Device and method for synergistically treating domestic sewage and nitrate wastewater by heterotrophic denitrification and sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation

Abstract

The device and method for treating domestic sewage and nitrate wastewater by coupling heterotrophic denitrification and sulfur autotrophic denitrification with anaerobic ammonia oxidation belong to the field of biological denitrification of wastewater.The device comprises a water inlet tank, a sequencing batch reactor (SBR), a peristaltic pump, a water outlet valve, a water outlet tank and the like.The steps of the application include: (1) adding sulfur particles into the first SBR, introducing the nitrate wastewater and domestic sewage into the SBR, and converting the nitrate nitrogen into nitrogen gas under anaerobic conditions through sulfur autotrophic denitrification, so that the nitrate nitrogen is reduced to nitrite nitrogen, and the COD is from the domestic sewage; (2) adjusting the proportion of ammonia nitrogen and nitrite in the effluent of the first SBR, and realizing the stable removal of ammonia nitrogen and nitrite through anaerobic ammonia oxidation.In the two-stage system, 100% of the aeration and external carbon source are saved, and a new idea is provided for the pure autotrophic system for the synergistic denitrification of industrial wastewater and domestic sewage.

Description

Technical Field

[0001] This invention relates to an apparatus for the synergistic treatment of nitrate wastewater by coupling heterotrophic denitrification and sulfur autotrophic denitrification with anaerobic ammonia oxidation. It utilizes heterotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria to achieve biological denitrification of domestic sewage and nitrate wastewater, and belongs to the field of biological wastewater treatment. Background Technology

[0002] With the acceleration of industrialization, the volume of wastewater requiring treatment is constantly increasing. The rapid development of industries such as light pharmaceuticals and petrochemicals has resulted in a large amount of industrial wastewater containing nitrogenous pollutants (mainly nitrate nitrogen) and sulfur-containing compounds (mainly sulfates). Meanwhile, emission standards for these pollutants are becoming increasingly stringent, and traditional wastewater treatment methods are struggling to meet the technical requirements for achieving these standards. - As a water pollutant, NO3 poses a serious threat to human health. - The removal methods generally include biological denitrification, ion-exchange membrane exchange, and reverse osmosis. How to treat these pollutants before wastewater discharge is a very urgent issue.

[0003] Biological denitrification has long been considered the most economical and efficient nitrogen removal method. However, traditional biological denitrification processes require organic matter as a carbon source, increasing the cost of chemical dosing. Furthermore, traditional biological denitrification suffers from drawbacks such as high alkalinity and high sludge production. In recent years, sulfur autotrophic denitrification processes using sulfur sources (such as elemental sulfur) as electron donors have been extensively studied both domestically and internationally. Sulfur autotrophic denitrification processes using elemental sulfur as electron donors refer to processes where, under anaerobic or anoxic conditions, sulfur autotrophic denitrifying bacteria (such as denitrifying thiobacilli) use elemental sulfur as the electron donor for NO3. - NO2 - Compared to heterotrophic denitrification, sulfur autotrophic denitrification, which uses elemental sulfur as an electron acceptor, does not require an external carbon source, significantly reducing treatment costs and sludge production, and also reducing greenhouse gas emissions. This greatly reduces investment and operating costs.

[0004] Domestic sewage contains a large amount of ammonia nitrogen. Ammonia nitrogen serves as the substrate for anaerobic ammonium oxidation (ANAO). The carbon source for short-cut denitrification comes from the organic carbon source in domestic sewage, supplementing the lack of nitrite, another substrate in ANAO. Simultaneously, the nitrate nitrogen produced during ANAO can be removed simultaneously through heterotrophic short-cut denitrification and sulfur autotrophic denitrification, improving nitrogen removal efficiency. The reaction formula involved in this invention is as follows:

[0005] (1) The heterotrophic denitrification reaction formula is as follows:

[0006] 0.625CH3COO - +1NO3 - +0.375H + →1.25HCO3 - +0.5N2+0.5H2O

[0007] (2) The sulfur autotrophic denitrification reaction formula is as follows:

