Sewage treatment device and sewage treatment method for treating COD (Chemical Oxygen Demand) and nitro nitrogen

Abstract

The invention relates to the technical field of sewage treatment, in particular to a sewage treatment device for treating COD and nitro nitrogen and a sewage treatment method.The sewage treatment device comprises a treatment part making contact with sewage, and a carbon material modification layer is arranged on the surface, making contact with the sewage, of the treatment part; sewage treatment microorganisms screened by low-voltage current are inoculated on the carbon material modified layer; the carbon material modified layer comprises a carbon material and a binder; the carbon material comprises a net-shaped or long-strip-shaped carbon material and a granular carbon material. According to the sewage treatment method, COD and NO3 <->-N in sewage are degraded simply and efficiently through the conductive microorganisms, so that the effect of removing pollutants in a water body is achieved, and degradation of the pollutants can be accelerated through the respiration effect of the conductive microorganisms in the sewage treatment method. As oxygen does not need to participate in the degradation process of the conductive microorganisms, the device does not need strict aerobic and anaerobic treatment, and the method is simple and convenient in process and low in cost.

Description

Technical Field

[0001] The invention relates to a sewage treatment device and a sewage treatment method for treating COD and nitric nitrogen, belonging to the technical field of sewage treatment. Background Art

[0002] At present, traditional sewage treatment technologies have certain limitations in the actual sewage treatment process. For example, chemical treatment methods are costly, have poor sustainability, and produce a large amount of sludge. In biological treatment methods, aerobic microorganisms need to be continuously aerated during sewage treatment, consume a lot of electricity, and need to add glucose to cultivate microbial activity. Sludge accumulation will also occur, and the treatment process is cumbersome and the treatment cost is high. Anaerobic microorganisms have low activity and a long growth cycle during sewage treatment, so the sewage treatment equipment takes a long time to start up, and pollutants will be degraded into intermediate products, causing secondary pollution. In addition, the anaerobic treatment system needs to be carried out under anaerobic conditions, and the treatment conditions are harsh, which will further increase its treatment cost. Based on the shortcomings of traditional sewage treatment methods, it is of great significance to develop a low-cost, green, efficient, simple and feasible sewage treatment technology.

[0003] The invention patent application with publication number CN113461138A discloses a device and a method for treating sewage, wherein electroactive microorganisms are grown on conventional sewage treatment fillers to treat sewage, and NO3 in the sewage is removed. - -N is removed through direct denitrification, and COD is treated based on the respiration of conductive microorganisms. However, this technical solution only uses traditional sewage treatment carriers. Electroactive microorganisms have low activity and low concentration, and are easily contaminated and replaced by traditional sewage treatment carriers. In addition, traditional sewage treatment carriers have problems such as high cost, poor biocompatibility, and poor conductivity, which restrict the attachment, enrichment, and growth of electroactive microorganisms. Moreover, this technology only verifies the sewage artificially configured in the laboratory, and has low efficiency in treating actual domestic sewage and traditional textile printing and dyeing industry sewage. Summary of the invention

[0004] Aiming at the actual situation of low sewage treatment efficiency and complicated treatment process in traditional sewage treatment process, the present invention provides a sewage treatment device and sewage treatment method for treating COD and nitric nitrogen, so that COD and NO3 - -N can be effectively treated to relieve the treatment pressure of subsequent sewage treatment plants and significantly improve the efficiency of municipal sewage treatment.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: a sewage treatment device for treating COD and nitrate nitrogen, the sewage treatment device comprising a treatment component in contact with sewage, a carbon material modified layer is provided on the surface of the treatment component in contact with sewage, and the carbon material modified layer is inoculated with sewage treatment microorganisms screened by low-voltage current; The carbon material modified layer includes a carbon material and a binder; the carbon material includes a mesh or long strip carbon material and a granular carbon material.

[0006] Furthermore, the processing component is a metal pipe, a plastic pipe and a ceramic pipe.

[0007] Furthermore, the mass ratio of the mesh or elongated carbon material to the granular carbon material is 1:(1.5-2.0); The mesh or long strip carbon material is selected from at least one of carbon fiber and carbon nanotube; The granular carbon material is selected from at least one of carbon black, activated carbon and biochar.

[0008] Further, the mass ratio of the carbon material to the binder is 1:(1.2-1.5); The binder is selected from at least one of phenolic resin, epoxy resin and silicone resin.

