Electrically-assisted anaerobic reactor and method for treating sewage to produce methane by electrically-assisted anaerobic reactor

Abstract

The invention provides an electrically-assisted anaerobic reactor and a method for producing methane by treating sewage. The electrically-assisted anaerobic reactor comprises an inner cylinder and an outer cylinder, the outer cylinder is sleeved outside the inner cylinder and is of a sleeve type structure, and a top cover is arranged at the top of the outer cylinder; the top cover is provided with a water inlet pipe; the inner barrel is divided into a plurality of inner barrel compartments by a plurality of radially arranged inner barrel partition plates; each inner cylinder compartment is provided with a guide plate; the space between the inner barrel and the outer barrel is divided into a plurality of outer barrel compartments through outer barrel partition plates which are arranged in an up-and-down staggered manner; an outer barrel water outlet pipe is arranged on the outer barrel; the guide plate guides water flow to be baffled up and down in each inner cylinder compartment, penetrate through each inner cylinder compartment and enter the outer cylinder from the water outlet hole of the inner cylinder; the water flow is baffled up and down between the outer cylinder compartments through the outer cylinder partition plates which are staggered up and down and flows out from the outer cylinder water outlet pipe; the inner cylinder is provided with an inner cylinder electrode, the outer cylinder is provided with an outer cylinder electrode, the inner cylinder electrode and the outer cylinder electrode are connected with a direct-current power supply, through gas circulation, the methane concentration in the biogas and the total yield of methane are increased, and the sewage energy recovery efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment and resource utilization, and specifically relates to an electrically assisted anaerobic reactor and a method for treating sewage and producing methane thereof. Background Art

[0002] Due to the severe energy situation and the requirements for controlling carbon emissions, the goal of sewage treatment has expanded from the original environmental pollution control to the recovery of sewage resources and energy. Sewage itself contains a lot of energy. Using anaerobic technology to recover the energy in sewage in the form of biogas, converting it into heat or electricity to feed back to other treatment stages will make it possible to achieve energy self-sufficiency in the entire treatment process and reduce disordered carbon emissions.

[0003] The anaerobic baffled reactor (ABR) is a highly efficient anaerobic biological treatment device. The ABR divides the reactor into multiple reaction chambers through vertical partitions. The sewage is baffled up and down along the guide plates in each reaction chamber and repeatedly passes through the sludge bed to remove the organic matrix. The unique grating structure and plug flow state of the ABR can domesticate and cultivate microbial communities that are more adapted to the environmental conditions in each reaction chamber, achieve biological phase separation in space, and thus obtain higher treatment efficiency. However, the traditional ABR reactor aims to remove pollutants, and has certain technical limitations in sewage energy recovery, such as long reaction time, poor operating stability, low methane production, etc., and the methane content in the generated biogas is usually low, which is not conducive to resource utilization.

[0004] As an emerging technology, microbial electrochemical system (BES) has shown great potential in the field of sewage treatment and resource utilization. BES can achieve the removal and transformation of pollutants through electrochemical processes, and can recover energy in the form of hydrogen or methane. In addition, by applying a micro-electric field, the enrichment and domestication of anaerobic functional communities (especially methanogenic functional communities) can be promoted, thereby strengthening the anaerobic digestion process. By coupling BES with an anaerobic baffle reactor, the anaerobic digestion time can be shortened and the sewage treatment efficiency can be improved. For example, invention patent 201310203153.1 discloses a microbial electric-assisted anaerobic baffle fermentation hydrogen production reactor, which, on the basis of a traditional anaerobic baffle reactor, inserts two opposing microbial electrodes in the upflow zone of each compartment to promote the degradation of the substrate, shorten the treatment cycle, and improve the volume utilization rate. Invention patent CN117263368B discloses a microbial electrolytic cell-assisted anaerobic baffle reactor, which is equipped with multiple sets of electrodes on the top of the baffle compartment to simultaneously achieve water purification and solid-liquid separation functions.

[0005] The existing coupling technology between BES and anaerobic baffled reactors mainly attempts to embed additional microbial electrodes in traditional anaerobic baffled reactors. The electrodes need to maintain a large area and a small electrode spacing to obtain good electrochemical efficiency, but the embedding of large-sized electrodes will interfere with the flow state of the anaerobic system, easily forming a dead zone in the middle of the electrode, affecting mass transfer. At the same time, high-concentration anaerobic sludge will also interfere with the microbial electrodes, resulting in reduced electrochemical efficiency. In addition, there are certain differences in the promoting role of electrochemistry in the acid production stage and the methane production stage. The existing technology does not optimize the structure and operation mode of the electrode according to the functions required in each stage, which is not conducive to giving full play to the promoting function of the electrochemical system, thereby affecting the energy recovery efficiency of the system. Summary of the invention

[0006] In view of the above technical problems, the present invention provides an electrically assisted anaerobic reactor, aiming to further improve the efficiency of wastewater energy recovery.

[0007] The invention also provides a method for treating sewage to produce methane by utilizing the electrically assisted anaerobic reactor.

