A method and system for simultaneous deamination and enhanced methanogenic anaerobic digestion of organic matter by direct voltage coupling oxides

Abstract

This invention discloses a method and system for simultaneous ammonia removal and enhanced anaerobic digestion of sludge via DC voltage coupling, belonging to the field of sludge treatment and organic solid waste resource utilization in urban wastewater treatment plants. The method includes: treating sludge substrate from a wastewater treatment plant through an MEC anaerobic digestion subsystem, stabilizing the oxidation-reduction potential after inoculation; monitoring ORP values ​​and hydrogen partial pressure through a PLC control subsystem, and controlling the on / off state of a controllable power switch; controlling an air pump through an air intake subsystem to deliver oxide air to the MEC anaerobic digestion subsystem, generating micro-nano bubbles using a microporous aerator, and controlling ORP and hydrogen partial pressure within a set range. This invention achieves both anaerobic digestion and ammonia removal of the sludge, mitigating the adverse effects of ammonia nitrogen and excessively high hydrogen partial pressure on methanogens, improving the utilization efficiency of acetic acid by methanogens, thereby promoting the anaerobic digestion reaction of the sludge and increasing methane production.

Description

Technical Field

[0001] This invention relates to the fields of sludge treatment in urban wastewater treatment plants and resource utilization of organic solid waste, and particularly to a method and system for simultaneous deammoniation of oxides and enhanced anaerobic digestion to produce methanates via DC voltage coupling. Background Technology

[0002] Anaerobic digestion is a biological treatment technology that utilizes microorganisms in an anaerobic environment to decompose and transform organic matter, producing resources such as biogas. The reaction involves four stages: hydrolysis, acid production, hydrogen and acetic acid production, and methanogenesis. Its core lies in the synergistic effect of anaerobic microorganisms (such as hydrolytic acidifying bacteria and methanogenic bacteria) to gradually decompose complex organic matter into simpler substances, ultimately generating biogas primarily composed of methane and carbon dioxide. Anaerobic digestion technology has advantages such as simple process, no need for aeration, and the ability to produce renewable energy, and is widely used in urban wastewater sludge treatment and the resource utilization of organic solid waste. However, this technology still has shortcomings. The metabolism of microorganisms in anaerobic systems is easily affected by the substrate. For example, the decomposition of protein-containing substances produces ammonia nitrogen, which has a toxic effect on anaerobic microorganisms, thereby inhibiting biological metabolism and leading to problems such as insufficient substrate degradation and poor system stability.

[0003] In microbial electrolyzer (MEC) anaerobic digestion systems, the anaerobic digestion process and the electrochemical process exhibit a significant synergistic interaction. Specifically, the electrochemical process effectively promotes the efficient execution of kinetically limited reaction steps in traditional anaerobic digestion by providing additional energy driving force. Simultaneously, the substrate produced by anaerobic digestion and the metabolic activities of microorganisms continuously supply electrons and protons to the electrochemical process, maintaining the stability of the current and voltage in the electrolyzer and ensuring the continuous operation of the system. The microbial community constructs a complex ecological community on the electrode surface and in the liquid phase environment of the electrolyzer, further promoting the metabolic processes of anaerobic digestion through cooperative mechanisms and enhancing the system's methanogenesis efficiency.

[0004] The substrates accepted by the anaerobic digestion system produce ammonia nitrogen after degradation, which inhibits the metabolism of electroactive methanogenic microorganisms in the system and reduces methane production efficiency. Furthermore, during the hydrogen and acetic acid production stages, volatile fatty acids are converted into acetic acid and hydrogen by anaerobic bacteria. This reaction is reversible; however, excessive hydrogen in the system, leading to a high hydrogen partial pressure, inhibits acetic acid production and consequently affects the methanogenesis reaction. Studies have shown that adding appropriate amounts of oxides can oxidize ammonia nitrogen, reducing its inhibitory effect on microorganisms, while simultaneously increasing the system's redox potential (ORP), reducing hydrogen partial pressure, and promoting acetic acid production. Some researchers use oxides such as CaO and H₂O₂, but these methods are complex to control and have high oxide consumption costs. In contrast, air (oxygen) is readily available and simple to operate.

[0005] Therefore, introducing a small amount of air into the anaerobic digestion system through the air intake system can reduce the adverse effects of ammonia nitrogen on microorganisms, lower the system's hydrogen partial pressure, remove ammonia nitrogen from the substrate, and simultaneously enhance the system's methanogenesis efficiency. With the support of a microbial electrolyzer, simultaneous ammonia removal and enhanced anaerobic digestion for methanogenesis can be achieved. Summary of the Invention

[0006] The problem to be solved by this invention is to provide a method and system for simultaneous deammoniation and enhanced anaerobic digestion methanogenesis using DC voltage coupled oxides. Air (oxygen) is selected as the oxide, which enhances methanogenesis while simultaneously deammonigenating, and controls ORP and hydrogen partial pressure within a set range. This solves the problems of limited microbial metabolism and insufficient substrate degradation caused by the inhibition of substrate ammonia nitrogen and high hydrogen partial pressure in existing anaerobic digestion systems.