[0009] Furthermore, the preparation method of the carbon material modified layer is: The carbon material and the binder are added into ethanol to obtain a modified suspension, and the modified suspension is canned into the treatment component and allowed to stay for a period of time, and then the modified suspension is discharged, and the treatment component is heat-treated so that the binder undergoes a high-temperature cross-linking reaction to generate a high-molecular network polymer, so that the carbon material is fixed on the surface of the treatment component to form the carbon material modified layer.

[0010] Furthermore, the method of inoculating sewage treatment microorganisms on the carbon material modified layer is: (1) Inoculating bacteria into a treatment component covered with a carbon material modification layer; and introducing artificially prepared sewage, wherein the artificially prepared sewage contains a carbon source, a nitrogen source, Vitamin B12 and trace metals; (2) Apply low voltage current to the processing components to screen conductive microorganisms in a targeted manner.

[0011] Furthermore, the bacterial species include Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Saccharomyces, and Mycorrhiza.

[0012] Furthermore, CH3COONa is added to the artificially prepared sewage as a carbon source and NaNO3 as a nitrogen source; The concentration of CH3COONa is 1.6-1.7 g / L, the concentration of NaNO3 is 1.2-1.3 g / L, the concentration of Vitamin B12 is 4-6 mL / L, and the content of trace metals is 1.7-2.0 g / L; The trace metals include MgSO4 1.3-1.4 g / L, ZnSO4 0.1-0.3 g / L, CaCl2 0.10-0.15 g / L, KAI(SO4)2 0.01-0.03 g / L, and FeSO4 0.11-0.13 g / L.

[0013] Furthermore, the low voltage current is 0.5-2 mA cm -2 ; The application time of the low voltage current is 14-20 days; During the application of the low voltage current, the artificially prepared sewage in the treatment component is replaced at least once a day.

[0014] A sewage treatment method, the sewage treatment method comprising: introducing the sewage to be treated into the sewage treatment device of the present invention to treat COD and nitrate nitrogen in the sewage, wherein the residence time of the sewage to be treated in the sewage treatment device is 6-15 hours; The pH of the sewage to be treated is 6-8, the salinity is not higher than 5 mg / L, the COD value is not higher than 1000 mg / L, and the NO3 - -N is not higher than 400 mg / L.

[0015] The beneficial effects of the present invention are: The present invention provides a simple and efficient method for degrading COD and NO3 in sewage by using conductive microorganisms. - -N, thereby removing pollutants from the water body. The sewage treatment method of the present invention utilizes the respiration of conductive microorganisms to accelerate the degradation of pollutants. Since the conductive microorganisms do not require the participation of oxygen in the degradation process, the device does not require strict aerobic and anaerobic conditions, so the method is simple in process and low in cost.

[0016] The sewage treatment device of the present invention can screen electroactive microorganisms by applying low-voltage current. Electroactive sewage treatment microorganisms can grow and enrich rapidly under the advantageous condition of electricity, while microorganisms without electroactivity quickly die under the disadvantageous condition of electricity. Therefore, highly enriched electroactive microorganisms are obtained in the sewage treatment device. In the actual sewage treatment process, it is beneficial to improve the treatment efficiency and obtain water that can be discharged directly in compliance with the standards.

[0017] In the sewage treatment device described in the present invention, the carbon material in the carbon material modified layer is easy to conduct electricity, which can significantly improve the electron transfer efficiency of electroactive microorganisms, and then improve the sewage treatment efficiency; carbon materials such as carbon black and carbon fiber also have excellent biocompatibility, and microorganisms are more likely to attach to their surfaces, and the modified surface of the treatment component has a certain roughness, which increases the contact area of ​​the microorganisms, and is also conducive to the attachment, enrichment, and growth of microorganisms. Moreover, the use of the carbon material modified layer attached to the metal pipe wall can significantly improve the corrosion resistance of the metal pipe, increase the service life of the metal pipe, and reduce the cost of use. In addition, in the carbon material modified layer in the sewage treatment device described in the present invention, the mesh or long strip carbon material and the granular carbon material cooperate with each other, which is more conducive to the firm attachment of the carbon material modified layer on the treatment component, and is also conducive to the formation of a roughness structure that is conducive to the attachment of microorganisms, thereby being more conducive to the efficient and long-life treatment of sewage by the sewage treatment device.

