Sulfur disproportionation-mediated low-temperature high-efficiency low-carbon denitrification synchronous ammonium recovery method for sewage

Abstract

The invention discloses a sulfur disproportionation-mediated low-temperature high-efficiency low-carbon denitrification and synchronous ammonium recovery method for sewage, belongs to the field of sewage treatment, and aims to solve the problems that an existing autotroph denitrification process cannot adapt to water quality fluctuation and seasonal variation and is poor in engineering applicability. Polyculture denitrification and elemental sulfur disproportionation (SD) are used as an effective enhanced denitrification scheme and are applied to a low-temperature SDAD system of actual sewage. Sulfide and polysulfide generated in situ through elemental sulfur disproportionation reaction and low-concentration sodium acetate under the polyculture condition are used as supplementary electron donors, so that the denitrification rate is remarkably increased. The process of reducing dissimilatory nitrate into ammonium (DNRA) in the SD-MixBNR system is beneficial to emission reduction of greenhouse gases while realizing ammonium recovery. According to the method, the SD-MixBNR system can be promoted to be widely applied to actual engineering projects under the carbon neutralization background, and the stability and adaptability of the SD-MixBNR system in the face of various water quality fluctuations and seasonal changes are enhanced.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and specifically relates to a method for realizing low-temperature, high-efficiency, deep denitrification of sewage and simultaneous greenhouse gas emission reduction through sulfur disproportionation-mediated polyculture denitrification. Background Art

[0002] Nitrogen content is a key indicator of water quality. Efficient nitrogen removal in wastewater treatment plants (WWTPs) is essential to address nitrogen pollution and protect health. Nitrous oxide is a greenhouse gas with a global warming potential of about 300 times that of carbon dioxide. It accounts for about 3% of global emissions from WWTPs, becoming a significant carbon footprint. Although the traditional heterotrophic denitrification process (HD) is efficient and applicable, it is limited by the carbon source. Municipal sewage in some countries has a low carbon-nitrogen ratio, which requires additional carbon sources, which increases costs and carbon emissions. Therefore, autotrophic denitrification reactions using inorganic compounds as electron donors, such as sulfur-based autotrophic denitrification (SDAD), are gaining attention. SDAD simultaneously reduces nitrate or nitrite to nitrogen gas through the redox state of sulfur, does not require an exogenous carbon source, and can overcome the bottleneck of heterotrophic denitrification. SDAD has the ability to reduce greenhouse gas emissions such as carbon dioxide and nitrous oxide and reduce the injection of organic carbon sources (about 100%), and has been widely used in treating sewage with low C / N ratios. However, the rate of SDAD is severely restricted by the limited solubility of sulfur, which is only 5 μg or 0.16 μmol per liter at 25°C, which hinders the rapid growth of sulfur-utilizing microorganisms. In addition, in northern China, the sewage temperature drops to about 10°C in winter, resulting in the inhibition of microbial denitrification and failure to meet sewage discharge standards. Substantially improving the bioavailability of sulfur is the key to overcoming the technical barrier of low SDAD rates. In recent years, various strategies have been adopted, such as adding exogenous electron donors such as thiosulfate, sulfide, and organic compounds to improve the denitrification efficiency of SDAD biofilters. However, these methods inevitably affect the cost-effectiveness of SDAD.

[0003] The elemental sulfur disproportionation (SD) process may be a more promising approach. Elemental sulfur (S 0) can be converted into polysulfide forms that are more accessible to microorganisms during the SDAD process, thereby accelerating the denitrification rate. Previous studies have also reported that the presence of elemental sulfur disproportionation may improve the denitrification effect in SDAD systems and can be considered as a solution to achieve efficient denitrification. However, elemental sulfur disproportionation is generally considered to be an autotrophic and endothermic process. In practical applications, it remains unclear whether elemental sulfur disproportionating bacterial communities can survive and maintain efficient denitrification when faced with fluctuations in influent nitrate and organic matter loads and seasonal temperature changes, and the impact of elemental sulfur disproportionation on greenhouse gases. This information is crucial for evaluating the robustness and adaptability of the mixed-breeding biological denitrification (SD-MixBNR) process mediated by elemental sulfur disproportionation.

