Electrocatalytic biological denitrification system and denitrification method of ruthenium-plated electrode composite hollow fiber membrane

Abstract

The invention discloses an electrocatalytic biological denitrification system and denitrification method of a ruthenium-plated electrode composite hollow fiber membrane, and is characterized in that the system comprises a positive / negative electrode chamber arranged on a double-chamber UASB reactor, and a composite biological electrode in the chamber, the composite biological electrode adopts a ruthenium-plated iridium-titanium mesh barrel with a carbon felt wrapped on the periphery as a negative electrode, and the ruthenium-plated iridium-titanium mesh barrel is coated with a hollow fiber membrane. A hollow fiber membrane separation sludge is arranged in the barrel; a ruthenium-iridium-plated titanium mesh is coated with a carbon felt to serve as an anode, electroactive bacteria produce nitrogen / nitrate through anaerobic ammonia oxidation, ammonia nitrogen is electrochemically oxidized into nitrite, anode nitrogen enters a cathode to strengthen mass transfer, cathode nitrite flows back to the anode to be recycled, and efficient conversion and removal of nitrogen are achieved. Compared with the prior art, the system has the advantages of efficient conversion and removal of nitrogen, the pollution of the hollow fiber membrane is reduced and the membrane loss is reduced by utilizing the N2 synthesized by degrading the pre-degradation matrix through the electroactive microorganisms and the additional electrochemical action of the two electrodes, and the system is simple in structure and convenient to maintain and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of bioelectrocatalytic membrane reaction devices, in particular to an electrocatalytic biological denitrification system with a ruthenium-plated electrode composite hollow fiber membrane and a denitrification method thereof. Background Art

[0002] The nitrification-denitrification system in traditional denitrification processes has the disadvantages of low denitrification efficiency and high energy consumption. Therefore, the patent "Wastewater Treatment Method and System Based on Anaerobic Ammonium Oxidation Reactor" (application publication number CN117923657A, application publication date April 26, 2024) proposed a reactor based on anaerobic ammonium oxidation. Although the denitrification efficiency is improved compared with the traditional nitrification-denitrification system, it has the disadvantages of slow growth, low activity of AnAOB, and the generation of nitrate by-products during the reaction process. Moreover, actual sewage cannot meet the high-concentration NO2 2- -N environment required by Anammox, resulting in low removal efficiency. The bioelectrocatalytic technology can enrich electroactive microbial membranes on the electrode surface, enabling the degradation of pollutants, and can promote the secretion of EPS by microorganisms, forming a three-dimensional bridging matrix with metal ions in the system, making the refined AnGS granulate. Some studies have shown that AnAOB has the ability of extracellular electron transfer. Therefore, by applying an appropriate voltage, it is beneficial to enhance the biological ammonia oxidation ability and nitrate reduction ability, and is conducive to sludge granulation, increasing the stability of the system.

[0003] The membrane separation and reflux technology is applied to the sludge treatment process, mainly using a membrane with a small pore diameter to intercept sludge and macromolecular substances. The Chinese patent "A High-Efficiency Denitrification and Carbon Removal Sewage Treatment Equipment with Hollow Fiber Membrane" (application publication number CN115636528A, application publication date January 24, 2023) proposes that water and small molecular substances that can pass through the membrane are separated from the sludge solution under pressure drive, which can not only re-treat the sewage but also recycle it. Although the membrane separation technology for sludge treatment has the advantages of small floor area, being conducive to the attachment of microorganisms, and good effluent quality, compared with the general sludge treatment process, there are more colloids and membrane pollutants in the sludge mixture, causing serious membrane fouling. Severe membrane fouling will lead to a short membrane operation cycle and an increased cleaning frequency, further increasing the operating cost and severely restricting the further application of the membrane separation technology for sludge treatment. There are studies at home and abroad that during the operation of a membrane bioreactor, by increasing the electric field, the membrane module is negatively charged, and using the characteristics of the main membrane pollutants (such as proteins, colloids, etc.) being negatively charged, the membrane fouling can be slowed down and controlled, and the effluent quality can be improved by the electrocoagulation effect of the electrode.

