Anaerobic biofilm wastewater treatment device and method

Abstract

This invention provides an anaerobic biofilm wastewater treatment device and method. The device includes a reactor, within which a packing electrode layer comprising an anode packing layer and a cathode packing layer is disposed. The anode packing layer and cathode packing layer are electrically connected to the positive and negative terminals of a regulated DC power supply, respectively. The regulated DC power supply continuously supplies power to the packing electrode layer during the electrode start-up and packing biofilm formation stages, and intermittently supplies power to the packing electrode layer during normal operation. Intermittent power supply during normal operation effectively reduces energy consumption without affecting wastewater treatment efficiency. By acquiring the pH and redox potential values ​​within the reactor, acid inhibition within the reactor can be avoided during normal operation when no power is supplied.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an anaerobic biofilm wastewater treatment device and method. Background Technology

[0002] With the continuous development of society and industrialization, people's demand for energy has increased significantly. In recent years, the over-exploitation and consumption of fossil fuels has not only caused an energy crisis but also brought about serious environmental pollution problems. Therefore, all sectors need to carry out in-depth technological innovations for energy conservation and carbon reduction. With the improvement of living standards, the discharge of urban domestic sewage has also shown a gradual increasing trend. Sewage contains a large number of organic pollutants, and if discharged into natural water bodies without proper treatment, it will seriously damage the aquatic ecological environment and lead to water quality deterioration.

[0003] Traditional wastewater treatment technologies typically employ aerobic biological treatment processes, such as the activated sludge process, as their core technology. This involves a significant energy input to remove pollutants. While this method achieves good treatment results, it consumes substantial amounts of energy and generates significant carbon emissions. Compared to aerobic biological treatment, anaerobic biological technology offers numerous advantages, including lower operating costs, less sludge production, higher volumetric loading rates, and the ability to recover bioenergy. Therefore, vigorously developing anaerobic wastewater digestion technology can not only meet wastewater treatment needs but also provide a new technological pathway for energy conservation and carbon reduction in the water pollution control industry.

[0004] However, successful anaerobic methanogenesis requires the synergistic action of multiple microorganisms. Due to significant differences in growth and metabolic rates between methanogenic and fermentative microorganisms, acid accumulation is easily caused, disrupting system stability. Large wastewater volumes, low organic matter concentrations, complex compositions, and low temperatures are also highly unfavorable for anaerobic digestion. Therefore, wastewater anaerobic methanogenesis processes often suffer from bottlenecks such as low gas production rates, long start-up cycles, and poor stability. The rate-limiting step in anaerobic methanogenesis lies in the electron transfer process between methanogenic and symbiotic microorganisms. Methanogenesis is generally believed to occur primarily through interspecies hydrogen transfer or formic acid transfer. Recent studies have discovered a direct interspecies electron transfer (DIET) mechanism within methanogenic functional communities, which can achieve direct electron transfer via nanowires, cytochromes, or conductive materials, resulting in a higher metabolic rate. Therefore, introducing an electrochemical system into the anaerobic system can, to some extent, promote the development and metabolism of the DIET methanogenic functional community, thereby improving the efficiency of anaerobic methanogenesis.