[0004] Patent CN114409096B discloses a method for coupling elemental sulfur disproportionation with sulfur autotrophic denitrification to achieve efficient deep denitrification of wastewater. Sulfur disproportionating bacteria and sulfur-oxidizing denitrifying bacteria are inoculated and enriched in a sulfur autotrophic denitrification bioreactor filled with elemental sulfur. The symbiotic and cooperative relationship between sulfur disproportionating bacteria and sulfur-oxidizing denitrifying bacteria is maintained by controlling the reaction conditions, so that the elemental sulfur in the sulfur autotrophic denitrification reactor is continuously converted into S through the sulfur disproportionation reaction.

[0005] Patent CN115124139B discloses a method for starting a sulfur autotrophic denitrification system in a low-temperature environment, wherein activated sludge is inoculated into a denitrification denitrification device; the inoculated activated sludge is internally circulated in the denitrification denitrification device; after the internal circulation is completed, the first nitrate nitrogen sewage is introduced into the denitrification denitrification device, and the first sulfur source is added to carry out the first stage of sulfur autotrophic denitrification acclimation; the second nitrate nitrogen sewage is introduced into the denitrification denitrification device, and the second sulfur source is added to carry out the second stage of sulfur autotrophic denitrification acclimation; the third nitrate nitrogen sewage is introduced into the denitrification denitrification device, and the third sulfur source is added to carry out the third stage of sulfur autotrophic denitrification acclimation, and then the startup procedure is terminated. This invention solves the problem that the sulfur autotrophic denitrification system in the prior art is difficult to start in a low-temperature environment and takes a long time. However, the system uses sulfur powder and sodium thiosulfate as sulfur sources, and the chemical properties of sodium thiosulfate are unstable and do not have economic benefits. Moreover, the nitrate nitrogen removal rate only reached 76% on the 58th day, which was not conducive to a quick start.

[0006] Therefore, the existing sulfur autotrophic denitrification (SDAD) process cannot adapt to the actual needs of low-carbon nitrogen removal from wastewater under water quality fluctuations and seasonal changes. Summary of the invention

[0007] In order to solve the problem that the existing sulfur autotrophic denitrification (SDAD) process cannot adapt to water quality fluctuations and seasonal changes, and has poor engineering applicability, the present invention uses mixed culture denitrification and elemental sulfur disproportionation (SD) as effective enhanced denitrification schemes and is applied to the low-temperature SDAD system of actual sewage. The present invention uses sulfides and polysulfides generated in situ by elemental sulfur disproportionation reaction, and low-concentration sodium acetate as a supplementary electron donor under mixed culture conditions, thereby significantly accelerating the denitrification rate. The dissimilatory nitrate reduction to ammonium (DNRA) process in the SD-MixBNR system is beneficial to greenhouse gas emission reduction while achieving ammonium recovery. The present invention can promote the SD-MixBNR system to be widely used in actual engineering projects under the background of carbon neutrality, and enhance the stability and adaptability in the face of various water quality fluctuations and seasonal changes.

[0008] The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation of the present invention is carried out according to the following steps:

[0009] 1. A circular porous plate (4) is arranged at the lower part of an upflow elemental sulfur bioreactor (1), the upper part of the circular porous plate (4) is a reaction zone, gravel is filled in the reaction zone to form a gravel layer (3), and a mixture of elemental sulfur and limestone is filled on the gravel layer (3) to form an elemental sulfur and limestone layer (2); sewage in a sewage container (5) is introduced into the reaction zone through the bottom of the upflow elemental sulfur bioreactor (1) in an upward flow manner, the exhaust port of an inert gas bag (6) is connected to the top of the sewage container (5), the denitrification gas product is discharged from the top exhaust port (7), and the sewage after the reaction is discharged from the top of the upflow elemental sulfur bioreactor (1);

