Device and method for treating industrial organic wastewater by utilizing microelectrolysis and microbiological degradation

Abstract

The invention relates to a device and a method for treating industrial organic wastewater by using microelectrolysis and microbial degradation, belonging to the field of wastewater treatment, a wastewater injection pump injects organic wastewater into a bioreactor through a water inlet, pollutants in the organic wastewater are biodegraded by activated sludge, an aeration device releases rising bubbles from the bottom end of the bioreactor, and the bubbles are discharged from the bottom end of the bioreactor. Organic wastewater and activated sludge are evenly mixed through bubble rising and power of a wastewater injection pump, the first ceramic membrane assembly and the second ceramic membrane assembly are composed of a plurality of rows of iron-doped carbon ceramic membranes, the iron-doped carbon ceramic membranes in each row are arranged in parallel after being inclined, and iron-carbon material electrodes are arranged on the surfaces of the iron-doped carbon ceramic membranes. Each iron-doped carbon ceramic membrane in the first ceramic membrane assembly and the second ceramic membrane assembly is connected with a positive electrode and a negative electrode of a variable voltage electrode power supply for micro-electrolysis reaction, active species and electrons are released to participate in pollutant degradation, and treated wastewater flows into a water production pipe from the lower ends of the iron-doped carbon ceramic membranes and then flows out from an outlet of the water production pipe. And deep removal of pollutants is realized.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and specifically relates to a device and a method for treating industrial organic wastewater by utilizing micro-electrolysis and microbial degradation. Background Art

[0002] For traditional anaerobic treatment technologies, such as anaerobic sedimentation tanks and upflow anaerobic blanket methods, it is difficult to further reduce the concentrations of suspended solids and dissolved organic matter in the filtrate, which limits its application in high-level decontamination. In recent years, people have tried to introduce ceramic membrane microfiltration technology into anaerobic treatment processes to produce anaerobic ceramic membrane bioreactors (AnMBR). AnMBR technology integrates membrane separation, efficient sludge retention, and the synergistic effect of aerobic and anaerobic microorganisms. Compared with traditional processes, it has the advantages of higher removal rate, smaller footprint, and better sludge settling properties. However, AnMBR also has certain problems, such as a higher risk of membrane fouling and residual nutrients in the treated water. In addition, the activity of microorganisms in AnMBR is also difficult to improve, which seriously restricts its application in high-efficiency and deep treatment.

[0003] In recent years, micro-electrolysis technology has received extensive attention in the field of wastewater deep treatment. In general micro-electrolysis reactors, iron oxide is the most common anode material. When a weak voltage is applied, Fe 2+ The released electrons participate in the reduction reaction of pollutants. Compared with traditional electrolysis processes, micro-electrolysis technology has higher current efficiency and can avoid the side reactions produced by traditional electrolysis. In addition, the participation of iron ions can also improve the selectivity of the reaction and produce more valuable compounds. At the same time, people have also noticed that micro-electrolysis can stimulate extracellular electron-respiring bacteria such as power bacteria. These bacteria can use electrodes as electron acceptors under anaerobic conditions to promote the oxidative degradation of pollutants instead of oxygen. This technology is called microbial fuel cell (MFC) technology. In MFC, the electrons after anodic oxidation are obtained by extracellular electron-respiring bacteria and used for the degradation of various substrates, including organic matter and nutrients in wastewater. In addition, anodic oxidation can also produce substances such as hydrogen, which can also promote the metabolism of anaerobic bacteria.

[0004] In order to further exert the synergistic effect of micro-electrolysis and extracellular electron respiration, there are relevant reports combining the two into various traditional treatment processes, such as activated sludge process, anaerobic digestion process, etc., but the treatment efficiency is limited, and the removal rate of some difficult-to-degrade organic matter and nutrients is low. In addition, a large amount of energy consumption is required, such as ventilation and stirring, and the area occupied is large. The amount of sludge produced is large and the sludge treatment cost is high. The activity of biological strains is difficult to maintain and improve, and there is a risk of inactivation. Summary of the invention

[0005] In response to the problems existing in the prior art, the present invention proposes a device and method for treating industrial organic wastewater using micro-electrolysis and microbial degradation, combining micro-electrolysis, extracellular electron respiration and a bioreactor. The electrodes can provide hydrogen and other substances through micro-electrolysis reactions to activate the metabolism of extracellular electron-respiring bacteria. At the same time, the electrons released by the electrodes can also be used for the reduction reaction of pollutants to achieve deep removal.

[0006] The present invention is achieved through the following technical solutions:

[0007] A device for treating industrial organic wastewater by micro-electrolysis and microbial degradation, comprising a bioreactor, a variable voltage electrode power supply, a first ceramic membrane assembly and a second ceramic membrane assembly;

[0008] The bioreactor is used for perfusing activated sludge. A wastewater injection pump connected to the water inlet of the bioreactor is installed on one side of the bioreactor. The wastewater is industrial organic wastewater. The first ceramic membrane assembly and the second ceramic membrane assembly are both composed of a plurality of rows of iron-doped carbon ceramic membranes. The iron-doped carbon ceramic membranes in each row are tilted and arranged parallel to each other, and the angles between all the tilted iron-doped carbon ceramic membranes and the horizontal direction are equal.

[0009] The surface of the iron-doped carbon ceramic membrane is an iron-carbon material electrode. Each iron-doped carbon ceramic membrane in the first ceramic membrane assembly is connected to the positive electrode of the variable voltage electrode power supply, and each iron-doped carbon ceramic membrane in the second ceramic membrane assembly is connected to the negative electrode of the variable voltage electrode power supply. The bottom end of the bioreactor is fixedly connected to an aeration device, the lower ends of the first ceramic membrane assembly and the second ceramic membrane assembly are connected to the inlet of the water production pipe, and the outlet of the water production pipe is connected to a suction pump.

[0010] A further improvement of the present invention is:

[0011] The aeration device comprises a blower, an air delivery pipe and an aeration plate;

[0012] The gas pipeline includes a main pipeline, the end of which is divided into several branch pipelines after entering the bioreactor. The air outlet of the blower is connected to the inlet of the main pipeline. Each branch pipeline has several air outlets, and an aeration plate is installed at each air outlet. All aeration plates are located at the bottom of the bioreactor.