[0004] In summary, the enhanced denitrification system of the electrocatalytic coupled membrane device and the method of rapidly increasing the total nitrogen removal load in the prior art are all completed under high concentration nitrite environment, which is obviously not ideal in practical application. In the current research on the optimization of anaerobic ammonium oxidation reaction under low concentration nitrite, its total nitrogen removal rate still needs to be improved and cannot break through the limitations of traditional anaerobic ammonium oxidation. In addition, membrane fouling is also a major problem. Therefore, in order to achieve low concentration NO2 2- In order to enhance the denitrification system and rapidly increase the total nitrogen removal load under -N environment, it is necessary to propose a method to effectively enhance the denitrification reaction. Summary of the invention

[0005] The purpose of the present invention is to provide an electrocatalytic biological denitrification system and denitrification method of a ruthenium-plated electrode composite hollow fiber membrane in view of the deficiencies of the prior art. The electrocatalytic biological denitrification system adopts a double-chamber UASB reactor with a cathode / anode chamber separated by a porous filter plate. The electrocatalytic anode adopts a ruthenium-plated iridium titanium mesh and a conductive carbon felt. The electroactive bacteria produce nitrogen gas / nitrate through anaerobic ammonia oxidation, and electrochemically oxidize ammonia nitrogen to nitrite. The cathode combines a ruthenium-plated iridium titanium mesh barrel with carbon felt to reduce nitrate to nitrite. The cathode is built with a hollow fiber membrane to separate sludge, a DC power supply drives the reaction, anode nitrogen enters the cathode to enhance mass transfer, and cathode nitrite flows back to the anode for recycling. The system couples electrochemistry and biological action to form ammonia nitrogen oxidation-nitrate reduction synergistic path, optimizes electron transfer efficiency through the electrode structure, and realizes efficient conversion and removal of nitrogen. The system has a simple structure, good denitrification effect, and has good application prospects.

[0006] The specific technical solution for achieving the object of the present invention is as follows: An electrocatalytic biological denitrification system for a ruthenium-plated electrode composite hollow fiber membrane, characterized in that the electrocatalytic biological denitrification system includes: a two-chamber UASB reactor with an anode chamber and a cathode chamber separated by a porous filter plate, a hollow fiber membrane, a DC power supply, a reflux peristaltic pump, a feed peristaltic pump, and an effluent peristaltic pump. The anode uses a ruthenium-iridium-titanium mesh and a conductive carbon felt, and the cathode uses a ruthenium-iridium-titanium mesh barrel and a carbon felt. The anode is a composite biological electrode disposed in the anode chamber, and this electrode is composed of a ruthenium-iridium-coated helical blade titanium alloy mesh, a ruthenium-iridium-coated titanium alloy rod, and an anode conductive carbon felt wrapped around the periphery of the titanium alloy mesh; the cathode is a composite biological electrode disposed in the cathode chamber, and this electrode is composed of a ruthenium-iridium-coated titanium alloy mesh barrel and a cathode conductive carbon felt fixed to its periphery; the hollow fiber membrane is disposed inside the cathode composite biological electrode for separating sludge and small molecule substances; the DC power supply is respectively connected to the anode composite biological electrode and the cathode composite biological electrode through an anode power supply port and a cathode power supply port using titanium wires for binding to provide a constant potential to drive the electrochemical reaction; the nitrogen gas generated in the anode chamber enters the cathode chamber through the porous filter plate, and is collected in a nitrogen gas collection bag by sleeving a hose at the cathode gas outlet, and the nitrogen gas is pumped in using a cathode gas internal circulation pump; the nitrite generated in the cathode chamber is recycled to the anode chamber through the reflux peristaltic pump; the anode conductive carbon felt is loaded with electroactive functional bacteria to generate nitrogen gas and nitrate through the anaerobic ammonium oxidation reaction, and directly oxidize ammonia nitrogen to nitrite through the anode electrochemical action; the cathode conductive carbon felt is loaded with electroactive functional bacteria to reduce the nitrate transmitted from the anode to nitrite; the feed peristaltic pump is sleeved with a hose to the anode feed port of the two-chamber UASB reactor for transporting a pre-degraded substrate into the two-chamber UASB reactor, and is connected to a liquid circulation pump by a hose at the anode effluent port for circulating part of the anode effluent to the anode feed port; the effluent peristaltic pump is connected by a hose through the cathode effluent port to a pipe opening disposed at the top of the hollow fiber membrane for sucking the water and small molecule substances separated by the membrane; the hollow fiber membrane is made of polyvinylidene fluoride.

