Biological deamination treatment process based on iron-carbon coupling method

Abstract

The invention relates to the technical field of wastewater treatment, and particularly discloses a biological deamination treatment process based on an iron-carbon coupling method. The invention discloses a biological deamination treatment process based on an iron-carbon coupling method. The biological deamination treatment process comprises the following steps: pretreatment: filling a reactor with iron-carbon composite filler with a sandwich structure; then circularly contacting the surface of the filler with an iron reducing bacteria solution and a sulfur autotrophic bacteria solution, and culturing and biofilm culturing to form a composite membrane; wherein the iron-carbon composite filler with the sandwich structure comprises two conductive net layers and an iron powder layer arranged between the two net layers; wastewater treatment: adjusting the pH and temperature of the wastewater, then introducing the wastewater into a reactor, and using hydrogen generated by iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, automatically closing aeration to enter a denitrification mode, and when the hydrogen concentration is less than 0.2%, starting aeration to convert into a nitrification mode; the composite membrane formed in the reactor continuously degrades ammonia nitrogen, and deamination treatment is completed.

Description

Technical Field

[0001] This application relates to the technical field of wastewater treatment, and in particular to a biological deammoniation treatment process based on iron-carbon coupling. Background Technology

[0002] Eutrophication of surface water and pollution of groundwater caused by large amounts of wastewater with low C / N ratios have seriously affected people's lives. Utilizing denitrifying bacteria for denitrification is one of the main approaches to wastewater treatment. However, the reduction process using denitrifying bacteria requires organic carbon sources in the water as electron donors. But wastewater with low C / N ratios has low organic carbon source content, making it difficult to achieve deep denitrification using traditional biological methods. Existing technologies typically use external carbon sources to address the insufficient carbon source in the wastewater denitrification process. Common carbon sources include sucrose, glucose, acetic acid, ethanol, and methanol. However, external carbon sources are prone to secondary pollution, and the type of carbon source has a significant impact on the denitrification rate, leading to problems such as nitrate nitrogen accumulation and high treatment costs. Furthermore, the addition of carbon sources increases CO2 emissions. Therefore, the application of external carbon source denitrification in deep denitrification of wastewater with low C / N ratios is greatly limited, and it cannot achieve continuous and efficient ammonia nitrogen degradation. Summary of the Invention

[0003] To achieve continuous and efficient ammonia nitrogen degradation in wastewater, this application provides a biological ammonia removal process based on iron-carbon coupling.

[0004] This application provides a biological deammoniation treatment process based on iron-carbon coupling, which adopts the following technical solution: A biological deammoniation treatment process based on iron-carbon coupling includes the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing is loaded into the reactor; then, iron-reducing bacteria solution and sulfur autotrophic bacteria solution are circulated to contact the surface of the packing to cultivate and form a composite membrane; the sandwich-structured iron-carbon composite packing includes two conductive mesh layers and an iron powder layer set between the two mesh layers. Wastewater treatment: The pH and temperature of the wastewater are adjusted, and then the wastewater is introduced into the reactor. The hydrogen produced by the iron-carbon reaction is used as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically turned off and the denitrification mode is entered; when it is less than 0.2%, the aeration is turned on and the nitrification mode is entered. The composite membrane formed in the reactor continuously degrades ammonia nitrogen and completes the ammonia removal treatment.

[0005] By adopting the above technical solution, a sulfur autotrophic bacteria-iron reducing bacteria composite microbial community is implanted to form a double-layer biofilm on the surface of the packing material. The outer layer of sulfur bacteria uses the sulfate generated by the iron-carbon reaction for autotrophic deammoniation, while the inner layer of iron reducing bacteria regenerates ferrous ions, forming a closed material cycle chain and reducing sludge production. The sandwich-structured iron-carbon composite packing material forms a stable electron transport network, allowing electrons generated by iron corrosion to directly act on the biofilm. Furthermore, the hydrogen gas generated by the iron-carbon reaction is used as a signal source to achieve the switching between denitrification and nitrification, reducing power consumption. Through self-powered electron transport and the symbiotic microbial community system, ammonia nitrogen removal is achieved without the need for an external carbon source, thus achieving continuous and efficient ammonia nitrogen degradation of wastewater.