[0005] Currently, the anode electrode is typically pre-cultured in a microbial fuel cell. Then, the anode electrode is removed and placed in an anaerobic reactor along with the cathode electrode, pretreated activated sludge, and activated carbon. Power is continuously supplied to the anode and cathode electrodes to improve methane yield and COD removal rate. However, an external voltage needs to be continuously supplied throughout the entire operation, which greatly increases the energy consumption. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an anaerobic biofilm wastewater treatment device and method, which solves the technical problem that the continuous supply of external voltage to the anode and cathode electrodes in the anaerobic reactor to improve methane yield and COD removal rate results in significantly increased energy consumption.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] An anaerobic biofilm wastewater treatment device includes a reactor. A packing electrode layer is disposed within the reactor. The packing electrode layer includes a cathode packing layer and an anode packing layer, which are respectively connected to the negative and positive terminals of a regulated DC power supply. The regulated DC power supply continuously supplies power to the packing electrode layer during the electrode start-up phase and the packing biofilm formation phase to promote the growth of an anaerobic biofilm on the packing electrode layer. During normal operation, the regulated DC power supply intermittently supplies power to the packing electrode layer based on the pH value and redox potential value within the reactor to eliminate acid inhibition.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: Introducing the packing electrode layer into a complex anaerobic digestion system, the packing electrode layer functions to regulate the microbial community structure within the reactor and construct the anaerobic biofilm. After the biofilm formation stage is completed, whether the packing electrode layer is energized or not has minimal impact on wastewater treatment efficiency. By continuously supplying power to the packing electrode layer only during the electrode startup and biofilm formation stages, and intermittently supplying power during normal operation, the energy consumption of the reactor can be reduced without affecting wastewater treatment efficiency, thus improving the energy return rate. During normal operation, when no power is supplied, the organic load of the wastewater is easily excessive. Acid inhibition can occur due to factors such as substrate C / N imbalance, the presence of harmful substances in the substrate, or the presence of other adverse environmental factors. This inhibits the methanogenic activity of the anaerobic biofilm, leading to system instability or even collapse. By monitoring the pH and redox potential values ​​within the reactor, it can be determined whether the reactor is in an unstable state. By supplying power to the packing electrode layer, a positive intervention can be applied, allowing anodic microorganisms to metabolize small-molecule organic acids and generate electrons, thus mitigating acid accumulation to some extent. Excess hydrogen ions can synthesize hydrogen gas at the cathode, increasing the pH value of the system and providing substrate for the anaerobic biofilm, promoting its metabolic activity, avoiding acid inhibition, and ensuring the stability of the system.

[0010] Furthermore, both the cathode packing layer and the anode packing layer are electrically connected to an electrochemical monitoring component. A monitoring probe is installed on the reactor, and the monitoring probe is electrically connected to the regulated DC power supply through an automatic controller. The monitoring probe is used to monitor the pH value and redox potential value in the reactor.

[0011] Furthermore, a triangular outlet weir and a porous water distribution plate are arranged from top to bottom inside the reactor to divide the reactor into a recovery zone, a treatment zone, and an inlet zone. The triangular outlet weir and the inner side wall of the reactor enclose a water collection tank located in the recovery zone. The side wall of the reactor is connected to an inlet pipe and an outlet pipe. The inlet pipe is connected to the inlet zone, and the outlet pipe is connected to the recovery zone. The packing electrode layer is located in the treatment zone.

[0012] Furthermore, the cathode packing layer includes a plurality of packing discs evenly distributed radially along the reactor. Each packing disc includes a hub-shaped frame and a plurality of conductive brushes embedded in the hub-shaped frame. Metal terminals are provided at opposite ends of the hub-shaped frame, and the two metal terminals are used to electrically connect to the regulated DC power supply and the electrochemical monitoring component, respectively.

[0013] Furthermore, the diameter of the conductive brush gradually increases from the center of the hub-shaped frame towards the side edge of the hub-shaped frame.

[0014] Furthermore, the material of the hub-shaped frame is titanium wire, copper wire, or stainless steel wire, and the material of the conductive brush is carbon fiber filament.

[0015] Furthermore, a gas collection assembly is installed on the reactor, which includes a main gas collection pipe and a branch pipe. The branch pipe is located in the recovery zone. One end of the main gas collection pipe is connected to the branch pipe, and the other end of the main gas collection pipe passes through the top of the reactor and is connected in sequence to a control valve and a flow meter. The branch pipe is connected to several gas collection branch pipes. The end of the gas collection branch pipe away from the branch pipe passes through the triangular effluent weir and is connected to a three-phase separator, which is located in the treatment zone.