[0007] The ruthenium-iridium-coated helical blade titanium alloy mesh and the ruthenium-iridium-coated titanium alloy rod are disposed at the center of the anode composite biological electrode; the anode conductive carbon felt is fixed to the periphery of the ruthenium-iridium-coated helical blade titanium alloy mesh by titanium wires.

[0008] The ruthenium-iridium-coated titanium alloy mesh barrel and the hollow fiber membrane are disposed at the center of the cathode composite biological electrode; the cathode conductive carbon felt is fixed to the periphery of the ruthenium-iridium-coated titanium alloy mesh barrel by titanium wires.

[0009] The porous filter plate is vertically disposed in the middle of the two-chamber UASB reactor; the surface of the porous filter plate is evenly distributed with hydrophobic micropores for blocking the sludge migration between the anode chamber and the cathode chamber and allowing unidirectional gas permeation.

[0010] A denitrification method for an electrocatalytic biological denitrification system of a ruthenium-plated electrode composite hollow fiber membrane is characterized in that the automated operation of the electrocatalytic biological denitrification of the ruthenium-plated electrode composite hollow fiber membrane is realized by using a computer terminal device and a set operating program, and specifically comprises the following steps: 1) The pre-degraded substrate is transported to the anode chamber of the dual-chamber UASB reactor, and the electroactive functional bacteria loaded on the anode composite bioelectrode undergo anaerobic ammonia oxidation reaction to generate nitrogen gas and nitrate, while ammonia nitrogen is directly oxidized to generate nitrite through the anode electrochemical action; 2) Nitrate is input into the cathode chamber, and the electroactive functional bacteria loaded on the cathode composite bioelectrode reduce the nitrate to nitrite; 3) Separating the sludge and small molecules in the cathode chamber through the hollow fiber membrane; 4) applying a constant potential to the anode composite bioelectrode and the cathode composite bioelectrode to drive the electrochemical reaction; 5) The nitrogen generated in the anode chamber is introduced into the cathode chamber through a porous filter plate and collected at the nitrogen collection bag for internal circulation; 6) The nitrite generated in the cathode chamber is refluxed to the anode chamber for a cyclic reaction, thereby realizing automatic biological denitrification of the ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system.

[0011] The computer terminal device includes one or more processors and a memory; the memory is coupled to the processor and is used to store one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors realize the biological denitrification of the ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system.

[0012] Compared with the prior art, the present invention has the following beneficial technical effects and significant technical progress: 1) Compared with traditional carbon rods and titanium wires, composite bioelectrodes have better conductivity, are more prone to electrochemical redox reactions, are more conducive to electron transfer and microbial attachment, and utilize electroactive microorganisms and anaerobic ammonia-oxidizing bacteria to oxidize NH 4+ -N synthesizes N2 to achieve the purpose of denitrification, and circulates N2 through the cathode gas internal circulation pump to reduce the pollution of the hollow fiber membrane.

[0013] 2) The liquid circulation pump increases the time that the pre-degraded matrix stays at the anode, enabling the composite anode to further denitrify the wastewater.

[0014] 3) The outlet peristaltic pump can make the sewage flow back, so that the NO2 produced by the cathode reaction 2- -N reflows to the anode to further improve the total nitrogen removal efficiency.

[0015] 4) Couple electrochemistry with biological action to form a synergistic path of ammonia nitrogen oxidation - nitrate reduction, optimize the electron transfer efficiency through electrode structure, and achieve efficient conversion and removal of nitrogen.

[0016] 5) Strengthen the anaerobic ammonia oxidation system and rapidly increase the total nitrogen removal load. The system has a simple structure, good denitrification effect, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the present invention; Figure 2 It is a schematic structural diagram of the anode composite bioelectrode; Figure 3 It is a schematic structural diagram of the cathode composite bioelectrode. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention provides a novel ruthenium - plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system, which reduces the pollution to the hollow fiber membrane by applying an electric field in the sludge; at the same time, uses electrochemistry and membrane separation technologies to accelerate the growth of AnAOB, improve the microbial activity and effluent quality, and finally add reflux to further enhance the sludge denitrification performance.