[0013] The first ceramic membrane assembly and the second ceramic membrane assembly are arranged in the bioreactor through a membrane tube support, an upper clamping plate and a lower clamping plate;

[0014] The bioreactor is a rectangular structure, and the membrane tube support is a frame of a rectangular structure. The length of the frame is smaller than the length of the bioreactor, the width of the frame is smaller than the width of the bioreactor, and the height of the frame is smaller than the height of the bioreactor. The center of the membrane tube support coincides with the center of the bioreactor. The upper clamp is clamped on the upper end surface of the inner wall of the membrane tube support in the horizontal direction, and the lower clamp is clamped on the inner wall of the membrane tube support near the bottom in the horizontal direction. A through hole with the same outer diameter as the iron-doped carbon ceramic membrane is provided in the upper clamp and the lower clamp, and the upper end of each iron-doped carbon ceramic membrane is inserted into the corresponding through hole of the upper clamp, and the lower end of each iron-doped carbon ceramic membrane is inserted into the corresponding through hole of the lower clamp, and the water production pipe and the aeration plate are located directly below the lower clamp in sequence.

[0015] The distance between two adjacent iron-doped carbon ceramic membranes in the first ceramic membrane assembly and two adjacent iron-doped carbon ceramic membranes in the second ceramic membrane assembly are equal, and the value is 1 to 3 times the outer diameter of the iron-doped carbon ceramic membrane. The distance between two adjacent iron-doped carbon ceramic membranes in the first ceramic membrane assembly and the second ceramic membrane assembly is 5 times the outer diameter of the iron-doped carbon ceramic membrane.

[0016] The iron-doped carbon ceramic membrane comprises a ceramic tube and a filter layer distributed on the outer wall of the ceramic tube. The filter layer is an iron-doped carbon ceramic membrane with nano-scale or micro-scale pores.

[0017] It also includes a backwash pump, which is connected to the outlet of the water production pipe through a backwash water inlet pipe.

[0018] A method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation, based on any one of the above-mentioned devices for treating industrial organic wastewater by using micro-electrolysis and microbial degradation, comprises the following steps:

[0019] S1, the wastewater injection pump injects the industrial organic wastewater into the bioreactor through the water inlet of the bioreactor, and the aeration device releases rising bubbles from the bottom of the bioreactor. The industrial organic wastewater and the activated sludge are mixed evenly by the rising bubbles and the power of the wastewater injection pump, and the pollutants in the industrial organic wastewater are biodegraded by the activated sludge;

[0020] S2, starting the variable voltage electrode power supply, the iron-carbon material electrodes on the surface of the first ceramic membrane assembly and the second ceramic membrane assembly undergo micro-electrolysis reaction, and a weak electric field is generated on the surface of the iron-carbon ceramic membrane, releasing active species and electrons to participate in the degradation of pollutants;

[0021] S3, start the suction pump, the treated wastewater is filtered through the iron-doped carbon ceramic membrane in the first ceramic membrane assembly and the second ceramic membrane assembly, water molecules and small molecules enter the inner side of the iron-doped carbon ceramic membrane through the membrane pores, and the purified water flows into the water production pipe from the lower end of the iron-doped carbon ceramic membrane, and then flows out from the outlet of the water production pipe.

[0022] Furthermore, in S1, the aeration device releases rising bubbles from the bottom of the bioreactor (4) to make the dissolved oxygen 0.1-0.3 mg·L -1 .

[0023] Further, the micro-electrolysis reaction in S2 has the following two modes:

[0024] Method 1 is: a variable voltage electrode power supply applies a voltage of 0.2 to 0.8 V to the first ceramic membrane assembly and the second ceramic membrane assembly to continuously perform a micro-electrolysis reaction;

[0025] Method 2 is to set the first ceramic membrane assembly and the second ceramic membrane assembly as the anode and cathode respectively, apply a voltage of 0.4 to 0.8 V, stop the micro-electrolysis reaction after 1 to 3 hours, then reverse the electrode polarity, reduce the voltage and continue the micro-electrolysis reaction for 25 to 35 minutes, and then return to the initial process for intermittent reversal cycle operation.

[0026] Furthermore, the current density in the method 1 is 5 to 20 mA / cm 2 In method 2, the micro-electrolysis reaction is stopped for 10 to 30 minutes, and then the electrode polarity is reversed, and the voltage is reduced by 0.2 V before continuing the micro-electrolysis reaction.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] The invention discloses a device for treating industrial organic wastewater by utilizing micro-electrolysis and microbial degradation. The device can be used to inject activated sludge into a bioreactor. A wastewater injection pump can inject the industrial organic wastewater into the bioreactor through a water inlet of the bioreactor. An aeration device can release rising bubbles from the bottom of the bioreactor. The rising bubbles and the power of the wastewater injection pump can be used to evenly mix the industrial organic wastewater and the activated sludge. Meanwhile, a necessary oxidation environment (microaerobic state) is provided for anaerobic biological reaction, so that the sludge is kept in a suspended state, precipitation is avoided, a certain shear force and flushing effect are generated, and excessive accumulation of pollutants on the membrane surface is prevented to block external membrane pores and delay membrane pollution. The activated sludge is rich in various anaerobic bacteria and facultative anaerobic bacteria, and contains a large number of extracellular electron-respiring bacteria that can transfer electrons inside the cell to terminal receptors outside the cell through membrane proteins (electrodes can be used as terminal electron receptors to oxidize and degrade organic pollutants and nutrients under anaerobic conditions, thereby improving the removal of COD, nitrogen and phosphorus), and acetobacter that can completely mineralize small and medium molecular organic matter such as acetate into inorganic matter such as carbon dioxide. Facultative anaerobes and Acetobacter are mainly responsible for hydrolyzing and acidifying complex organic pollutants into small molecules, providing substrates for subsequent degradation by extracellular electron-respiring bacteria. Facultative anaerobes, Acetobacter and extracellular electron-respiring bacteria are interdependent, forming a metabolic chain that synergistically degrades organic pollutants and inorganic nutrients. After starting the variable voltage electrode power supply, the structural design of the iron-doped carbon ceramic membrane in the first and second ceramic membrane assemblies can ensure that there is a certain flow space between the iron-doped carbon ceramic membranes to contact the liquid, but it will not be too dispersed to affect the filtration efficiency. The iron-carbon material electrode on the surface can carry out micro-electrolysis reaction, and aeration provides dissolved oxygen as an oxidant to the anode, which promotes the micro-electrolysis reaction and generates a weak electric field on the surface of the iron-doped carbon ceramic membrane, releasing the active species Fe 2+ , H + and OH - , participating in the degradation of pollutants. Start the suction pump, the treated wastewater can be filtered through the iron-doped carbon ceramic membrane in the first and second ceramic membrane components, water molecules and small molecules enter the inner side of the iron-doped carbon ceramic membrane through the membrane pores, while pollutants such as macromolecular organic matter and bacteria are blocked on the mixed liquid side by the nano- or micron-scale pores of the filter layer, and remain in the reactor to continue to degrade. The purified water can flow into the water production pipe from the lower end of the iron-doped carbon ceramic membrane, and then flow out from the outlet of the water production pipe, realizing biodegradation, filtration separation, aeration and stirring, and exerting the integrated function of micro-electric field stimulating microbial metabolism (extracellular electron transfer).