[0008] 55S+50NO3 - +38H2O+20CO2+4NH4 + →4C5H7O2N+25N2+55SO4 2- +64H +

[0009] (3) The anaerobic ammonium oxidation reaction formula is as follows:

[0010] NH4 + +1.32NO2 - +0.066HCO3 - +0.13H + →1.02N2+0.26NO3 - +0.066CH2N 0.15 +2.03H2O

[0011] Because sulfur autotrophic denitrification requires a large amount of alkalinity to maintain the pH balance of the denitrification system, this invention addresses the aforementioned problem by coupling heterotrophic and sulfur autotrophic denitrification for synergistic nitrogen removal, offering the following advantages:

[0012] ①This invention achieves simultaneous denitrification of domestic sewage and nitrate wastewater.

[0013] A two-stage process combining sulfur autotrophic denitrification and heterotrophic denitrification coupled with anaerobic ammonia oxidation was used to achieve deep denitrification of nitrate wastewater and domestic sewage, providing a new solution for treating practical wastewater with low C / N ratios.

[0014] ②The sulfur autotrophic reactor of the present invention achieves rapid enrichment of sulfur-oxidizing bacteria in ordinary residual sludge by adding elemental sulfur, and achieves efficient removal of nitrates from wastewater by autotrophic and heterotrophic denitrifying bacteria.

[0015] ③This invention provides a new approach to the supply of nitrite substrates for anaerobic ammonia oxidation.

[0016] Domestic sewage provides an organic carbon source for short-cut denitrification, which converts nitrates in the influent into nitrites and retains them effectively, providing a sufficient nitrite matrix for anaerobic ammonium oxidation. This offers a new approach to addressing the major problem of insufficient nitrite supply in mainstream anaerobic ammonium oxidation engineering applications.

[0017] ④ This invention does not require an external carbon source, which can reduce the cost of the denitrification process.

[0018] This invention mainly utilizes sulfur autotrophic denitrification and heterotrophic denitrification coupled with anaerobic ammonia oxidation to simultaneously treat nitrate wastewater and domestic sewage. In the biological denitrification process, the carbon source for heterotrophic denitrification comes from domestic sewage, thus treating waste with waste and saving the cost of adding carbon source.

[0019] ⑤ The low biomass yield in this invention minimizes the cost of subsequent sludge treatment.

[0020] Both sulfur-autotrophic denitrifying bacteria and anaerobic ammonia-oxidizing bacteria are chemoautotrophic bacteria with low growth rates, long doubling times, and low sludge production.

[0021] ⑥ No additional pH adjustment is required, saving operating costs.

[0022] The alkali produced by heterotrophic denitrification and the acid produced by sulfur autotrophic denitrification achieve acid-base complementarity, which can reduce SO4 in sulfur autotrophic denitrification. 2- . production. Summary of the Invention

[0023] This invention provides an apparatus and method for the synergistic treatment of domestic sewage and nitrate wastewater by coupling heterotrophic denitrification and sulfur autotrophic denitrification with anaerobic ammonia oxidation. The two-stage process of coupling heterotrophic denitrification and sulfur autotrophic denitrification with anaerobic ammonia oxidation achieves synergistic denitrification of nitrate wastewater and urban domestic sewage.

[0024] A method for the synergistic treatment of domestic sewage and nitrate wastewater by coupling heterotrophic and sulfur autotrophic denitrification with anaerobic ammonium oxidation is proposed. This method introduces domestic sewage as a carbon source for heterotrophic denitrification, and the heterotrophic and sulfur autotrophic denitrification processes can achieve acid-base complementarity during the treatment of nitrate wastewater, thereby controlling most of the NO3- produced during the process. - It is reduced to N2, with a small amount of NO3. - Due to insufficient carbon source, it is reduced to NO2. - It provides a substrate for the anaerobic ammonia oxidation reaction, and ammonia nitrogen and nitrite then enter the anaerobic ammonia oxidation reactor to undergo anaerobic ammonia oxidation, achieving the simultaneous removal of ammonia nitrogen and nitrite nitrogen.

