concentration is 89-106ug / L.

[0053] turn out: 1. Achieved >99.99% pathogen removal; 2. Water outlet Cu 2+ Concentration <0.1 mg / L; 3. The concentration of tetracycline in the effluent water is lower than the detection limit; 4. The water flux is stable at 1.4-2.3L / m 2 .h; 5. The TN concentration of the effluent is reduced to 12.3-21.5 mg / L; 6. The TP concentration of the effluent is reduced to 0.4-0.5 mg / L.

[0054] It can be seen that the treatment device of this embodiment can significantly reduce heavy metals, antibiotics and pathogens in water, maintain a relatively high concentration of nitrogen and phosphorus resources, and achieve safe and efficient resource utilization of wastewater.

[0055] Example 5: The tail water from a pig farm in Jilin Province was treated by the treatment device in Example 1. The water quality was as follows: COD value was 97.2-110.0 mg / L, ammonia nitrogen concentration was 19.5-21.5 mg / L, TN concentration was 36.2-38.7 mg / L, TP concentration was 3.0-3.3 mg / L, Cu 2+ The concentration is 1.4-1.6mg / L, and the tetracycline concentration is 388-435ug / L.

[0056] turn out: 1. Achieved >99.99% pathogen removal; 2. Water outlet Cu 2+ Concentration <0.3 mg / L; 3. The concentration of tetracycline in the effluent water should be maintained at 3.4-16.5ug / L; 4. The water flux is stable at 4.3.1-6.2L / m 2 .h; 5. The TN concentration of the effluent water dropped to 23.4-24.9 mg / L; 6. The TP concentration of the effluent is reduced to 2.2-2.5 mg / L.

[0057] It can be seen that the treatment device of this embodiment can significantly reduce heavy metals, antibiotics and pathogens in water, maintain a relatively high concentration of nitrogen and phosphorus resources, and achieve safe and efficient resource utilization of wastewater.

[0058] like Figure 2 As shown, the COD concentration of the influent is about 100 mg / L, and the effluent concentration does not exceed 40 mg / L when stable.

[0059] like Figure 3 As shown, the total nitrogen concentration in the influent is about 37 mg / L, and the effluent concentration is not less than 23 mg / L when stable, indicating that the total nitrogen removal is low and the nitrogen resources in the sewage are better retained.

[0060] like Figure 4 As shown, the total phosphorus concentration in the influent is about 3 mg / L, and the effluent concentration is not less than 2.2 mg / L when stable, indicating that the total phosphorus removal is low and the phosphorus resources in the sewage are better retained.

[0061] like Figure 5 As shown, the copper concentration in the influent is about 1.5 mg / L, and the effluent concentration is no higher than 0.3 mg / L when stable, indicating that heavy metal removal is good.

[0062] like Figure 6 As shown, the tetracycline concentration in the influent is about 400ug / L, and the effluent concentration is no higher than 17ug / L when stable, indicating that tetracycline is well removed.

[0063] like Figure 7 As shown, the relative abundance of tetracycline resistance genes in raw water and treated water was measured on the 30th and 60th days, respectively. It can be seen that the relative abundance of tetracycline resistance genes in wastewater after bioelectrochemical low-pressure ultrafiltration treatment was greatly reduced.

[0064] like Figure 8 As shown, when the system flux reaches stability, it stabilizes at 4.3-6.2L / m 2 .h, indicating that the flux can be stable and high when the system is running for a long time.

[0065] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A low-pressure ultrafiltration wastewater treatment method based on bioelectrochemical enhancement, characterized in that: The following steps are involved: A. Water in the water inlet tank (1) enters the constant water level tank (2); B. The float valve and water level sensor of the constant water level tank (2) control the liquid level difference between the liquid surface of the constant water level tank (2) and the ultrafiltration membrane (8) to maintain 0.2-1.0 bar; C. The pre-filtration layer-anode (7) is inoculated and laid on the ultrafiltration membrane (8). The biological filter cake layer (6) formed thereon removes organic matter and antibiotics through biological action; the biological filter cake layer (6), the pre-filtration layer-anode (7) and the ultrafiltration membrane (8) adsorb and retain heavy metals and pathogens; D. Microorganisms in the biological filter cake layer (6) can generate electrons by degrading organic matter and antibiotics, which are then transferred to the cathode (3) through an external circuit. Heavy metals are further removed at the cathode (3) through reduction. E. Since heavy metals are effectively removed at the cathode (3) and antibiotics are enhanced in the pre-filtration layer-anode (7), the accumulation of heavy metals and antibiotics in the biological filter cake layer (6) is reduced, thereby reducing the heavy metal-antibiotic selective pressure and reducing the generation of ARGs and the risk of ARGs transmission; F. The water in the constant water level tank (2) flows out after passing through the biological filter cake layer (6), the pre-filtration layer-anode (7), and the ultrafiltration membrane (8) and is collected in the water collection device (9).