[0008] Note that the description of these objectives does not prevent the existence of other objectives. One embodiment of the present invention does not need to achieve all of the above objectives. Objectives other than the above objectives can be extracted from the description of the specification, drawings, and claims.

[0009] The present invention achieves the above technical objectives through the following technical means.

[0010] An electrically assisted anaerobic reactor comprises an inner cylinder and an outer cylinder;

[0011] The outer cylinder is sleeved outside the inner cylinder to form a sleeve structure. A top cover is provided on the top of the outer cylinder. The top cover is provided with a water inlet pipe, which is located above the inner cylinder.

[0012] The inner cylinder is divided into a plurality of inner cylinder compartments by a plurality of radially arranged inner cylinder partition plates; each inner cylinder compartment is provided with a guide plate, and the inner cylinder is provided with an inner cylinder water outlet hole; the inner cylinder and the outer cylinder are divided into a plurality of outer cylinder compartments by the outer cylinder partition plates arranged in an up-and-down staggered manner, and the outer cylinder is provided with an outer cylinder water outlet pipe; the guide plate is used to guide the water flow to bend up and down in each inner cylinder compartment, and pass through each inner cylinder compartment in turn, and finally flow out from the inner cylinder water outlet hole into the outer cylinder; the outer cylinder partition plates arranged in an up-and-down staggered manner are used to make the water flow bend up and down between the outer cylinder compartments and flow out from the outer cylinder water outlet pipe;

[0013] The inner cylinder is provided with an inner cylinder electrode, and the outer cylinder is provided with an outer cylinder electrode. The inner cylinder electrode and the outer cylinder electrode are connected to a direct current power supply through a wire passing through the top cover.

[0014] In the above scheme, an air pump and an air outlet pipe are installed on the top cover, and an aeration head is provided at the bottom of the outer tube; the air inlet of the air pump is connected to the air collecting hood located above the inner tube, and the air outlet is connected to the aeration head; the gas is extracted by the air pump and then aerated from the aeration head, passes through the reaction area of ​​the outer tube from bottom to top, and escapes from the air outlet pipe for collection and storage.

[0015] In the above scheme, the inner cylinder electrode includes an inner cylinder cathode and an inner cylinder anode, the inner cylinder cathode is located at the center of the inner cylinder, and the inner cylinder anode is located on the inner wall of the inner cylinder; the outer cylinder electrode includes an outer cylinder anode and an outer cylinder cathode, the outer cylinder anode is located on the outer wall of the inner cylinder, and the outer cylinder cathode is located on the inner wall of the outer cylinder, an insulating layer is provided between the inner cylinder anode and the outer cylinder anode, and the inner cylinder electrode and the outer cylinder electrode are connected to a DC power supply through a wire passing through the top cover.

[0016] Furthermore, the inner cylinder cathode material is a stainless steel rod or a carbon rod, the inner cylinder anode material is a stainless steel mesh, a stainless steel sheet or a carbon cloth; the outer cylinder anode material is a porous conductive material such as carbon felt, carbon fiber cloth, or carbon cloth, and the outer cylinder cathode material is a conductive material such as stainless steel, nickel mesh, carbon felt, carbon fiber cloth or carbon cloth.

[0017] In the above scheme, the inner cylinder comprises 3 to 6 inner cylinder compartments, each inner cylinder compartment is provided with a guide plate, and the water flow first descends and then rises in each inner cylinder compartment.

[0018] Furthermore, anaerobic sludge is added to the upflow zone.

[0019] In the above scheme, the outer cylinder comprises 4 or 6 outer cylinder compartments, and only partitions are provided, and water flows up and down alternately between the outer cylinder compartments.

[0020] In the above scheme, an inner tube vent pipe is provided at the bottom of the inner tube; and an outer tube vent pipe is provided at the bottom of the outer tube.

[0021] A method for treating sewage to produce methane according to the electrically assisted anaerobic reactor comprises the following steps:

[0022] The inner cylinder electrode and the outer cylinder electrode are started, the inner cylinder and the outer cylinder are filled with electrode start-up nutrient solution, and a small amount of inoculated mud is added to the outer cylinder compartment respectively, the top cover is closed, and a preset external voltage is applied to both the inner cylinder and the outer cylinder. The reactor performs self-circulation operation, and the culture solution is replaced every preset time until the anode potential of the outer cylinder is lower than -400mV and the circuit current tends to be stable. It is considered that the outer cylinder electrode has been successfully started, the top cover is opened, the inner cylinder compartment is emptied, and anaerobic sludge is added to the inner cylinder compartment respectively, and then the top cover is closed, and sewage is continuously injected from the water inlet pipe to start formal operation. The sewage enters the inner cylinder through the water inlet pipe; the water flow first descends and then rises in each inner cylinder compartment under the guidance of the inner cylinder partition plate and the guide plate, and the water flow is deflected up and down in each inner cylinder compartment, and passes through the inner cylinder compartment in turn, and finally flows out from the inner cylinder outlet hole and enters the outer cylinder; the water flow is deflected up and down between the outer cylinder compartments, and finally flows out from the outer cylinder outlet pipe;

[0023] The gas generated in the reactor is pumped out from the aeration head after being extracted by the air pump, passes through the outer tube reaction area from bottom to top, and escapes from the outlet pipe for collection and storage. Through forced gas circulation, the produced biogas repeatedly passes through the microbial electrochemical action area, realizing the fixation of carbon dioxide and in-situ purification of biogas.

