A kind of MEC reactor for coupling oxide to promote sludge deamination and strengthen anaerobic digestion capacity

Abstract

This invention discloses an MEC reactor that couples oxides to promote ammonia removal from sludge and enhances anaerobic digestion capacity, relating to the fields of anaerobic digestion of sludge in wastewater treatment plants and biogas resource utilization. The reactor comprises: an MEC reactor, an oxidation-reduction potential (ORP) detection device, a hydrogen detection device, a PLC control module, and an oxide dosing device. The oxide dosing device uses air as the oxide, which is converted into micro-nano bubbles through a microporous aerator, oxidizing ammonia nitrogen to nitrate nitrogen. The ORP and hydrogen partial pressure within the MEC reactor are monitored in real time by the ORP and hydrogen detection devices, respectively, and transmitted to the PLC control module. Based on a negative feedback adjustment mechanism, the ORP and hydrogen partial pressure within the MEC reactor are intelligently and precisely controlled. This invention's MEC reactor, while removing ammonia from sludge, alleviates the inhibitory effect of ammonia nitrogen and hydrogen partial pressure on methanogens, increases biogas production, and enhances the anaerobic digestion capacity of the MEC reactor.

Description

Technical Field

[0001] This invention relates to the field of anaerobic digestion of sludge from wastewater treatment plants and biogas resource utilization, and particularly to an MEC reactor that couples oxides to promote sludge deammoniation and enhance anaerobic digestion capacity. Background Technology

[0002] Anaerobic digestion is a green and low-carbon municipal wastewater sludge treatment technology that removes organic matter from wastewater under anaerobic conditions, while simultaneously helping to reduce, recycle, and stabilize sludge. This technology relies on microorganisms such as acid-producing bacteria and methanogens to decompose organic matter in wastewater or sludge into biogas. The reaction process consists of three stages: hydrolysis and acidification, hydrogen and acetic acid production, and methanogenesis. The biogas produced by anaerobic digestion can be used for heating and power generation, contributing to the achievement of carbon neutrality.

[0003] In existing technologies, microbial electrolyzer (MEC) anaerobic digestion technology adds an external power source and electrodes to anaerobic digestion, which is beneficial for enhancing the enrichment of electroactive methanogens and improving biogas production efficiency. However, this method is easily affected by the substrate matrix during operation, especially ammonia nitrogen. The release of ammonia nitrogen during sludge anaerobic digestion inhibits the metabolism of electroactive methanogens, reducing anaerobic digestion capacity. In addition, excessively high hydrogen partial pressure within the anaerobic digestion system can inhibit acetic acid production, further reducing anaerobic digestion capacity.

[0004] Therefore, controlling the concentration of ammonia nitrogen and the partial pressure of hydrogen in the reactor is crucial for enhancing the reactor's anaerobic digestion capacity. Adding oxides to the reactor can oxidize ammonia nitrogen, reducing its concentration, while simultaneously increasing the redox potential and decreasing hydrogen production and partial pressure. The dosage and method of oxide addition are critical to reactor operation. Insufficient oxide concentration will fail to achieve the desired ammonia nitrogen oxidation, while excessively high concentrations will cause the entire system to lose its anaerobic environment. Traditional control methods struggle to achieve stable and precise control of oxide dosage; therefore, it is necessary to explore an intelligent and precise oxide dosing device. Summary of the Invention

[0005] The problem to be solved by this invention is to provide a MEC reactor that uses coupled oxides to promote sludge deammoniation and enhance anaerobic digestion capacity. Air is used as the oxide, and micro-nano bubbles are used to oxidize ammonia nitrogen into nitrate nitrogen. Based on the negative feedback regulation mechanism, intelligent and precise control of the oxidation-reduction potential (ORP) and hydrogen partial pressure in the reactor is achieved, which alleviates the inhibitory effect of ammonia nitrogen and reduces the hydrogen partial pressure in the reactor, thereby enhancing the anaerobic digestion capacity of the reactor.