[0029] The present invention discloses a method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation. The rising bubbles generated by the aeration device and the power of the wastewater injection pump can continuously mix the industrial organic wastewater with the activated sludge until the mixture is uniform, provide the necessary microaerobic state for the anaerobic biological reaction, keep the sludge in a suspended state, avoid precipitation, generate a certain shear force and scouring effect, prevent the excessive accumulation of pollutants on the membrane surface from blocking the external membrane pores and delaying membrane pollution. The activated sludge is rich in various anaerobic bacteria and facultative anaerobic bacteria, and contains a large number of extracellular electron-respiring bacteria that can transfer electrons inside the cell to the terminal receptor outside the cell through membrane proteins. The electrode can be used as a terminal electron receptor to oxidize and degrade organic pollutants and nutrients under anaerobic conditions, thereby improving the removal of COD, nitrogen and phosphorus. The acetobacter can completely mineralize small and medium-molecule organic matter such as acetate into inorganic matter such as carbon dioxide. Facultative anaerobic bacteria and acetobacter hydrolyze and acidify complex organic pollutants into small molecules, providing substrates for the subsequent degradation of extracellular electron-respiring bacteria. The iron-carbon material electrodes on the surfaces of the first and second ceramic membrane components can perform micro-electrolysis reactions. Aeration provides dissolved oxygen as an oxidant to the anode, promoting the micro-electrolysis reaction, generating a weak electric field on the surface of the iron-doped carbon ceramic membrane and releasing active species Fe 2+ , H + and OH - The electrons released by the anode and the hydrogen produced by the cathode can activate the metabolism of microorganisms and enhance their ability to degrade organic pollutants. Hydrogen can degrade halogen-containing, difficult-to-degrade organic pollutants by reducing and dehalogenating. Electrons can activate the metabolism of extracellular electron-respiring bacteria, which can enhance the degradation of difficult-to-degrade organic pollutants by microorganisms and improve the removal effect of COD. 2+ It can promote the reduction reaction of pollutants to generate intermediates (small molecule organic matter and carboxylates), which is beneficial to biodegradation or chemical conversion and realizes resource utilization; some extracellular electron-respiring bacteria can remove nutrients and improve the efficiency of micro-electrolysis. Start the suction pump, and the treated wastewater can be filtered through the iron-doped carbon ceramic membrane in the first and second ceramic membrane assemblies. Water molecules and small molecules enter the inner side of the iron-doped carbon ceramic membrane through the membrane pores, while pollutants such as macromolecular organic matter and bacteria are blocked on the mixed liquid side by the nano- or micron-scale pores of the filter layer, and remain in the reactor to continue to degrade. The purified water can flow into the water production pipe from the lower end of the iron-doped carbon ceramic membrane, and then flow out from the outlet of the water production pipe. The present invention can significantly improve the removal effect of indicators such as COD, nitrogen and phosphorus nutrients in industrial organic wastewater. The field effect generated by micro-electrolysis can also improve the activity of microorganisms. At the same time, the electron transfer of the electrode can also directly participate in the transformation of pollutants into valuable intermediates, thereby improving the processing capacity of the bioreactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of the device for degrading and treating industrial organic wastewater according to the present invention;

[0031] Figure 2 for Figure 1 A top view of the interior of the bioreactor;

[0032] Figure 3 for Figure 1 Schematic diagram of wastewater filtration using iron-doped carbon ceramic membrane.

[0033] Wherein: 1-cable, 2-wire, 3-wire connector, 4-bioreactor, 5-upper card plate, 6-variable voltage electrode power supply, 7-iron-doped carbon ceramic membrane, 8-blower, 9-air transmission pipe, 10-membrane tube support, 11-water collecting pipe, 12-water production pipe, 13-aeration plate, 14-lower card plate, 15-water production port, 16-suction pump, 17-backwash pump, 18-backwash water inlet, 19-backwash water inlet pipe, 20-water inlet. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0035] See also Figure 1 The present invention discloses a device for treating industrial organic wastewater by using micro-electrolysis and microbial degradation, which integrates biodegradation, filtration separation, and aeration stirring, and exerts the effect of micro-electric field stimulating microbial metabolism (extracellular electron transfer). The device includes a variable voltage electrode power supply 6, a ceramic membrane bioreactor 4, an aeration plate 13, an iron-doped carbon ceramic membrane 7, a suction pump 16, and a backwash pump 17. A water outlet 15 is provided on the bioreactor 4, and the variable voltage electrode power supply 6 is used to provide a weak voltage to drive the micro-electrolysis reaction.