[0010] 2. Domestication: placing the upflow elemental sulfur bioreactor (1) in an environment below 9-11°C, sending the influent of the secondary sedimentation tank of the sewage treatment plant from bottom to top into the upflow elemental sulfur bioreactor, and adding trace nutrients, alkali solution and nitrate to the upflow elemental sulfur bioreactor (1); and inoculating one or two of the sludge from the secondary sedimentation tank of the urban sewage treatment plant and the estuary sediment downstream of the sewage treatment plant into the upflow elemental sulfur bioreactor (1) to domesticate autotrophic sulfur-oxidizing denitrifying bacteria (a-soNRB), dissimilatory nitrate reducing ammonium (DNRA) bacteria, sulfur dismutation (SD) bacteria and psychrophilic bacteria; when the nitrate removal rate of the upflow elemental sulfur bioreactor (1) reaches more than 95% and sulfide is continuously produced, the domestication is successful;

[0011] 3. Continuous sewage treatment

[0012] In an anaerobic environment of 9-11°C, the sewage is continuously fed into an upflow elemental sulfur bioreactor to achieve sulfur disproportionation-mediated mixed culture denitrification, achieving low-temperature and efficient deep denitrification of sewage, simultaneous ammonium recovery and greenhouse gas emission reduction.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The sulfur disproportionation-mediated mixed biological denitrification (SD-MixBNR) process of the present invention achieves efficient denitrification under low temperature conditions based on the influent conditions of the secondary sedimentation tank of an actual sewage treatment plant. When the hydraulic retention time (HRT) is 1 hour and the nitrate nitrogen (NO 3 When the concentration of -N is 40 mg / L, the nitrate removal efficiency of SD-MixBNR is close to 100%; under low temperature conditions, the nitrate removal efficiency is about 4.59-11.58 times that of the traditional sulfur-based autotrophic denitrification (SDAD) process. The results of this study verify the feasibility of achieving efficient nitrate removal based on the SD-MixBNR process in low-temperature engineering applications, and provide valuable guidance for the operation of actual wastewater treatment plants in winter.

[0015] 2. In the traditional sulfur filling system, there is an active dissimilatory nitrate reduction to ammonium (DNRA) process. The ammonium production mediated by DNRA is considerable, and its contribution to the total bioconversion of nitrate is about 10%-40%. Different from previous studies, the polyculture conditions of the present invention not only did not increase, but also increased nitrous oxide (N 2 O) emissions were reduced by 64.14%-84.20%. This is due to the synergistic effect of the excess electron donors provided by the polyculture conditions and the DNRA process. In the context of carbon neutrality, it has significant potential for greenhouse gas emission reduction while achieving ammonium recovery in wastewater treatment plants.

[0016] 3. The present invention establishes the interaction mechanism of the core functional microorganisms involved in the conversion of nitrogen and sulfur in the SD-MixBNR system by comprehensive 16SrRNA amplicon sequencing, microbial network succession analysis and metagenomic analysis. The functional microbial reaction mechanism of the present invention is: sulfur disproportionate bacteria can produce sulfide, and sulfide can further react with elemental sulfur to generate polysulfide. The sulfide and polysulfide generated in the above process can be further used as electron donors by autotrophic sulfur-oxidizing denitrifying bacteria to gradually reduce nitrate to nitrogen gas. Moreover, sulfide and polysulfide are usually more bioavailable than elemental sulfur, so the denitrification rate is significantly accelerated. At the same time, psychrophilic bacteria (red bacteria) as electroactive microorganisms, after degrading organic matter to generate electrons, can transfer electrons to denitrifying bacteria by direct (nanowire) or indirect (quinone-based structure) mode, and autotrophic sulfur-oxidizing denitrifying bacteria use the electrons transferred by red bacteria to gradually reduce nitrate or nitrite to nitrogen gas under anaerobic conditions, thereby achieving low-temperature denitrification. On the other hand, nitrate can also be reduced to ammonium by DNRA bacteria. Since nitrous oxide is not an intermediate product in this step, ammonium recovery is achieved while reducing nitrogen oxide emissions, which is in line with the concept of carbon neutrality in sewage treatment plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of an upflow elemental sulfur bioreactor;

[0018] Figure 2 This is a diagram showing the denitrification effect at each operating stage of the upflow elemental sulfur bioreactor;

[0019] Figure 3 This is a test chart of microbial abundance in each operating stage of the upflow elemental sulfur bioreactor. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any reasonable combination of the specific implementation modes.