[0016] Furthermore, the bottom of the reactor is provided with a vent pipe communicating with the inlet area, the side wall of the reactor is provided with a sludge discharge pipe communicating with the treatment area, the sludge discharge pipe is located between the packing electrode layer and the porous water distribution plate, and the top of the reactor is provided with an inspection port and a pressure relief valve.

[0017] The present invention also provides an anaerobic biofilm wastewater treatment method, applied to the anaerobic biofilm wastewater treatment device described in the above technical solution, comprising the following steps:

[0018] The inoculum source is mixed with the nutrient solution to form a mixture. The mixture is pumped into the reactor until it submerges and overflows the reactor. The overflowing mixture is then pumped back into the reactor to complete the total reflux operation.

[0019] A regulated DC power supply is used to power the filler electrode layer, which includes a cathode filler layer and an anode filler layer. The circuit current and the potential of the anode filler layer are monitored. When the circuit current is stable and the potential of the anode filler layer is lower than the potential threshold, the electrode start-up stage is determined to be completed.

[0020] The carbon-sulfur ratio of the first wastewater to be treated is adjusted to form biofilm-forming wastewater. The biofilm-forming wastewater is pumped into the reactor until the biofilm-forming wastewater submerges the reactor. The regulated DC power supply is used to power the packing electrode layer so that an anaerobic biofilm can grow on the packing electrode layer. When the gas production of the reactor stabilizes, the biofilm formation stage of the packing is considered complete.

[0021] The second wastewater to be treated is pumped into the reactor, and the regulated DC power supply is turned off to carry out wastewater treatment during normal operation. The pH value and oxidation-reduction potential value in the reactor are obtained. When the pH value is less than a first threshold and / or the oxidation-reduction potential value is greater than a second threshold, the regulated DC power supply is controlled to supply power to the packing electrode layer until the pH value is greater than the first threshold and the oxidation-reduction potential value is less than the second threshold, and then the regulated DC power supply is controlled to be turned off.

[0022] Furthermore, the carbon-sulfur ratio is in the range of 2.5 g COD / g SO4. 2- ~10gCOD / gSO4 2- . Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the anaerobic biofilm wastewater treatment device in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the packing disc in the anaerobic biofilm wastewater treatment device of Embodiment 1 of the present invention;

[0025] Figure 3 This is a flowchart of the anaerobic biofilm wastewater treatment method in Embodiment 2 of the present invention;

[0026] Explanation of key component symbols:

[0027] 1. Reactor; 2. Inlet pipe; 3. Vent pipe; 4. Perforated water distribution plate; 5. Sludge discharge pipe; 6. Packed electrode layer; 7. Regulated DC power supply; 8. Reference electrode; 9. Electrochemical monitoring component; 10. Three-phase separator; 11. Triangular outlet weir; 12. Water collection tank; 13. Outlet pipe; 14. Gas collection branch pipe; 15. Gas collection main pipe; 16. Control valve; 17. Flow meter; 18. Inspection port; 19. Pressure relief valve; 21. Monitoring probe; 22. Automatic controller; 61. Hub-shaped frame; 62. Conductive brush; 63. Metal terminal.

[0028] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0029] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0030] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Please see Figure 1 and Figure 2 Embodiment 1 of the present invention provides an anaerobic biofilm wastewater treatment device, including a reactor 1. The reactor 1 is provided with a triangular effluent weir 11 and a porous water distribution plate 4 arranged from top to bottom to divide the reactor 1 into a recovery zone, a treatment zone and an inlet zone from top to bottom. The triangular effluent weir 11 and the inner side wall of the reactor 1 enclose a water collection tank 12 located in the recovery zone. The side wall of the reactor 1 is connected to an inlet pipe 2 and an outlet pipe 13. The inlet pipe 2 is connected to the inlet zone and the outlet pipe 13 is connected to the recovery zone. It can be understood that the outlet pipe 13 is positioned corresponding to the water collection tank 12. Liquid can be introduced into the reactor 1 through the inlet pipe 2. When the liquid gradually submerges the inlet zone and the treatment zone, it overflows into the water collection tank 12 through the triangular effluent weir 11 and is discharged or overflows through the outlet pipe 13.