[0006] In one specific implementation, the conductive mesh layer comprises a conductive activated carbon fiber mesh with a pore size of 5-10 micrometers.

[0007] In one specific implementation, the raw materials of the iron powder layer include the following components in parts by weight: 75-80 parts iron powder, 5-8 parts micron-sized copper powder, 2-4 parts micron-sized nickel powder, and 3-5 parts nano-manganese dioxide.

[0008] By adopting the above technical solution, iron is the main anode that corrodes preferentially, and the generated electrons are quickly transferred to the conductive carbon mesh; copper, nickel and other metals with higher potential are protected as cathodes and are gradually exposed in the later stage, forming catalytic sites for activating persulfate in situ, generating highly oxidizing sulfate free radicals, extending the effective cycle of the oxidation process, improving the overall electron transfer and utilization efficiency, and further improving the treatment effect of wastewater.

[0009] In one specific implementation, the preparation method of the sandwich-structured iron-carbon composite filler includes the following steps: Iron powder, micron-sized copper powder, micron-sized nickel powder, and nano-manganese dioxide are stirred and mixed evenly to obtain a mixed powder. Then, PVA aqueous solution is added, stirred and mixed evenly, and dried to obtain granules. The granules are added to a mold and pressed at room temperature to obtain a pressed material; then, under nitrogen protection, the material is first degreased at 300-500℃ and then sintered at 600-750℃ to obtain an iron powder layer. By combining the iron powder layer with the conductive mesh layer and hot-pressing, a sandwich-structured iron-carbon composite filler is obtained.

[0010] By adopting the above technical solution, iron powder, micron-sized copper powder, micron-sized nickel powder, and nano-manganese dioxide are first mixed, then PVA aqueous solution is added, stirred and dried to obtain particulate matter; then it is pressed into shape, degreased, sintered, and finally composited with a conductive mesh layer to obtain a sandwich structure iron-carbon composite filler.

[0011] In one specific feasible implementation, the pretreatment step, the method for cultivating biofilm formation includes the following steps: Pump the iron-reducing bacteria solution into the reactor, turn off aeration and stirring, and let it stand at 30°C for 4-6 hours for adsorption. Mix the iron-reducing bacterial solution and the sulfur-autotrophic bacterial solution, place them in a shaker at 30℃, and culture them at a low speed of 80 rpm for 3-5 days to obtain a composite bacterial solution. Pump the solution into the reactor, turn on the circulation pump, and circulate it at a flow rate of 0.2-0.5 m / h for 12-24 hours. Then stop the circulation and seal the reactor. Start the circulation pump. For days 1-3, control the temperature at 30±2℃, pH at 7.0-7.5, DO < 0.2mg / L, and circulation flow rate at 0.5m / h. For days 4-10, gradually increase the influent ammonia nitrogen from 50mg / L to 200mg / L, and aerate intermittently for 20min every 4h to complete the culture and biofilm formation.

[0012] By adopting the above technical solution, iron-reducing bacteria solution is first introduced and allowed to stand at 30°C for adsorption. Then, a composite bacterial solution of iron-reducing bacteria solution and sulfur autotrophic bacteria solution is introduced and circulated at a low speed. Finally, the circulation pump is started for gradient acclimatization and operation to complete the culture and biofilm formation.

[0013] In one specific implementation scheme, the weight ratio of iron-reducing bacterial solution to sulfur-autotrophic bacterial solution in the compound bacterial solution is (30-40):(60-70).

[0014] In one specific implementation scheme, each liter of the iron-reducing bacterial solution contains the following components: NaHCO3: 2g, CH3COONa: 0.8g, NH4Cl: 0.3g, KH2PO4: 0.2g, MgCl2: 0.1g, Fe(OH)3 colloid: 10g, and trace element solution: 1mL; the volume fraction of iron-reducing bacteria in the iron-reducing bacterial solution is 5-10%.