[0021] Specific implementation method 1: The method for low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery of sewage mediated by sulfur disproportionation in this implementation method is carried out according to the following steps:

[0022] 1. A circular porous plate (4) is arranged at the lower part of an upflow elemental sulfur bioreactor (1), the upper part of the circular porous plate (4) is a reaction zone, gravel is filled in the reaction zone to form a gravel layer (3), and a mixture of elemental sulfur and limestone is filled on the gravel layer (3) to form an elemental sulfur and limestone layer (2); sewage in a sewage container (5) is introduced into the reaction zone through the bottom of the upflow elemental sulfur bioreactor (1) in an upward flow manner, the exhaust port of an inert gas bag (6) is connected to the top of the sewage container (5), the denitrification gas product is discharged from the top exhaust port (7), and the sewage after the reaction is discharged from the top of the upflow elemental sulfur bioreactor (1);

[0023] 2. Domestication: placing the upflow elemental sulfur bioreactor (1) in an environment below 9-11°C, sending the influent of the secondary sedimentation tank of the sewage treatment plant from bottom to top into the upflow elemental sulfur bioreactor, and adding trace nutrients, alkali solution and nitrate to the upflow elemental sulfur bioreactor (1); and inoculating one or two of the sludge from the secondary sedimentation tank of the urban sewage treatment plant and the estuary sediment downstream of the sewage treatment plant into the upflow elemental sulfur bioreactor (1) to domesticate autotrophic sulfur-oxidizing denitrifying bacteria (a-soNRB), dissimilatory nitrate reducing ammonium (DNRA) bacteria, sulfur dismutation (SD) bacteria and psychrophilic bacteria; when the nitrate removal rate of the upflow elemental sulfur bioreactor (1) reaches more than 95% and sulfide is continuously produced, the domestication is successful;

[0024] 3. Continuous sewage treatment

[0025] In an environment of 9 to 11°C, the sewage is continuously fed into an upflow elemental sulfur bioreactor to achieve sulfur disproportionation-mediated polyculture denitrification, achieving low-temperature and high-efficiency deep denitrification of sewage, simultaneous ammonium recovery and greenhouse gas emission reduction.

[0026] This implementation has the following beneficial effects:

[0027] 1. The sulfur disproportionation-mediated mixed biological denitrification (SD-MixBNR) process of this embodiment achieves efficient denitrification under low temperature conditions based on the influent conditions of the secondary sedimentation tank of an actual sewage treatment plant. When the hydraulic retention time (HRT) is 1 hour and the nitrate nitrogen (NO 3 When the concentration of -N is 40 mg / L, the nitrate removal efficiency of SD-MixBNR is close to 100%; under low temperature conditions, the nitrate removal efficiency is about 4.59-11.58 times that of the traditional sulfur-based autotrophic denitrification (SDAD) process. The results of this study verify the feasibility of achieving efficient nitrate removal based on the SD-MixBNR process in low-temperature engineering applications, and provide valuable guidance for the operation of actual wastewater treatment plants in winter.

[0028] 2. In the traditional sulfur filling system, there is an active dissimilatory nitrate reduction to ammonium (DNRA) process. The ammonium production mediated by DNRA is considerable, and its contribution to the total bioconversion of nitrate is about 10%-40%. Different from previous studies, the polyculture conditions in this embodiment not only did not increase, but also increased nitrous oxide (N 2 O) emissions were reduced by 64.14%-84.20%. This is due to the synergistic effect of the excess electron donors provided by the polyculture conditions and the DNRA process. In the context of carbon neutrality, it has significant potential for greenhouse gas emission reduction while achieving ammonium recovery in wastewater treatment plants.