[0033] The bottom of the reactor 1 is provided with a vent pipe 3 communicating with the inlet area. After the sewage treatment is completed, the internal cleaning of the reactor 1 can be completed through the vent pipe 3. The side wall of the reactor 1 is provided with a sludge discharge pipe 5 communicating with the treatment area. The sludge discharge pipe 5 is located between the packing electrode layer 6 and the porous water distribution plate 4. Preferably, the sludge discharge pipe 5 is adjacent to the porous water distribution plate 4. The top of the reactor 1 is provided with an inspection port 18 and a pressure relief valve 19.

[0034] A packed electrode layer 6 is disposed within the reactor 1, and it is understood that the packed electrode layer 6 is located within the processing zone. The packed electrode layer 6 includes a cathode packed layer and an anode packed layer. The cathode packed layer is electrically connected to the negative terminal of a regulated DC power supply 7, and the anode packed layer is electrically connected to the positive terminal of the regulated DC power supply 7. Both the cathode packed layer and the anode packed layer are electrically connected to an electrochemical monitoring component 9. The electrochemical monitoring component 9 is used to monitor the potential of the cathode packed layer and the anode packed layer, and to monitor the circuit current. Preferably, a reference electrode 8 is disposed between the cathode packed layer and the anode packed layer. The reference electrode 8 is electrically connected to the electrochemical monitoring component 9, and the reference electrode 8 assists the electrochemical monitoring component 9 in completing the monitoring of the potential of the cathode packed layer and the anode packed layer.

[0035] In some embodiments, a plurality of packing electrode layers 6 are provided in the reactor 1. The plurality of packing electrode layers 6 are evenly distributed from top to bottom in the reactor 1. By providing a plurality of packing electrode layers 6, the packing area can be expanded, thereby expanding the growth area of ​​the anaerobic biofilm and the contact area with the sewage, and improving the efficiency of subsequent sewage treatment.

[0036] The cathode packing layer includes several packing discs evenly distributed radially along the reactor 1. Each packing disc includes a hub-shaped frame 61 and several conductive brushes 62 embedded in the hub-shaped frame 61. Metal terminals 63 are provided at opposite ends of the hub-shaped frame 61, and the two metal terminals 63 are used for electrical connection to the regulated DC power supply 7 and the electrochemical monitoring component 9, respectively. The diameter of the conductive brushes 62 gradually increases from the center of the hub-shaped frame 61 towards its side edge. Preferably, the hub-shaped frame 61 is made of titanium wire, copper wire, or stainless steel wire, and the conductive brushes 62 are made of carbon fiber filament. The conductive brushes 62 are embedded in the hub-shaped frame 61 by embedding the brush fibers of the conductive brushes 62 between multiple strands of metal wire in the hub-shaped frame 61, and by twisting the metal wire, the conductive brushes 62 are fixed to the hub-shaped frame 61. The structure of the anode packing layer is the same as that of the cathode packing layer, and will not be described again here. Through the specific structural design of the packing electrode layer 6, the electrochemical acclimatization effect on the anaerobic functional community can be fully utilized. At the same time, the larger packing area also provides more attachment space for microorganisms, effectively improving the efficiency of sewage treatment.

[0037] A monitoring probe 21 is installed on the reactor 1. The monitoring probe 21 is used to monitor the pH value and oxidation-reduction potential value in the reactor. The monitoring probe 21 is electrically connected to the regulated DC power supply 7 through an automatic controller 22. The regulated DC power supply 7 is used to continuously supply power to the packing electrode layer 6 during the electrode start-up stage and the packing biofilm formation stage, so as to grow an anaerobic biofilm on the packing electrode layer 6. During normal operation, the regulated DC power supply 7 is used to intermittently supply power to the packing electrode layer 6 based on the pH value and oxidation-reduction potential value in the reactor to eliminate acid inhibition. It can be understood that during normal operation, the pH value and oxidation-reduction potential value in the reactor 1 are obtained through the monitoring probe 21, and the automatic controller 22 controls the on / off state of the regulated DC power supply 7 based on the monitoring results.