[0015] In one specific implementation scheme, each liter of the sulfur autotrophic bacterial solution contains the following components: Na2S2O3·5H2O: 2.5g, NaHCO3: 1.5g, NH4Cl: 0.5g, KH2PO4: 0.5g, MgSO4·7H2O: 0.2g, and trace element solution: 1mL; the volume fraction of sulfur autotrophic bacteria in the sulfur autotrophic bacterial solution is 5-10%.

[0016] In one specific implementation, each liter of the trace element solution contains the following components: FeCl3·6H2O: 0.25g, ZnSO4·7H2O: 0.22g, CoCl2·6H2O: 0.24g, MnSO4·H2O: 0.23g, Na2MoO4·2H2O: 0.22g, NiCl2·6H2O: 0.21g, CuSO4·5H2O: 0.08g.

[0017] In summary, this application includes at least one of the following beneficial technical effects: The process described in this application incorporates a sulfur autotrophic bacteria-iron reducing bacteria composite microbial community, forming a double-layer biofilm on the packing surface. The outer layer of sulfur bacteria utilizes sulfate generated from the iron-carbon reaction for autotrophic deammoniation, while the inner layer of iron reducing bacteria regenerates ferrous ions, forming a closed material cycle chain and reducing sludge production. The sandwich-structured iron-carbon composite packing forms a stable electron transport network, allowing electrons generated by iron corrosion to directly act on the biofilm. Furthermore, hydrogen gas generated from the iron-carbon reaction is used as a signal source to achieve the switching between denitrification and nitrification, reducing power consumption. Through self-powered electron transport and a symbiotic microbial system, ammonia nitrogen removal is achieved without the need for an external carbon source, thus achieving continuous and efficient ammonia nitrogen degradation of wastewater. In this application, iron is the primary anode that preferentially corrodes, and the generated electrons are rapidly transferred to the conductive carbon mesh. Copper, nickel, and other metals with higher potential are protected as cathodes and are gradually exposed in the later stages, forming catalytic sites for activating persulfate in situ, generating highly oxidizing sulfate free radicals, extending the effective cycle of the oxidation process, improving the overall electron transfer and utilization efficiency, and further enhancing the treatment effect on wastewater. In this application, iron-reducing bacteria solution is first introduced and allowed to stand at 30°C for adsorption. Then, a composite bacterial solution of iron-reducing bacteria solution and sulfur autotrophic bacteria solution is introduced and circulated at a low speed. Finally, the circulation pump is started for gradient acclimatization and operation to complete the culture and biofilm formation. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] All raw materials used in the examples are commercially available. Preparation Example

[0020] Preparation Example 1 Preparation Example 1 provides a method for preparing a sandwich-structured iron-carbon composite filler, comprising the following steps: 75 kg of iron powder, 5 kg of micron-sized copper powder, 2 kg of micron-sized nickel powder, and 3 kg of nano-manganese dioxide were stirred and mixed evenly to obtain a mixed powder. Then, a 5% PVA aqueous solution was added, stirred and mixed evenly, and dried to obtain granules. The particle size of the iron powder, micron-sized copper powder, and micron-sized nickel powder was 100-200 microns. The PVA accounted for 5% of the weight of the mixed powder. The granules are added to a mold and pressed at room temperature to obtain a pressed material; then, under nitrogen protection, the material is first degreased at 400°C and then sintered at 675°C to obtain an iron powder layer. An iron powder layer is placed between two conductive mesh layers and hot-pressed at 7.5 MPa and 200°C to obtain a sandwich-structured iron-carbon composite filler; wherein the conductive mesh layer is a conductive activated carbon fiber mesh with a pore size of 10 micrometers.

[0021] Preparation Example 2 Preparation Example 2 provides a method for preparing a sandwich-structured iron-carbon composite filler, comprising the following steps: 77.5 kg of iron powder, 6.5 kg of micron-sized copper powder, 3 kg of micron-sized nickel powder, and 4 kg of nano-manganese dioxide were stirred and mixed evenly to obtain a mixed powder. Then, a 5% PVA aqueous solution was added, stirred and mixed evenly, and dried to obtain granules. The particle size of the iron powder, micron-sized copper powder, and micron-sized nickel powder was 100-200 microns. The PVA accounted for 5% of the weight of the mixed powder. The granules are added to a mold and pressed at room temperature to obtain a pressed material; then, under nitrogen protection, the material is first degreased at 400°C and then sintered at 675°C to obtain an iron powder layer. An iron powder layer is placed between two conductive mesh layers and hot-pressed at 7.5 MPa and 200°C to obtain a sandwich-structured iron-carbon composite filler; wherein the conductive mesh layer is a conductive activated carbon fiber mesh with a pore size of 10 micrometers.