[0018] The sewage treatment device described in the present invention can directly use pipes. The sewer pipes in the existing municipal pipe network can be simply modified to construct the sewage treatment device described in the present invention, so that the sewage can be degraded during the pipeline transportation process, which greatly reduces the sewage treatment cost and reduces the sewage treatment pressure of the municipal pipe network. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The conductive microorganisms in the present invention degrade COD and NO3 by respiration. - -N mechanism diagram; Figure 2 A schematic diagram of the device effects of Embodiments 1 to 3 of the present invention; Figure 3 In a single cycle of Example 1 of the present invention, NO3 - -N concentration decreases over time; Figure 4 The effect diagram of COD concentration decreasing over time in a single cycle in Example 1 of the present invention; Figure 5 Community distribution diagram of microbial membrane at the phylum level in the tube wall microbial sampling in Example 1 of the present invention; Figure 6 Distribution diagram of microbial membrane communities at the phylum level in the tube wall microbial sampling in Example 2 of the present invention; Figure 7 Community distribution diagram of microbial film at genus level in pipe wall microbial sampling in Example 1 of the present invention; Figure 8 Community distribution diagram of microbial film at genus level in tube wall microbial sampling in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is described in detail below. The present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

[0022] A sewage treatment device for treating COD and nitrate nitrogen, the sewage treatment device comprising a treatment component in contact with sewage, a carbon material modified layer being provided on the surface of the treatment component in contact with sewage, and the carbon material modified layer being inoculated with sewage treatment microorganisms screened by low-voltage current; The carbon material modified layer includes a carbon material and a binder; the carbon material includes a mesh or long strip carbon material and a granular carbon material.

[0023] Specifically, the treatment component may be a sewage treatment pipe, a sewage treatment tank, a sewage treatment filler, etc. Any treatment component that can come into direct contact with sewage can be used.

[0024] Preferably, the treatment component is a metal pipe, a plastic pipe, or a ceramic pipe. The pipe is more convenient to use, and the existing sewer pipes in the municipal pipe network can be simply modified to construct the sewage treatment device of the present invention, so that the sewage can be degraded during the pipeline transportation process, which greatly reduces the sewage treatment cost and reduces the sewage treatment pressure of the municipal pipe network.

[0025] Specifically, the mass ratio of the mesh or elongated carbon material to the granular carbon material is 1:(1.5-2.0); The mesh or long strip carbon material is selected from at least one of carbon fiber and carbon nanotube; The granular carbon material is selected from at least one of carbon black, activated carbon and biochar.

[0026] More specifically, the carbon fiber is of intermediate modulus (IM) grade, and the carbon nanotube is a single-walled carbon nanotube; The carbon black has a specific surface area of ​​100-500m 2 / g, the activated carbon has a specific surface area of ​​100-500m 2 / g, the biochar has a specific surface area of ​​100-500m 2 / g.

[0027] Specifically, the mass ratio of the carbon material to the binder is 1:(1.2-1.5); The binder is selected from at least one of phenolic resin, epoxy resin and silicone resin.

[0028] Specifically, the preparation method of the carbon material modified layer is: The carbon material and the binder are added into ethanol to obtain a modified suspension, and the modified suspension is canned into the treatment component and allowed to stay for a period of time, and then the modified suspension is discharged, and the treatment component is heat-treated so that the binder undergoes a high-temperature cross-linking reaction to generate a high-molecular network polymer, so that the carbon material is fixed on the surface of the treatment component to form the carbon material modified layer.

[0029] More specifically, the residence time of the modified suspension in the treatment component is 6-36 hours; more preferably, the residence time is 12-24 hours.

[0030] More specifically, the heating treatment temperature is 80-150° C., and the heating treatment time is 3-10 hours. During the heating treatment, the ethanol evaporates, and the binder undergoes a high-temperature cross-linking reaction, so that the carbon material modified layer is attached to the treatment component.

[0031] More preferably, the preparation process of the carbon material modified layer is continuously performed at least three times, so that the carbon material modified layer with a sufficient thickness is attached to the inside of the pipeline (ie, the processing component).

[0032] Specifically, the method of inoculating sewage treatment microorganisms on the carbon material modified layer is: (1) Inoculating bacteria into a treatment component covered with a carbon material modification layer; and introducing artificially prepared sewage, wherein the artificially prepared sewage contains a carbon source, a nitrogen source, Vitamin B12 and trace metals; (2) Apply low voltage current to the processing components to screen conductive microorganisms in a targeted manner.

[0033] Specifically, the bacterial species include Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Saccharomyces, and Mycorrhiza.