[0006] The present invention adopts the following technical solution: an MEC reactor that couples oxides to promote sludge deammoniation and enhance anaerobic digestion capacity, comprising: an MEC reactor body, an oxidation-reduction potential detection device, a hydrogen detection device, a PLC control module, and an oxide dosing device.

[0007] The MEC reactor body includes: a power electrode assembly, a reactor vessel, a stirring device, and a biogas collection device; it is used for microbial enrichment, anaerobic digestion for methanogenesis, and deamination reactions.

[0008] The oxidation-reduction potential detection device, including an ORP probe and an oxidation-reduction potential detector, is used to monitor the ORP value within the MEC reactor body and transmit it to the PLC control module.

[0009] The hydrogen detection device includes a hydrogen detection sensor and a hydrogen detector, used to monitor the partial pressure of hydrogen in the MEC reactor body and transmit it to the PLC control module;

[0010] The PLC control module includes a PLC controller and a controllable power switch, which is used to intelligently adjust the ORP value in the main body of the MEC reactor, control the ORP value to be stable within the preset range, and alleviate the inhibition of methanogenic bacteria by ammonia nitrogen and hydrogen partial pressure.

[0011] The oxide dosing device includes an air pump and a microporous aerator. The microporous aerator is located at the bottom of the MEC reactor body. After the air pump is turned on, the oxide is transformed into micro-nano bubbles through the microporous aerator and uniformly enters the MEC reactor body to oxidize ammonia nitrogen into nitrate nitrogen, thereby improving the oxygen utilization efficiency in the MEC reactor body.

[0012] Preferably, the reactor vessel forms a sealed internal space through the reactor wall, reactor cover, and bottom plate, and the reactor cover is connected to the reactor wall by fixing bolts;

[0013] The sludge to be treated enters the sealed internal space through the feed inlet, and the entire anaerobic digestion reaction takes place in a sealed reactor container. The residual waste is discharged through the discharge outlet.

[0014] Preferably, the power supply electrode assembly includes: a DC regulated power supply, a bio-anode plate, a bio-cathode plate, and wires. The bio-anode plate and the bio-cathode plate are disposed on both sides inside the reactor container and are respectively connected to the positive and negative terminals of the DC regulated power supply through wires.

[0015] Preferably, the DC regulated power supply voltage is 0.3 to 0.8V, and the bioanode plate and biocathode plate are made of carbon felt material.

[0016] Preferably, the electroactive microorganisms in the bioanode plate and biocathode plate convert organic matter into biogas through electron transfer.

[0017] Preferably, the stirring device includes a motor and a stirring paddle; the biogas collection device includes a biogas collection pipe and a biogas collection tank.

[0018] The stirring paddle is positioned between the bioanode plate and the biocathode plate. When the motor is turned on, it drives the stirring paddle to rotate, uniformly stirring the mixture inside the reactor container to generate biogas, which enters the biogas collection tank through the biogas collection pipe.

[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. The other end of the PLC controller is connected to the air pump via a controllable power switch.

[0020] The ORP probe extends into the reactor vessel, and the oxidation-reduction potential detector monitors the real-time ORP value inside the reactor vessel through the ORP probe, and turns the controllable power switch on or off through the PLC controller.

[0021] Preferably, one end of the hydrogen detector is connected to a hydrogen detection sensor, and the other end is connected to a PLC controller; the hydrogen detection sensor is installed at the connection between the biogas collection pipe and the internal reaction zone.

[0022] The hydrogen detector monitors the partial pressure of hydrogen inside the reactor vessel using a hydrogen detection sensor.

[0023] Preferably, the oxide dosing device further includes: a main intake pipe and an intake branch pipe;

[0024] The start and stop of the air pump are controlled by a controllable power switch. After the air pump is turned on, the oxide added to the main body of the MEC reactor passes through the main air inlet pipe and the branch air inlet pipe in sequence, and is transformed into micro-nano bubbles through the microporous aerator.