[0019] Refer to Figure 1 , the ruthenium - plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system of the present invention includes: nitrogen gas collection bag 1, hollow fiber membrane 2, cathode gas internal circulation pump 3, cathode conductive carbon felt 4, cathode composite bioelectrode 5, anode composite bioelectrode 6, anode conductive carbon felt 7, liquid circulation pump 8, DC power supply 9, double - chamber UASB reactor 10, effluent peristaltic pump 11, reflux peristaltic pump 12, influent peristaltic pump 13, porous filter plate 14, membrane pressure gauge 15, cathode water outlet 16, cathode gas outlet 17, anode power supply connection port 18, anode power supply connection port 19, anode water outlet 20, anode influent port 21, ruthenium - plated iridium titanium alloy mesh barrel 22, ruthenium - plated iridium titanium alloy rod 23, ruthenium - plated iridium helical blade titanium alloy mesh 24.

[0020] The ruthenium - plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system is composed of a double - chamber UASB reactor 10 carrying an anode composite bioelectrode 6 and a cathode composite bioelectrode 5. The porous filter 14 separates the anode chamber from the cathode chamber; the nitrogen gas generated in the anode chamber enters the cathode chamber through the porous filter plate 14 and is collected by the nitrogen gas collection bag 1, and the nitrogen gas collected by the nitrogen gas collection bag 1 is circulated in the cathode chamber by the cathode gas internal circulation pump 3; the anode composite bioelectrode 6 is a helical blade electrode arranged in the anode chamber, which is wrapped by the anode conductive carbon felt 7 and loaded with electroactive functional bacteria, and uses anaerobic ammonia oxidation to react NH 4+ -N with NO2 2- -N to generate N2 and NO3 2--N is directly oxidized to NH under anodic electrochemical action 4 + -N, generating NO3 2- -N and NO2 2— N. Among them, NO2 2- -N can be reused by anaerobic ammonium-oxidizing bacteria, thereby fully removing NH 4+ -N; the cathode composite bioelectrode 5 is a mesh barrel electrode arranged in the cathode chamber, which is wrapped with carbon felt and loaded with electroactive functional bacteria, and reduces NO3 2- -N from the anode sewage to NO2 2- -N through denitrification; the DC power supply 9 is respectively connected to the anode composite bioelectrode 6 and the cathode composite bioelectrode 5 through a circuit to provide a constant potential and drive the electrode reaction to occur; the outlet of the inlet peristaltic pump 13 is connected to the anode inlet 2; the membrane pressure gauge 15 is arranged on the pipeline connecting the cathode outlet 16 and the outlet peristaltic pump 11.

[0021] Refer to Figure 2 , the cathode composite bioelectrode 5 includes: a hollow fiber membrane 2, a ruthenium-iridium-plated titanium alloy mesh barrel 22, and a cathode conductive carbon felt 4. The hollow fiber membrane 2 is arranged inside the ruthenium-iridium-plated titanium alloy mesh barrel 22; the ruthenium-iridium-plated titanium alloy mesh barrel 22 is wrapped with the cathode conductive carbon felt 4 on the outside; Refer to Figure 3 , the anode composite bioelectrode 6 includes: an anode conductive carbon felt 7, a ruthenium-iridium-plated titanium alloy rod 23, and a ruthenium-iridium-plated helical blade titanium alloy mesh 24. Several symmetrically arranged ruthenium-iridium-plated helical blade titanium alloy meshes 24 are mounted on the ruthenium-iridium-plated titanium alloy rod 23; the ruthenium-iridium-plated helical blade titanium alloy mesh 24 is wrapped with the anode conductive carbon felt 7 on the outside.

[0022] The present invention will be further described in detail below with specific embodiments. It should be noted that, without conflict, the features in each embodiment can be combined with each other. The steps in the embodiments can be executed in a computer system with a set of executable instructions. The logical order shown in the flowchart can, in some cases, be different from the order of execution or description of the steps here.

[0023] The present invention will be further described in detail below with specific embodiments. Embodiment

[0024] Refer to Figure 1, in this embodiment, a ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system is provided, which includes: an anode chamber and a cathode chamber arranged on a two-chamber UASB reactor 10 and separated by a porous filter plate 14, an anode composite biological electrode 6 arranged in the anode chamber, and a cathode composite biological electrode 5 arranged in the cathode chamber. The two-chamber UASB reactor 10 is an upflow anaerobic sludge bed; the anode composite biological electrode 6 and the cathode composite biological electrode 5 are provided with a constant potential by a DC power supply 9 to drive the electrochemical reaction.