[0024] In the above scheme, the voltage applied to the inner cylinder electrode of the inner cylinder is 0.6V~0.8V, the voltage applied to the outer cylinder electrode of the outer cylinder is 0.3V~0.6V, the anaerobic sludge inoculation amount of each inner cylinder compartment is 20%~50% of the total volume, the operating temperature is room temperature, and the hydraulic retention time is 8~24h.

[0025] The working principle of the present invention is to use the separation structure of the inner cylinder and the outer cylinder to create phase separation in the anaerobic digestion process. The inner cylinder mainly completes the anaerobic hydrolysis and acid production process, while the outer cylinder mainly carries out the methane production process. At the same time, two sets of electrochemical electrodes are used to apply electrochemical intervention to the inner cylinder and the outer cylinder respectively, but the promotion effects of the inner cylinder electrode and the outer cylinder electrode are different. The inner cylinder mainly relies on the micro-voltage electric field generated by the non-biological electrode to stimulate the growth and development of anaerobic sludge, improve the activity of functional enzymes, and enhance the hydrolysis and acidification efficiency; the outer cylinder mainly relies on the biological electrode to create a colonization environment suitable for the growth and metabolism of methanogenic bacteria, and realize the rapid enrichment and metabolic enhancement of methanogenic functional bacteria. At the same time, the microbial electrochemical anode can further remove organic pollutants in the water, especially small molecular acids, improve the organic matter removal efficiency of the system, prevent acidification, and improve the stability of the system. The cathode participates in the methane production process through hydrogen evolution reaction or direct electron transfer, thereby increasing the methane production rate. In addition, the gas in the reactor is intermittently extracted by the air pump 7 and escapes from the aeration head 9 at the bottom of the outer tube. Through the electrochemical action of microorganisms, the fixation of carbon dioxide and the in-situ purification of methane can be effectively achieved.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The inner cylinder of the present invention is an electrically assisted anaerobic baffled reactor, and the outer cylinder is a microbial electrolytic cell reactor. Through the sleeve structure, the anaerobic digestion process is phase-separated in space, the fermentation and acid production process can be completed quickly, and under the stimulation of the electrode electrostatic field, the metabolic activity of the fermentation and acid production bacteria can be improved to a certain extent, accelerating the acid production process.

[0028] 2. The outer cylinder of the present invention further purifies the water effluent from the inner cylinder with the help of microbial electrochemical electrodes, strengthens the degradation of small molecular organic acids, and improves the removal rate of organic matter. At the same time, the microbial electrodes with rich pore structures in the outer cylinder serve as carriers with negative potential, providing a good habitat for the methanogenic bacteria, which is very conducive to their colonization, growth and metabolism.

[0029] 3. The gas generated in the reactor of the present invention is extracted by the air pump and then aerated from the aeration head, passes through the outer cylinder reaction area from bottom to top, and escapes from the outlet pipe. Through gas circulation, hydrogen, carbon dioxide and other metabolic substrates are provided for methanogens, which can increase the methane concentration in the biogas and the total methane production, and enhance the energy recovery effect of the system.

[0030] Note that the description of these effects does not prevent the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. Effects other than the above can be clearly seen and extracted from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a front view structural schematic diagram of a sleeve-type electrically assisted anaerobic baffled reactor according to one embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the top view of the structure of a sleeve-type electrically assisted anaerobic baffled reactor according to one embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the inner cylinder structure of a sleeve-type electrically assisted anaerobic baffled reactor according to one embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of each compartment of the inner cylinder of a sleeve-type electrically assisted anaerobic baffled reactor according to one embodiment of the present invention, wherein Figure 4 (a) is a schematic diagram of the structure of the first inner cylinder compartment. Figure 4 (b) is a schematic diagram of the structure of the second inner cylinder compartment or the third inner cylinder compartment, Figure 4 (c) is a schematic diagram of the structure of the fourth inner cylinder compartment;

[0035] Figure 5 FIG. 1 is a schematic diagram of a guide plate structure according to an embodiment of the present invention, wherein Figure 5 (a) is a schematic diagram of the main structure of the guide plate. Figure 5(b) is a schematic diagram of the side view of the guide plate;

[0036] Figure 6 Schematic diagram of the outer cylinder structure of a sleeve-type electrically assisted anaerobic baffled reactor according to one embodiment of the present invention, wherein Figure 6 (a) is a schematic diagram of the structure of the first outer cylinder compartment and the fourth outer cylinder compartment, Figure 6 (b) is a schematic diagram of the structure of the second outer cylinder compartment and the third outer cylinder compartment;

[0037] Figure 7 A schematic diagram of gas circulation in a sleeve-type electrically assisted anaerobic baffled reactor according to an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of electrochemical electrodes of a sleeve-type electrically-assisted anaerobic baffled reactor according to one embodiment of the present invention.