[0038] Introducing the packing electrode layer 6 into a complex anaerobic digestion system, the packing electrode layer 6 functions to regulate the microbial community structure within the reactor 1 and construct the anaerobic biofilm. Understandably, the anaerobic biofilm includes methanogenic functional bacteria. After the biofilm formation stage, whether or not the packing electrode layer 6 is energized has minimal impact on wastewater treatment efficiency. By continuously supplying power to the packing electrode layer 6 only during the electrode startup and biofilm formation stages, and intermittently supplying power during normal operation, the energy consumption of the reactor 1 can be reduced without affecting wastewater treatment efficiency, thus improving energy return rate. During normal operation, when no power is supplied, acid inhibition can easily occur due to excessively high organic load in the wastewater, substrate C / N imbalance, the presence of certain harmful substances in the substrate, or other adverse environmental factors. This inhibits the methanogenic activity of the anaerobic biofilm, i.e., the methanogenic functional bacteria, leading to system instability or even collapse. By obtaining… By measuring the pH and redox potential values ​​within reactor 1, it can be determined whether reactor 1 is in an unstable state. Then, by supplying power to the packing electrode layer 6, a positive intervention is applied, allowing anodic microorganisms to metabolize small-molecule organic acids and generate electrons, thus mitigating acid accumulation to some extent. Excess hydrogen ions can synthesize hydrogen gas at the cathode, increasing the pH value of the system and providing substrate for the anaerobic biofilm, promoting its metabolic activity, avoiding acid inhibition, and ensuring the stability of the system. Furthermore, the influence of the packing electrode layer 6 in the anaerobic system is limited, generally only significantly affecting a small surrounding area. Therefore, to fully utilize the positive influence of the packing electrode layer 6 on the construction of the anaerobic biofilm during the start-up phase, the electrode and the packing material of reactor 1 are combined into the packing electrode layer 6. During the electrode start-up phase and the packing biofilm formation phase, the packing electrode layer 6 acts as a microbial electrode, and by supplying an external voltage, the formation of the anaerobic biofilm on its surface is regulated. When the reactor 1 starts up successfully, that is, when the anaerobic biofilm on the surface of the packing electrode layer 6 is successfully attached, no external voltage regulation is needed. At this time, the power supply to the packing electrode layer 6 is disconnected, and the reactor 1 is transformed into a normal anaerobic biofilm reactor, which treats wastewater and completes the production process by relying on the anaerobic biofilm on the packing electrode layer 6.

[0039] A gas collection assembly is installed on the reactor 1. The gas collection assembly includes a main gas collection pipe 15 and a branch pipe. The branch pipe is located in the recovery zone. One end of the main gas collection pipe 15 is connected to the branch pipe, and the other end of the main gas collection pipe 15 passes through the top of the reactor 1 and is connected in sequence to a control valve 16 and a flow meter 17. The branch pipe is connected to several gas collection branch pipes 14. The end of the gas collection branch pipe 14 away from the branch pipe passes through the triangular effluent weir 11 and is connected to a three-phase separator 10. The three-phase separator 10 is located in the treatment zone. During wastewater treatment, organic pollutants in the wastewater are degraded by the anaerobic biofilm on the packing electrode layer 6, and gas including biogas is generated. The gas rises with the water flow to the three-phase separator 10, enters the gas collection branch pipes 14, and is collected through the gas collection branch pipes 14 and the branch pipe to the main gas collection pipe 15, and then leaves the reactor 1. The gas is measured by the flow meter 17 and its components are analyzed. The anaerobic biofilm that falls off the packing electrode layer 6 rises with the water flow to the three-phase separator 10, where it is blocked and settles back to the packing electrode layer 6, the bottom of the reactor 1, or above the porous water distribution plate 4. The deposited sludge is periodically discharged through the sludge discharge pipe 5 to avoid blockage.