[0007] This invention adopts the following technical solution: a method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis using DC voltage coupling, comprising the following steps:

[0008] S1. Introduce nitrogen into the substrate to be treated to maintain an anaerobic environment. Add the substrate to the MEC anaerobic digestion subsystem, turn on the motor to rotate the stirring paddle, and turn on the DC regulated power supply until the redox potential of the MEC anaerobic digestion subsystem is stably lower than the preset threshold. The MEC anaerobic digestion subsystem is now started up.

[0009] S2. The air intake subsystem supplies air to the MEC anaerobic digestion subsystem. The air oxidizes the ammonia nitrogen in the reaction zone of the MEC anaerobic digestion subsystem into high-valence nitrogen, reducing the ammonia nitrogen concentration and performing ammonia removal treatment.

[0010] The substrate to be treated undergoes anaerobic digestion and methanogenesis in the MEC anaerobic digestion subsystem under the action of bioanode and biocathode plates;

[0011] S3. During the anaerobic digestion and methanogenesis process, the transported air enters the MEC anaerobic digestion subsystem through a microporous aerator, generating micro- and nano-bubbles. The air is then stirred by a stirring paddle to balance the oxygen concentration inside the MEC anaerobic digestion subsystem.

[0012] The oxidation-reduction potential detector monitors the oxidation-reduction potential value of the system through the ORP probe, the hydrogen detector monitors the hydrogen partial pressure of the system through the hydrogen detection sensor, and the PLC controller controls the oxidation-reduction potential and hydrogen partial pressure within the set range by turning the controllable power switch on and off, so as to carry out simultaneous deammoniation and anaerobic digestion to produce methanogens.

[0013] The methane produced by the S4 and MEC anaerobic digestion subsystems is collected in a methane collection tank through a methane collection pipe, and the reaction residue is discharged through the outlet.

[0014] Preferably, in step S1, the substrate to be treated comes from sludge from a municipal wastewater treatment plant, with a volatile matter ratio (VS / TS) of 40% to 70%, and is added to the MEC anaerobic digestion subsystem through the feed inlet;

[0015] Before the MEC anaerobic digestion subsystem can be stably operated, substrate inoculation and startup are required. The sign of successful startup of the MEC anaerobic digestion subsystem is that the redox potential of the system is stably below -400mV, which takes 5 to 10 days.

[0016] Preferably, in step S2, after the MEC anaerobic digestion subsystem is successfully started, the air intake subsystem supplies air to the MEC anaerobic digestion subsystem through an air pump;

[0017] Air enters the MEC anaerobic digestion subsystem through the air inlet pipe and microporous aerator, oxidizing ammonia nitrogen to high-valence nitrogen, reducing the toxic effect of ammonia nitrogen on methanogenic electroactive microorganisms, and completing the deammoniation treatment. At the same time, the oxygen in the air increases the redox potential of the MEC anaerobic digestion subsystem, reduces the hydrogen partial pressure, and promotes the acetic acid production reaction.

[0018] Preferably, in step S3, the redox potential detector and the hydrogen detector are installed in the PLC control subsystem; the redox potential detector monitors the redox potential of the MEC anaerobic digestion subsystem through the ORP probe, and the hydrogen detector monitors the hydrogen partial pressure of the MEC anaerobic digestion subsystem through the hydrogen detection sensor, and the controllable power switch is turned on or off through the PLC controller.

[0019] Preferably, one end of the oxidation-reduction potential detector is connected to the ORP probe, and the other end is connected to the PLC controller; one end of the hydrogen detector is connected to the hydrogen detection sensor, and the other end is connected to the PLC controller; the other end of the PLC controller is connected to the gas pump via a controllable power switch.

[0020] The ORP probe extends into the reaction zone of the MEC anaerobic digestion subsystem, and the hydrogen detection sensor is installed at the connection between the top methane collection pipe and the internal reaction zone of the MEC anaerobic digestion subsystem.

[0021] Preferably, the simultaneous deamination and anaerobic digestion for methanogenesis in step S3 is performed as follows:

[0022] Step S3.1: After the anaerobic digestion subsystem is successfully started, the redox potential value is below -400mV, and the hydrogen partial pressure increases continuously as the anaerobic digestion reaction proceeds.