[0036] The bioreactor 4 is filled with activated sludge, and a wastewater injection pump connected to the water inlet 20 of the bioreactor 4 is installed on one side of the bioreactor 4 for injecting wastewater into the reactor and ensuring that the wastewater can be fully mixed with the activated sludge after entering the reactor. The wastewater is industrial organic wastewater. All the iron-doped carbon ceramic membranes 7 are spliced ​​together to form the first and second ceramic membrane assemblies, which serve as the anode and cathode. The surface of the iron-doped carbon ceramic membrane 7 is an iron-carbon material electrode. After the ceramic membrane assembly is arranged in the bioreactor 4, it is respectively connected to the positive and negative electrodes of the variable voltage electrode power supply 6. The bottom end of the bioreactor 4 is fixedly connected with an aeration device, specifically including a blower 8, an air pipe 9 and an aeration plate 13. The air pipe 9 includes a main pipeline, and its end is divided into several branch pipelines after penetrating into the bioreactor 4. The air outlet of the blower 8 is connected to the inlet of the main pipeline. Each branch pipeline has several air outlets, and an aeration plate 13 is installed at each air outlet. All aeration plates 13 are located at the bottom end of the bioreactor 4. The first and second ceramic membrane assemblies are arranged in the bioreactor 4 through a membrane tube support 10, an upper clamping plate 5 and a lower clamping plate 14. The lower end thereof is connected to the inlet of the water production pipe 12 through a water collecting pipe 11. The outlet of the water production pipe 12 is connected to a suction pump 16. The end of the water production pipe 12 connected to the suction pump 16 is provided with a water production port 15. During the membrane filtration process, the function of the suction pump 16 is to maintain a certain negative pressure or pressure difference to help the wastewater pass through the ceramic membrane, thereby completing the solid-liquid separation. The power of the suction pump usually needs to be designed and selected according to the actual sewage treatment flow, pipeline resistance and elevation requirements. Excessive power will increase unnecessary energy consumption, and too little power cannot meet the demand for effluent. If the processing capacity of the reactor is 500m3 / d, the power of the effluent pump is usually 5-10kW. The backwash pump 17 is connected to the outlet of the water production pipe 12 through the backwash inlet pipe 19.

[0037] The backwash pump 17 introduces water flow through the backwash water inlet 18. When the membrane assembly is contaminated or blocked, the backwash pump 17 cleans the membrane surface through reverse water flow to remove the blockage and restore the filtering function of the membrane. The backwash pump 17 cleans the filtering equipment by providing reverse water flow to remove impurities blocked on the filter screen or filter membrane, thereby restoring its filtering function. The working principle of the backwash pump generally involves controlling the backwash valve to spray high-pressure water flow in the reverse direction, thereby flushing away solid particles blocked on the filter screen or filter membrane. This cleaning process not only increases the filtering effect and filtering volume, but also improves the filtering accuracy without affecting the flow rate or filtering cycle, thereby increasing the water output without affecting other indicators. This design is intended to avoid the problem of garbage blocking the pipe mouth, and can effectively flush away garbage and dirt to maintain a good operating state.

[0038] Specifically, combined Figure 1 and Figure 2The bioreactor 4 is a rectangular parallelepiped structure, and the membrane tube support 10 is a rectangular parallelepiped frame, the length, width and height of which are all smaller than the corresponding parameters 9 (length, width and height) of the bioreactor 4. The center of the membrane tube support 10 coincides with the center of the bioreactor 4. The upper clamping plate 5 is clamped on the upper end surface of the inner wall of the membrane tube support 10 in the horizontal direction, and the lower clamping plate 14 is clamped on the inner wall of the membrane tube support 10 near the bottom in the horizontal direction. The upper and lower clamping plates 14 are provided with through holes with the same outer diameter as the iron-doped carbon ceramic membrane 7. The upper end of each iron-doped carbon ceramic membrane 7 is inserted into the through hole of the upper clamping plate 5, and the lower end is inserted into the through hole of the lower clamping plate 14. The water production pipe 12 and the aeration plate 13 are located directly below the lower clamping plate 14 in sequence.

[0039] The iron-doped carbon ceramic membrane 7 includes a ceramic tube and a filter layer. The ceramic tube serves as a support layer and mainly plays a supporting role. It is a hollow tube in the up and down directions, and has micropores in the cross-sectional direction for liquid to pass through. The filter layer is located outside the support layer and is an iron-doped carbon ceramic membrane with nano-scale or micron-scale pores. It plays a key role in filtering and separation, preventing bacteria and macromolecules from passing through but allowing small molecules and water molecules to pass through, thereby achieving solid-liquid separation. According to the size of the reactor, a hollow tubular iron-doped carbon ceramic membrane 7 with different fluxes (cross-sectional area and length) is selected and installed at a certain position inside the reactor. The total number of iron-doped carbon ceramic membranes 7 is a multiple of 4, and all iron-doped carbon ceramic membranes 7 are divided into two groups (first and second ceramic membrane assemblies) and the upper and lower ends are flush. The iron-doped carbon ceramic membranes 7 in each group are divided into two rows. The iron-doped carbon ceramic membranes 7 in each row are arranged parallel to each other after tilting. The angles of all tilted iron-doped carbon ceramic membranes 7 with the horizontal direction are equal, and the value is 60 to 70 degrees, forming a first ceramic membrane assembly and a second ceramic membrane assembly. The upper end of each iron-doped carbon ceramic membrane 7 in the first ceramic membrane assembly is connected to the positive electrode of the variable voltage electrode power supply 6, and the upper end of each iron-doped carbon ceramic membrane 7 in the second ceramic membrane assembly is connected to the negative electrode of the variable voltage electrode power supply 6. The ceramic membranes are arranged parallel to each other after being tilted, which can optimize the flow path of the water flow. The tilted arrangement can reduce the dead zone (area with slow flow or stagnation) in the reactor, ensuring that the wastewater can fully flow through each membrane surface, thereby improving the overall mass transfer efficiency. This arrangement method reduces the deposition of fouling substances on the membrane surface by increasing the water flow velocity on the membrane surface, effectively prolonging the service life of the membrane and slowing down membrane pollution. Because the water flow forms a certain angle with the tilted membrane surface, it can generate greater shear force and reduce the deposition of pollutants on the membrane surface. This shearing action is very critical to maintaining membrane permeability, helping to improve filtration efficiency and avoid membrane clogging. The tilted arrangement makes the electric field distribution between membrane components more uniform. In micro-electrolysis reactions, the uniformity of the electric field is very important for the generation of active species (such as Fe 2+ , H + and OH -) is crucial. The parallel and inclined arrangement not only ensures that the current density in each area of ​​the membrane surface is consistent, but also avoids the electric field from being concentrated in certain local areas, thereby improving the overall reaction efficiency. This arrangement method improves the efficiency of the micro-electrolysis reaction by extending the time that the liquid stays on the membrane surface, ensuring that the pollutants have sufficient contact with the membrane electrode. The longer contact time helps to degrade and remove pollutants more completely. The distance between the two adjacent iron-doped carbon ceramic membranes 7 in the first ceramic membrane assembly and the two adjacent iron-doped carbon ceramic membranes 7 in the second ceramic membrane assembly are equal, and the value is 1-3 times the outer diameter of the iron-doped carbon ceramic membrane 7 (the outer diameter of the ceramic membrane is 6mm-25mm), which can ensure that there is enough flow space between the iron-doped carbon ceramic membranes 7 to contact the liquid, and it will not be too evacuated to affect the filtration efficiency. A gap area is reserved in the middle position, which is the boundary area between the anode and the cathode. The distance between the two adjacent iron-doped carbon ceramic membranes 7 in the first ceramic membrane assembly and the second ceramic membrane assembly is 5 times the outer diameter of the iron-doped carbon ceramic membrane 7. The iron-doped carbon ceramic membrane 7 on one side is connected to the positive electrode of the variable voltage electrode power supply 6 as the anode region, and the iron-doped carbon ceramic membrane 7 on the other side is connected to the negative electrode of the variable voltage electrode power supply 6 as the cathode region. Specifically, the iron-doped carbon ceramic membrane 7 and the wire 2 can be connected through the wire connector 3, and then the wire 2 can be connected to the positive or negative electrode of the variable voltage electrode power supply 6 through the cable 1. Figure 1 There are 16 in each, totaling 32 on the left and right. This unique multi-level structural design can give the membrane component multiple functions of filtration separation, support reinforcement, and electrochemical activation, realizing an integrated reaction. Figure 3 The inner side and the outer side of the iron-doped carbon ceramic membrane 7 are respectively the filtrate side and the mixed liquid side (represented as the raw liquid in the figure, i.e., the mixed liquid of wastewater and activated sludge).

