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

Abstract

The invention discloses a device and a method for cooperatively treating domestic sewage and nitrate wastewater by coupling heterotrophic denitrification and sulfur autotrophic denitrification with anaerobic ammonia oxidation, and belongs to the field of biological denitrification of sewage. The device comprises a water inlet tank, a sequencing batch reactor (SBR), a peristaltic pump, a drain valve, a water outlet tank and the like. The method comprises the following steps: (1) adding sulfur particles into a first SBR (Sequencing Batch Reactor), introducing nitrate wastewater and domestic sewage into the SBR, converting nitrate nitrogen into nitrogen through sulfur autotrophic denitrification under an anaerobic condition, and reducing the nitrate nitrogen into nitrite nitrogen when COD (Chemical Oxygen Demand) comes from the domestic sewage; and (2) adjusting the proportion of ammonia nitrogen and nitrite in the effluent of the first SBR, and stably removing ammonia nitrogen and nitrite through anaerobic ammonia oxidation. In the two-stage system, 100% of aeration and external carbon sources are saved, and a new thought is provided for synergistic denitrification of pure autotrophic systems of industrial wastewater and domestic sewage.

Description

Technical Field

[0001] The invention relates to a device for synergistically treating nitrate wastewater by coupling heterotrophic denitrification with sulfur autotrophic denitrification and anaerobic ammonia oxidation, and uses heterotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria to synergistically achieve biological denitrification of domestic sewage and nitrate wastewater, belonging to the field of biological sewage treatment. Background Art

[0002] With the acceleration of industrialization, the amount of sewage treatment is increasing. The rapid development of light pharmaceutical, petrochemical and other industries has caused many industrial wastewaters to contain nitrogen pollutants (mainly nitrate nitrogen) and sulfur compounds (mainly sulfate). However, the pollutant emission standards are becoming more and more stringent, and traditional sewage treatment methods are difficult to meet the technical requirements of standard emissions. - As a water pollutant, NO3 poses a serious threat to human health. - The removal methods are generally biological denitrification, ion membrane exchange and reverse osmosis. How to treat the above pollutants before wastewater discharge is a very urgent issue.

[0003] Biological denitrification has always been considered the most economical and effective way to remove nitrogen. However, the traditional biological denitrification process requires organic matter as a carbon source, which increases the cost of dosing. At the same time, traditional biological denitrification has the defects of high alkalinity and sludge production. In recent years, there have been many studies on the sulfur autotrophic denitrification process using sulfur sources (such as elemental sulfur) as electron donors at home and abroad. The sulfur autotrophic denitrification process using elemental sulfur as an electron donor refers to the process in which sulfur autotrophic denitrifying bacteria (such as denitrifying sulfur bacteria, etc.) use elemental sulfur as an electron donor to produce NO3 under anaerobic or anoxic conditions. - 、NO2 - Compared with heterotrophic denitrification, sulfur autotrophic denitrification, which is reduced to N2 and uses elemental sulfur as an electron acceptor, does not require an external carbon source, greatly reduces treatment costs and sludge production, and also reduces greenhouse gas emissions, which greatly reduces investment and operating costs.

[0004] Domestic sewage contains a large amount of ammonia nitrogen, which is used as a substrate for anaerobic ammonium oxidation. The carbon source for short-range denitrification comes from the organic carbon source in domestic sewage, which supplements the deficiency of nitrite, another substrate for anaerobic ammonium oxidation. At the same time, the nitrate nitrogen produced by the anaerobic ammonium oxidation process can be removed synchronously by heterotrophic short-range denitrification and sulfur autotrophic denitrification, thereby improving the denitrification efficiency. The reaction formula involved in the present invention is as follows:

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

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

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

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

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

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

[0011] Since the sulfur autotrophic denitrification process requires a large amount of alkalinity to maintain the pH balance of the denitrification system, in order to solve the above problem, the present invention couples heterotrophic and sulfur autotrophic denitrification to synergistically denitrify, which has the following advantages:

[0012] ① The present invention realizes the simultaneous denitrification of domestic sewage and nitrate wastewater.