[0025] The anode composite biological electrode 6 includes a ruthenium-iridium-plated helical blade titanium alloy mesh 24 and an anode conductive carbon felt 7 wrapped around its periphery. It is arranged in the anode chamber to load electroactive functional bacteria, generate nitrogen and nitrate through anaerobic ammonium oxidation reaction, and directly oxidize ammonia nitrogen to nitrite through anodic electrochemical action.

[0026] The cathode composite biological electrode 5 is composed of a hollow fiber membrane 2, a ruthenium-iridium-plated titanium alloy mesh barrel 22, and a cathode conductive carbon felt 4 fixed on its periphery. It is arranged in the cathode chamber to load electroactive functional bacteria and reduce the nitrate transferred from the anode to nitrite; the hollow fiber membrane 2 passes through the inside of the cathode composite biological electrode 5 to separate sludge from small molecules; the DC power supply 9 is respectively connected to the anode composite biological electrode 6 and the cathode composite biological electrode 5 through the anode power supply port 19 and the cathode power supply port 18 by titanium wire binding to provide a constant potential to drive the electron movement in the two-chamber UASB reactor 10 and promote microbial electron transfer at the same time.

[0027] The nitrogen generated in the anode chamber enters the cathode chamber through the porous filter plate 14, and is collected at the cathode gas outlet 17 with a hose sleeve to a nitrogen gas collection bag 1. The cathode gas internal circulation pump 3 is used to pump the nitrogen into the cathode chamber for internal circulation. The generated nitrite passes through the reflux peristaltic pump 12 and is recycled from the cathode water outlet 16 at the top of the cathode chamber to the anode chamber through the anode water inlet 21.

[0028] The cathode composite biological electrode 5 and the anode composite biological electrode 6 are both arranged inside the corresponding cathode and anode chambers of the two-chamber UASB reactor 10, and electroactive functional bacteria are loaded on the surface; the porous filter plate 14 is arranged between the anode chamber and the cathode chamber; the hollow fiber membrane 2 is arranged in the cathode chamber of the two-chamber UASB reactor 10 and is located inside the cathode composite biological electrode 5; the anode water outlet 20 at the top of the anode chamber is refluxed to the anode bottom inside the anode chamber through the liquid circulation pump 8; the DC power supply 9 is respectively connected to the anode composite biological electrode 6 and the cathode composite biological electrode 5 through an electric circuit to provide a constant potential to drive the electrode reaction to occur; the membrane pressure gauge 15 is respectively connected to the hollow fiber membrane 2 and the effluent peristaltic pump 11.

[0029] As an implementation mode in this embodiment, it further includes an inlet peristaltic pump 13, which is connected to the bottom of the double-chamber UASB reactor 10 through a pipeline and is used to transport the pre-degraded substrate into the double-chamber UASB reactor 10. A liquid circulation pump 8 is connected to the anode water outlet 20 by a hose and is used to circulate part of the anode effluent to the anode water inlet 21.

[0030] Specifically, it further includes an outlet peristaltic pump 11, which is connected to the top of the hollow fiber membrane 2 through a pipeline and is used to suck out the small molecule substances and water separated from the sludge from the double-chamber UASB reactor 10.

[0031] As an implementation mode in this embodiment, the hollow fiber membrane 2 is made of polyvinylidene fluoride (PVDF).

[0032] As an implementation mode in this embodiment, the structure of the anode composite biocathode 6 includes: A ruthenium-iridium-plated helical blade titanium alloy mesh 24 and a ruthenium-iridium-plated titanium alloy rod 23, and they are arranged at the center of the anode composite biocathode 6; the anode conductive carbon felt 7 is fixed to the periphery of the ruthenium-iridium-plated helical blade titanium alloy mesh 24 by titanium wires.

[0033] Specifically, the anode composite biocathode 6 includes: four ruthenium-iridium-plated helical blade titanium alloy meshes 24 arranged on the ruthenium-iridium-plated titanium alloy rod 23, and the anode conductive carbon felt 7 is respectively fixed to the periphery of the helical blade titanium mesh 24 by titanium wires.

[0034] As an implementation mode in this embodiment, the structure of the cathode composite biocathode 5 includes: A ruthenium-iridium-plated titanium alloy mesh barrel 22 and a hollow fiber membrane 2, and they are arranged at the center of the cathode composite biocathode 5; the cathode conductive carbon felt 4 is fixed to the periphery of the ruthenium-iridium-plated titanium alloy mesh barrel 22 by titanium wires.