[0040] The specific preparation method of the iron-doped carbon ceramic membrane 7 is as follows: the raw materials include high-purity alumina (α-Al2O3) powder, nano iron powder (Fe), and activated carbon powder (C), Fe accounts for 5-10wt% of the total mass of all raw materials, and C accounts for 1-5wt% of the total mass of all raw materials. Deionized water and polyvinyl alcohol as a binder are added to form a ceramic slurry, which is fully mixed by ball milling to obtain a uniform suspended slurry, in which polyvinyl alcohol accounts for 1-5% of the total weight of the ceramic slurry. Combined with a ceramic tube, a ceramic membrane intermediate is prepared by a phase tube method, and then dried and solidified into a shape. The temperature is gradually increased to 1400-1600°C in a muffle furnace and then kept warm for 3-5 hours. The heating rate is controlled at 2-5°C / min. Avoid material cracking or structural defects caused by too fast temperature rise and fall. For example, if the final sintering temperature is set to 1500℃, the following heating program can be adopted: room temperature-400℃, heating rate 2℃ / min, 400℃-800℃, heating rate 3℃ / min, 800℃--1500℃, heating rate 5℃ / min, cooling naturally to room temperature, and obtaining a dense phase structure of iron-doped carbon ceramic membrane. The iron-carbon material electrodes are evenly distributed on the surface, which is an in-situ micro-electrolysis and filtration composite functional electrode. The ceramic membrane can be partially immersed in the liquid surface or completely immersed, which is easier to operate, avoiding the problem of local uneven distribution when installing electrodes separately, and achieving more efficient micro-electrolysis. After high-temperature sintering, the iron-carbon particles and the ceramic matrix will form a good chemical bond, enhance the affinity between the two, and improve the stability of the electrode. Compared with the external electrode, the doped electrode does not need to pass through the membrane layer, which can reduce the resistance to the permeating fluid.

[0041] The present invention discloses a method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation, comprising the following steps:

[0042] Step 1: The activated sludge from the anaerobic tank of the municipal sewage treatment plant is injected into the reactor at one time. The injection volume of the activated sludge is half of the reactor volume. The industrial organic wastewater in the sump enters the reactor through the water inlet and is evenly distributed in the activated sludge layer, ultimately ensuring that the sludge concentration in the reactor is between 10,000 and 25,000 mg / L. The wastewater and activated sludge are continuously mixed in the reactor through aeration and wastewater injection pumps. The aeration disk releases fine bubbles to make the dissolved oxygen (DO) 0.1-0.3 mg·L -1, using the power of rising bubbles to mix the liquid and sludge, so that the sludge remains suspended, avoiding sedimentation, generating a certain shear force and flushing effect, preventing excessive accumulation of pollutants on the membrane surface from clogging the external membrane pores and delaying membrane pollution, and combining with the wastewater injection pump to ensure that the wastewater can be evenly distributed in the activated sludge layer, avoiding local overload, and fully contacting and reacting the sludge and wastewater, so that the pollutants are gradually fully biodegraded by the activated sludge. Micro-aeration is more helpful in improving the effect of anaerobic biological treatment. Micro-aeration can effectively increase methane production and stabilize the anaerobic digestion process by regulating the microbial community and promoting the growth of facultative taxa. In addition, micro-aeration can also accelerate the hydrolysis process, remove hydrogen sulfide, and affect the diversity of microorganisms, thereby promoting the anaerobic digestion (AD) process. Activated sludge is rich in various anaerobic and facultative anaerobic bacteria, including a large number of extracellular electron-respiring bacteria that can transfer electrons inside the cell to the terminal receptors outside the cell through membrane proteins (electrodes can be used as terminal electron receptors to oxidize and degrade organic pollutants and nutrients under anaerobic conditions, thereby improving the removal of COD, nitrogen and phosphorus), and Acetobacter that can completely mineralize small and medium-molecule organic matter such as acetate into inorganic substances such as carbon dioxide. Facultative anaerobic bacteria and Acetobacter are mainly responsible for hydrolyzing and acidifying complex organic pollutants into small molecules, providing substrates for the subsequent degradation of extracellular electron-respiring bacteria. Facultative anaerobic bacteria, Acetobacter, and extracellular electron-respiring bacteria are interdependent, forming a metabolic chain that synergistically degrades organic pollutants and inorganic nutrients.