[0034] More specifically, when the bacterial strains are introduced into the treatment component covered with the carbon material modification layer, the sewage in the biochemical pool of the municipal sewage treatment plant or the riverbed sludge in the natural river is directly poured into the treatment component covered with the carbon material modification layer, and stays at room temperature for at least 2 hours, so as to achieve the introduction of the bacterial strains. The sewage in the biochemical pool of the municipal sewage treatment plant or the riverbed sludge in the natural river contains microorganisms of Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Saccharomyces, Mycota and other categories. Directly using the sewage in the biochemical pool of the municipal sewage treatment plant or the riverbed sludge in the natural river to provide bacterial strains is more cost-effective and more convenient to use.

[0035] The sewage used in the embodiment of the present invention is from the biochemical pool of Ningdong Sewage Treatment Plant in Ningxia.

[0036] Specifically, CH3COONa is added to the artificially prepared sewage as a carbon source and NaNO3 is added as a nitrogen source; The concentration of CH3COONa is 1.6-1.7 g / L, the concentration of NaNO3 is 1.2-1.3 g / L, the concentration of Vitamin B12 is 4-6 mL / L, and the content of trace metals is 1.7-2.0 g / L; The trace metals include MgSO4 1.3-1.4 g / L, ZnSO4 0.1-0.3 g / L, CaCl2 0.10-0.15 g / L, KAI(SO4)2 0.01-0.03 g / L, and FeSO4 0.11-0.13 g / L.

[0037] Specifically, the low voltage current is 0.5-2 mA cm -2 ; The application time of the low voltage current is 14-20 days; During the application of the low voltage current, the artificially prepared sewage in the treatment component is replaced at least once a day.

[0038] A sewage treatment method, the sewage treatment method comprising: introducing the sewage to be treated into the sewage treatment device to treat COD and nitrate nitrogen in the sewage, wherein the residence time of the sewage to be treated in the sewage treatment device is 6-15 hours; The pH of the sewage to be treated is 6-8, the salinity is not higher than 5 mg / L, the COD value is not higher than 1000 mg / L, and the NO3 - -N is not higher than 400 mg / L.

[0039] The wastewater to be treated used in the embodiment of the present invention is: the traditional textile printing and dyeing industry wastewater is first filtered to remove insoluble suspended matter, the pH of the wastewater is adjusted to 6-8, and the heavy metal salts in the wastewater are removed by membrane filtration process, the salinity is less than 5 mg / L, the COD value is 480 mg / L, and the NO3 - -N is 200 mg / L.

[0040] Figure 1 The conductive microorganisms in the present invention degrade COD and NO3 by respiration. - -N mechanism diagram; Conductive microorganisms attach to the conductive tube wall and catalyze different bioelectrochemical reactions, including organic matter oxidation and nitrate reduction. Electrons are transferred or exchanged over short and long distances through conductive carriers to achieve the purpose of efficient degradation of pollutants.

[0041] Example 1 A sewage treatment device and sewage treatment method for treating COD and nitric nitrogen: (1) Carbon material (carbon black, carbon fiber) and phenolic resin (PF, molecular weight <500, China Xincheng Engineering Binder Co., Ltd.) were uniformly mixed in a mass ratio of 1:1.2, and a certain amount of ethanol was added to prepare a modified suspension of 4 g / L, in which the mass ratio of carbon fiber to carbon black was 1:1.5.

[0042] The modified suspension was filled into the metal pipe and kept in the pipe for 12 hours. Then the modified suspension in the pipe was poured out and the modified metal pipe was placed in a high-temperature oven and heated at 150°C for 10 hours to allow it to undergo high-temperature cross-linking.

[0043] According to the above modification method, the pipeline system was modified three times so that the carbon material modified layer could fully adhere to the inner wall of the pipeline. The pipeline sewage treatment system was assembled using 16 single 50 cm long metal pipes.

[0044] (2) Artificially prepared sewage with a C / N ratio of 2.4 was added to the piped sewage treatment system, to which 1.64 g / L CH3COONa and 1.214 g / L NaNO3 were added as carbon and nitrogen sources, 5 mL / L Vitamin B12 and 1.8 g / L trace metals were added to provide the required nutrients for microorganisms; among them, the trace metals included MgSO41.34 g / L, ZnSO40.2 g / L, CaCl20.12 g / L, KAI(SO4)20.02 g / L, and FeSO40.12 g / L.

[0045] (3) The device is inoculated with bacterial strains from a sewage treatment plant (the bacterial strains are sewage from a biochemical pool of a municipal sewage treatment plant, which contains a large number of several types of sewage treatment microorganisms, such as bacteria or fungi). The inoculation method is as follows: inject the bacterial strains into the pipe sewage treatment system so that the bacterial strains remain in the sewage treatment system for at least 2 hours. After that, the sewage in the device is replaced regularly every day. The amount of artificial sewage added to the device each time is 2 L, accounting for 79.6% of the volume of the sewage treatment device.