[0029] 3. The present embodiment establishes the interaction mechanism of the core functional microorganisms involved in the conversion of nitrogen and sulfur in the SD-MixBNR system by comprehensive 16SrRNA amplicon sequencing, microbial network succession analysis and metagenomic analysis. The functional microbial reaction mechanism of the present embodiment is: sulfur disproportionate bacteria can produce sulfide, and sulfide can further react with elemental sulfur to generate polysulfide. The sulfide and polysulfide generated by the above process can be further used as electron donors by autotrophic sulfur-oxidizing denitrifying bacteria to gradually reduce nitrate to nitrogen gas. Moreover, sulfide and polysulfide are usually more bioavailable than elemental sulfur, so the denitrification rate is significantly accelerated. At the same time, psychrophilic bacteria (red brooding bacteria) as electroactive microorganisms, after degrading organic matter to generate electrons, can transfer electrons to denitrifying bacteria by direct (nanowire) or indirect (quinone-based structure) mode, and autotrophic sulfur-oxidizing denitrifying bacteria use the electrons transferred by red brooding bacteria to gradually reduce nitrate or nitrite to nitrogen gas under anaerobic conditions, thereby achieving low-temperature denitrification. On the other hand, nitrate can also be reduced to ammonium by DNRA bacteria. Since nitrous oxide is not an intermediate product in this step, ammonium recovery is achieved while reducing nitrogen oxide emissions, which is in line with the concept of carbon neutrality in sewage treatment plants.

[0030] Patent CN114409096B is an autotrophic condition, while this embodiment is a polytrophic condition; Patent CN114409096B is a room temperature reaction, while this embodiment is a low temperature reaction and psychrophilic bacteria are domesticated in the reactor to achieve low temperature denitrification; Patent CN114409096B system has a large amount of sulfide, which is easy to cause an increase in greenhouse gas emissions, while this embodiment domesticates DNRA bacteria, which can synchronize ammonium recovery and nitrous oxide emission reduction; Patent CN114409096B does not have DNRA bacteria, and this embodiment and Patent CN114409096B are not bacteria of the same genus, and this embodiment is The formula can also carry out sulfur disproportionation under mixed culture conditions; therefore, compared with the present embodiment, patent CN114409096B has the following shortcomings: 1) CN114409096B can only be operated through self-distributed water and room temperature laboratory, and it is difficult to achieve the application of multi-scenario load water quality; 2) The carbon-nitrogen ratio of sewage that can be treated by CN114409096B during operation is 6-9.5, and a high ammonia nitrogen removal rate can only be guaranteed under autotrophic conditions, and deep denitrification and carbon removal under low carbon-nitrogen ratio conditions cannot be achieved; (3) The system of CN114409096B contains a large amount of sulfide, which is easy to lead to increased greenhouse gas emissions.

[0031] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that: the exterior of the upflow elemental sulfur bioreactor (1) in step 1 is covered with a shading cloth.

[0032] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that: the volume ratio of elemental sulfur and limestone in step one is 2:1.

[0033] Specific implementation method 4: This implementation method is different from any one of specific implementation methods 1 to 3 in that: in step 1, the particle size of the elemental sulfur is 5-8 mm; the particle size of the limestone is 3-5 mm; and the particle size of the gravel is 8-16 mm.

[0034] Specific implementation method five: This implementation method is different from any one of specific implementation methods one to four in that: the sewage in the sewage container (5) in step one is the influent water of the secondary sedimentation tank of the sewage treatment plant.

[0035] Specific embodiment 6: This embodiment differs from any one of the specific embodiments 1 to 5 in that: in step 2, trace nutrients including EDTA, ZnSO are added to the upflow elemental sulfur bioreactor (1). 4 , CaCl 2 、MnCl 2 ·4H 2 O, FeSO 4 NH 4 ) 2 MoO 4 ,CuSO4 ·5H 2 O and CoCl 2 6H 2 O.