[0022] Preparation Example 3 Preparation Example 3 provides a method for preparing a sandwich-structured iron-carbon composite filler, comprising the following steps: 80 kg of iron powder, 8 kg of micron-sized copper powder, 4 kg of micron-sized nickel powder, and 5 kg of nano-manganese dioxide were stirred and mixed evenly to obtain a mixed powder. Then, a 5% PVA aqueous solution was added, stirred and mixed evenly, and dried to obtain granules. The particle size of the iron powder, micron-sized copper powder, and micron-sized nickel powder was 100-200 microns. The PVA accounted for 5% of the weight of the mixed powder. The granules are added to a mold and pressed at room temperature to obtain a pressed material; then, under nitrogen protection, the material is first degreased at 400°C and then sintered at 675°C to obtain an iron powder layer. An iron powder layer is placed between two conductive mesh layers and hot-pressed at 7.5 MPa and 200°C to obtain a sandwich-structured iron-carbon composite filler; wherein the conductive mesh layer is a conductive activated carbon fiber mesh with a pore size of 10 micrometers.

[0023] Preparation Example 4 Preparation Example 4 provides a method for preparing an iron-reducing bacterial solution, comprising the following steps: Add the following components to each liter of deionized water: NaHCO3: 2g, CH3COONa: 0.8g, NH4Cl: 0.3g, KH2PO4: 0.2g, MgCl2: 0.1g, Fe(OH)3 colloid: 10g, and trace element solution: 1mL to obtain an iron-reducing bacteria culture medium. Add the iron-reducing bacteria and, under anaerobic conditions, adjust the pH to 6.8 with NaOH or HCl. Incubate in a sealed container at 30℃ for 7 days. Finally, centrifuge at 4000rpm for 10min, discard the supernatant, and dilute with 0.85% NaCl sterile physiological saline. The solution was resuspended until the wet bacterial sludge concentration was 15 g / L to obtain an iron-reducing bacterial solution. The iron-reducing bacteria were *Geobacterium thioreducing*, and the volume fraction of iron-reducing bacteria in the culture medium was 7.5%. Each liter of trace element solution contained the following components: FeCl3·6H2O: 0.25 g, ZnSO4·7H2O: 0.22 g, CoCl2·6H2O: 0.24 g, MnSO4·H2O: 0.23 g, Na2MoO4·2H2O: 0.22 g, NiCl2·6H2O: 0.21 g, CuSO4·5H2O: 0.08 g.

[0024] Preparation Example 5 Preparation Example 5 provides a method for preparing a sulfur autotrophic bacterial culture, comprising the following steps: Add the following components to each liter of deionized water: Na₂S₂O₃·5H₂O: 2.5g, NaHCO₃: 1.5g, NH₄Cl: 0.5g, KH₂PO₄: 0.5g, MgSO₄·7H₂O: 0.2g, and trace element solution: 1mL to obtain a sulfur autotrophic bacteria culture medium. Add sulfur autotrophic bacteria, adjust the pH to 7.2 with NaOH or HCl, and incubate at 30℃ with dissolved oxygen (DO) of 3.0 mg / L using a shaker at 150 rpm for 72 h. Finally, centrifuge at 4000 rpm for 10 min, discard the supernatant, and use a solution with a mass concentration of 0. The microbial sludge was resuspended in 85% NaCl sterile physiological saline until the wet microbial sludge concentration was 20 g / L to obtain a sulfur autotrophic bacterial solution. The sulfur autotrophic bacteria were *Thiobacillus denitrificationis*, and the volume fraction of sulfur autotrophic bacteria in the culture medium was 7.5%. Each liter of trace element solution contained the following components: FeCl3·6H2O: 0.25 g, ZnSO4·7H2O: 0.22 g, CoCl2·6H2O: 0.24 g, MnSO4·H2O: 0.23 g, Na2MoO4·2H2O: 0.22 g, NiCl2·6H2O: 0.21 g, CuSO4·5H2O: 0.08 g. Example