[0023] Step S3.2: The PLC controller presets the upper limit threshold of oxidation-reduction potential and hydrogen partial pressure. When the hydrogen partial pressure detected by the hydrogen detection sensor is higher than the upper limit threshold, the MEC anaerobic digestion subsystem starts to intake air. The PLC control subsystem turns on the controllable power switch and turns on the air pump to deliver air to the microporous aerator to generate micro-nano bubbles and regulate the ORP and hydrogen partial pressure of the MEC anaerobic digestion subsystem.

[0024] Step S3.3: The redox potential value increases and the hydrogen partial pressure value decreases within the MEC anaerobic digestion subsystem.

[0025] Step S3.4: When the oxidation-reduction potential is higher than the upper limit threshold, the PLC control subsystem turns off the controllable power switch, the air pump turns off, and the MEC anaerobic digestion subsystem stops air intake;

[0026] In step S3.5, the redox potential value in the MEC anaerobic digestion subsystem begins to decrease, the hydrogen partial pressure value increases, and it gradually returns to the state after the system has been successfully started.

[0027] Preferably, the upper limit threshold of hydrogen partial pressure is 1×10⁻⁶. -4 The upper limit threshold of the redox potential is -325 mV. Preferably, a bioanode plate and a biocathode plate are respectively arranged on both sides of the reaction zone inside the MEC anaerobic digestion subsystem, and a stirring paddle connected to a motor is arranged in the middle of the reaction zone;

[0028] The substrate to be treated, added to the MEC anaerobic digestion subsystem, is degraded into water-soluble small-molecule volatile acids by the electroactive microorganisms on the bioanodine plate, producing carbon dioxide, protons and electrons, thus converting organic matter into carbon dioxide.

[0029] Electrons reach the biological cathode plate through the external circuit, and protons reach the biological cathode plate through the mixed liquid and combine with electrons to produce hydrogen gas. Methanogenic bacteria use the electrons from the biological cathode plate and the produced hydrogen gas to reduce carbon dioxide to methane.

[0030] Preferably, the MEC anaerobic digestion subsystem has a reaction temperature of 20–60°C and a stirring speed of 50–200 rpm. The bioanode plate and biocathode plate are connected to a DC regulated power supply with a voltage of 0.3–0.8V.

[0031] Preferably, the microporous aerator is installed at the bottom of the MEC anaerobic digestion subsystem. The top of the MEC anaerobic digestion subsystem is connected to a methane collection tank via a methane collection pipe to collect the methane produced by the system; the bottom is connected to an outlet to discharge the system reaction residue.

[0032] The present invention also provides: a DC voltage coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system, for implementing any of the above-mentioned methods, comprising: an MEC anaerobic digestion subsystem, a PLC control subsystem, and an air intake subsystem;

[0033] The MEC anaerobic digestion subsystem is used for system inoculation and start-up, anaerobic digestion methanogenic treatment and simultaneous deammoniation treatment. Bioanode plates and biocathode plates are respectively set on both sides of the internal reaction zone, and a stirring paddle connected to a motor is set in the middle of the reaction zone.

[0034] The PLC control subsystem connects the MEC anaerobic digestion subsystem and the air intake subsystem. It monitors the oxidation-reduction potential and hydrogen partial pressure of the MEC anaerobic digestion subsystem through an ORP probe and a hydrogen detection sensor, respectively. The PLC controller controls the opening and closing of the air intake subsystem based on the values ​​of oxidation-reduction potential and hydrogen partial pressure.

[0035] The air intake subsystem is used to transport oxidized air and, together with the PLC control subsystem, ensures that the oxidation-reduction potential and hydrogen partial pressure of the MEC anaerobic digestion subsystem are within the set range. The air intake subsystem delivers air into the microporous aerator via an air pump, which generates micro-nano bubbles that are uniformly introduced into the MEC anaerobic digestion subsystem. This creates a micro-oxygen environment for the MEC anaerobic digestion subsystem to perform ammonia removal treatment. Furthermore, the addition of oxygen increases the oxidation-reduction potential of the MEC anaerobic digestion subsystem, reduces the hydrogen partial pressure, and promotes acetic acid production.

[0036] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0037] 1. The present invention provides a DC voltage coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system, which realizes both anaerobic digestion and deammoniation of sludge, enhances the anaerobic digestion methanogenesis reaction of sludge, and improves methanogenesis efficiency.