[0039] In the figure: 1, inner cylinder, 1-1, first inner cylinder compartment, 1-2, second inner cylinder compartment, 1-3, third inner cylinder compartment, 1-4, fourth inner cylinder compartment, 1-5, inner cylinder partition plate, 1-6, guide plate, 1-7, inner cylinder vent pipe; 2, outer cylinder, 2-1, first outer cylinder compartment, 2-2, second outer cylinder compartment, 2-3, third outer cylinder compartment, 2-4, fourth outer cylinder compartment, 2-5, outer cylinder partition plate, 2-6, outer cylinder vent pipe; 3, water inlet pipe, 4, top cover, 5, inner cylinder water outlet hole, 6, water outlet pipe, 7, air pump, 8, air collecting hood, 9, aeration pump, 10, air outlet pipe, 11, inner cylinder cathode, 12, inner cylinder anode, 13, outer cylinder anode, 14, outer cylinder cathode, 15, DC power supply. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "front", "back", "left", "right", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Figure 1-8 The figure shows a preferred embodiment of the electrically assisted anaerobic reactor, wherein the electrically assisted anaerobic reactor comprises an inner cylinder 1 and an outer cylinder 2;

[0044] The outer cylinder 2 is sleeved outside the inner cylinder 1, the inner cylinder 1 is an electrically assisted anaerobic baffle reactor, the outer cylinder 2 is a microbial electrolytic cell reactor, and a top cover 4 is provided on the top of the inner cylinder 1 and the outer cylinder 2; the top cover 4 is provided with a water inlet pipe 3, and the water inlet pipe 3 is located above the inner cylinder 1;

[0045] The inner cylinder 1 is divided into a plurality of inner cylinder compartments by a plurality of radially arranged inner cylinder partition plates 1-5; each inner cylinder compartment is respectively provided with a guide plate 1-6, and the inner cylinder 1 is provided with an inner cylinder water outlet hole 5; the inner cylinder 1 and the outer cylinder 2 are divided into a plurality of outer cylinder compartments by outer cylinder partition plates 2-5 arranged in an up-and-down staggered manner, and the outer cylinder 2 is provided with an outer cylinder water outlet pipe 6; the guide plates 1-6 are used to guide the water flow to bend up and down in each inner cylinder compartment, and pass through each inner cylinder compartment in turn, and finally flow out from the inner cylinder water outlet hole 5 and enter the outer cylinder 2; the outer cylinder partition plates 2-5 arranged in an up-and-down staggered manner are used to make the water flow bend up and down between the outer cylinder compartments and flow out from the outer cylinder water outlet pipe 6.

[0046] The inner cylinder partition plates 1-5 are vertical partition plates. The height of the first inner cylinder partition plate 1-5 (i.e., the partition plate on the water inlet side of the first inner cylinder compartment) is flush with the top of the inner cylinder 1, and the heights of the remaining inner cylinder partition plates 1-5 decrease successively along the circumferential direction (the direction of water flow). The sewage flows over the top of the partition plates from the previous inner cylinder compartment to the next inner cylinder compartment in turn, and flows into the outer cylinder 2 at the inner cylinder water outlet hole 5 of the last inner cylinder compartment.

[0047] The guide plates 1-6 are flush with the top of the inner tube 1, and have gaps between the bottom and the bottom of the inner tube 1, and are folded up at the bottom to guide the water flow. Figure 5 (a) and Figure 5 As shown in (b), the inner cylinder 1 is provided with an inner cylinder partition plate 1-5 and a guide plate 1-6, so that the sewage first flows downward in each inner cylinder compartment, flows to the bottom and bypasses the guide plate 1-6, then flows upward to the position of the inner cylinder partition plate 1-5 between the next inner cylinder compartment, then passes over the inner cylinder partition plate 1-5, and then flows downward.

[0048] The outer cylinder 2 is not provided with a guide plate, but only with outer cylinder partition plates 2-5 staggered up and down, and the sewage is diverted up and down between different outer cylinder compartments. Among them, the top of the first outer cylinder partition plate 2-5 is flush with the inner cylinder 2, and the bottom is connected to the bottom of the cylinder; along the water flow direction, the top of the second outer cylinder partition plate 2-5 is flush with the inner cylinder 2, and there is a gap between the bottom and the bottom of the outer cylinder 2; the bottom of the third outer cylinder partition plate 2-5 is flush with the bottom of the inner cylinder 2, and the top is lower than the top of the outer cylinder 2; the top of the fourth outer cylinder partition plate 2-5 is flush with the inner cylinder 2, and the arrangement is based on this rule. The outer cylinder partition plates 2-5 staggered up and down are used to make the water flow divert up and down between the outer cylinder compartments and flow out from the outer cylinder outlet pipe 6.

[0049] It also includes two sets of electrochemical systems, namely, an inner cylinder electrode and an outer cylinder electrode; the inner cylinder 1 is provided with the inner cylinder electrode, and the outer cylinder 2 is provided with the outer cylinder electrode, and the inner cylinder electrode and the outer cylinder electrode are connected to the DC power supply 15 through a wire passing through the top cover 4.