[0025] Example 1 Example 1 provides a biological deammoniation treatment process based on iron-carbon coupling, including the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing material from Preparation Example 1 was loaded into the reactor; The iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the solution was allowed to stand at 30°C for 4 hours for adsorption. The iron-reducing bacterial solution from Preparation Example 4 and the sulfur-autotrophic bacterial solution from Preparation Example 5 were mixed and placed in a shaker at 30°C. The mixture was cultured at a low speed of 80 rpm for 3 days to obtain a composite bacterial solution. The composite bacterial solution was pumped into the reactor, and the circulation pump was turned on to circulate at a flow rate of 0.2 m / h for 12 hours. The circulation was then stopped and the reactor was sealed. The weight ratio of the iron-reducing bacterial solution to the sulfur-autotrophic bacterial solution in the composite bacterial solution was 30:70. Start the circulation pump. For the first 1-3 days, maintain the temperature at 30℃, pH at 7.0, DO < 0.2 mg / L, and circulation flow rate at 0.5 m / h. For the second 10 days, gradually increase the influent ammonia nitrogen from 50 mg / L to 200 mg / L, and aerate intermittently for 20 minutes every 4 hours to complete the cultivation and biofilm formation, thus forming a composite membrane. Wastewater treatment: Adjust the pH of the wastewater to 7.0-8.5 and the temperature to 25-35℃, then introduce it into the reactor. Use the hydrogen produced by the iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically shut off and the denitrification mode is entered; when it is less than 0.2%, the aeration is started and the nitrification mode is entered. The composite membrane formed in the reactor continuously degrades ammonia nitrogen, completing the ammonia removal treatment.

[0026] Example 2 Example 2 provides a biological deammoniation treatment process based on iron-carbon coupling, including the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing material from Preparation Example 1 was loaded into the reactor; The iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the solution was allowed to stand at 30°C for 5 hours for adsorption. The iron-reducing bacterial solution from Preparation Example 4 and the sulfur-autotrophic bacterial solution from Preparation Example 5 were mixed and placed in a shaker at 30°C. The mixture was cultured at a low speed of 80 rpm for 4 days to obtain a composite bacterial solution. The composite bacterial solution was pumped into the reactor, and the circulation pump was turned on to circulate at a flow rate of 0.3 m / h for 18 hours. The circulation was then stopped and the reactor was sealed. The weight ratio of the iron-reducing bacterial solution to the sulfur-autotrophic bacterial solution in the composite bacterial solution was 30:70. Start the circulation pump. For the first 1-3 days, maintain the temperature at 30℃, pH at 7.0, DO < 0.2 mg / L, and circulation flow rate at 0.5 m / h. For the second 10 days, gradually increase the influent ammonia nitrogen from 50 mg / L to 200 mg / L, and aerate intermittently for 20 minutes every 4 hours to complete the cultivation and biofilm formation, thus forming a composite membrane. Wastewater treatment: Adjust the pH of the wastewater to 7.0-8.5 and the temperature to 25-35℃, then introduce it into the reactor. Use the hydrogen produced by the iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically shut off and the denitrification mode is entered; when it is less than 0.2%, the aeration is started and the nitrification mode is entered. The composite membrane formed in the reactor continuously degrades ammonia nitrogen, completing the ammonia removal treatment.