[0025] To achieve the above objectives, the present invention employs the following technical solution to rapidly realize the synergistic treatment of nitrate wastewater and domestic sewage through heterotrophic and sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation:

[0026] This invention relates to a device for the synergistic treatment of domestic sewage and nitrate wastewater using heterotrophic and sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation, comprising:

[0027] The nitrate wastewater tank (1) and the domestic sewage tank (2) are mixed in the intermediate tank (3) and enter the first SBR (4) through the first peristaltic pump (4.1). The reactor is equipped with a stirring device (4.2). The first SBR (4) is connected to the first effluent tank (5) through the first drain valve (4.3). The first effluent tank (5) enters the second SBR (6) through the second peristaltic pump (6.1). The reactor is equipped with a stirring device (6.2) and a pH online monitoring device system (6.3). The reactor temperature is monitored by the temperature detection system (6.4). The effluent is discharged to the second effluent tank (7) through the second drain valve (6.5).

[0028] The apparatus for the synergistic treatment of domestic sewage and nitrate wastewater by coupled heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation in this invention includes the following steps:

[0029] (1) Reactor start-up stage: The first SBR is inoculated with excess sludge, and the MLSS is maintained at 3000-4000 mg / L. Elemental sulfur is added to the reactor in one go, and the filling volume is 10%-15% to build a sulfur autotrophic denitrification system. The second SBR is inoculated with anaerobic ammonia oxidation granular sludge with an average particle size greater than 200 micrometers, and the MLSS is maintained at 2000-3000 mg / L.

[0030] (2) Reactor operation stage: Nitrate wastewater and domestic sewage are mixed in the intermediate tank (3) and then pumped into the first SBR (4) through the first peristaltic pump (4.1). The hydraulic retention time of the reactor is 12h. The specific operating parameters are: 10min for influent and effluent, 10h for anoxic stirring, 40min for sedimentation, and 1h for idle. The reaction is carried out at room temperature and the pH is not controlled throughout the process. After the mixed wastewater enters the first SBR (4), the nitrate nitrogen in the water is reduced to nitrogen gas through sulfur autotrophic denitrification reaction, and the C / N ratio is controlled at 2.0. The COD in the domestic sewage provides an organic carbon source for biological short-cut denitrification, and the nitrate nitrogen is reduced to nitrite nitrogen. The addition of domestic sewage not only provides a carbon source for the heterotrophic denitrification system, but also helps to maintain the stability of the pH inside the system through the coupling of sulfur autotrophic denitrification and denitrification. The effluent from the first SBR (4) mainly consists of nitrite nitrogen and ammonia nitrogen that has not been removed from domestic sewage. The effluent from the first SBR (4) enters the first effluent tank (5) through the first drain valve (4.3). The mass concentration ratio of ammonia nitrogen to nitrite nitrogen in the tank is adjusted to 1:1.32-1.5. The effluent is then pumped into the second SBR (6) through the second peristaltic pump (6.1). The hydraulic retention time of the reactor is 8 hours. The specific operating mode is as follows: 10 minutes for influent and effluent, 6 hours for anoxic stirring, 40 minutes for sedimentation, and 1 hour for idle. The reaction temperature is controlled at 30±5℃, and the pH is maintained at 7.0-7.5. The temperature is monitored by the temperature detection system (6.4), and the pH is monitored by the online monitoring system (6.3). The stable removal of ammonia nitrogen from domestic sewage can be achieved through anaerobic ammonia oxidation. The effluent from the second SBR (6) is discharged to the second effluent tank (7) through the second drain valve (6.5).