[0038] 2. This invention employs a DC voltage microbial electrolysis cell anaerobic digestion subsystem, where the anaerobic digestion process and the electrochemical process work together to enhance the metabolic activity of methanogenic electroactive microorganisms. Simultaneously, after the oxides enter the MEC anaerobic digestion subsystem, the system ammonia nitrogen concentration is reduced by controlling the redox potential, achieving the effect of simultaneous ammonia removal and enhanced anaerobic digestion for methanogenesis, which aligns with the actual engineering expectation of simultaneous removal of multiple pollutants in the treatment process.

[0039] 3. This invention uses oxygen from the air as an oxide to enhance the methanogenesis reaction. It is easy to obtain and simple to operate. The addition of oxygen oxidizes ammonia nitrogen in the system to high-valence nitrogen, reducing the toxic effect of ammonia nitrogen on electroactive methanogenic microorganisms. At the same time, it increases the system's ORP, reduces the partial pressure of hydrogen, promotes the production of acetic acid, and increases methane production. Attached Figure Description

[0040] Figure 1 This is a flowchart of the DC voltage-coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system of the present invention;

[0041] Figure 2 This is a schematic diagram of the DC voltage-coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system of the present invention;

[0042] Explanation of markings in the diagram:

[0043] 1-DC regulated power supply, 2-Bio-anode plate, 3-Bio-cathode plate, 4-Motor, 5-Agitator, 6-Inlet, 7-Outlet, 8-Methane collection pipe, 9-Methane collection tank, 10-ORP probe, 11-Oxidation-reduction potential detector, 12-PLC controller, 13-Controllable power switch, 14-Air pump, 15-Inlet pipe, 16-Microporous aerator, 17-Hydrogen detection sensor, 18-Hydrogen detector. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the application will be further described in detail below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments involved in this invention. All non-innovative embodiments based on these embodiments by other researchers in the art are within the protection scope of this invention. Furthermore, the step numbers in the embodiments of this invention are only set for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0045] Example 1:

[0046] This embodiment provides a DC voltage-coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system, such as... Figure 1 As shown, it includes: MEC anaerobic digestion subsystem, PLC control subsystem and air intake subsystem.

[0047] The MEC anaerobic digestion subsystem is used to complete system inoculation and start-up, anaerobic digestion methanogenesis treatment and simultaneous deammoniation treatment;

[0048] The PLC control subsystem is used to monitor the redox potential of the MEC anaerobic digestion subsystem, control the running time of the air pump in the intake subsystem, and control the redox potential numerical value.

[0049] The air intake subsystem is used to transport oxide air (oxygen), and micro-nano bubbles generated by microporous aerators are uniformly introduced into the MEC anaerobic digestion subsystem.

[0050] Specifically, such as Figure 2As shown, a bioanode plate 2 and a biocathode plate 3 are respectively installed on both sides of the reaction zone inside the MEC anaerobic digestion subsystem. A stirring paddle 5 connected to a motor 4 is installed in the middle of the reaction zone. The bioanode plate 2 and the biocathode plate 3 are connected to a DC regulated power supply 1. The substrate to be treated is added into the MEC anaerobic digestion subsystem through the feed inlet 6.

[0051] The MEC anaerobic digestion subsystem has a methane collection tank 9 connected to the top via a methane collection pipe 8 to collect the methane produced by the system; and an outlet 7 connected to the bottom to discharge the system reaction residue.

[0052] The PLC control subsystem connects the MEC anaerobic digestion subsystem and the gas intake subsystem, and includes: an oxidation-reduction potential detector 11, an ORP probe 10, a hydrogen detection sensor 17, a hydrogen detector 18, a PLC controller 12, and a controllable power switch 13.

[0053] Specifically, in this embodiment, the redox potential detector 11 monitors the redox potential value of the system through the ORP probe 10, and the hydrogen detector 18 monitors the partial pressure of hydrogen in the system through the hydrogen detection sensor 17.

[0054] One end of the oxidation-reduction potential detector 11 is connected to the ORP probe 10, and the other end is connected to the PLC controller 12; one end of the hydrogen detector 18 is connected to the hydrogen detection sensor 17, and the other end is connected to the PLC controller 12; the other end of the PLC controller 12 is connected to the gas pump 14 through the controllable power switch 13.

[0055] The ORP probe 10 extends into the reaction zone of the MEC anaerobic digestion subsystem. The hydrogen detection sensor 17 is installed at the connection between the methane collection pipe 8 at the top of the MEC anaerobic digestion subsystem and the internal reaction zone. The PLC control subsystem monitors the oxidation-reduction potential of the MEC anaerobic digestion subsystem through the ORP probe 10 and the hydrogen partial pressure of the system through the hydrogen detection sensor 17. The PLC controller 12 controls the start and stop of the controllable power switch 13 according to the value of the oxidation-reduction potential, thereby controlling the oxidation-reduction potential and hydrogen partial pressure within the set range to achieve simultaneous deammoniation and anaerobic digestion to produce methane.