[0027] Example 3 Example 3 provides a biological deammoniation treatment process based on iron-carbon coupling, including the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing material from Preparation Example 1 was loaded into the reactor; The iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the solution was allowed to stand at 30°C for 6 hours for adsorption. The iron-reducing bacterial solution from Preparation Example 4 and the sulfur-autotrophic bacterial solution from Preparation Example 5 were mixed and placed in a shaker at 30°C. The mixture was cultured at a low speed of 80 rpm for 5 days to obtain a composite bacterial solution. The composite bacterial solution was pumped into the reactor, and the circulation pump was turned on to circulate at a flow rate of 0.5 m / h for 24 hours. The circulation was then stopped and the reactor was sealed. The weight ratio of the iron-reducing bacterial solution to the sulfur-autotrophic bacterial solution in the composite bacterial solution was 30:70. Start the circulation pump. For the first 1-3 days, maintain the temperature at 30℃, pH at 7.5, DO < 0.2 mg / L, and circulation flow rate at 0.5 m / h. For the second 10 days, gradually increase the influent ammonia nitrogen from 50 mg / L to 200 mg / L, and aerate intermittently for 20 minutes every 4 hours to complete the cultivation and biofilm formation, thus forming a composite membrane. Wastewater treatment: Adjust the pH of the wastewater to 7.0-8.5 and the temperature to 25-35℃, then introduce it into the reactor. Use the hydrogen produced by the iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically shut off and the denitrification mode is entered; when it is less than 0.2%, the aeration is started and the nitrification mode is entered. The composite membrane formed in the reactor continuously degrades ammonia nitrogen, completing the ammonia removal treatment.

[0028] Example 4 The difference between Example 4 and Example 2 is the pretreatment: the sandwich knots prepared in Example 2 are... The iron-carbon composite packing material was packed into the reactor; the iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the reactor was allowed to stand at 30°C for 5 hours for adsorption; the remaining steps were the same as in Example 2.

[0029] Example 5 The difference between Example 5 and Example 2 is the pretreatment: the sandwich knots prepared in Example 3 are... The iron-carbon composite packing material was packed into the reactor; the iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the reactor was allowed to stand at 30°C for 5 hours for adsorption; the remaining steps were the same as in Example 2.

[0030] Example 6 The difference between Example 6 and Example 4 is that the iron-reducing bacterial solution from Example 4 and the sulfur-autotrophic bacterial solution from Example 5 were mixed and placed in a shaker at 30°C and cultured at a low speed of 80 rpm for 4 days to obtain a composite bacterial solution. This composite bacterial solution was pumped into the reactor, and the circulation pump was turned on to circulate at a flow rate of 0.3 m / h for 18 hours. Then, the circulation was stopped and the reactor was sealed. The weight ratio of the iron-reducing bacterial solution to the sulfur-autotrophic bacterial solution in the composite bacterial solution was 35:65. The remaining steps were the same as in Example 4.

[0031] Example 7 The difference between Example 7 and Example 4 is that the iron-reducing bacterial solution from Example 4 and the sulfur-autotrophic bacterial solution from Example 5 were mixed and placed in a shaker at 30°C and cultured at a low speed of 80 rpm for 4 days to obtain a composite bacterial solution. This composite bacterial solution was pumped into the reactor, and the circulation pump was turned on to circulate it at a flow rate of 0.3 m / h for 18 hours. Then, the circulation was stopped and the reactor was sealed. The weight ratio of the iron-reducing bacterial solution to the sulfur-autotrophic bacterial solution in the composite bacterial solution was 40:60. The remaining steps were the same as in Example 4. Comparative Example

[0032] Comparative Example 1 Comparative Example 1 provides a biological ammonia removal process based on iron-carbon coupling, comprising the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing material from Preparation Example 1 was loaded into the reactor; The sulfur autotrophic bacterial solution from Preparation Example 5 was pumped into the reactor, the circulation pump was turned on, and the solution was circulated at a flow rate of 0.2 m / h for 12 h. Then the circulation was stopped and the reactor was sealed. Start the circulation pump. For the first 1-3 days, maintain the temperature at 30℃, pH at 7.0, DO < 0.2 mg / L, and circulation flow rate at 0.5 m / h. For the next 4-10 days, gradually increase the influent ammonia nitrogen from 50 mg / L to 200 mg / L, and aerate intermittently for 20 minutes every 4 hours to complete the cultivation and biofilm formation. Wastewater treatment: Adjust the pH of the wastewater to 7.0-8.5 and the temperature to 25-35℃, then introduce it into the reactor. Use the hydrogen produced by the iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically turned off and the denitrification mode is entered; when it is less than 0.2%, the aeration is turned on and the nitrification mode is entered. The biofilm formed in the reactor continuously degrades ammonia nitrogen, completing the ammonia removal treatment.