[0013] The deep denitrification of nitrate wastewater and domestic sewage is achieved through a two-stage process of sulfur autotrophic denitrification and heterotrophic denitrification coupled with anaerobic ammonia oxidation, providing a new solution for treating actual wastewater with low C / N ratio.

[0014] ② The sulfur autotrophic reactor of the present invention realizes the rapid enrichment of sulfur-oxidizing bacteria in common residual sludge by adding sulfur, and the autotrophic and heterotrophic denitrifying bacteria realize the efficient removal of nitrate in wastewater.

[0015] ③The present invention provides a new idea for the nitrite substrate supply pathway for anaerobic ammonium oxidation.

[0016] Domestic sewage provides an organic carbon source for short-term denitrification, which converts the nitrate in the influent into nitrite and effectively retains it, providing sufficient nitrite substrate for anaerobic ammonium oxidation, and providing new ideas for solving the major problem of insufficient nitrite supply in mainstream anaerobic ammonium oxidation engineering applications.

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

[0018] The present invention mainly utilizes sulfur autotrophic denitrification and heterotrophic denitrification coupled with anaerobic ammonia oxidation to synchronously treat nitrate wastewater and domestic sewage. In the biological denitrification process, the carbon source of heterotrophic denitrification comes from domestic sewage, which can treat waste with waste and save the cost of adding carbon source.

[0019] ⑤ The biomass yield in the present invention is low, which minimizes the subsequent sludge treatment cost.

[0020] Sulfur autotrophic denitrification bacteria and anaerobic ammonia oxidizing bacteria are both chemoautotrophic bacteria with low growth rate, long doubling time 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- of production. Summary of the invention

[0023] The present invention provides a device and method for synergistically treating domestic sewage and nitrate wastewater by coupling heterotrophic denitrification with sulfur autotrophic denitrification and anaerobic ammonia oxidation. The synergistic denitrification of nitrate wastewater and urban domestic sewage is achieved through a two-stage process of heterotrophic denitrification with sulfur autotrophic denitrification and anaerobic ammonia oxidation.

[0024] The method of heterotrophic and sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation to synergistically treat domestic sewage and nitrate wastewater proposes the introduction of urban domestic sewage to provide a carbon source for heterotrophic denitrification. Heterotrophic denitrification and sulfur autotrophic denitrification can achieve acid-base complementarity in the process of treating nitrate wastewater. Most of the NO3 - Reduced to N2 and a small amount of NO3 - Reduced to NO2 due to insufficient carbon source - It provides substrate for anaerobic ammonium oxidation reaction, and ammonia nitrogen and nitrite then enter the anaerobic ammonium oxidation reactor to undergo anaerobic ammonium oxidation reaction, achieving the simultaneous removal of ammonia nitrogen and nitrite nitrogen.

[0025] To achieve the above objectives, the present invention adopts the following technical scheme to quickly realize the synergistic treatment of nitrate nitrogen wastewater and domestic sewage by coupling heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation:

[0026] The present invention is a device for treating domestic sewage and nitrate wastewater by coupling heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation, comprising:

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

[0028] In the present invention, a device for synergistically treating domestic sewage and nitrate wastewater by coupling heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation comprises the following steps:

[0029] (1) Reactor startup phase: The first SBR was inoculated with residual sludge, and the MLSS was maintained at 3000-4000 mg / L. Sulfur was added to the reactor at one time, with a filling ratio of 10%-15% by volume, to construct a sulfur autotrophic denitrification system; the second SBR was inoculated with anaerobic ammonium oxidation granular sludge with an average particle size greater than 200 μm, and the MLSS was maintained at 2000-3000 mg / L.