[0036] Specific embodiment 7: This embodiment differs from any one of specific embodiments 1 to 6 in that: the content of the trace nutrients added to the upflow elemental sulfur bioreactor (1) in step 2 is: EDTA: 50.0 g / L; ZnSO 4 :22.0g / L; CaCl 2 :5.54g / L; MnCl 2 ·4H 2 O: 5.06 g / L; FeSO 4 :4.99g / L; (NH 4 ) 2 MoO 4 :1.10g / L;CuSO 4 ·5H 2 O: 1.57 g / L; CoCl 2 6H 2 O: 1.61 g / L.

[0037] Specific embodiment eight: This embodiment differs from any one of the specific embodiments one to seven in that: the alkali solution in step two is NaHCO 3 The solution has an alkali concentration of 50 to 200 mg / L in the upward-flow elemental sulfur bioreactor (1).

[0038] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that: the nitrate in step 2 is KNO 3 , the nitrate concentration in the upward-flow elemental sulfur bioreactor (1) is 10 to 100 mg / L.

[0039] Specific implementation method ten: The difference between this implementation method and any one of specific implementation methods one to nine is that the hydraulic retention time for continuous sewage treatment in step three is set to: the hydraulic retention time from 0 to 60 days is 20 hours, the hydraulic retention time from 60 to 200 days is 10 hours, the hydraulic retention time from 200 to 250 days is 5 hours, the hydraulic retention time from 250 to 280 days is 2.5 hours, and the hydraulic retention time from 280 to 320 days is 1 hour.

[0040] Embodiment 1:

[0041] The method for low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery of sewage mediated by sulfur disproportionation in this embodiment is carried out according to the following steps:

[0042] 1. A circular porous plate (4) is arranged at the lower part of an upflow elemental sulfur bioreactor (1); a reaction zone is formed above the circular porous plate (4); gravel is filled in the reaction zone to form a gravel layer (3); a mixture of elemental sulfur and limestone is filled on the gravel layer (3) to form an elemental sulfur and limestone layer (2); elemental sulfur is used as a sulfur source and limestone particles are used as an alkalinity source to neutralize acidic substances; the gravel layer (3) plays a role in fluid distribution to withstand column pressure and prevent biomass loss; sewage in a sewage container (5) is introduced into the reaction zone through the bottom of the upflow elemental sulfur bioreactor (1) in an upward flow manner; an inert gas bag (6) is connected to the top of the sewage container (5); ) is provided at an exhaust port, denitrification gas products are discharged from the top exhaust port (7), and the sewage after the reaction is discharged from the top of the upflow elemental sulfur bioreactor (1); the inert gas bag (6) is used to maintain a strict anaerobic environment and can also balance the pressure loss caused by the change of the influent; the exterior of the upflow elemental sulfur bioreactor (1) is covered with a shade cloth to prevent the growth and reproduction of photosynthetic bacteria such as algae; a peristaltic pump (10) is provided on the water inlet pipeline between the sewage container (5) and the upflow elemental sulfur bioreactor (1); a water outlet pipe (8) is provided on one side of the upper part of the upflow elemental sulfur bioreactor (1), and the water outlet pipe (8) is connected to the water outlet bucket (9);

[0043] The volume ratio of elemental sulfur to limestone is 2:1; the particle size of elemental sulfur is 5-8 mm; the particle size of limestone is 3-5 mm; the particle size of gravel is 8-16 mm;

[0044] The sewage in the sewage container (5) is the influent of the secondary sedimentation tank of the sewage treatment plant;

[0045] 2. Domestication: The upflow elemental sulfur bioreactor (1) is placed in an environment below 9-11°C, the influent of the secondary sedimentation tank of the sewage treatment plant is sent from bottom to top into the upflow elemental sulfur bioreactor, and trace nutrients, alkali solution and nitrate are added to the upflow elemental sulfur bioreactor (1); the sludge from the secondary sedimentation tank of the urban sewage treatment plant and the estuary sediment downstream of the sewage treatment plant are inoculated into the upflow elemental sulfur bioreactor (1) to domesticate autotrophic sulfur-oxidizing denitrifying bacteria (a-soNRB), dissimilatory nitrate reducing ammonium (DNRA) bacteria, sulfur disproportionation (SD) bacteria and psychrophilic bacteria; when the nitrate removal rate of the upflow elemental sulfur bioreactor (1) reaches more than 95% and sulfide is continuously produced, the domestication is successful; during the domestication period of this embodiment, NO 3 The concentration of -N is 15mgL, NO 3 -N removal rate was 80%, sulfide production was 5 mgS / L, and ammonium generation rate was 17%;