[0050] The inner cylinder electrode comprises an inner cylinder cathode 11 and an inner cylinder anode 12, wherein the inner cylinder cathode 11 is located at the center of the inner cylinder 1, and the inner cylinder anode 12 is located at the inner wall of the inner cylinder 1; the outer cylinder electrode comprises an outer cylinder anode 13 and an outer cylinder cathode 14, wherein the outer cylinder anode 13 is located at the outer wall of the inner cylinder 1, and the outer cylinder cathode 14 is located at the inner wall of the outer cylinder 2, an insulating layer is provided between the inner cylinder anode 12 and the outer cylinder anode 13, and the inner cylinder electrode and the outer cylinder electrode are connected to a DC power supply 15 through a wire passing through the top cover 4. The electrode configuration of the reactor of the present invention is simpler, and can make full use of the structural space of the reactor, increase the electrode size, shorten the electrode spacing, and do not interfere with the reactor flow state.

[0051] The inner cylinder cathode 11 is made of stainless steel rod or carbon rod, the inner cylinder anode 12 is made of stainless steel mesh, stainless steel sheet or carbon cloth; the outer cylinder anode 13 is made of porous conductive materials such as carbon felt, carbon fiber cloth or carbon cloth, and the outer cylinder cathode 14 is made of conductive materials such as stainless steel, nickel mesh, carbon felt, carbon fiber cloth or carbon cloth.

[0052] An air pump 7 and an air outlet pipe 10 are installed on the top cover 4, and an aeration head 9 is provided at the bottom of the outer tube 2; the air inlet of the air pump 7 is connected to the air collecting hood 8 located above the inner tube 1, and the air outlet is connected to the aeration head 9; the gas is extracted by the air pump 7 and then released from the aeration head 9, passes through the reaction area of ​​the outer tube 2 from bottom to top, and escapes from the air outlet pipe 10 for collection and storage.

[0053] The inner cylinder 1 comprises 3 to 6 inner cylinder compartments, each of which is provided with a guide plate 1-6, and the water flows firstly down and then up in each inner cylinder compartment.

[0054] Anaerobic sludge is added into the upflow zone to form a sludge bed structure.

[0055] In a specific embodiment of the present invention, each outer barrel compartment of the outer barrel 2 is connected with a small amount of sludge as an inoculum, and the inoculum source is not necessarily sludge, but sewage or other electrochemical reactor effluent can also be used as the inoculum source.

[0056] The outer cylinder 2 comprises 4 or 6 outer cylinder compartments, only partitions are provided, and water flows up and down alternately between the outer cylinder compartments.

[0057] An inner tube vent pipe 1-7 is provided at the bottom of the inner tube 1; an outer tube vent pipe 2-6 is provided at the bottom of the outer tube 2.

[0058] A method for treating sewage to produce methane according to the electrically assisted anaerobic reactor comprises the following steps:

[0059] Start the inner and outer cylinder electrodes, fill the inner and outer cylinders 1 and 2 with electrode start-up nutrient solution, add a small amount of inoculated mud to the outer cylinder compartments, close the top cover 4, apply a preset external voltage to both the inner and outer cylinders 1 and 2, and the reactor performs self-circulation operation, and replaces the culture solution every 72 hours. When the potential of the outer cylinder anode 13 is lower than -400mV and the circuit current tends to be stable, it is considered that the outer cylinder anode 13 has been successfully started, open the top cover 4, empty the inner cylinder compartment, and add a small amount of inoculated mud to the inner cylinder compartments. Anaerobic sludge is added to the cylinder compartments respectively, and then the top cover 4 is closed, and sewage is continuously injected from the water inlet pipe 3 to start formal operation. Sewage enters the inner cylinder 1 through the water inlet pipe 3; the water flow first descends and then rises in each inner cylinder compartment under the guidance of the inner cylinder partition plates 1-5 and the guide plates 1-6. The water flow turns up and down in each inner cylinder compartment, and passes through the inner cylinder compartments in turn, and finally flows out from the inner cylinder water outlet hole 5 and enters the outer cylinder 2; the water flow turns up and down between the outer cylinder compartments, and finally flows out from the outer cylinder outlet pipe 6;

[0060] The gas generated in the reactor is extracted by the air pump 7 and then exposed from the aeration head 9, passing through the reaction area of ​​the outer tube 2 from bottom to top, and escaping from the outlet pipe 10 for collection and storage. Through forced gas circulation, the produced biogas repeatedly passes through the microbial electrochemical action area to achieve carbon dioxide fixation and in-situ purification of biogas.

[0061] Preferably, the voltage applied to the inner cylinder electrode of the inner cylinder 1 is 0.6V to 0.8V, the voltage applied to the outer cylinder electrode of the outer cylinder 2 is 0.3V to 0.6V, the anaerobic sludge inoculation amount of each inner cylinder compartment is 20% to 50% of the total volume, the operating temperature is room temperature, and the hydraulic retention time is 8 to 24h. The present invention can apply different forms of electrochemical influences to different stages of the anaerobic digestion process, thereby giving full play to the electrochemical promotion effect to a greater extent.