[0030] (2) Reactor operation stage: Nitrate wastewater and domestic sewage are mixed in the intermediate water tank (3) and pumped into the first SBR (4) through the first peristaltic pump (4.1). The hydraulic retention time of the reactor is 12 hours. The specific operation parameters are: 10 minutes for inlet and outlet water, 10 hours of anoxic stirring, 40 minutes of sedimentation, and 1 hour of idleness. The reaction is operated 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 the sulfur autotrophic denitrification reaction, and the C / N is controlled at 2.0. The COD in the domestic sewage provides an organic carbon source for biological short-term 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 maintain the stability of the internal pH of the system through the coupling of sulfur autotrophic denitrification and denitrification. The effluent of the first SBR (4) is mainly composed of nitrite nitrogen and ammonia nitrogen that has not been removed from domestic sewage. The effluent of the first SBR (4) enters the first outlet tank (5) through the first drain valve (4.3), and the mass concentration ratio of ammonia nitrogen:nitrite nitrogen in the water tank is adjusted to 1:1.32-1.5. The effluent is 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 operation mode is: water inlet and outlet for 10 minutes, anoxic stirring for 6 hours, sedimentation for 40 minutes, idle for 1 hour, the reaction temperature is controlled at 30±5°C, 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 anaerobic ammonia oxidation reaction can achieve stable removal of ammonia nitrogen in domestic sewage. The effluent of the second SBR (6) is discharged to the second outlet tank (7) through the second drain valve (6.5).

[0031] The device and method for synergistically treating nitrate nitrogen wastewater and domestic sewage by coupling heterotrophic and sulfur autotrophic denitrification with anaerobic ammonia oxidation can provide an organic carbon source for denitrification by utilizing COD in domestic sewage, and cultivate a symbiotic system of sulfur autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria, which not only saves costs but also provides sufficient substrate for the anaerobic ammonia oxidation process. The entire system can achieve the synchronous removal of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0033] (1) Nitrate wastewater tank (2) Domestic sewage tank (3) Intermediate water 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 It is the basic operating mode of the anaerobic sequencing batch reactor. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings and examples:

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

[0037] (1) nitrate wastewater tank (2) domestic sewage tank (3) intermediate water tank (4) first SBR (4.1) first peristaltic pump (4.2) stirring device (4.3) first drain valve (5) first water 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 water outlet tank.

[0038] 1. Start-up and operation of the first SBR

[0039] The first SBR (4) is inoculated with ordinary residual sludge, and the MLSS is maintained at 3000-4000 mg / L. It is operated anaerobically for 2 cycles per day, with a hydraulic retention time of 12 hours and an SBR discharge ratio of 50%. The nitrate nitrogen concentration in the nitrate wastewater is controlled at 200-300 mgN / L by adding nitrate to the water, and is pumped into the SBR (4) through the first peristaltic pump (4.1). Sulfur particles are added to the reactor with a particle size of 1-3 mm and a filling volume ratio of 10%-15%. The pH is not controlled during the reaction process, and the reaction is operated at room temperature. When the nitrate nitrogen removal rate is stabilized at more than 80%, it indicates that the sulfur autotrophic denitrification system is successfully started; the nitrate wastewater and domestic sewage are mixed and pumped into the SBR (4) through a peristaltic pump (4.1). The COD concentration of the domestic sewage is 160-200 mg / L, and C / N is adjusted to 2.0. When NO2 is detected in the effluent - When the nitrite accumulation rate is greater than 15 mg / L and is maintained above 50%, the reactor is considered to have been successfully started. After successful startup, it continues to operate stably and the main pollutant is NO2 - and NH4 + The outflowing water is discharged into the first water outlet tank (5) through the first drainage valve (4.3) for standby use.