[0046] (4) Apply a constant 1.5 mA cm to the sewage device. -2 Electric current, directional screening of conductive microorganisms. On the seventh day of cultivation in the sewage treatment plant, COD and NO3 were tested six hours after replacing artificial sewage every day. - -N concentration, when the device was cultured for 14 days, COD and NO3 were tested every two hours after replacing the artificial sewage. - -N concentration, and on the 16th day, the low-voltage current screening of sewage treatment microorganisms was completed, and a sewage treatment device capable of treating COD and nitrate nitrogen was obtained.

[0047] (5) The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 6 hours, NO3 - The -N content dropped below the national emission standard (not higher than 15 mg / L), and the specific content was 9.8 mg / L at 12 hours.

[0048] After the treated sewage stayed in the pipeline for 10 hours, the COD content dropped below the national emission standard (no higher than 60 mg / L), and the specific content was 44 mg / L after 12 hours.

[0049] The results of Example 1 show that the sewage treatment device has a good sewage treatment effect. Moreover, after the sewage treatment device has been in operation for 2 months, the above treatment effect can still be maintained.

[0050] The community analysis of microorganisms sampled from the tube wall showed that the relative abundance of Proteobacteria was greater than 70%, and the sum of the relative abundances of Actinobacteria, Bacteroidetes, and Firmicutes exceeded 90% under all conditions.

[0051] Example 2 A sewage treatment device and sewage treatment method for treating COD and nitric nitrogen: (1) Carbon material (carbon black, carbon fiber) and phenolic resin (PF, molecular weight <500, China Xincheng Engineering Binder Co., Ltd.) were uniformly mixed in a mass ratio of 1:1.5, and a certain amount of ethanol was added to prepare a modified suspension of 6 g / L, in which the mass ratio of carbon fiber to carbon black was 1:2.

[0052] The modified suspension was filled into the PC pipe and kept in the pipe for 16 hours. Then the modified suspension in the pipe was poured out and the modified PC pipe was placed in a high-temperature oven and heated at 120°C for 8 hours to allow it to undergo high-temperature cross-linking.

[0053] According to the above modification method, the pipeline system was modified three times to allow the carbon material modified layer to fully adhere to the inner wall of the pipeline. The pipeline sewage treatment system was assembled using 16 single 50 cm long PC pipes.

[0054] (2) Artificially prepared sewage with a C / N ratio of 2.4 was added to the piped sewage treatment system, to which 1.64 g / L CH3COONa and 1.214 g / L NaNO3 were added as carbon and nitrogen sources, 5 mL / L Vitamin B12 and 1.8 g / L trace metals were added to provide the required nutrients for microorganisms; among them, the trace metals included MgSO41.34 g / L, ZnSO40.2 g / L, CaCl20.12 g / L, KAI(SO4)20.02 g / L, and FeSO40.12 g / L.

[0055] (3) The device is inoculated with bacterial strains from a sewage treatment plant (the bacterial strains are sewage from a biochemical pool of a municipal sewage treatment plant, which contains a large number of several types of sewage treatment microorganisms, such as bacteria or fungi). The inoculation method is as follows: inject the bacterial strains into the pipe sewage treatment system so that the bacterial strains remain in the sewage treatment system for at least 2 hours. After that, the sewage in the device is replaced regularly every day. The amount of artificial sewage added to the device each time is 2 L, accounting for 79.6% of the volume of the sewage treatment device.

[0056] (4) Apply a constant 2 mA cm to the sewage device. -2 Electric current, directional screening of conductive microorganisms. On the seventh day of cultivation in the sewage treatment plant, COD and NO3 were tested six hours after replacing artificial sewage every day. - -N concentration, when the device was cultured for 14 days, COD and NO3 were tested every two hours after replacing the artificial sewage. - -N concentration, and on the 16th day, the low-voltage current screening of sewage treatment microorganisms was completed, and a sewage treatment device capable of treating COD and nitrate nitrogen was obtained.

[0057] (5) The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 6 hours, NO3 - The -N content dropped below the national emission standard (not higher than 15 mg / L), and the specific content was 11 mg / L at 12 hours.

[0058] After the treated sewage stays in the pipeline for 10 hours, the COD content drops below the national emission standard (no higher than 60 mg / L), and the specific content is 50 mg / L after 12 hours.