[0043] Step 2: The iron-doped carbon ceramic membrane components installed in the reactor undergo micro-electrolysis after being powered on, generating a weak electric field on the membrane surface, releasing electrons to participate in the degradation of pollutants. At the same time, the micro-electrolysis reaction will produce reducing substances such as hydrogen, promote the oxidative degradation of organic pollutants, and further improve the removal effect of pollution indicators such as COD.

[0044] Step 3, start the suction pump 16, and the treated wastewater is filtered synchronously or intermittently through the ceramic membrane assembly, so that the hydraulic retention time is 6 to 8 hours. Water molecules and small molecules enter the filtrate side through the membrane pores to obtain purified water, while pollutants such as macromolecular organic matter and bacteria are blocked on the mixed liquid side by the nano-scale or micron-scale pores of the filter layer and remain in the reactor for further degradation. The purified water is discharged from the reactor from the water outlet 15 through the water collection pipe 11 and the water production pipe 12, and enters the next step of treatment or direct discharge. The suction pump 16 can maintain the continuous flow of wastewater and activated sludge, which can increase the contact opportunity between the membrane and the liquid, and help to evenly distribute the pollutant load and biological nutrients.

[0045] Two treatment methods are designed for micro-electrolysis in step 2: Treatment method 1 is membrane surface micro-electrolysis, and the specific process steps are as follows:

[0046] Step 2a, turn on the variable voltage electrode power supply 6, energize the iron-doped carbon ceramic membrane assembly 7, and the iron-doped carbon ceramic membrane assembly 7 starts to work, and applies a voltage of 0.2-0.8V, specifically 0.4-0.6V, to perform micro-electrolysis on the membrane surface. Aeration provides dissolved oxygen as an oxidant to the anode to promote the micro-electrolysis reaction.

[0047] Forward reaction: Anode: Fe->Fe 2+ +2e - (Iron Oxidation); 2H2O->O2+4H + +4e - (Water oxidation), cathode: O2+4e - +2H2O->4OH - (oxygen reduction), producing active species Fe 2+ , H + and OH - , improve the removal effect of COD, Fe 2+ It can promote the reduction reaction of pollutants to generate intermediates (small molecule organic matter and carboxylates), which is beneficial to biodegradation or chemical transformation and realizes resource utilization.

[0048] Too low a voltage (<0.2V) cannot effectively stimulate the micro-electrolysis reaction, and too high a voltage (>0.8V) will cause side reactions, such as Fe 2+ ->Fe 3+ , and produces a large amount of hydrogen, which not only consumes more electricity, but also inhibits the growth of anaerobic bacteria in AnMBR. The current density is 5-20mA / cm 2 , specifically 10-15mA / cm 2 This has the following effects: First, the anode iron material will dissolve faster to generate Fe 2+ ions, accompanied by the production of hydrogen. 2+ and H2 are key active species for micro-electrolysis enhancement; secondly, they provide electrons for extracellular electron-respiring bacteria (such as iron-reducing bacteria), activate their metabolism, help produce reactive oxygen and free radicals, and promote the degradation of pollutants (organic matter and ammonia nitrogen); thirdly, they are conducive to the production of ·OH, H2O2, as well as SO4-·, CO2-· on the anode surface. These species can oxidize and degrade some difficult-to-degrade organic pollutants, preventing over-electrolysis and energy waste. Current density is too high (>20mA / cm 2 ) will lead to excessive H2 production, which is not conducive to anaerobic reactions and will also trigger side reactions; Fourth, it can moderately inhibit cathode passivation and the deposition of pollutants on the membrane surface, which is beneficial to the maintenance of membrane filtration separation performance.

[0049] Some extracellular electron-respiring bacteria can remove nutrients and improve the efficiency of micro-electrolysis (nitrate-reducing bacteria can use nitrate (NO3-) as the terminal electron acceptor for respiration. Under anaerobic conditions, they transfer the electrons obtained from the oxidation of organic matter or hydrogen to nitrate, reducing nitrate to gaseous products such as nitrogen or nitric oxide, thereby removing nitrate from the water. Some iron-reducing bacteria, such as Geobacter, can use soluble iron (Fe3+) as an electron acceptor for respiration, transferring the electrons obtained from the oxidation of organic matter to Fe3+, reducing Fe3+ to Fe2+. Fe2+ can further combine with phosphate ions to form iron phosphate precipitates, thereby removing phosphate from the water. Extracellular electron-respiring bacteria can also directly transport electrons inside the cell to external acceptors such as iron oxides and electrodes through membrane proteins. In this process, they oxidize substrates such as organic matter or hydrogen to obtain electrons, and transport the electrons outside the cell to degrade some complex organic pollutants that are difficult to be directly used by organisms.

[0050] The metabolism of extracellular electron-respiring bacteria will produce soluble intermediates and extracellular secretions, which will lead to different degrees of membrane pollution. For example, the intermediates in the treatment of leather wastewater mainly include small molecular fatty acids, alcohols and ketone compounds, aromatic intermediates, phenols and phenolic acids, disulfides and hydrogen sulfide. In the process of degradation of organic matter by extracellular electron-respiring bacteria, complex organic molecules such as proteins and polysaccharides will first be hydrolyzed into small molecular organic acids such as acetic acid, propionic acid, butyric acid, etc. These small molecular fatty acids are soluble intermediates. When some extracellular electron-respiring bacteria degrade special organic molecules, they will produce soluble intermediates such as methanol, ethanol, acetone and other alcohols and ketones. When degrading some aromatic compounds such as phenol and naphthalene, soluble intermediates such as muconate and catechol will be generated first. When degrading complex aromatic polymers such as lignin, soluble intermediates such as phenols and phenolic acids such as pyrophenol and coumaric acid will be produced. Some extracellular electron-respiring bacteria can also reduce sulfates and other substances to disulfides or hydrogen sulfide under anaerobic conditions.