[0025] Preferably, the PLC controller presets upper limit thresholds for oxidation-reduction potential and hydrogen partial pressure, receives real-time ORP and hydrogen partial pressure values ​​inside the MEC reactor body monitored by the oxidation-reduction potential detector and hydrogen detector, compares them with the preset upper limit thresholds, and turns the controllable power switch on or off through the PLC controller.

[0026] When the hydrogen partial pressure is higher than the preset upper limit threshold, the PLC controller turns on the controllable power switch, the gas pump starts, the MEC reactor body begins to intake gas, the ORP value increases, and the hydrogen partial pressure value decreases.

[0027] When the ORP exceeds the preset upper limit threshold, the PLC controller turns off the controllable power switch, the gas pump turns off, the MEC reactor body stops gas intake, the ORP value decreases, and the hydrogen partial pressure value increases.

[0028] When the hydrogen partial pressure exceeds the preset upper limit threshold, the PLC controller turns on the controllable power switch, and the gas pump then introduces gas again. This cycle repeats continuously, achieving intelligent and precise negative feedback control of the reactor's ORP and hydrogen partial pressure.

[0029] Preferably, the oxide added by the oxide adding device is air.

[0030] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0031] 1. High efficiency and stability: The MEC reactor of this invention uses air as an oxide, which is easy to obtain; ammonia nitrogen in sludge is oxidized and degraded, while the ORP in the reactor increases, hydrogen production and hydrogen partial pressure decrease, reducing the inhibitory effect of ammonia nitrogen and excessively high hydrogen partial pressure on anaerobic digestion, enhancing reactor stability and strengthening the anaerobic digestion capacity of the MEC reactor.

[0032] 2. Simultaneous ammonia removal: The MEC reactor of this invention utilizes micro-nano bubbles generated by air to oxidize ammonia nitrogen into nitrate nitrogen, thereby reducing the ammonia nitrogen concentration in the reactor and achieving simultaneous ammonia removal, thus enhancing the diversity of pollutants removed by the reactor.

[0033] 3. Intelligent and precise: The MEC reactor of this invention adopts a PLC control module. By setting the upper limit threshold of hydrogen partial pressure and upper limit threshold of ORP, it intelligently controls the start and stop of the controllable power switch and gas pump, so that the hydrogen partial pressure and ORP in the reactor are within the range most conducive to anaerobic digestion reaction, meeting the intelligent development needs of future reactors. Attached Figure Description

[0034] Figure 1 This is a side view of the MEC reactor structure of the present invention;

[0035] Figure 2 This is a top view of the MEC reactor of the present invention;

[0036] Explanation of markings in the diagram:

[0037] 11-DC regulated power supply, 12-Bioanode plate, 13-Biocathode plate, 14-Wire, 21-Inlet, 22-Outlet, 23-Reactor wall, 24-Reactor cover, 25-Fixing bolt, 26-Base plate, 31-Motor, 32-Agitator, 41-Biogas collection pipe, 42-Biogas collection tank, 51-ORP probe, 52-Oxidation-reduction potential detector, 61-PLC controller, 62-Controllable power switch, 71-Air pump, 72-Main air inlet pipe, 73-Branch air inlet pipe, 74-Microporous aerator, 81-Hydrogen detection sensor, 82-Hydrogen detector. Detailed Implementation

[0038] 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 this invention by other researchers in the art are within the protection scope of this invention.

[0039] In one embodiment of the present invention, a MEC reactor coupled with oxides promotes sludge deammoniation and enhances anaerobic digestion capacity, such as... Figure 1 As shown, it includes: the MEC reactor body, the redox potential detection device, the hydrogen detection device, the PLC control module, and the oxide dosing device.

[0040] Specifically, the main body of the MEC reactor includes: power electrode assembly, reactor vessel, stirring device and biogas collection device.

[0041] The power supply electrode assembly includes: a DC regulated power supply 11, a bioanode plate 12, a biocathode plate 13, and a wire 14.

[0042] The reactor vessel includes: inlet 21, outlet 22, reactor wall 23, reactor cover 24, fixing bolts 25, and bottom plate 26;

[0043] The stirring device includes: a motor 31 and a stirring paddle 32;

[0044] The biogas collection device includes: a biogas collection pipe 41 and a biogas collection tank 42.