2. A low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement, characterized by: It consists of a water inlet tank (1), a constant water level tank (2), a cathode (3), a resistor (4), a membrane assembly (5), a biological filter cake layer (6), a pre-filtration layer-anode (7), an ultrafiltration membrane (8), a water collection device (9), a data acquisition module (10) and a computer (11); The water inlet tank (1) contains collected sewage from the secondary sedimentation tank of the sewage treatment plant and tail water from livestock and poultry breeding wastewater. The bottom of the water inlet tank (1) is connected to the constant water level tank (2) via a pipeline equipped with a stop valve. A cathode (3) is installed in the constant water level tank (2). The cathode (3) is connected to the pre-filter layer-anode (7) in the membrane assembly (5) via a resistor (4) via a connecting wire. The bottom of the constant water level tank (2) is connected to the top of the membrane assembly (5) via a connecting pipeline equipped with a stop valve. The pre-filter layer-anode (7) is directly laid on the ultrafiltration membrane (8), and a biological filter cake layer (6) is provided above the pre-filter layer-anode (7). The membrane assembly (5) is provided with an operating pressure of 0.2-1.0 bar by the water depth, and the transmembrane pressure difference is achieved by using the gravitational potential energy generated by the corresponding water head. For continuous flow filtration, the side of the membrane assembly (5) is connected to the water collection device (9) through a connecting pipe, and a stop valve is also installed on the connecting pipe; the data acquisition module (10) is used to measure the voltage across the resistor (4); the computer (11) is used to collect the voltage data collected by the data acquisition module (10) and monitor the bioelectrochemical performance in real time.

3. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The constant water level tank (2) is provided with a float valve and a water level sensor, which can control the amount of water flowing from the water inlet tank (1) into the constant water level tank (2), so that the liquid level difference between the liquid surface of the constant water level tank (2) and the ultrafiltration membrane (8) remains constant.

4. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The cathode (3) is fixed at a position just submerged by the liquid surface in the constant water level tank (2).

5. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 4, characterized in that: The cathode (3) is made of carbon-based materials, including carbon paper, carbon felt, carbon rod, carbon fiber sheet, carbon brush, carbon foam, graphite plate, graphite rod, graphite sheet, graphite cloth, graphite particles, activated carbon and meshed glass carbon.

6. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The resistor (4) is a 100-1000 ohm resistor.

7. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The biological filter cake layer (6) is composed of initially inoculated organisms, filtered, retained and proliferated organisms, and substances retained by the pre-filtration layer-anode (7).

8. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The pre-filter layer-anode (7) is selected from one of carbon-based materials, noble metals, and metal oxides, or a combination of carbon-based materials and noble metals, or a combination of carbon-based materials and metal oxides; the carbon-based materials include carbon paper, carbon felt, carbon rods, carbon fiber sheets, carbon brushes, carbon foam, graphite plates, graphite rods, graphite sheets, graphite cloth, graphite particles, activated carbon, and reticulated glassy carbon; the noble metals include Au and Pd; and the metal oxides include MnO2, WO3, and TiO2.

9. The low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to claim 2, characterized in that: The ultrafiltration membrane (8) is a flat ultrafiltration membrane or a hollow fiber membrane.

10. Use of a low-pressure ultrafiltration sewage treatment device based on bioelectrochemical enhancement according to any one of claims 2 to 9, characterized in that: It is used to treat the effluent from the secondary sedimentation tank of a sewage treatment plant and the tail water of livestock and poultry breeding wastewater. The treated water can be used for agricultural irrigation.

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