[0040] Please see Figure 3 Embodiment 2 of the present invention provides an anaerobic biofilm wastewater treatment method, which is applied to the anaerobic biofilm wastewater treatment device described in the above embodiments. The method includes the following steps:

[0041] Step S10: Mix the inoculum with the nutrient solution to form a mixture, pump the mixture into the reactor until the mixture submerges and overflows the reactor, and pump the overflowing mixture back into the reactor to complete the total reflux operation.

[0042] The inoculation source includes at least one of excess sludge, digested sludge, anaerobic granular sludge, or effluent from an electrochemical reactor. The nutrient solution is composed of sodium acetate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium chloride, potassium chloride, Wolfe trace element solution, and Wolfe mineral element solution.

[0043] Preferably, the concentration of sodium acetate is 1 g / L to 2 g / L, the concentration of sodium dihydrogen phosphate is 5.618 g / L, the concentration of disodium hydrogen phosphate is 6.155 g / L, the concentration of ammonium chloride is 0.31 g / L, the concentration of potassium chloride is 0.13 g / L, the concentration of Wolfe trace element solution is 1 ml / L, and the concentration of Wolfe mineral element solution is 1 ml / L. Through this nutrient solution, the filler electrode layer can acquire electrochemical function during the electrode start-up phase. It should be noted that the nutrient solution is replaced every 48 hours.

[0044] Understandably, the mixture is pumped into the reactor through the inlet pipe and overflows from the reactor through the outlet pipe. By connecting the outlet pipe to the inlet pipe, the overflowed mixture can be pumped back into the reactor.

[0045] Step S20: Power the filler electrode layer, including the cathode filler layer and the anode filler layer, through a regulated DC power supply, monitor the circuit current and the potential of the anode filler layer, and determine that the electrode start-up stage is completed when the circuit current is stable and the potential of the anode filler layer is lower than the potential threshold.

[0046] In this step, the circuit current and the potential of the anode filler layer are monitored by an electrochemical monitoring component. The voltage supplied to the filler electrode layer by the regulated DC power supply is 0.5V to 1.0V, and the potential threshold is -400mV. That is, when the electrochemical monitoring component detects that the circuit current is stable and the potential of the anode filler layer is lower than -400mV, the electrode start-up stage is determined to be completed.

[0047] Step S30: Adjust the carbon-sulfur ratio of the first wastewater to be treated to form biofilm-forming wastewater. Pump the biofilm-forming wastewater into the reactor until the biofilm-forming wastewater submerges the reactor. Power the packing electrode layer with the regulated DC power supply to grow an anaerobic biofilm on the packing electrode layer. When the gas production of the reactor stabilizes, the biofilm formation stage of the packing is considered complete.

[0048] The carbon-sulfur ratio is in the range of 2.5 g COD / g SO4. 2- ~10gCOD / gSO4 2-In this embodiment, the carbon-to-sulfur ratio is adjusted by adding sulfate to the first wastewater to be treated. In a system containing conductive materials and an external voltage, the presence of a small amount of sulfate is beneficial for the construction of the anaerobic biofilm. The conductive material can induce the formation of a direct interspecies electron transport (DIET) methanogenic symbiotic system, that is, mediate electron transport between extracellular electron-respiring bacteria and methanogens, thereby accelerating the methanogenesis process, promoting the growth and metabolism of methanogens, and increasing methane yield. During the biofilm formation stage on the packing material, the presence of a small amount of sulfate can effectively enrich sulfate-reducing bacteria. Combined with the mediating and promoting effects of the conductive material and the external voltage, this allows for a more effective establishment of a DIET methanogenic system with the methanogens. After this symbiotic system is established, i.e., after the biofilm formation stage on the packing material is completed, the stimulation of sulfate is no longer needed. Specifically, by adjusting the carbon-to-sulfur ratio of the first wastewater to be treated, the directional enrichment of extracellular electron-respiring bacteria was achieved. Furthermore, by applying micro-voltage stimulation during the biofilm formation stage of the packing material, the construction of direct interspecies electron-transfer methanogenic functional communities was enhanced, thereby accelerating the anaerobic digestion process and increasing the methane yield. This shortened the reactor start-up cycle, improved the system stability, and thus enhanced the methanogenic efficiency of the wastewater.