[0045] The oxidation-reduction potential detection device includes an ORP probe 51 and an oxidation-reduction potential detector 52, which are used to transmit the monitored ORP values ​​to the PLC control module.

[0046] The hydrogen detection device includes a hydrogen detection sensor 81 and a hydrogen detector 82, which are used to monitor the partial pressure of hydrogen in the body of the MEC reactor and transmit it to the PLC control module.

[0047] The PLC control module includes a PLC controller 61 and a controllable power switch 62, which are used to realize intelligent negative feedback regulation of ORP in the MEC reactor and control the ORP to stabilize within a fixed range.

[0048] The oxide dosing device uses air (oxygen) as the oxide and includes: an air pump 71, an air inlet main pipe 72, an air inlet branch pipe 73, and a microporous aerator 74. After the air pump 71 is turned on, the air entering the reactor is transformed into micro-nano bubbles through the microporous aerator 74, thereby improving the oxygen utilization efficiency in the reactor.

[0049] Furthermore, in this embodiment, the DC regulated power supply 11 has a voltage of 0.3 to 0.8V, and the bioanode plate 12 and biocathode plate 13 are made of carbon felt material;

[0050] In use, the PLC controller 61 first sets the upper limit threshold of ORP and hydrogen partial pressure, then receives the real-time values ​​monitored by the oxidation-reduction potential detector 52 and the hydrogen detector 82, and adjusts the controllable power switch 62 to open and close according to the relationship between the values ​​and the upper limit threshold. The start and stop of the gas pump 71 are controlled by the controllable power switch 62.

[0051] Specifically, when the real-time hydrogen partial pressure value is higher than the preset upper limit threshold, the PLC controller 61 turns on the controllable power switch 62, the gas pump 71 turns on, and the MEC reactor body begins to intake gas.

[0052] Subsequently, the oxidizing power and ORP of the mixture in the MEC reactor increase, and the ORP value begins to rise. When the ORP exceeds the preset upper limit threshold, the controllable power switch 62 is turned off, the gas pump 71 is turned off, the main body of the MEC reactor stops gas intake, the oxidizing power and ORP of the mixture in the MEC reactor decrease, and the hydrogen partial pressure rises.

[0053] When the partial pressure of hydrogen exceeds the preset upper limit threshold, the controllable power switch 62 is turned on, and the gas pump 71 then introduces gas again. This cycle repeats to achieve intelligent and precise negative feedback control of the ORP in the reactor.

[0054] The MEC reactor operation process in this embodiment is as follows:

[0055] First, sludge inoculation and reactor startup are carried out. The DC regulated power supply 11 is turned on, and the sludge to be treated enters the reactor through the feed inlet 21. The motor 31 is turned on, driving the agitator 32 to rotate. After the reactor runs stably, it is successfully started.

[0056] Then, the PLC control module and oxide dosing device are operated to control the ORP in the reactor within the preset range. Electroactive microorganisms on the bioanode plate 12 and biocathode plate 13 convert organic matter into a mixture of gases such as methane, hydrogen, and carbon dioxide (biogas) through electron transfer.

[0057] Next, the micro-nano bubbles that enter the MEC reactor through the microporous aerator 74 oxidize ammonia nitrogen into nitrate nitrogen, reducing the inhibition of ammonia nitrogen on methanogenic electroactive microorganisms and simultaneously achieving ammonia removal treatment of sludge.

[0058] Finally, the stabilized sludge after anaerobic digestion is discharged through outlet 22, and the generated biogas enters biogas collection tank 42 through biogas collection pipe 41.

[0059] Furthermore, in this embodiment, the MEC reactor is used to treat sludge from a municipal wastewater treatment plant. The effective volume of the MEC is 2L. The sludge is taken from the secondary sedimentation tank of a wastewater treatment plant, with a total solids content (TS) of 6% and a volatile matter ratio (VS / TS) of 52%.