[0031] This invention provides an apparatus and method for the synergistic treatment of nitrate nitrogen wastewater and domestic sewage through heterotrophic and sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation. By utilizing the COD in domestic sewage as an organic carbon source for denitrification, a symbiotic system of sulfur autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria is cultivated. This not only saves costs but also provides sufficient substrate for the anaerobic ammonia oxidation process. The entire system can achieve simultaneous removal of ammonia nitrogen, nitrate nitrogen, and nitrite nitrogen. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a device for the synergistic treatment of nitrate wastewater and domestic sewage by coupled heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation. The specific device components are as follows:

[0033] (1) Nitrate wastewater tank (2) Domestic sewage tank (3) Intermediate tank (4) First SBR (4.1) First peristaltic pump (4.2) Stirring device (4.3) First drain valve (5) First outlet tank (6) Second SBR (6.1) Second peristaltic pump (6.2) Stirring device (6.3) pH online monitoring device system (6.4) Temperature detection system (6.5) Second drain valve (7) Second outlet tank

[0034] Figure 2 This is the basic operating mode of an anaerobic sequencing batch reactor. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples:

[0036] like Figure 1 As shown, the reaction apparatus includes:

[0037] (1) Nitrate wastewater tank (2) Domestic sewage tank (3) Intermediate tank (4) First SBR (4.1) First peristaltic pump (4.2) Stirring device (4.3) First drain valve (5) First outlet tank (6) Second SBR (6.1) Second peristaltic pump (6.2) Stirring device (6.3) pH online monitoring device system (6.4) Temperature detection system (6.5) Second drain valve (7) Second outlet tank.

[0038] 1. Startup and operation of the first SBR

[0039] Ordinary excess sludge was inoculated into the first SBR (4), and the MLSS was maintained at 3000-4000 mg / L. It was operated anaerobically for two cycles per day with a hydraulic retention time of 12 h and an SBR effluent ratio of 50%. The nitrate nitrogen concentration in the nitrate wastewater was controlled at 200-300 mgN / L by adding nitrate feed water. The nitrate was pumped into the SBR (4) through the first peristaltic pump (4.1). Sulfur particles with a particle size of 1-3 mm were added to the reactor, and the filling volume was controlled at 10%-15%. The pH was not controlled during the reaction process, and the reaction was carried out at room temperature. When the nitrate nitrogen removal rate was stable above 80%, it indicated that the sulfur autotrophic denitrification system had been successfully started. The nitrate wastewater and domestic sewage were mixed and pumped into the SBR (4) through the peristaltic pump (4.1). The COD concentration of the domestic sewage was 160-200 mg / L, and the C / N ratio was adjusted to 2.0. When NO2 was detected in the effluent, the reaction was completed. - The reactor is considered successfully started when the nitrite concentration is greater than 15 mg / L and the nitrite accumulation rate remains above 50%. After successful start-up, it continues to operate stably, with NO2 as the main pollutant. - and NH4 + The water is discharged into the first outlet tank (5) through the first drain valve (4.3) for standby.

[0040] 2. Start-up and operation of the second SBR

[0041] In the second SBR (6), anaerobic ammonia oxidation granular sludge with an average particle size greater than 200 micrometers was inoculated, and the MLSS was maintained at 2000-3000 mg / L. During the start-up phase, artificially synthesized wastewater was used as the influent. The specific composition and content of the influent water included: ammonium chloride (NH4Cl, 80-85 mg / L), sodium nitrite (NaNO2, 100-105 mg / L), potassium dihydrogen phosphate (KH2PO4, 0.03 g / L), calcium chloride dihydrate (CaCl2·2H2O, 0.14 g / L), magnesium sulfate heptahydrate (MgSO4·7H2O, 0.14 g / L), and potassium bicarbonate (KHCO3, 0.5 g / L).

[0042] When the concentration of ammonia nitrogen in the SBR effluent is below 5 mg N / L and the concentration of nitrite is below 1 mg N / L, and the system has been running stably for 15 days, the second SBR is considered to have been successfully started. After successful start-up, the mass concentration of ammonia nitrogen and nitrite nitrogen in the effluent of the first SBR (5) is adjusted to 1:1.32-1.5, and then pumped into the second SBR (6) through the second peristaltic pump (6.1). The hydraulic retention time of the second SBR is 8 hours, the temperature is controlled at 30±5℃, and the temperature is monitored by the temperature detection system (6.4). The pH is maintained at 7.0-7.5. When the pH exceeds the range, it is adjusted by adding hydrochloric acid or sodium hydroxide solution. The pH is monitored in real time by the pH online monitoring device (6.3). The reactor achieves simultaneous removal of ammonia nitrogen and nitrite nitrogen. At the same time, the effluent of the second SBR is discharged to the second effluent tank (7) through the second drain valve (6.5).