[0033] Comparative Example 2 Comparative Example 2 provides a biological ammonia removal process based on iron-carbon coupling, comprising the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing material from Preparation Example 1 was loaded into the reactor; The iron-reducing bacterial solution from Preparation Example 4 was pumped into the reactor, aeration and stirring were turned off, and the solution was allowed to stand at 30°C for 4 hours for adsorption. Start the circulation pump. For the first 1-3 days, maintain the temperature at 30℃, pH at 7.0, DO < 0.2 mg / L, and circulation flow rate at 0.5 m / h. For the next 4-10 days, gradually increase the influent ammonia nitrogen from 50 mg / L to 200 mg / L, and aerate intermittently for 20 minutes every 4 hours to complete the cultivation and biofilm formation. Wastewater treatment: Adjust the pH of the wastewater to 7.0-8.5 and the temperature to 25-35℃, then introduce it into the reactor. Use the hydrogen produced by the iron-carbon reaction as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically turned off and the denitrification mode is entered; when it is less than 0.2%, the aeration is turned on and the nitrification mode is entered. The biofilm formed in the reactor continuously degrades ammonia nitrogen, completing the ammonia removal treatment. Performance testing experiment

[0034] Continuous treatment effect: The ammonia nitrogen removal rate of each treatment process in each embodiment and comparative example was tested after 30 days of continuous wastewater treatment.

[0035] Table 1. Performance test results of wastewater

[0036] Combining Example 1 and Comparative Examples 1-2, the treatment process in Example 1 still maintained a high ammonia nitrogen removal rate after 30 days. This demonstrates that when treating wastewater, the implantation of a sulfur autotrophic bacteria-iron reducing bacteria composite microbial community forms a double-layer biofilm on the packing surface. The outer layer of sulfur bacteria utilizes the sulfate generated by the iron-carbon reaction for autotrophic deammoniation, while the inner layer of iron reducing bacteria regenerates ferrous ions, forming a closed material cycle chain and reducing sludge production. The sandwich-structured iron-carbon composite packing forms a stable electron transport network, allowing electrons generated by iron corrosion to directly act on the biofilm. Furthermore, the hydrogen gas generated by the iron-carbon reaction is used as a signal source to achieve the switching between denitrification and nitrification, reducing power consumption. Through self-powered electron transport and a symbiotic microbial system, ammonia nitrogen removal is achieved without the need for an external carbon source, thus achieving continuous and efficient ammonia nitrogen degradation of wastewater.

[0037] Based on Examples 1-3, it can be seen that the wastewater treatment effect is better when treated according to the treatment conditions in Examples 1-3.

[0038] Combining Examples 2, 4, and 5, it can be seen that when preparing sandwich-structured iron-carbon composite fillers, the iron powder layer is prepared according to the raw material ratio in Examples 1-3, resulting in sandwich-structured iron-carbon composite fillers with better performance.

[0039] Based on Examples 4, 6 and 7, it can be seen that when the weight ratio of iron-reducing bacterial solution to sulfur-autotrophic bacterial solution is (30-40):(60-70) when preparing the composite bacterial solution, the final composite membrane has a better treatment effect on wastewater.

[0040] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A biological deammoniation treatment process based on iron-carbon coupling, characterized in that: Includes the following steps: Pretreatment: The sandwich-structured iron-carbon composite packing is loaded into the reactor; then, iron-reducing bacteria solution and sulfur autotrophic bacteria solution are circulated to contact the surface of the packing to cultivate and form a composite membrane; the sandwich-structured iron-carbon composite packing includes two conductive mesh layers and an iron powder layer set between the two mesh layers. Wastewater treatment: The pH and temperature of the wastewater are adjusted, and then the wastewater is introduced into the reactor. The hydrogen produced by the iron-carbon reaction is used as a signal source: when the hydrogen concentration is greater than 0.5%, the aeration is automatically turned off and the denitrification mode is entered; when it is less than 0.2%, the aeration is turned on and the nitrification mode is entered. The composite membrane formed in the reactor continuously degrades ammonia nitrogen and completes the ammonia removal treatment.

2. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 1, characterized in that: The conductive mesh layer comprises a conductive activated carbon fiber mesh with a pore size of 5-10 micrometers.

3. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 2, characterized in that: The raw materials of the iron powder layer include the following components in parts by weight: 75-80 parts iron powder, 5-8 parts micron-sized copper powder, 2-4 parts micron-sized nickel powder, and 3-5 parts nano-manganese dioxide.

4. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 3, characterized in that: The preparation method of the sandwich-structured iron-carbon composite filler includes the following steps: Iron powder, micron-sized copper powder, micron-sized nickel powder, and nano-manganese dioxide are stirred and mixed evenly to obtain a mixed powder. Then, PVA aqueous solution is added, stirred and mixed evenly, and dried to obtain granules. The granules are added to a mold and pressed at room temperature to obtain a pressed material; then, under nitrogen protection, the material is first degreased at 300-500℃ and then sintered at 600-750℃ to obtain an iron powder layer. By combining the iron powder layer with the conductive mesh layer and hot-pressing, a sandwich-structured iron-carbon composite filler is obtained.

5. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 1, characterized in that: The pretreatment step, specifically the method for cultivating biofilm formation, includes the following steps: Pump the iron-reducing bacteria solution into the reactor, turn off aeration and stirring, and let it stand at 30°C for 4-6 hours for adsorption. Mix the iron-reducing bacterial solution and the sulfur-autotrophic bacterial solution, place them in a shaker at 30℃, and culture them at a low speed of 80 rpm for 3-5 days to obtain a composite bacterial solution. Pump the solution into the reactor, turn on the circulation pump, and circulate it at a flow rate of 0.2-0.5 m / h for 12-24 hours. Then stop the circulation and seal the reactor. Start the circulation pump. For days 1-3, control the temperature at 30±2℃, pH at 7.0-7.5, DO < 0.2mg / L, and circulation flow rate at 0.5m / h. For days 4-10, gradually increase the influent ammonia nitrogen from 50mg / L to 200mg / L, and aerate intermittently for 20min every 4h to complete the culture and biofilm formation.

6. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 5, characterized in that: The weight ratio of iron-reducing bacterial solution to sulfur-autotrophic bacterial solution in the compound bacterial solution is (30-40):(60-70).

7. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 5, characterized in that: The iron-reducing bacteria solution is obtained by culturing iron-reducing bacteria in an iron-reducing bacteria culture medium. Each liter of the iron-reducing bacteria culture medium contains the following components: NaHCO3: 2g, CH3COONa: 0.8g, NH4Cl: 0.3g, KH2PO4: 0.2g, MgCl2: 0.1g, Fe(OH)3 colloid: 10g, and trace element solution: 1mL; the volume fraction of iron-reducing bacteria in the iron-reducing bacteria culture medium is 5-10%.

8. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 5, characterized in that: The sulfur autotrophic bacteria solution is obtained by culturing sulfur autotrophic bacteria in a sulfur autotrophic bacteria culture medium. Each liter of the sulfur autotrophic bacteria solution contains the following components: Na2S2O3·5H2O: 2.5g, NaHCO3: 1.5g, NH4Cl: 0.5g, KH2PO4: 0.5g, MgSO4·7H2O: 0.2g, and trace element solution: 1mL; the volume fraction of sulfur autotrophic bacteria in the sulfur autotrophic bacteria culture medium is 5-10%.

9. The biological deammoniation treatment process based on iron-carbon coupling method according to claim 8, characterized in that: Each liter of the trace element solution contains the following components: FeCl3·6H2O: 0.25g, ZnSO4·7H2O: 0.22g, CoCl2·6H2O: 0.24g, MnSO4·H2O: 0.23g, Na2MoO4·2H2O: 0.22g, NiCl2·6H2O: 0.21g, CuSO4·5H2O: 0.08g.

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