[0056] In the air intake subsystem, the air pump 14 is connected to the microporous aerator 16 through the air intake pipe 15. The microporous aerator 16 is located at the bottom of the MEC anaerobic digestion subsystem. The air intake subsystem delivers air into the microporous aerator 16 through the air pump 14, and uses the microporous aerator 16 to generate micro-nano bubbles, which are then uniformly introduced into the MEC anaerobic digestion subsystem.

[0057] Furthermore, in this embodiment, the MEC anaerobic digestion subsystem needs to be inoculated and started before it can be put into stable operation. The substrate comes from sludge from a municipal wastewater treatment plant, with a volatile matter ratio (VS / TS) of 40% to 70%, and the DC regulated power supply 1 has a voltage of 0.3 to 0.8V.

[0058] The sign of successful startup of the MEC anaerobic digestion subsystem is that the system's redox potential stabilizes below -400mV, which takes 5 to 10 days.

[0059] The reaction temperature of the MEC anaerobic digestion subsystem is 20–60℃, and the stirring speed of the agitator 5 is 50–200 rpm.

[0060] After the MEC anaerobic digestion subsystem is operating stably, the electroactive microorganisms on the bioanode plate 2 convert organic matter into carbon dioxide, and the electroactive microorganisms on the biocathode plate 3 convert carbon dioxide into methane. The oxygen that enters the MEC anaerobic digestion subsystem through the air intake subsystem oxidizes ammonia nitrogen into high-valence nitrogen, reducing the toxic effect of ammonia nitrogen on methanogenic electroactive microorganisms and simultaneously completing the deammoniation treatment.

[0061] The PLC control subsystem monitors the system's ORP value through the oxidation-reduction potential detector 11 and the ORP probe 10, thereby monitoring the oxidation-reduction potential of the MEC anaerobic digestion subsystem. It also monitors the system's hydrogen partial pressure through the hydrogen detection sensor 17 and the hydrogen detector 18. The PLC controller 12 controls the on / off state of the controllable power switch of the intake subsystem based on the values ​​of oxidation-reduction potential and hydrogen partial pressure.

[0062] As a preferred setting, in this embodiment, the upper limit threshold of hydrogen partial pressure is preset to 1×10⁻⁶. -4 The upper limit threshold of the redox potential atm is preset to -325mV.

[0063] When the hydrogen partial pressure detected by the hydrogen detection sensor 17 is higher than 1×10 -4 At time amin, the MEC anaerobic digestion subsystem begins to intake gas.

[0064] In the air intake subsystem, the air delivered by the air pump 14 enters the microporous aerator 16 through the air intake pipe 15. The microporous aerator 16 generates micro-nano bubbles, which are then uniformly introduced into the MEC anaerobic digestion subsystem. Together with the PLC control subsystem, the air intake subsystem ensures that the oxidation-reduction potential of the MEC anaerobic digestion subsystem remains stable within the set range.

[0065] Specifically, during the methane production process of the MEC anaerobic digestion subsystem, the microporous aerator 16 generates micro-nano bubbles, which uniformly deliver oxygen from the air to the MEC anaerobic digestion subsystem. Through the stirring paddle 5, the redox potential inside the MEC anaerobic digestion subsystem is further balanced, so that the entire subsystem is in a micro-oxygen environment and the ORP is controlled below -325mV.

[0066] Example 2:

[0067] This example provides a method for simultaneous deammoniation and enhanced anaerobic digestion of sludge from a municipal wastewater treatment plant using a DC voltage-coupled oxide microbial electrolyzer (MEC). The MEC has an effective volume of 3L. The sludge was taken from a sludge thickening tank of a wastewater treatment plant, with a total solids content (TS) of 5% and a volatile matter ratio (VS / TS) of 48%.

[0068] The processing flow in this embodiment is as follows:

[0069] Step 1: Before the MEC anaerobic digestion subsystem can be stably operated, substrate inoculation and startup are required.

[0070] First, nitrogen gas is introduced into the substrate to be treated to maintain an anaerobic environment for 5 minutes.

[0071] Then, 2.5L of sludge is injected into the MEC anaerobic digestion subsystem through the feed inlet 6, the motor 4 is started, and the stirring paddle 5 is driven to stir the mixture; the DC regulated power supply 1 is connected with a voltage of 0.5V, and the temperature of the reaction zone of the MEC anaerobic digestion subsystem is maintained at 40±1℃ by water bath heating.