[0059] The results of Example 2 show that the sewage treatment device has a good sewage treatment effect. Moreover, after the countless treatment devices have been in operation for 2 months, the above treatment effects can still be maintained.

[0060] Microbial community analysis was performed on samples of the tube wall, and the dominant species were Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes.

[0061] Example 3 A sewage treatment device and sewage treatment method for treating COD and nitric nitrogen: (1) Carbon materials (activated carbon, carbon nanotubes) and epoxy resin (molecular weight <500, China Xincheng Engineering Adhesive Co., Ltd.) were uniformly mixed in a mass ratio of 1:1.5, and a certain amount of ethanol was added to prepare a modified suspension of 5 g / L, in which the mass ratio of carbon nanotubes to activated carbon was 1:2.

[0062] The modified suspension was filled into the PC pipe and kept in the pipe for 15 hours. Then the modified suspension in the pipe was poured out and the modified PC pipe was placed in a high-temperature oven and heated at 80°C for 12 hours to allow high-temperature cross-linking to occur.

[0063] According to the above modification method, the pipeline system was modified three times to allow the carbon material modified layer to fully adhere to the inner wall of the pipeline. The pipeline sewage treatment system was assembled using 16 single 50 cm long PC pipes.

[0064] (2) Artificially prepared sewage was added to the piped sewage treatment system, to which 1.70 g / L CH3COONa and 1.30 g / L NaNO3 were added as carbon and nitrogen sources, 6 mL / L Vitamin B12 and 1.99 g / L trace metals were added to provide the required nutrients for microorganisms; among them, the trace metals included MgSO41.4 g / L, ZnSO40.3 g / L, CaCl20.15 g / L, KAI(SO4)20.01 g / L, and FeSO40.13 g / L.

[0065] (3) The device is inoculated with bacterial strains from a sewage treatment plant (the bacterial strains are sewage from a biochemical pool of a municipal sewage treatment plant, which contains a large number of several types of sewage treatment microorganisms, such as bacteria or fungi). The inoculation method is as follows: inject the bacterial strains into the pipe sewage treatment system so that the bacterial strains remain in the sewage treatment system for at least 2 hours. After that, the sewage in the device is replaced regularly every day. The amount of artificial sewage added to the device each time is 2 L, accounting for 79.6% of the volume of the sewage treatment device.

[0066] (4) Apply a constant 1.8 mA cm to the sewage device. -2 Electric current, directional screening of conductive microorganisms. On the seventh day of cultivation in the sewage treatment plant, COD and NO3 were tested six hours after replacing artificial sewage every day. - -N concentration, when the device was cultured for 14 days, COD and NO3 were tested every two hours after replacing the artificial sewage. - -N concentration, and completed the low-voltage current screening of sewage treatment microorganisms on the 20th day, and obtained a sewage treatment device that can treat COD and nitrate nitrogen.

[0067] (5) The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 6 hours, NO3 - The -N content dropped below the national emission standard (not higher than 15 mg / L), and the specific content was 11.5 mg / L at 12 hours.

[0068] After the treated sewage stayed in the pipeline for 10 hours, the COD content dropped below the national emission standard (no higher than 60 mg / L), and the specific content was 50.4 mg / L after 12 hours.

[0069] The results of Example 3 show that the sewage treatment device has a good sewage treatment effect. Moreover, after the treatment device has been in operation for 2 months, the above treatment effect can still be maintained.

[0070] Microbial community analysis was performed on samples of the tube wall, and the dominant species were Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes.

[0071] From the experimental results of the above examples 1 to 3, it can be seen that the conductive microorganisms of the sewage treatment device of the present invention have all produced conductive microorganisms through microbial community analysis, and the relative abundance of conductive microorganisms is relatively high. The sewage treatment effect of Example 1 is better than that of Example 2 because the metal pipe has better conductivity, which is more conducive to the electron transfer of conductive microorganisms, improves the respiration of conductive microorganisms, and then improves the sewage treatment capacity.

[0072] Figure 2 The schematic diagram of the device effect of Example 1 to Example 3 shows that the conductive microorganisms are attached to the pipe wall, and the sewage is transported from the storage tank to the pipeline system by the peristaltic pump. The sewage passes through the pipeline sewage treatment system to achieve the purpose of removing pollutants. The output at the outlet is COD and NO3 - - Wastewater with low N content.

[0073] Figure 3 and Figure 4 This is a graph showing the effect of the reduction of NO3-N and COD concentrations over time in a single cycle in Example 1 of the present invention. Figure 3 , Figure 4 It can be seen that the COD and NO3 of the sewage treatment system in the pipes modified with the coating and attached with conductive microorganisms - -N can be degraded to below the national emission standard within 6-12 hours. The sewage is removed through the pipe sewage treatment system, and the output at the outlet is COD and NO3 - - Wastewater with low N content.