[0062] In a specific embodiment of the present invention, the inner cylinder 1 comprises four inner cylinder compartments, namely a first inner cylinder compartment 1-1, a second inner cylinder compartment 1-2, a third inner cylinder compartment 1-3 and a fourth inner cylinder compartment 1-4. Figure 4 As shown, Figure 4 (a) is a schematic diagram of the structure of the first inner cylinder compartment 1-1, Figure 4 (b) is a schematic diagram of the structure of the second inner cylinder compartment 1-2 or the third inner cylinder compartment 1-3, Figure 4 (c) is a schematic diagram of the structure of the fourth inner cylinder compartment 1-4; the outer cylinder 2 includes four outer cylinder compartments, namely the first outer cylinder compartment 2-1, the second outer cylinder compartment 2-2, the third outer cylinder compartment 2-3, and the fourth outer cylinder compartment 2-4, combined with Figure 6 As shown, Figure 6 (a) is a schematic diagram of the structure of the first outer cylinder compartment 2-1 and the fourth outer cylinder compartment 2-4, Figure 6 (b) is a schematic diagram of the structure of the second outer cylinder compartment 2-2 and the third outer cylinder compartment 2-3.

[0063] Sewage enters the first inner cylinder compartment 1-1 through the water inlet pipe 3 and the top cover 4, and then passes through the inner cylinder guide plate 1-6 from top to bottom, then rises and crosses the partition plate 1-5, and then enters the second inner cylinder compartment 1-2, the third inner cylinder compartment 1-3 and the fourth inner cylinder compartment 1-4 in sequence, and enters the first outer cylinder compartment 2-1 from the inner cylinder water outlet hole 5, and then bypasses the outer cylinder partition plate 2-5 and flows up and down to pass through the second outer cylinder compartment 2-2, the third outer cylinder compartment 2-3, and the fourth outer cylinder compartment 2-4 in sequence, and finally flows out from the water outlet pipe 6. Each inner cylinder compartment is provided with an inner cylinder vent pipe 1-7, and each outer cylinder compartment is provided with an outer cylinder vent pipe 2-6.

[0064] like Figure 7 As shown, the gas in the reactor is extracted and then exposed from the aeration head 9 installed at the bottom of the outer cylinder, passes through the reaction area of ​​the outer cylinder from bottom to top, and escapes from the gas outlet pipe 10 to be collected and stored.

[0065] Compared with the common anaerobic baffle reactor, the electrically assisted anaerobic reactor of the present invention has a more compact cylindrical design and saves space. The sleeve structure of the inner cylinder 1 and the outer cylinder 2 realizes the phase separation of the anaerobic digestion process in the physical space, and promotes the anaerobic digestion process by introducing the electrochemical action of microorganisms, thereby obtaining better organic matter removal and energy recovery efficiency. Compared with other anaerobic-electrochemical coupling systems, the electrode configuration of the reactor of the present invention is simpler, which can make full use of the structural space of the reactor, increase the electrode size, shorten the electrode spacing, and does not interfere with the flow state of the reactor. In addition, different forms of electrochemical influences can be applied to different stages of the anaerobic digestion process, thereby maximizing the promotion effect of electrochemistry. The present invention combines the respective advantages of the electrochemical system and the anaerobic system to provide a sewage treatment solution that is efficient, energy-saving and has a small footprint.

[0066] The present invention will be further described in detail below in conjunction with a specific embodiment of the present invention, but the implementation manner of the present invention is not limited thereto.

[0067] use Figures 1 to 8 The shown electrically assisted anaerobic reactor treats organic sewage. Preferably, the reactor body is made of organic glass, the diameter of the inner cylinder 1 is 10 cm, the diameter of the outer cylinder 2 is 16 cm, the height of the cylindrical part is 30 cm, and the effective volume is 5 L. The inner cylinder 2 includes 4 inner cylinder compartments, and the angle between the guide plates 1-6 and the inner cylinder partition plates 1-5 in each inner cylinder compartment is 30°. An inner cylinder cathode 11 is provided at the center of the inner cylinder 1. The inner cylinder cathode 11 is a stainless steel rod cathode with a diameter of 1 cm and a height of 30 cm. In the upflow area of ​​each inner cylinder compartment, a 100-mesh stainless steel mesh is pasted along the inner wall of the inner cylinder 2 as an inner cylinder anode 12, with a size of 30 cm in length and 5.2 cm in width. The anodes of each inner cylinder compartment are connected at the top with titanium wire. The outer cylinder is provided with 4 outer cylinder compartments, and a graphite felt cloth anode is pasted on the outer wall of the inner cylinder as the outer cylinder anode, and a graphite felt cloth cathode is pasted on the inner wall of the outer cylinder as the outer cylinder cathode. The size of the outer cylinder anode is 30 cm in length, 7.8 cm in width, and 2 mm in thickness. The size of the outer cylinder cathode is 30 cm in length, 12.5 cm in width, and 2 mm in thickness. The anode and the cathode are connected between each compartment with titanium wire, and the wire is connected at the upper end, passing through the top cover 4, and connected to the positive and negative poles of the DC power supply 15 respectively, as shown in FIG. Figure 8 shown.