[0072] At this point, the redox potential in the MEC anaerobic digestion subsystem fluctuates continuously due to the unstable reaction. Once the redox potential stabilizes below -400mV, the MEC anaerobic digestion subsystem is successfully started, which takes 7 days. The MEC anaerobic digestion subsystem is then fully started.

[0073] Step 2: After the MEC anaerobic digestion subsystem is successfully started, the air intake subsystem begins to supply air to the MEC anaerobic digestion subsystem. The air supplied by the air pump 14 enters the microporous aerator 16 through the air intake pipe 15, generating micro-nano bubbles. The agitator 5 further balances the oxygen concentration inside the system by stirring, with a stirring speed of 90 rpm.

[0074] Air oxidizes ammonia nitrogen in the reaction zone of the MEC anaerobic digestion subsystem to higher valence nitrogen, reducing the ammonia nitrogen concentration and performing ammonia removal treatment.

[0075] Meanwhile, the substrate to be treated undergoes anaerobic digestion and methanogenesis under the action of bioanode plate 2 and biocathode plate 3 in the MEC anaerobic digestion subsystem;

[0076] Specifically, the electrochemically active microorganisms on the bioanode plate 2 carry out an oxidation reaction using sludge as a substrate. Under the action of the microorganisms on the bioanode plate 2, the sludge is degraded into water-soluble small molecule volatile acids, releasing protons and electrons and producing carbon dioxide.

[0077] Electrons are transmitted through the external circuit to the biological cathode plate 3. Protons migrate to the biological cathode plate 3 and combine with electrons to generate hydrogen gas. Methanogenic bacteria use protons to further convert carbon dioxide into methane.

[0078] Step 3: During the anaerobic digestion and methanogenesis process, the supplied air enters the MEC anaerobic digestion subsystem through the microporous aerator 16, generating micro-nano bubbles. The air is then stirred by the stirring paddle 5 to balance the oxygen concentration inside the MEC anaerobic digestion subsystem.

[0079] The oxidation-reduction potential detector 11 monitors the oxidation-reduction potential value of the system through the ORP probe 10, the hydrogen detector 18 monitors the hydrogen partial pressure of the system through the hydrogen detection sensor 17, and the PLC controller 12 controls the oxidation-reduction potential and hydrogen partial pressure within the set range by turning the controllable power switch 13 on and off, so as to carry out simultaneous deammoniation and anaerobic digestion to produce methanogens.

[0080] Specifically, after the anaerobic digestion subsystem is successfully started, the redox potential value is below -400mV, and the hydrogen partial pressure continuously increases as the anaerobic digestion reaction proceeds.

[0081] The upper limit threshold for the preset hydrogen partial pressure is 1×10. -4 The preset upper limit threshold of the redox potential is -325mV.

[0082] When the hydrogen partial pressure detected by the hydrogen detection sensor 17 is higher than 1×10 -4 At time ATM, the MEC anaerobic digestion subsystem begins to intake air. The PLC control subsystem turns on the controllable power switch 13, and the air pump 14 starts, delivering air to the microporous aerator 16 to generate micro-nano bubbles, thereby regulating the ORP and hydrogen partial pressure of the MEC anaerobic digestion subsystem.

[0083] Then, the ORP value in the MEC anaerobic digestion subsystem begins to rise, and the hydrogen partial pressure value begins to fall. When the ORP is higher than -325mV, the PLC system will turn off the controllable power switch 13, the air pump 14 will stop the air intake, the ORP value will begin to decrease, the hydrogen partial pressure value will begin to rise, and gradually return to the state after the system has been successfully started.

[0084] When the partial pressure of hydrogen is higher than 1×10 -4 When the ATM is reached, the PLC system will turn on the controllable power switch 13 again, the air pump 14 will start to intake air, the ORP value will rise again, and the hydrogen partial pressure value will drop again.

[0085] Through cyclic control, the entire subsystem is kept in a micro-oxygen environment, and the ORP and hydrogen partial pressure in the main body of the MEC anaerobic digestion subsystem are intelligently and precisely controlled according to the negative feedback regulation mechanism.

[0086] Step 4: The system reaction residue is discharged through outlet 7, and the generated methane enters the 1.5L methane collection tank 9 through methane collection pipe 8.

[0087] The oxygen introduced into the MEC anaerobic digestion subsystem through the air intake subsystem oxidizes ammonia nitrogen into higher valence nitrogen, reducing the toxic effect of ammonia nitrogen on methanogenic electroactive microorganisms and achieving simultaneous deammoniation and enhanced anaerobic digestion for methanogenesis.