[0074] Figure 5-Figure 8 This is the community analysis spectrum of the tube wall microorganism sampling in Example 1 and Example 2 of the present invention, from Figure 5-Figure 8It can be seen that the conductive microorganisms have been analyzed through the microbial community, and the relative abundance of conductive microorganisms is relatively high. The sewage treatment effect of Example 1 is better than that of Example 2. In Example 2, this is because the relative abundance of Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes is relatively high. Because the metal pipe has better conductivity, it is more conducive to the electron transfer of conductive microorganisms, improves the respiration of conductive microorganisms, and then improves the sewage treatment capacity.

[0075] In summary, the present invention has developed a new type of sewage treatment device and treatment method, based on a conductive material microbial pipeline sewage treatment device, simulating a municipal sewage network, so that COD and NO3 in sewage - -N is degraded to a relatively low concentration in the process of flowing through the sewage treatment plant in the pipeline, reducing the treatment pressure of the sewage treatment plant and improving the treatment capacity of the urban sewage pipe network and the corresponding sewage treatment plant.

[0076] Comparative Example 1 The same method as in Example 1 is adopted to treat sewage, except that in this comparative example 1, no carbon material modification layer is attached to the inner wall of the pipe.

[0077] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content is 194 mg / L.

[0078] After the treated sewage stayed in the pipe for 12 hours, the COD content was 476 mg / L.

[0079] The difference between Example 1 and Comparative Example 1 is that Comparative Example 1 is not modified by a carbon material modification layer, and the carbon material modification layer can increase the biocompatibility, adhesion and conductivity of the inner wall of the pipe, so as to facilitate the attachment and growth of conductive microorganisms. Therefore, it is difficult for the microorganisms in Comparative Example 1 to directly attach to the metal pipe wall, resulting in that Comparative Example 1 has basically no sewage treatment capacity.

[0080] Comparative Example 2 The same method as in Example 2 is adopted to treat sewage, except that in this comparative example 2, no carbon material modification layer is attached to the inner wall of the pipe.

[0081] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content is 198 mg / L.

[0082] After the treated sewage stayed in the pipe for 12 hours, the COD content was 478 mg / L.

[0083] The difference between Example 2 and Comparative Example 2 is that Comparative Example 2 has not been modified with a carbon material modification layer, and the tube wall of Comparative Example 2 is made of PC material, conductive microorganisms cannot grow on the tube wall, and the tube wall has no biocompatibility and low adhesion, resulting in Comparative Example 2 having basically no sewage treatment capacity.

[0084] Comparative Example 3 The same method as in Example 1 is used to treat sewage, except that in this comparative example 3, no low-voltage current is applied to the sewage device in step (4).

[0085] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content 35 mg / L.

[0086] After the treated sewage stayed in the pipe for 12 hours, the COD content was 88 mg / L.

[0087] From the comparison of the experimental results of Comparative Example 3 and Example 1, it can be seen that if the sewage treatment device is not treated with low-voltage current, although the sewage treatment device will have a certain COD and nitrate nitrogen degradation treatment capacity, the treatment effect will be significantly reduced.

[0088] Comparative Example 4 The same method as in Example 1 was used to treat the wastewater, except that in this comparative example 4, the current was increased in step (4), and a constant current of 3 mA cm was applied to the wastewater device in this comparative example 4. -2 Electric current.

[0089] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content: 124 mg / L.

[0090] After the treated sewage stayed in the pipe for 12 hours, the COD content was 368 mg / L.

[0091] From the comparison of the experimental results of Comparative Example 4 and Example 1, it can be seen that if the current is too large, it will damage the microorganisms, and eventually lead to a significant decrease in the COD and nitrate nitrogen degradation treatment capacity of the sewage treatment device.

[0092] Comparative Example 5 The same method as in Example 1 was adopted to treat sewage, except that in Comparative Example 5, only carbon black was used as the carbon material, and no carbon fiber was added.

[0093] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content: 81 mg / L.

[0094] After the treated sewage stayed in the pipe for 12 hours, the COD content was 136 mg / L.

[0095] Comparative Example 6 The same method as in Example 1 was adopted to treat sewage, except that in Comparative Example 6, only carbon fiber was used as the carbon material, and no carbon black was added.