[0051] Treatment method 2 is intermittent reversal operation, and the specific process steps are as follows:

[0052] Step 2b, turning on the variable voltage electrode power supply 6, the iron-carbon material electrode installed on the surface of the iron-doped carbon ceramic membrane assembly 7 starts working in mode 1, and performs the intermittent reversal voltage operation of mode 2, using the existing power supply control device to cycle, and the activated sludge is kept in a suspended state through the aeration disk 13;

[0053] Mode 1: Set one set of electrodes as anode and the other set as cathode, apply 0.4-0.8V voltage, current density 10-15mA / cm 2After starting the micro-electrolysis reaction for 1-3 hours, set an intermittent rest phase of 10-30 minutes to stabilize the system.

[0054] Mode 2: Switch to iron ion recovery mode, reverse the electrode polarity, set the previous anode to cathode, and the cathode to anode. Current density 1-10mA / cm 2 , and at the same time reduce the applied voltage by 0.2V for 30 minutes. At this time, electrons will flow from the anode to the cathode, and iron ions will undergo an in-situ reduction reaction on the electrode surface and deposit. In addition, the power control device can also monitor the current and measure the amount of electricity to monitor the reaction process.

[0055] Reversing the electrode reduces the micro-electrolysis voltage for a period of time. When the electrode polarity is reversed and the original anode becomes a new cathode, the extracellular electron-respiring bacteria (such as iron-reducing bacteria) transfer the electrons obtained from the oxidation of organic matter at the anode to the new cathode surface through the extracellular electron transfer pathway. The cathode surface is enriched with electrons from the oxidation of organic matter, forming a potential difference with the anode, which can capture and store this part of the electrical energy after the electrons are released. While the cathode is recovering electrical energy, the external voltage is appropriately reduced to avoid excessive energy consumption. By alternating in this way, a cycle of micro-electrolysis reaction at the anode and electrical energy recovery at the cathode is achieved. The advantage of this method is that the surface area and active sites of the cathode and anode are fully utilized. When micro-electrolysis is carried out at the anode, more hydrogen and active species can be produced to promote extracellular electron transfer. In the stage of recovering electrical energy at the cathode, the catalytic effect of microorganisms is utilized to improve the electron transfer efficiency, thereby obtaining a higher hydrogen yield and electron transfer rate.

[0056] Treatment method 1 (membrane surface micro-electrolysis): hydrogen production rate is about 0.15-0.25m 3 / (m 3 reactor volume) / day, the electron transfer rate is about 20-30mA / m 2 (m 2 =Membranes area). Treatment method 2 (intermittent reversal operation): hydrogen yield is about 0.3-0.5m 3 / m 3 (reactor volume) / day, the electron transfer rate is about 40-60mA / m 2 (m 2 = (membrane area). Compared with treatment method 1, treatment method 2 increases hydrogen yield by 1-2 times and electron transfer rate by 1.5-2 times.

[0057] When micro-electrolysis is carried out at the anode, more electrons and reducing species (such as hydrogen) can be provided. The catalytic effect of microorganisms is utilized in the stage of recovering electricity at the cathode. The two synergistically promote the overall reaction efficiency. The microenvironmental disturbance caused by the reversal also helps to accelerate material transfer and refresh the reaction interface. The voltage regulation of intermittent reversal operation can avoid energy loss caused by excessive voltage. In the time dimension, the anode and cathode can effectively divide the work and continuously drive the reaction. The combined effect of the above factors has significantly improved the hydrogen yield and electron transfer rate of treatment method 2 compared with treatment method 1. At the same time, it also has the characteristics of a microbial fuel cell system and can recover part of the electrical energy.

[0058] Example 1

[0059] The micro-electrolysis in step 2 is carried out using treatment method 1, and the remaining steps remain unchanged.

[0060] The voltage of the variable voltage electrode power supply 6 is 0.4V and the current density is 10mA / cm 2 The temperature of the mixed system of activated sludge and wastewater was 35°C, pH 7.5, and micro-electrolysis was carried out on the membrane surface.

[0061] The COD and ammonia nitrogen concentrations after treatment were reduced by 25% and 15% respectively compared with those before treatment.

[0062] Example 2

[0063] The micro-electrolysis in step 2 is carried out using treatment method 2, and the remaining steps remain unchanged.

[0064] The voltage of the variable voltage electrode power supply 6 is 0.6V, and the current density is 15mA / cm 2 , the temperature of the mixed system of activated sludge and wastewater was 35 °C, pH 7, and after micro-electrolysis on the membrane surface for 2 hours, an intermittent rest stage of 20 min was set;

[0065] Then reverse the operation, switch the electrode polarity, and the current density is 8mA / cm 2 , reducing the applied voltage by 0.2V for 30 minutes, and recovering the electric energy at the cathode. Then the operation is reversed and repeated alternately. The COD and phosphorus concentrations after treatment were reduced by 40% and 30% respectively compared with the wastewater before treatment.

[0066] It can be seen from the examples that, compared with the traditional AnMBR, the present invention can significantly improve the removal effect of COD and ammonia nitrogen indicators through micro-electrolysis and the stimulation of extracellular electron-respiring bacteria.

Claims

1. A device for treating industrial organic wastewater using micro-electrolysis and microbial degradation, characterized in that: It comprises a bioreactor (4), a variable voltage electrode power supply (6), a first ceramic membrane assembly and a second ceramic membrane assembly; The bioreactor (4) is used for perfusing activated sludge. A wastewater injection pump connected to a water inlet (20) of the bioreactor (4) is installed on one side of the bioreactor (4). The wastewater is industrial organic wastewater. The first ceramic membrane assembly and the second ceramic membrane assembly are both composed of a plurality of rows of iron-doped carbon ceramic membranes (7). The iron-doped carbon ceramic membranes (7) in each row are tilted and arranged parallel to each other. The angles between all the tilted iron-doped carbon ceramic membranes (7) and the horizontal direction are equal. The surface of the iron-doped carbon ceramic membrane (7) is an iron-carbon material electrode, each iron-doped carbon ceramic membrane (7) in the first ceramic membrane assembly is connected to the positive electrode of the variable voltage electrode power supply (6), and each iron-doped carbon ceramic membrane (7) in the second ceramic membrane assembly is connected to the negative electrode of the variable voltage electrode power supply (6). The bottom end of the bioreactor (4) is fixedly connected to an aeration device, the lower ends of the first ceramic membrane assembly and the second ceramic membrane assembly are connected to the inlet of the water production pipe (12), and the outlet of the water production pipe (12) is connected to a suction pump (16).