[0068] Reactor startup operation method: first, start the outer cylinder 2 biological electrode, and fill the inner cylinder 1 and outer cylinder 2 of the reactor with electrode startup nutrient solution respectively. Preferably, the nutrient solution includes 2000 mg / L sodium acetate, 2130 mg / L disodium hydrogen phosphate, 4580 mg / L sodium dihydrogen phosphate, 130 mg / L potassium chloride, 310 mg / L ammonium chloride and a small amount of mineral elements and vitamins required for microbial growth, and a small amount of residual sludge is respectively connected to each outer cylinder compartment as an inoculum, close the top cover 4, apply 0.8V voltage to the inner cylinder 1, and apply 0.6V voltage to the outer cylinder 2, connect the outlet pipe 6 to the inlet pipe 3, and the reactor is self-circulated. The culture solution is replaced every 72 hours until the potential of the outer cylinder anode 13 is lower than -400mV and the circuit current tends to be stable, and it is considered that the outer cylinder anode 13 has been successfully started. Open the top cover 4, empty each inner cylinder compartment, and put inoculated sludge into each inner cylinder compartment, the inoculation amount is 30% of the total volume, then close the top cover 4, continuously inject sewage from the water inlet pipe 6, and start formal operation. The operating temperature is room temperature, and the hydraulic retention time is gradually shortened from 24h to 8h.

[0069] The reactor of the present invention is a sleeve-type structure, the inner cylinder 1 is an electrically assisted anaerobic baffle reactor, and the outer cylinder 2 is a microbial electrolytic cell reactor. The inner cylinder 1 is divided into a plurality of inner cylinder compartments, each of which is provided with guide plates 1-6. The sewage is baffled in each inner cylinder compartment through the guide plates 1-6, and finally flows out from the inner cylinder outlet hole 5 and enters the outer cylinder 2. In the outer cylinder 2, the sewage passes through a plurality of outer cylinder compartments in sequence, and then flows out from the outlet pipe 6. The reactor is provided with a set of electrodes in the inner cylinder 1 and the outer cylinder 2, respectively. The cathode of the inner cylinder electrode is located at the center of the inner cylinder 1, and the anode is the inner wall of the inner cylinder 1; the anode of the outer cylinder electrode is fixed to the outer wall of the inner cylinder 1, and the cathode is fixed to the inner wall of the outer cylinder 2. An insulating layer is provided between the inner cylinder anode and the outer cylinder anode. In addition, by forced gas circulation, the produced biogas is repeatedly passed through the microbial electrochemical action zone, so as to achieve the fixation of carbon dioxide and the in-situ purification of biogas, increase the methane concentration in the biogas and the total methane production, and enhance the energy recovery effect of the system.

[0070] The present invention realizes phase separation in the physical space of the anaerobic digestion process through a sleeve-type structural design, and installs large-sized, short-spaced microbial electrodes along the cylinder wall to obtain good electrochemical efficiency, while effectively avoiding the flow interference of the electrodes on the anaerobic system. At the same time, through the gas circulation design, the in-situ purification of biogas is realized, thereby achieving more efficient sewage treatment and energy recovery.

[0071] The present invention optimizes the coupling reactor of the microbial electrochemical system (BES) and the anaerobic baffle reactor, strengthens the coupling form to avoid mutual interference between the electrode and the anaerobic system, and further, there are certain differences in the promoting effects of electrochemistry in the acid production stage and the methane production stage. The structure and operation mode of the electrode are optimized according to the functions required in each stage, which is conducive to giving full play to the promoting function of the electrochemical system, thereby improving the energy recovery efficiency of the system.

[0072] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0073] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrically assisted anaerobic reactor, characterized in that: It comprises an inner cylinder (1) and an outer cylinder (2); The outer cylinder (2) is sleeved outside the inner cylinder (1) and is a sleeve-type structure. A top cover (4) is provided on the top of the outer cylinder (2); the top cover (4) is provided with a water inlet pipe (3), and the water inlet pipe (3) is located above the inner cylinder (1); The inner cylinder (1) is divided into a plurality of inner cylinder compartments by a plurality of radially arranged inner cylinder partition plates (1-5); each inner cylinder compartment is provided with a guide plate (1-6), and the inner cylinder (1) is provided with an inner cylinder water outlet hole (5); the inner cylinder (1) and the outer cylinder (2) are divided into a plurality of outer cylinder compartments by outer cylinder partition plates (2-5) arranged in an up-and-down staggered manner, and the outer cylinder (2) is provided with an outer cylinder water outlet pipe (6); the guide plates (1-6) are used to guide the water flow to bend up and down in each inner cylinder compartment, and to pass through each inner cylinder compartment in sequence, and finally to flow out from the inner cylinder water outlet hole (5) and enter the outer cylinder (2); the outer cylinder partition plates (2-5) arranged in an up-and-down staggered manner are used to make the water flow bend up and down between the outer cylinder compartments and flow out from the outer cylinder water outlet pipe (6); The inner cylinder (1) is provided with an inner cylinder electrode, and the outer cylinder (2) is provided with an outer cylinder electrode. The inner cylinder electrode and the outer cylinder electrode are connected to a direct current power source (15) through a wire passing through the top cover (4).