[0035] As an implementation mode in this embodiment, the porous filter plate 14 is vertically arranged in the middle of the double-chamber UASB reactor 10, and hydrophobic micropores are evenly distributed on the surface of the porous filter plate 14, which is used to block the sludge migration between the anode chamber and the cathode chamber and allow the one-way permeation of gas.

[0036] As an additional implementation mode in this embodiment, the electro-carbon felt is made of a material with a conductive polymer and has a good three-dimensional structure. The anode conductive carbon felt 7 and the cathode conductive carbon felt 4 are made of a conductive polymer material with a good three-dimensional structure.

[0037] As an additional implementation mode in this embodiment, the anode composite bioelectrode 6 is made of ruthenium-iridium-plated titanium alloy-graphite felt and loaded with microorganisms, and can utilize NH 4+ -N and NO2 2- -N to react to generate N2 and NO3 2- -N through anaerobic ammonium oxidation, and can directly oxidize NH 4+ -N under the action of anodic electrochemistry to produce NO3 2- -N and NO2 2- -N, and are reused by anaerobic ammonium-oxidizing bacteria, thereby fully removing NH 4+ -N. In addition, the N2 generated in this process can enter the cathode through the porous filter plate 14 to alleviate membrane fouling.

[0038] As an additional implementation mode in this embodiment, the cathode composite bioelectrode 5 is made of ruthenium-iridium-plated titanium alloy-graphite felt and loaded with microorganisms, and reduces NO3 2- -N from the anode sewage to NO2 2- -N through denitrification.

[0039] Based on this, a ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system provided by an embodiment of the present invention, compared with the prior art, the composite bioelectrode of the present invention has better electrical conductivity than traditional carbon rods and titanium wires, is more likely to undergo electrochemical oxidation-reduction reactions, is more conducive to electron transfer and microbial attachment, and uses electroactive microorganisms and anaerobic ammonium-oxidizing bacteria to oxidize NH 4+ -N to synthesize N2 to achieve the purpose of denitrification, and the N2 is circulated by the cathode gas internal circulation pump 3 to reduce the fouling of the hollow fiber membrane. Moreover, the liquid circulation pump 8 increases the residence time of the pre-degraded substrate in the anode, enabling the composite anode to further denitrify the sewage; the effluent peristaltic pump can make the sewage flow back, enabling the NO2 2- -N generated by the cathode reaction to flow back to the anode to further improve the total nitrogen removal efficiency.

[0040] The advantages of this embodiment are elaborated below through three experimental cases: Experimental Case 1: Refer to Figure 1 , and the cultivation device uses a 2.5 L two-chamber UASB reactor. Among them, each of the anode chamber and the cathode chamber is 1 L, including a 500 mL top space for biogas collection. The anode and the cathode are connected to a DC power supply through an external circuit between the two poles to provide the required 2.5 V potential.

[0041] Refer to Figures 2 to 3, both the anode and cathode electrode materials used are carbon rod electrodes wrapped with graphite felt. The sludge in the anode chamber is taken from the anaerobic ammonium oxidation raw sludge domesticated in a solid waste laboratory as the inoculated sludge and electrolyte is added; the sludge in the cathode chamber is taken from the activated sludge of a sewage treatment plant as the inoculated sludge, and the effluent from the lower anode is used as the electrolyte. The daily N2 internal circulation aeration flow rate is set at 2 L / minute, and the aeration time is controlled at 8 h / day. Before the experiment starts, the pH of the solution in both the anode and cathode chambers is adjusted to 7.0 to suit the growth of electroactive functional bacteria. At regular intervals, a certain volume of biogas (N2) is taken from the top space of the cathode chamber with a syringe and analyzed by a gas chromatograph equipped with a thermal conductivity detector. The total nitrogen degradation rate is measured by the national standard method. After the reactor runs for 15 days, the total nitrogen removal rate of this system reaches 69.16%, which is about 38.85% higher than that of the ordinary system.

[0042] Experimental Case 2: The electrolyte added to the anode and cathode, the preparation of trace solutions, and the usage method are the same as those in Experimental Case 1, and an anode reflux device is added. A potential of 2.5 V is applied to the cathode through circuit control devices such as a potentiostat. The daily N2 internal circulation aeration flow rate is set at 2 L / minute, and the aeration time is controlled at 8 h / day. The enhanced anaerobic ammonium oxidation system and the system for rapidly increasing the total nitrogen removal load provided by the present invention, compared with the Anammox system without installing a hollow fiber membrane and without adding reflux, under the same reaction conditions, the total nitrogen removal rate has increased by 16.9% (reaching 86.06%), which is about 55.75% higher than that of the ordinary system. At the same time, the reflux in the anode chamber reduces the concentration of pollutants, and after the reaction ends, the hollow fiber membrane does not show any pollution phenomenon.