2. The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to claim 1, characterized in that: The aeration device comprises a blower (8), an air delivery pipe (9) and an aeration plate (13); The gas delivery pipe (9) comprises a main pipeline, the end of which penetrates into the bioreactor (4) and is divided into a plurality of branch pipelines. The air outlet of the blower (8) is connected to the inlet of the main pipeline. Each branch pipeline has a plurality of air outlets. An aeration plate (13) is installed at each air outlet. All aeration plates (13) are located at the bottom end of the bioreactor (4).

3. The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to claim 2, characterized in that: The first ceramic membrane assembly and the second ceramic membrane assembly are arranged in a bioreactor (4) via a membrane tube support (10), an upper clamping plate (5) and a lower clamping plate (14); The bioreactor (4) is a rectangular parallelepiped structure, the membrane tube support (10) is a rectangular parallelepiped frame, the length of the frame is less than the length of the bioreactor (4), the width of the frame is less than the width of the bioreactor (4), the height of the frame is less than the height of the bioreactor (4), the center of the membrane tube support (10) coincides with the center of the bioreactor (4), the upper clamping plate (5) is clamped on the upper end surface of the inner wall of the membrane tube support (10) in the horizontal direction, and the lower clamping plate ( 14) is horizontally engaged with the inner wall of the membrane tube support (10) near the bottom, and a through hole with the same outer diameter as the iron-doped carbon ceramic membrane (7) is opened in the upper clamping plate (5) and the lower clamping plate (14). The upper end of each iron-doped carbon ceramic membrane (7) is inserted into the corresponding through hole of the upper clamping plate (5), and the lower end of each iron-doped carbon ceramic membrane (7) is inserted into the corresponding through hole of the lower clamping plate (14). The water production pipe (12) and the aeration plate (13) are located directly below the lower clamping plate (14) in sequence.

4. The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to claim 1, characterized in that: The distance between two adjacent iron-doped carbon ceramic membranes (7) in the first ceramic membrane assembly and the distance between two adjacent iron-doped carbon ceramic membranes (7) in the second ceramic membrane assembly are equal, and the value is 1 to 3 times the outer diameter of the iron-doped carbon ceramic membrane (7); the distance between two adjacent iron-doped carbon ceramic membranes (7) in the first ceramic membrane assembly and the second ceramic membrane assembly is 5 times the outer diameter of the iron-doped carbon ceramic membrane (7).

5. The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to claim 1, characterized in that: The iron-doped carbon ceramic membrane (7) comprises a ceramic tube and a filter layer distributed on the outer wall of the ceramic tube, and the filter layer is an iron-doped carbon ceramic membrane with nano-scale or micro-scale pores.

6. The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to claim 1, characterized in that: It also includes a backwash pump (17), which is connected to the outlet of the water production pipe (12) through a backwash water inlet pipe (19).

7. A method for treating industrial organic wastewater using micro-electrolysis and microbial degradation, characterized in that: The device for treating industrial organic wastewater by micro-electrolysis and microbial degradation according to any one of claims 1 to 6 comprises the following steps: S1, the wastewater injection pump injects the industrial organic wastewater into the bioreactor (4) through the water inlet (20) of the bioreactor (4), the aeration device releases rising bubbles from the bottom of the bioreactor (4), and the industrial organic wastewater and the activated sludge are mixed evenly by using the rising bubbles and the power of the wastewater injection pump, and the pollutants in the industrial organic wastewater are biodegraded by the activated sludge; S2, starting the variable voltage electrode power supply (6), the iron-carbon material electrodes on the surfaces of the first ceramic membrane assembly and the second ceramic membrane assembly undergo a micro-electrolysis reaction, and a weak electric field is generated on the surface of the iron-carbon-doped ceramic membrane (7), releasing active species and electrons to participate in the degradation of pollutants; S3, start the suction pump (16), the treated wastewater is filtered through the iron-doped carbon ceramic membrane (7) in the first ceramic membrane assembly and the second ceramic membrane assembly, water molecules and small molecules enter the inner side of the iron-doped carbon ceramic membrane (7) through the membrane pores, and the purified water flows into the water production pipe (12) from the lower end of the iron-doped carbon ceramic membrane (7), and then flows out from the outlet of the water production pipe (12).

8. The method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation according to claim 7, characterized in that: In S1, the aeration device releases rising bubbles from the bottom of the bioreactor (4) to make the dissolved oxygen 0.1-0.3 mg·L -1 .

9. The method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation according to claim 7, characterized in that: The micro-electrolysis reaction in S2 has the following two modes: Method 1 is: a variable voltage electrode power supply (6) applies a voltage of 0.2 to 0.8 V to the first ceramic membrane assembly and the second ceramic membrane assembly to continuously perform a micro-electrolysis reaction; Method 2 is to set the first ceramic membrane assembly and the second ceramic membrane assembly as the anode and cathode respectively, apply a voltage of 0.4 to 0.8 V, stop the micro-electrolysis reaction after 1 to 3 hours, then reverse the electrode polarity, reduce the voltage and continue the micro-electrolysis reaction for 25 to 35 minutes, and then return to the initial process for intermittent reversal cycle operation.

10. The method for treating industrial organic wastewater by using micro-electrolysis and microbial degradation according to claim 9, characterized in that: The current density in the method 1 is 5-20 mA / cm 2 In method 2, the micro-electrolysis reaction is stopped for 10 to 30 minutes, and then the electrode polarity is reversed, and the voltage is reduced by 0.2 V before continuing the micro-electrolysis reaction.

Images