[0046] The composition and content of the trace nutrients added to the upflow elemental sulfur bioreactor (1) are as follows: EDTA: 50.0 g / L; ZnSO 4 :22.0g / L; CaCl 2 :5.54g / L; MnCl 2 ·4H 2 O: 5.06 g / L; FeSO 4 :4.99g / L; (NH 4 ) 2 MoO 4 :1.10g / L;CuSO 4 ·5H 2 O: 1.57 g / L; CoCl 2 6H 2 O: 1.61 g / L; the alkali solution is NaHCO 3 solution, the alkali concentration in the upward-flow elemental sulfur bioreactor (1) is 60 mg / L; the nitrate is KNO 3 ,

[0047] The nitrate concentration in the upward elemental sulfur bioreactor (1) is 40 mg / L; the carbon-nitrogen ratio of the influent of the secondary sedimentation tank of the sewage treatment plant is 1.5-3.0:1, the ammonia nitrogen concentration is 2-5 mg-N / L; the nitrate nitrogen concentration is 30-40 mg-N / L; COD: 20-40 mg / L, and the influent pH is 7.8±0.2; this embodiment is selected from the influent of the secondary sedimentation tank of the Harbin Wenchang sewage treatment plant;

[0048] 3. Continuous sewage treatment

[0049] In an anaerobic environment at 9-11°C, the sewage is continuously fed into an upflow elemental sulfur bioreactor to achieve sulfur disproportionation-mediated polyculture denitrification, achieve low-temperature and high-efficiency deep denitrification of sewage, simultaneous ammonium recovery and greenhouse gas emission reduction;

[0050] The hydraulic retention time of the continuous sewage treatment is set as: 20 hours for the 0th to 60th day, 10 hours for the 60th to 200th day, 5 hours for the 200th to 250th day, 2.5 hours for the 250th to 280th day, and 1 hour for the 280th to 320th day.

[0051] Figure 1 The invention is a schematic structural diagram of an upflow elemental sulfur bioreactor; the invention comprises: an upflow elemental sulfur bioreactor (1), an elemental sulfur and limestone layer (2), a gravel layer (3), a circular porous plate (4), a sewage container (5), an inert gas bag (6), an exhaust port (7), a water outlet pipe (8), a water outlet bucket (9), and a peristaltic pump (10);

[0052] Figure 2 The figure is a diagram of the denitrification effect of each operation stage of the upflow elemental sulfur bioreactor; the average nitrate concentration of the influent of the continuous sewage treatment in this embodiment is 40 mg-N / L, the influent pH is 7.8±0.2, the average sulfide concentration of the effluent of the upflow elemental sulfur bioreactor (1) in this embodiment is 13.3 mgS / L, the nitrate nitrogen removal efficiency is 100%, and the ammonium generation rate reaches 39%.

[0053] The sludge in the upflow elemental sulfur bioreactor of this embodiment was subjected to microbial community analysis. Figure 3 The figure is a test diagram of microbial abundance in each operation stage of the upflow elemental sulfur bioreactor, indicating that the efficient denitrification achieved by the present invention is the result of the combined action of autotrophic sulfur-oxidizing denitrifying bacteria (a-soNRB: Thiobacillus, 9.29%), dissimilatory nitrate reduction to ammonium (DNRA bacteria: Geobacter, 2.69%), psychrophilic bacteria (Rhodoferax, 8.9153%) and sulfur dismutation (SD: Desulfocapsa, 1.88%) bacteria.