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

[0041] The second SBR (6) was inoculated with anaerobic ammonium oxidation granular sludge with an average particle size greater than 200 μm, and the MLSS was maintained at 2000-3000 mg / L. During the startup phase, artificial synthetic wastewater was used as the influent. The specific influent water quality components and contents 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 (CaCl2·2H20, 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 detected in the SBR effluent is lower than 5 mgN / L, the concentration of nitrite detected is lower than 1 mgN / L and the second SBR is considered to be successfully started after stable operation for 15 days. After successful startup, 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 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℃, the temperature is monitored by the temperature detection system (6.4), the pH is maintained at 7.0-7.5, and when the pH exceeds the range value, it is adjusted by adding hydrochloric acid or sodium hydroxide solution, and the pH is monitored in real time by the pH online monitoring device (6.3). The reactor realizes the simultaneous removal of ammonia nitrogen and nitrite nitrogen. At the same time, the effluent of the second SBR is discharged to the second outlet tank (7) through the second drain valve (6.5).

[0043] In the present invention, the domestic sewage introduced after the first SBR is successfully started is the domestic sewage of a certain community, and the raw water quality is as follows: the ammonia nitrogen concentration is 50-60 mg / L, the mass concentrations of nitrite nitrogen and nitrate nitrogen are both lower than 1 mgN / L, and the COD is 160-200 mg / L. The effluent can meet the national Class A discharge standard.

Claims

1. A device for synergistically treating domestic sewage and nitrate wastewater by coupling heterotrophic denitrification with sulfur autotrophic denitrification and anaerobic ammonia oxidation, characterized in that: The invention comprises a nitrate wastewater tank (1) and a domestic sewage tank (2) which are mixed in an intermediate water tank (3) through a first peristaltic pump (4.1) and enter a first SBR (4) reactor which is provided with a stirring device (4.2); the first SBR (4) is connected to a first outlet water tank (5) through a first drain valve (4.3); the first outlet water tank (5) enters a second SBR (6) reactor which is provided with a stirring device (6.2) and a pH online monitoring device system (6.3); the temperature of the SBR is monitored through a temperature detection system (6.4); and the outlet water is discharged to a second outlet water tank (7) through a second drain valve (6.5).

2. A method for applying the device as claimed in claim 1, characterized in that include: (1) Reactor startup phase: The first SBR is inoculated with residual sludge, and the MLSS is maintained at 3000-4000 mg / L. Sulfur is added to the reactor at a one-time rate, with a filling volume ratio of 10%-15%, to construct a sulfur autotrophic denitrification system. When the nitrate nitrogen removal rate is stabilized at more than 80%, the reactor is successfully started; the second SBR is inoculated with anaerobic ammonium oxidation granular sludge with an average particle size greater than 200 μm, and the MLSS is maintained at 2000-3000 mg / L; (2) Reactor operation stage: after mixing nitrate wastewater with a concentration of 200-300 mgN / L and domestic sewage with a COD concentration of 160-200 mg / L in the intermediate water tank (3), the mixture is pumped into the first SBR (4) through the first peristaltic pump (4.1). The reactor is operated for 12 hours per cycle. The specific operation parameters are: 10 minutes for inlet and outlet water, 10 hours for anoxic stirring, 40 minutes for sedimentation, 1 hour for idleness, pH is not controlled during the whole process, and the reaction is operated at room temperature. 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 C / N is adjusted to 2.

0. The nitrite accumulation rate of the effluent is maintained at more than 50%, and the nitrate nitrogen is reduced to nitrite nitrogen. The effluent of the first SBR (4) is Water enters the first water outlet tank (5) through the first drain valve (4.3), and the mass concentration ratio of ammonia nitrogen:nitrite nitrogen in the water tank is adjusted to 1:1.32-1.

5. The water is 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 parameters are: water inlet and outlet for 10 minutes, anoxic stirring for 6 hours, precipitation for 40 minutes, idle for 1 hour, pH maintained at 7.0-7.5, when the pH exceeds the range value, it is adjusted by adding hydrochloric acid or sodium hydroxide solution, and the pH is monitored by the online monitoring system (6.3). The temperature is controlled at 30±5°C and the temperature is monitored by the temperature detection system (6.4). The outlet water of the second SBR (6) is discharged to the second water outlet tank (7) through the second drain valve (6.5).

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