[0096] The sewage to be treated is introduced into the sewage treatment device (pipeline). After the sewage stays in the pipeline for 12 hours, NO3 - -N content: 69 mg / L.

[0097] After the treated sewage stayed in the pipe for 12 hours, the COD content was 117 mg / L.

[0098] From the comparison of the experimental conditions of Comparative Example 5, Comparative Example 6 and Example 1, it can be seen that when the mesh or long strip carbon material is used together with the granular carbon material, it is more conducive to the attachment of the carbon material modification layer and more conducive to the access of the bacterial species, thereby achieving efficient treatment of sewage.

[0099] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, all of which belong to the protection scope of the present invention. The protection scope of the present invention shall be based on the attached claims.

Claims

1. A sewage treatment device for treating COD and nitrate nitrogen, characterized in that: The sewage treatment device comprises a treatment component in contact with sewage, a surface of the treatment component in contact with sewage is provided with a carbon material modification layer, and the carbon material modification layer is inoculated with sewage treatment microorganisms screened by low-voltage current; The carbon material modified layer includes a carbon material and a binder; the carbon material includes a mesh or long strip carbon material and a granular carbon material.

2. A sewage treatment device for treating COD and nitric nitrogen according to claim 1, characterized in that: The processing components are metal pipes, plastic pipes and ceramic pipes.

3. A sewage treatment device for treating COD and nitric nitrogen according to claim 1, characterized in that: The mass ratio of the mesh or elongated carbon material to the granular carbon material is 1:(1.5-2.0); The mesh or long strip carbon material is selected from at least one of carbon fiber and carbon nanotube; The granular carbon material is selected from at least one of carbon black, activated carbon and biochar.

4. A sewage treatment device for treating COD and nitric nitrogen according to claim 1, characterized in that: The mass ratio of the carbon material to the binder is 1:(1.2-1.5); The binder is selected from at least one of phenolic resin, epoxy resin and silicone resin.

5. A sewage treatment device for treating COD and nitric nitrogen according to claim 1, characterized in that: The preparation method of the carbon material modified layer is: The carbon material and the binder are added into ethanol to obtain a modified suspension, and the modified suspension is canned into the treatment component and allowed to stay for a period of time, and then the modified suspension is discharged, and the treatment component is heat-treated so that the binder undergoes a high-temperature cross-linking reaction to generate a high-molecular network polymer, so that the carbon material is fixed on the surface of the treatment component to form the carbon material modified layer.

6. A sewage treatment device for treating COD and nitric nitrogen according to claim 1, characterized in that: The method of inoculating sewage treatment microorganisms on the carbon material modified layer is: (1) Inoculating bacteria into a treatment component covered with a carbon material modification layer; and introducing artificially prepared sewage, wherein the artificially prepared sewage contains a carbon source, a nitrogen source, Vitamin B12 and trace metals; (2) Apply low voltage current to the processing components to screen conductive microorganisms in a targeted manner.

7. A sewage treatment device for treating COD and nitrate nitrogen according to claim 6, characterized in that: The bacterial species include Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Saccharomyces, and Mycorrhiza.

8. A sewage treatment device for treating COD and nitrate nitrogen according to claim 6, characterized in that: CH3COONa is added to the artificially prepared sewage as a carbon source and NaNO3 is added as a nitrogen source; The concentration of CH3COONa is 1.6-1.7 g / L, the concentration of NaNO3 is 1.2-1.3 g / L, the concentration of VitaminB12 is 4-6 mL / L, and the content of trace metals is 1.7-2.0 g / L; The trace metals include MgSO4 1.3-1.4 g / L, ZnSO4 0.1-0.3 g / L, CaCl2 0.10-0.15 g / L, KAI(SO4)2 0.01-0.03 g / L, and FeSO4 0.11-0.13 g / L.

9. A sewage treatment device for treating COD and nitrate nitrogen according to claim 6, characterized in that: The low voltage current is 0.5-2 mA cm -2 ; The application time of the low voltage current is 14-20 days; During the application of the low voltage current, the artificially prepared sewage in the treatment component is replaced at least once a day.

10. A method for treating sewage, characterized in that: The sewage treatment method comprises: introducing the sewage to be treated into the sewage treatment device according to any one of claims 1 to 9 to treat COD and nitrate nitrogen in the sewage, wherein the residence time of the sewage to be treated in the sewage treatment device is 6 to 15 hours; The pH of the sewage to be treated is 6-8, the salinity is not higher than 5 mg / L, the COD value is not higher than 1000 mg / L, and the NO3 - -N is not higher than 400mg / L.

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