2. The electrically assisted anaerobic reactor according to claim 1, characterized in that: An air pump (7) and an air outlet pipe (10) are installed on the top cover (4), and an aeration head (9) is provided at the bottom of the outer cylinder (2); the air inlet of the air pump (7) is connected to an air collecting hood (8) located above the inner cylinder (1), and the air outlet is connected to the aeration head (9); after being extracted by the air pump (7), the gas is aerated from the aeration head (9), passes through the reaction area of ​​the outer cylinder (2) from bottom to top, and escapes from the air outlet pipe (10).

3. The electrically assisted anaerobic reactor according to claim 1, characterized in that: The inner cylinder electrode comprises an inner cylinder cathode (11) and an inner cylinder anode (12), wherein the inner cylinder cathode (11) is located at the center of the inner cylinder (1), and the inner cylinder anode (12) is located on the inner wall of the inner cylinder (1); the outer cylinder electrode comprises an outer cylinder anode (13) and an outer cylinder cathode (14), wherein the outer cylinder anode (13) is located on the outer wall of the inner cylinder (1), and the outer cylinder cathode (14) is located on the inner wall of the outer cylinder (2), an insulating layer is provided between the inner cylinder anode (12) and the outer cylinder anode (13), and the inner cylinder electrode and the outer cylinder electrode are connected to a DC power supply (15) through a wire passing through a top cover (4).

4. The electrically assisted anaerobic reactor according to claim 3, characterized in that: The inner cylinder cathode (11) is made of a stainless steel rod or a carbon rod, the inner cylinder anode (12) is made of a stainless steel mesh, a stainless steel sheet or a carbon cloth; the outer cylinder anode (13) is made of carbon felt, carbon fiber cloth or carbon cloth, and the outer cylinder cathode (14) is made of stainless steel, a nickel mesh, carbon felt, carbon fiber cloth or carbon cloth.

5. The electrically assisted anaerobic reactor according to claim 1, characterized in that: The inner cylinder (1) comprises 3 to 6 inner cylinder compartments, each of which is provided with a guide plate (1-6), and the water flow first descends and then ascends in each inner cylinder compartment.

6. The electrically assisted anaerobic reactor according to claim 5, characterized in that: Anaerobic sludge is added into the upflow zone.

7. The electrically assisted anaerobic reactor according to claim 1, characterized in that: The outer cylinder (2) comprises 4 or 6 outer cylinder compartments.

8. The electrically assisted anaerobic reactor according to claim 1, characterized in that: An inner cylinder vent pipe (1-7) is provided at the bottom of the inner cylinder (1); and an outer cylinder vent pipe (2-6) is provided at the bottom of the outer cylinder (2).

9. A method for treating sewage to produce methanogens in an electrically assisted anaerobic reactor according to any one of claims 1 to 8, characterized in that: The following steps are involved: The inner cylinder electrode and the outer cylinder electrode are started, the inner cylinder (1) and the outer cylinder (2) are filled with electrode start-up nutrient solution, and inoculated mud is added to the outer cylinder compartment respectively, the top cover (4) is closed, and a preset external voltage is applied to the inner cylinder (1) and the outer cylinder (2). The reactor performs a self-circulating operation, and the culture solution is replaced every preset time until the potential of the outer cylinder anode (13) is lower than -400mV and the circuit current tends to be stable. It is considered that the outer cylinder electrode (13) has been successfully started, the top cover (4) is opened, the inner cylinder compartment is emptied, and the inner cylinder compartment is filled with nutrient solution. Anaerobic sludge is added respectively, and then the top cover (4) is closed, and sewage is continuously injected from the water inlet pipe (3) to start formal operation. The sewage enters the inner cylinder (1) through the water inlet pipe (3); the water flow first descends and then rises in each inner cylinder compartment under the guidance of the inner cylinder partition plate (1-5) and the guide plate (1-6), and the water flow is deflected up and down in each inner cylinder compartment, and passes through the inner cylinder compartments in sequence, and finally flows out from the inner cylinder water outlet hole (5) and enters the outer cylinder (2); the water flow is deflected up and down between the outer cylinder compartments, and finally flows out from the outer cylinder water outlet pipe (6); The gas generated in the reactor is extracted by the air pump (7) and then discharged from the aeration head (9), passes through the reaction area of ​​the outer cylinder (2) from bottom to top, and escapes from the gas outlet pipe (10).

10. The method for treating sewage and producing methane using an electrically assisted anaerobic reactor according to claim 9, characterized in that: The voltage applied to the inner cylinder electrode of the inner cylinder (1) is 0.6V-0.8V, the voltage applied to the outer cylinder electrode of the outer cylinder (2) is 0.3V-0.6V, the anaerobic sludge inoculation amount of each inner cylinder compartment is 20%-50% of the total volume, the operating temperature is room temperature, and the hydraulic retention time is 8-24h.

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