[0043] In this invention, the domestic sewage introduced after the successful start-up of the first SBR is domestic sewage from a certain residential community. The raw water quality is as follows: ammonia nitrogen concentration 50-60 mg / L, nitrite nitrogen and nitrate nitrogen concentrations are both below 1 mgN / L, and COD is 160-200 mg / L. The effluent meets the national Class A discharge standard.

Claims

1. A method for the simultaneous treatment of domestic wastewater and nitrate wastewater by heterotrophic denitrification coupled with sulfur autotrophic denitrification and ANAMMOX, characterized in that: The apparatus used in this method includes a nitrate wastewater tank (1) and a domestic sewage tank (2). The nitrate wastewater in the nitrate wastewater tank (1) and the domestic sewage in the domestic sewage tank (2) are mixed in an intermediate tank (3). The intermediate tank (3) is connected to a first SBR (4) via a first peristaltic pump (4.1). The first SBR (4) is equipped with a first stirring device (4.2). The first SBR (4) is connected to a first outlet tank (5) via a first drain valve (4.3). The first outlet tank (5) is connected to a second SBR (6) via a second peristaltic pump (6.1). The second SBR (6) is equipped with a stirring device (6.2), a pH online monitoring system (6.3), and a temperature detection system (6.4). The temperature of the second SBR (6) is monitored by the temperature detection system (6.4). The effluent is discharged to the second outlet tank (7) via a second drain valve (6.5). The method includes: (1) Start-up stage: The first SBR is inoculated with excess sludge, and the MLSS is maintained at 3000-4000 mg / L. Elemental sulfur is added to the first SBR in one go, and the filling volume ratio is 10%-15% to construct a sulfur autotrophic denitrification denitrification system. When the nitrate nitrogen removal rate is stable at more than 80%, it indicates that the first SBR has been successfully started up. The second SBR is inoculated with anaerobic ammonia oxidation granular sludge with an average particle size greater than 200 micrometers, and the MLSS is maintained at 2000-3000 mg / L. (2) Operation phase: Nitrate wastewater with a concentration of 200-300 mgN / L and domestic sewage with a COD concentration of 160-200 mg / L are mixed in the intermediate water tank (3) and then pumped into the first SBR (4) through the first peristaltic pump (4.1). The first SBR runs for 12 hours per cycle. The specific operating parameters are: 10 min for each of influent and effluent, 10 h for anoxic stirring, 40 min for sedimentation, 1 h for idle, and no pH control throughout the process. The reaction is carried out under room temperature conditions. After the mixed wastewater enters the first SBR (4), the C / N ratio is adjusted to 2.

0. The nitrate nitrogen in the water is reduced to nitrogen gas through the sulfur autotrophic denitrification reaction. The nitrate nitrogen is reduced to nitrite nitrogen through the heterotrophic short-range denitrification reaction. The nitrite accumulation rate in the effluent is maintained above 50%. The effluent from the first SBR (4) enters the first effluent tank (5) through the first drain valve (4.3). The mass concentration ratio of ammonia nitrogen to nitrite nitrogen in the tank is adjusted to 1:1.32-1.

5. The effluent is then pumped into the second SBR (6) through the second peristaltic pump (6.1). The hydraulic retention time of the second SBR is 8 hours. The specific operating parameters are: 10 minutes for influent and effluent, 6 hours for anoxic stirring, 40 minutes for sedimentation, 1 hour for idle, and pH is maintained at 7.0-7.

5. When the pH exceeds the range, it is adjusted by adding hydrochloric acid or sodium hydroxide solution. The pH is monitored by the pH online monitoring system (6.3). The temperature is controlled at 30±5℃ and monitored by the temperature detection system (6.4). The effluent from the second SBR (6) is discharged to the second effluent tank (7) through the second drain valve (6.5).

Images