[0088] Furthermore, based on actual operational data verification, under the same experimental conditions, compared to an anaerobic digestion system without a DC regulated power supply and without air supply, the system used in this embodiment showed an 80% increase in methane production, a 225% increase in organic matter dissolution efficiency, a 137% increase in volatile acid production, and a 72% removal rate of ammonia nitrogen in sludge. It can operate stably at an organic load rate of 3 gVS / L / d.

[0089] The above results fully demonstrate that the DC voltage-coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system proposed in this invention has significant advantages in deammoniation and enhanced anaerobic digestion methanogenesis. It achieves both anaerobic digestion of sludge and deammoniation of sludge, and enhances the anaerobic digestion methanogenesis reaction of sludge, which can effectively improve the efficiency of methanogenesis.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis using DC voltage coupling, characterized in that, Includes the following steps: S1. Introduce nitrogen into the substrate to be treated to maintain an anaerobic environment, add it to the MEC anaerobic digestion subsystem, turn on the motor (4) to rotate the stirring paddle (5), turn on the DC regulated power supply (1) until the oxidation-reduction potential of the MEC anaerobic digestion subsystem is stable below the preset threshold, and the MEC anaerobic digestion subsystem is started up. S2. The air intake subsystem supplies air to the MEC anaerobic digestion subsystem through the air pump (14). The air oxidizes the ammonia nitrogen in the reaction zone of the MEC anaerobic digestion subsystem into high-valence nitrogen, reduces the ammonia nitrogen concentration, and performs deammoniation treatment. The substrate to be treated undergoes anaerobic digestion and methanogenesis under the action of the bioanode plate (2) and biocathode plate (3) in the MEC anaerobic digestion subsystem; S3. During the anaerobic digestion and methanogenesis process, the transported air enters the MEC anaerobic digestion subsystem through the microporous aerator (16) to generate micro-nano bubbles. The air is stirred by the stirring paddle (5) to balance the oxygen concentration inside the MEC anaerobic digestion subsystem. The redox potential detector (11) monitors the redox potential value of the system through the ORP probe (10), the hydrogen detector (18) monitors the hydrogen partial pressure of the system through the hydrogen detection sensor (17), and the PLC controller (12) controls the redox potential and hydrogen partial pressure within the set range by turning the controllable power switch (13) on and off, so as to carry out simultaneous deammoniation and anaerobic digestion to produce methanogens. The methane produced by the S4 and MEC anaerobic digestion subsystems is collected through the methane collection pipe (8) and enters the methane collection tank (9), while the reaction residue is discharged through the outlet (7). The simultaneous deamination and anaerobic digestion for methanogenesis described in step S3 are performed as follows: Step S3.1: After the anaerobic digestion subsystem is successfully started, the redox potential value is below -400mV, and the hydrogen partial pressure increases continuously as the anaerobic digestion reaction proceeds. Step S3.2: The PLC controller presets the upper limit threshold of oxidation-reduction potential and hydrogen partial pressure. When the hydrogen partial pressure detected by the hydrogen detection sensor (17) is higher than the upper limit threshold, the MEC anaerobic digestion subsystem starts to intake air, the PLC control subsystem turns on the controllable power switch (13), the air pump (14) turns on, and air is delivered to the microporous aerator (16) to generate micro-nano bubbles, thereby regulating the ORP and hydrogen partial pressure of the MEC anaerobic digestion subsystem. Step S3.3: The redox potential value increases and the hydrogen partial pressure value decreases within the MEC anaerobic digestion subsystem. Step S3.4: When the oxidation-reduction potential is higher than the upper limit threshold, the PLC control subsystem turns off the controllable power switch (13), the air pump (14) is turned off, and the MEC anaerobic digestion subsystem stops air intake; In step S3.5, the redox potential value in the MEC anaerobic digestion subsystem begins to decrease, the hydrogen partial pressure value increases, and it gradually returns to the state after the system has been successfully started.

2. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion to produce methanates via DC voltage coupling according to claim 1, characterized in that, In step S1, the substrate to be treated comes from sludge from a municipal wastewater treatment plant, with a volatile matter ratio (VS / TS) of 40% to 70%, and is added to the MEC anaerobic digestion subsystem through the feed inlet (6); Before the MEC anaerobic digestion subsystem can be stably operated, substrate inoculation and startup are required. The successful startup of the MEC anaerobic digestion subsystem is marked by the system's redox potential stabilizing below -400mV, which takes 5 to 10 days.

3. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion to produce methanates via DC voltage coupling according to claim 1, characterized in that, In step S2, after the MEC anaerobic digestion subsystem is successfully started, air enters the MEC anaerobic digestion subsystem through the air inlet pipe (15) and the microporous aerator (16), oxidizing ammonia nitrogen to high-valence nitrogen, reducing the toxic effect of ammonia nitrogen on methanogenic electroactive microorganisms, completing the deammoniation treatment, and at the same time increasing the oxidation-reduction potential value of the MEC anaerobic digestion subsystem by oxygen in the air, reducing the hydrogen partial pressure, and promoting the acetic acid production reaction.

4. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis according to claim 3, characterized in that, In step S3, the redox potential detector (11) and the hydrogen detector (18) are installed in the PLC control subsystem; The redox potential detector (11) monitors the redox potential of the MEC anaerobic digestion subsystem through the ORP probe (10), the hydrogen detector (18) monitors the hydrogen partial pressure of the MEC anaerobic digestion subsystem through the hydrogen detection sensor (17), and the controllable power switch (13) is turned on or off through the PLC controller (12).

5. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis according to claim 4, characterized in that, One end of the redox potential detector (11) is connected to the ORP probe (10), and the other end is connected to the PLC controller (12); one end of the hydrogen detector (18) is connected to the hydrogen detection sensor (17), and the other end is connected to the PLC controller (12); the other end of the PLC controller (12) is connected to the gas pump (14) through a controllable power switch (13). The ORP probe (10) extends into the reaction zone of the MEC anaerobic digestion subsystem, and the hydrogen detection sensor (17) is installed at the connection between the methane collection tube (8) at the top of the MEC anaerobic digestion subsystem and the internal reaction zone.

6. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis according to claim 1, characterized in that, The MEC anaerobic digestion subsystem has a bioanode plate (2) and a biocathode plate (3) on both sides of the internal reaction zone, and a stirring paddle (5) connected to a motor (4) is set in the middle of the reaction zone. The substrate to be treated, added to the MEC anaerobic digestion subsystem, is degraded into water-soluble small molecule volatile acids by the electroactive microorganisms on the bioanode plate (2), producing carbon dioxide, protons and electrons, and converting organic matter into carbon dioxide. Electrons reach the biological cathode plate (3) through the external circuit, and protons reach the biological cathode plate (3) through the mixed liquid and combine with electrons to produce hydrogen gas. Methanogenic bacteria use the electrons and the produced hydrogen gas from the biological cathode plate (3) to reduce carbon dioxide to methane.

7. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis according to claim 4, characterized in that, The MEC anaerobic digestion subsystem has a reaction temperature of 20~60℃ and a stirring speed of 50~200rpm for the stirring paddle (5); the bioanode plate (2) and the biocathode plate (3) are connected to a DC regulated power supply (1), and the voltage of the DC regulated power supply (1) is 0.3~0.8V.

8. The method for simultaneous deammoniation of oxides and enhanced anaerobic digestion for methanogenesis according to claim 1, characterized in that, The microporous aerator (16) is installed at the bottom of the MEC anaerobic digestion subsystem. The top of the MEC anaerobic digestion subsystem is connected to a methane collection tank (9) through a methane collection pipe (8) to collect the methane produced by the system. The bottom is connected to the discharge port (7) to discharge the system reaction residue.

9. A DC voltage-coupled oxide synchronous deammoniation and enhanced anaerobic digestion methanogenesis system, for implementing the method according to any one of claims 1 to 8, characterized in that, include: MEC anaerobic digestion subsystem, PLC control subsystem, and air intake subsystem; The MEC anaerobic digestion subsystem is used for system inoculation and start-up, anaerobic digestion and methanogenic treatment and simultaneous deammoniation treatment. A bioanode plate (2) and a biocathode plate (3) are respectively set on both sides of the internal reaction zone, and a stirring paddle (5) is set in the middle of the reaction zone and connected to a motor (4). The PLC control subsystem connects the MEC anaerobic digestion subsystem and the air intake subsystem. The ORP probe (10) and the hydrogen detection sensor (17) monitor the oxidation-reduction potential and hydrogen partial pressure of the MEC anaerobic digestion subsystem, respectively. The PLC controller (12) controls the opening and closing of the air intake subsystem based on the values ​​of oxidation-reduction potential and hydrogen partial pressure. The air intake subsystem is used to transport oxide air and works with the PLC control subsystem to ensure that the oxidation-reduction potential and hydrogen partial pressure of the MEC anaerobic digestion subsystem are within the set range. The air intake subsystem delivers air into the microporous aerator (16) through the air pump (14). The microporous aerator (16) generates micro-nano bubbles, which are uniformly introduced into the MEC anaerobic digestion subsystem, so that the MEC anaerobic digestion subsystem is in a micro-oxygen environment and undergoes deammoniation treatment. By adding oxygen, the oxidation-reduction potential of the MEC anaerobic digestion subsystem is increased, the hydrogen partial pressure is reduced, and acetic acid production is promoted.

Images