[0043] Experimental Case 3: The electrolyte added to the anode and cathode of the reactor, the preparation of trace solutions, and the usage method are the same as those in Experimental Case 2, and a cathode reflux device is added. A potential of 2.5 V is applied to the cathode through circuit control devices such as a potentiostat. The daily N2 internal circulation aeration flow rate is set at 2 L / minute, the aeration time is controlled at 8 h / day, and the cathode reflux ratio is set at 0.5. After adding the cathode reflux, compared with Case 2, under the same reaction conditions, the total nitrogen removal rate reaches 94.24%, which is about 63.94% higher than that of the ordinary system. In the case of low-concentration NO2 2- -N, efficient denitrification is achieved, and the transmembrane pressure difference is only -15 kPa.

[0044] Thus, the enhanced anaerobic ammonium oxidation system and the system for rapidly increasing the total nitrogen removal load provided by this embodiment have the following beneficial effects: 1) The composite bioelectrode has better conductivity than traditional carbon rods and titanium wires, is more prone to electrochemical oxidation-reduction reactions, degrades and denitrifies, and is more conducive to electron transfer and microbial attachment.

[0045] 2) Compared with traditional Anammox technology, it still has a high denitrification rate for wastewater with low concentration of nitrite nitrogen, saves costs, is low-carbon, and achieves the effect of energy recycling.

[0046] 3) It can utilize electroactive microorganisms to degrade the pre-degraded matrix to synthesize N2 and the additional electrochemical action of the two electrodes to reduce the fouling of the hollow fiber membrane, reduce the frequency of membrane washing, and reduce membrane loss.

[0047] 4) The present invention has a high degree of automation, is easy to install and maintain, can achieve long-term stable operation, and has low requirements on operators. Example

[0048] Based on the same general inventive concept, the present invention also provides a ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification method. The ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification method provided by the present invention is described below. The ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification method described below and the ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system described above can be mutually referenced. The method comprises: 1) The pre-degraded substrate is transported to the anode chamber of the dual-chamber UASB reactor 10, and the electroactive functional bacteria loaded on the anode composite bioelectrode 6 undergo anaerobic ammonia oxidation reaction to generate nitrogen gas and nitrate, while ammonia nitrogen is directly oxidized to generate nitrite through the anode electrochemical action.

[0049] 2) transferring the nitrate to the cathode chamber, and reducing the nitrate to nitrite by the electroactive functional bacteria carried by the cathode composite bioelectrode 5; 3) Separating the sludge and small molecules in the cathode chamber through the hollow fiber membrane 2; 4) applying a constant potential to the anode composite bioelectrode 6 and the cathode composite bioelectrode 5 to drive the electrochemical reaction; 5) The nitrogen generated in the anode chamber is introduced into the cathode chamber through the porous filter plate 14, and is collected at the nitrogen collecting bag 1 and circulated internally; 6) The nitrite generated in the cathode chamber is refluxed to the anode chamber for a cyclic reaction.

[0050] As an implementation method in this example, the delivery of the pre-degradable matrix is achieved by a water inlet peristaltic pump 13 , and the water inlet peristaltic pump 13 is connected to the bottom of the double-chamber UASB reactor 10 .

[0051] As an implementation method in this embodiment, the separation of sludge and small molecular substances is achieved by an outlet peristaltic pump 11 , and the outlet peristaltic pump 11 is connected to the top of the hollow fiber membrane 2 .

[0052] The ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification method of the above embodiments employs a computer terminal device including one or more processors; the processors are coupled to store one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement a ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification method.