[0060] First, nitrogen gas is passed through the inoculated sludge for 5 minutes to maintain an anaerobic environment.

[0061] Subsequently, 1.5L of sludge was injected into the MEC reactor through the feed inlet 21. The voltage of the DC regulated power supply 11 was set to 0.5V, and the temperature of the reaction zone was set to 37±1℃. Once the oxidation-reduction potential in the reactor stabilized below -400mV, the MEC reactor was successfully started up, and the hydrogen partial pressure continued to increase as the anaerobic digestion reaction proceeded.

[0062] As a preferred configuration, in this embodiment, the PLC controller presets the upper limit threshold of hydrogen partial pressure to 1×10⁻⁶. -4 atm, with a preset upper limit threshold for redox potential of -325mV.

[0063] When the hydrogen partial pressure detected by the hydrogen detector 82 is higher than 1×10 -4 At 1000 rpm, the MEC reactor body begins to receive air. The PLC control module turns on the controllable power switch 61. The air pump 71 delivers air and transforms it into micro-nano bubbles through the microporous aerator 71. The stirring speed of the stirring paddle 32 is set to 80 rpm. The redox potential value gradually increases, and the hydrogen partial pressure value gradually decreases.

[0064] When the ORP value is higher than -325mV, the controllable power switch 62 is turned off, the gas pump 71 stops intake, the ORP value begins to decrease, and the hydrogen partial pressure value begins to rise; when the hydrogen partial pressure is higher than 1×10 -4 When the temperature reaches atm, the controllable power switch 62 is turned on again, and the air pump 71 starts to intake air; this cycle continues, and the ORP and hydrogen partial pressure in the main body of the MEC reactor are intelligently and precisely controlled according to the negative feedback regulation mechanism.

[0065] Verified by actual operating data, under the same experimental conditions, compared with a general anaerobic reactor without a DC regulated power supply and without air supply, the MEC reactor in this embodiment increases methane production by 78%, volatile acid production by 128%, and the reactor achieves a 70.8% ammonia nitrogen removal rate from sludge.

[0066] Compared to an MEC reactor that only has a DC regulated power supply and no air is introduced, the MEC reactor in this embodiment increases methane production by 32% and volatile acid production by 44%.

[0067] The above results fully demonstrate that the MEC reactor of the present invention has significant advantages in ammonia removal and enhanced anaerobic digestion.

[0068] The above description is merely a preferred embodiment of the present invention, intended to help those skilled in the art understand and apply it. Those skilled in the art can modify the embodiments based on the principles and apply them to other scenarios. The scope of protection of the present invention is not limited to the above embodiments; all reasonable improvements and modifications made based on the present invention should be included within the scope of protection.

Claims

1. A MEC reactor with coupled oxides to promote sludge deammoniation and enhance anaerobic digestion capacity, characterized in that, include: MEC reactor body, redox potential detection device, hydrogen detection device, PLC control module, oxide dosing device; The MEC reactor body includes: a power electrode assembly, a reactor vessel, a stirring device, and a biogas collection device; used for microbial enrichment, anaerobic digestion for methanogenesis, and deamination reactions; The redox potential detection device includes an ORP probe (51) and a redox potential detector (52), which are used to monitor the redox potential value in the body of the MEC reactor and transmit it to the PLC control module. The hydrogen detection device includes a hydrogen detection sensor (81) and a hydrogen detector (82), which are used to monitor the partial pressure of hydrogen in the MEC reactor body and transmit it to the PLC control module. The PLC control module includes a PLC controller (61) and a controllable power switch (62), which is used to intelligently negatively regulate the ORP and hydrogen partial pressure in the main body of the MEC reactor, control the oxidation-reduction potential and hydrogen partial pressure to be stable within a preset range, and alleviate the inhibition of methanogenic bacteria by ammonia nitrogen and hydrogen partial pressure. The oxide dosing device includes an air pump (71) and a microporous aerator (74). The microporous aerator (74) is located at the bottom of the MEC reactor body and connected to the air pump (71). It is used to convert the oxide into micro-nano bubbles and uniformly enter the MEC reactor body to oxidize ammonia nitrogen into nitrate nitrogen and improve the oxide utilization efficiency in the MEC reactor body.

2. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 1, characterized in that, The reactor vessel forms a sealed internal space through the reactor wall (23), the reactor cover (24) and the bottom plate (26), and the reactor cover (24) is connected to the reactor wall (23) by fixing bolts (25); The sludge to be treated enters the sealed internal space through the feed inlet (21) for anaerobic digestion, and the residual waste is discharged through the discharge outlet (22).

3. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 2, characterized in that, The power electrode assembly includes: a DC regulated power supply (11), a biological anode plate (12), a biological cathode plate (13), and a wire (14); The bioanode plate (12) and biocathode plate (13) are located on both sides inside the reactor container and are connected to the positive and negative terminals of the DC regulated power supply (11) via wires (14).

4. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 3, characterized in that, The DC regulated power supply (11) has a voltage of 0.3 to 0.8V, and the bioanode plate (12) and biocathode plate (13) are made of carbon felt material.

5. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 3, characterized in that, The electroactive microorganisms in the bioanode plate (12) and biocathode plate (13) convert organic matter into biogas through electron transfer.

6. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 3, characterized in that, The stirring device includes a motor (31) and a stirring paddle (32); the biogas collection device includes a biogas collection pipe (41) and a biogas collection tank (42); The stirring paddle (32) is positioned between the bioanode plate (12) and the biocathode plate (13). After the motor (31) is turned on, it drives the stirring paddle (32) to rotate, uniformly stirring the mixture inside the reactor container to generate biogas, which enters the biogas collection tank (42) through the biogas collection pipe (41).

7. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 1, characterized in that, The oxidation-reduction potential detector (52) is connected to the ORP probe (51) at one end and to the PLC controller (61) at the other end. The other end of the PLC controller (61) is connected to the air pump (71) through the controllable power switch (62). The ORP probe (51) extends into the reactor vessel, and the oxidation-reduction potential detector (52) monitors the real-time oxidation-reduction potential value inside the reactor vessel through the ORP probe (51).

8. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 7, characterized in that, The hydrogen detector (82) is connected to the hydrogen detection sensor (81) at one end and to the PLC controller (61) at the other end. The hydrogen detection sensor (81) is installed at the connection between the biogas collection pipe (41) and the internal reaction zone. The hydrogen detector (82) monitors the partial pressure of hydrogen inside the reactor container through the hydrogen detection sensor (81).

9. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 8, characterized in that, The oxide dosing device further includes: an intake main pipe (72) and an intake branch pipe (73), wherein the oxide dosing device adds air; The air pump (71) is turned on and off by a controllable power switch (62). After the air pump (71) is turned on, the air added to the MEC reactor body passes through the main air intake pipe (72) and the branch air intake pipe (73) in sequence, and is transformed into micro-nano bubbles through the microporous aerator (74).

10. The MEC reactor for promoting sludge deammoniation and enhancing anaerobic digestion capacity with coupled oxides according to claim 1, characterized in that, The PLC controller (61) presets the upper limit threshold of oxidation-reduction potential and hydrogen partial pressure, receives the real-time oxidation-reduction potential value and hydrogen partial pressure value in the MEC reactor body monitored by oxidation-reduction potential detector (52) and hydrogen detector (82), compares them with the preset upper limit threshold, and turns the controllable power switch (62) on or off through the PLC controller (61). When the partial pressure of hydrogen is higher than the preset upper limit threshold, the PLC controller (61) turns on the controllable power switch (62), the gas pump (71) turns on, the MEC reactor body begins to enter gas, the oxidation-reduction potential value increases, and the hydrogen partial pressure value decreases. When the oxidation-reduction potential is higher than the preset upper limit threshold, the PLC controller (61) turns off the controllable power switch (62), the gas pump (71) turns off, the MEC reactor body stops gas intake, the oxidation-reduction potential value decreases, and the hydrogen partial pressure value increases.

Images