[0049] In this step, the voltage supplied by the regulated DC power supply to the packing electrode layer is 0.5V to 1.0V, and the first hydraulic residence time is 6h to 12h.

[0050] Step S40: Pump the second wastewater to be treated into the reactor and turn off the regulated DC power supply to treat the wastewater during normal operation. Obtain the pH value and oxidation-reduction potential value in the reactor. When the pH value is less than the first threshold and / or the oxidation-reduction potential value is greater than the second threshold, control the regulated DC power supply to supply power to the packing electrode layer until the pH value is greater than the first threshold and / or the oxidation-reduction potential value is less than the second threshold, then control the regulated DC power supply to turn off.

[0051] In this step, the pH value and redox potential value inside the reactor are obtained through a monitoring probe. The first threshold is 6.0, and the second threshold is -200mV. That is, when the monitoring probe detects that the pH value inside the reactor is less than 6.0 and / or the redox potential value is greater than -200mV, it is determined that there is a risk of instability in the reactor, resulting in acid inhibition. At this time, the automatic controller controls the regulated DC power supply to supply power to the packing electrode layer until the pH value inside the reactor is greater than 6.0 and the redox potential value is less than -200mV. Then, the monitoring probe controls the regulated DC power supply to be cut off through the automatic controller. It should be noted that in this step, the second hydraulic retention time is 4h to 24h.

[0052] Comparative Example 1 of this invention provides an anaerobic biofilm wastewater treatment method, which differs from the anaerobic biofilm wastewater treatment method described in Example 2 in that:

[0053] During the electrode startup phase and the packing membrane formation phase, no power is supplied to the packing electrode layer, and during the packing membrane formation phase, the carbon-sulfur ratio of the first wastewater to be treated is not adjusted.

[0054] Wastewater was treated using the anaerobic biofilm wastewater treatment methods described in Example 2 and Comparative Example 1, respectively. The anaerobic biofilm wastewater treatment method in Example 2 shortened the time for the biofilm formation stage of the packing material by 7 days compared to the method in Comparative Example 1. Furthermore, the methane content, methane production rate, and methane yield of the wastewater treated using the anaerobic biofilm wastewater treatment method in Example 2 were increased by 16%, 58%, and 47%, respectively, compared to the method in Comparative Example 1. Therefore, the anaerobic biofilm wastewater treatment method described in Example 2 can improve the efficiency of the methane production process in wastewater, playing an important role in the development of wastewater resource utilization technology.