[0053] The above are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the technical field of the present application within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electrocatalytic biological denitrification system for a ruthenium-plated electrode composite hollow fiber membrane, characterized in that, The denitrification system comprises: an anode chamber and a cathode chamber arranged on a double-chamber UASB reactor, and an anode composite bioelectrode arranged in the anode chamber and a cathode composite bioelectrode arranged in the cathode chamber, wherein the cathode chamber is provided with a gas circulation pipe and a liquid circulation pipe; the gas circulation pipe is composed of a nitrogen gas collecting bag and a cathode gas internal circulation pump connected by a pipeline; the nitrogen gas collecting bag is connected to the cathode gas outlet; the cathode gas internal circulation pump pumps the nitrogen collected by the nitrogen gas collecting bag into the cathode chamber from the bottom of the chamber; the liquid circulation pipe is composed of a reflux peristaltic pump and a membrane pressure gauge connected by a pipeline, and the reflux peristaltic pump pumps the liquid in the cathode chamber into the anode chamber through the anode water inlet; The anode chamber is provided with a reflux pipeline of a liquid circulation pump; two pipe openings of the liquid circulation pump are respectively connected to the anode water outlet and the anode water inlet; the denitrification system is provided with an inlet peristaltic pump for conveying pre-degraded substrates into the double-chamber UASB reactor and an outlet peristaltic pump for discharging liquid from the double-chamber UASB reactor; the inlet pipe opening of the outlet peristaltic pump is connected to the inlet pipe opening of the reflux peristaltic pump; the outlet pipe opening of the inlet peristaltic pump is connected to the anode water inlet; the anode composite bioelectrode and the cathode composite bioelectrode are provided with a constant potential by a DC power supply to drive the movement of electrons in the double-chamber UASB reactor, while promoting microbial electron transfer to achieve electrocatalytic biological denitrification.

2. The electrocatalytic biological denitrification system of the ruthenium-plated electrode composite hollow fiber membrane according to claim 1, characterized in that, The double-chamber UASB reactor is an upflow anaerobic sludge blanket.

3. The electrocatalytic biological denitrification system of the ruthenium-plated electrode composite hollow fiber membrane according to claim 1, characterized in that, The cathode composite bioelectrode is composed of a hollow fiber membrane arranged in a ruthenium-iridium-plated titanium alloy mesh barrel, and the outer periphery of the ruthenium-iridium-plated titanium alloy mesh barrel is wrapped with cathode conductive carbon felt; the hollow fiber membrane is made of polyvinylidene fluoride.

4. The electrocatalytic biological denitrification system of the ruthenium-plated electrode composite hollow fiber membrane according to claim 1, characterized in that, The anode composite bioelectrode is composed of a ruthenium-iridium-plated titanium alloy rod mounted with a plurality of symmetrically arranged ruthenium-iridium-plated spiral blade titanium alloy meshes, and the outer periphery of the ruthenium-iridium-plated spiral blade titanium alloy meshes is wrapped with anode conductive carbon felt.

5. The electrocatalytic biological denitrification system of the ruthenium-plated electrode composite hollow fiber membrane according to claim 1, characterized in that, The porous filter plate is provided with uniformly distributed hydrophobic micropores.

6. A denitrification method for an electrocatalytic biological denitrification system of a ruthenium-plated electrode composite hollow fiber membrane according to claim 1, characterized in that, The automatic biological denitrification of the ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system is realized by using computer terminal equipment and set operating procedures, which specifically includes the following steps: 1) The pre-degraded substrate is input into the anode chamber of the dual-chamber UASB reactor, and the electroactive functional bacteria loaded on the anode composite bioelectrode undergo anaerobic ammonia oxidation reaction to generate nitrogen gas and nitrate, while ammonia nitrogen is directly oxidized to generate nitrite through the anode electrochemical action; 2) transferring the generated nitrate to the cathode chamber, and reducing the nitrate to nitrite by the electroactive functional bacteria loaded on the cathode composite bioelectrode; 3) Separating the sludge and small molecules in the cathode chamber through the hollow fiber membrane; 4) applying a constant potential to the anode composite bioelectrode and the cathode composite bioelectrode to drive the electrochemical reaction; 5) introducing the nitrogen generated in the anode chamber into the cathode chamber through a porous filter plate; 6) The nitrite generated in the cathode chamber is refluxed to the anode chamber for cyclic reaction to achieve electrocatalytic biological denitrification.

7. The denitrification method of the electrocatalytic bio-denitrification system of the ruthenium-plated electrode composite hollow fiber membrane according to claim 7, characterized in that, The computer terminal device includes one or more processors and a memory, the memory is coupled to the processor, and when one or more programs are executed by one or more processors, the one or more processors implement automatic biological denitrification of the ruthenium-plated electrode composite hollow fiber membrane electrocatalytic biological denitrification system.

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