[0055] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An anaerobic biofilm wastewater treatment method, applied to an anaerobic biofilm wastewater treatment device, characterized in that, The anaerobic biofilm wastewater treatment device includes a reactor. A packing electrode layer is disposed within the reactor. The packing electrode layer includes a cathode packing layer and an anode packing layer, respectively connected to the negative and positive terminals of a regulated DC power supply. The regulated DC power supply continuously supplies power to the packing electrode layer during the electrode startup and biofilm formation phases to promote anaerobic biofilm growth. During normal operation, the regulated DC power supply intermittently supplies power to the packing electrode layer based on the pH and redox potential values ​​within the reactor to eliminate acid inhibition. Both the cathode and anode packing layers are electrically connected to an electrochemical monitoring component. A monitoring device is installed on the reactor. A monitoring probe is electrically connected to a regulated DC power supply via an automatic controller. The probe is used to monitor the pH and redox potential values ​​within the reactor. A triangular effluent weir and a porous water distribution plate are arranged from top to bottom within the reactor to divide it into a recovery zone, a treatment zone, and an inlet zone. The triangular effluent weir and the inner wall of the reactor enclose a water collection trough located within the recovery zone. An inlet pipe and an effluent pipe are connected to the side wall of the reactor. The inlet pipe connects to the inlet zone, and the effluent pipe connects to the recovery zone. The packing electrode layer is located in the treatment zone. The anaerobic biofilm wastewater treatment method includes the following steps: The inoculum source is mixed with the nutrient solution to form a mixture. The mixture is pumped into the reactor until it submerges and overflows the reactor. The overflowing mixture is then pumped back into the reactor to complete the total reflux operation. A regulated DC power supply is used to power the filler electrode layer, which includes a cathode filler layer and an anode filler layer. The circuit current and the potential of the anode filler layer are monitored. When the circuit current is stable and the potential of the anode filler layer is lower than the potential threshold, the electrode start-up stage is determined to be completed. The carbon-sulfur ratio of the first wastewater to be treated is adjusted to form biofilm-forming wastewater. The biofilm-forming wastewater is pumped into the reactor until the biofilm-forming wastewater submerges the reactor. The regulated DC power supply is used to power the packing electrode layer so that an anaerobic biofilm can grow on the packing electrode layer. When the gas production of the reactor stabilizes, the biofilm formation stage of the packing is considered complete. The second wastewater to be treated is pumped into the reactor, and the regulated DC power supply is turned off to carry out wastewater treatment during normal operation. The pH value and oxidation-reduction potential value in the reactor are obtained. When the pH value is less than a first threshold and / or the oxidation-reduction potential value is greater than a second threshold, the regulated DC power supply is controlled to supply power to the packing electrode layer until the pH value is greater than the first threshold and the oxidation-reduction potential value is less than the second threshold, and then the regulated DC power supply is controlled to be turned off.

2. The anaerobic biofilm wastewater treatment method according to claim 1, characterized in that, The cathode packing layer includes a plurality of packing discs evenly distributed radially along the reactor. Each packing disc includes a hub-shaped frame and a plurality of conductive brushes embedded in the hub-shaped frame. Metal terminals are provided at opposite ends of the hub-shaped frame, and the two metal terminals are used to electrically connect to the regulated DC power supply and the electrochemical monitoring component, respectively.

3. The anaerobic biofilm wastewater treatment method according to claim 2, characterized in that, The diameter of the conductive brush gradually increases from the center of the hub-shaped frame towards the side edge of the hub-shaped frame.

4. The anaerobic biofilm wastewater treatment method according to claim 2, characterized in that, The hub-shaped frame is made of titanium wire, copper wire, or stainless steel wire, and the conductive brush is made of carbon fiber filament.

5. The anaerobic biofilm wastewater treatment method according to claim 1, characterized in that, A gas collection assembly is installed on the reactor. The gas collection assembly includes a main gas collection pipe and a branch pipe. The branch pipe is located in the recovery zone. One end of the main gas collection pipe is connected to the branch pipe. The other end of the main gas collection pipe passes through the top of the reactor and is connected to a control valve and a flow meter in sequence. The branch pipe is connected to several gas collection branch pipes. The end of the gas collection branch pipe away from the branch pipe passes through the triangular effluent weir and is connected to a three-phase separator. The three-phase separator is located in the treatment zone.

6. The anaerobic biofilm wastewater treatment method according to claim 1, characterized in that, The bottom of the reactor is provided with a vent pipe communicating with the inlet area, and the side wall of the reactor is provided with a sludge discharge pipe communicating with the treatment area. The sludge discharge pipe is located between the packing electrode layer and the porous water distribution plate. The top of the reactor is provided with an inspection port and a pressure relief valve.

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