[0054] In this embodiment, in a sulfur reactor filled with elemental sulfur, sulfur disproportionation bacteria in the reaction layer undergo elemental sulfur disproportionation reaction to produce sulfide, which reacts with S 0 Synthesis of polysulfide S n 2- ; Sodium acetate, S 0 , sulfide and polysulfide together serve as electron donors for nitrate reduction, and nitrate and nitrite serve as electron acceptors. Under the action of sulfur-oxidizing denitrifying bacteria, nitrate reduction process occurs, thereby achieving efficient and deep denitrification of sewage. Nitrate in the influent is also reduced to ammonium by DNRA bacteria. The above reaction process is coupled under the cooperative drive of multiple microorganisms, so that the elemental sulfur reactor can continuously and efficiently denitrify while achieving ammonium recovery and greenhouse gas emission reduction.

[0055] The fastest denitrification rate of the traditional SDAD is 6.9 mg-N / (L·d) (reference: Supplementarysulfide during inoculation for improved sulfur autotrophic denitrificationperformance and adaptation to low temperature.), while the nitrate removal efficiency of this embodiment is as high as 1.32-3.33 mg-N / (L·h), which is about 4.59-11.58 times that of the traditional sulfur-based autotrophic denitrification (SDAD) process. 2 In the evaluation of O production, the measured nitrous oxide (N 2O) fluxes were between 5.72-94.70 μg / L and 7.30-60.14 μg / L, respectively, which are significantly lower than the previously reported flux range with SDAD (46.1±8.2~167.7±7.4 μg / L, reference: Sulfur cycle contributes to stable autotrophic denitrification and lower N2O accumulation in electrochemically integrated constructed wetlands: Electron transfers patterns and metagenome insights.). In this example, nitrous oxide (N 2 O) emissions were reduced by 64.14%-84.20%.

Claims

1. A method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation, characterized in that: The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation is carried out according to the following steps:

1. A circular porous plate (4) is arranged at the lower part of an upflow elemental sulfur bioreactor (1), the upper part of the circular porous plate (4) is a reaction zone, gravel is filled in the reaction zone to form a gravel layer (3), and a mixture of elemental sulfur and limestone is filled on the gravel layer (3) to form an elemental sulfur and limestone layer (2); sewage in a sewage container (5) is introduced into the reaction zone through the bottom of the upflow elemental sulfur bioreactor (1) in an upward flow manner, the exhaust port of an inert gas bag (6) is connected to the top of the sewage container (5), the denitrification gas product is discharged from the top exhaust port (7), and the sewage after the reaction is discharged from the top of the upflow elemental sulfur bioreactor (1); 2. Domestication: placing the upflow elemental sulfur bioreactor (1) in an environment below 9-11°C, feeding the influent of the secondary sedimentation tank of the sewage treatment plant into the upflow elemental sulfur bioreactor from bottom to top, and adding trace nutrients, alkali solution and nitrate to the upflow elemental sulfur bioreactor (1); and inoculating one or two of the sludge from the secondary sedimentation tank of the urban sewage treatment plant and the estuary sediment downstream of the sewage treatment plant into the upflow elemental sulfur bioreactor (1) to domesticate autotrophic sulfur-oxidizing denitrifying bacteria, dissimilatory nitrate-reducing bacteria to ammonium, sulfur disproportionating bacteria and psychrophilic bacteria; when the nitrate removal rate of the upflow elemental sulfur bioreactor (1) reaches more than 95% and sulfide is continuously produced, the domestication is successful; 3. Continuous sewage treatment In an anaerobic environment of 9-11°C, the sewage is continuously fed into an upflow elemental sulfur bioreactor to achieve sulfur disproportionation-mediated mixed culture denitrification, achieving low-temperature and efficient deep denitrification of sewage, simultaneous ammonium recovery and greenhouse gas emission reduction.

2. The method for low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery of sewage mediated by sulfur disproportionation according to claim 1, characterized in that: In step 1, the exterior of the upflow elemental sulfur bioreactor (1) is covered with a shading cloth.

3. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: In step 1, the volume ratio of elemental sulfur to limestone is 2:

1.

4. The method for low-temperature, high-efficiency, low-carbon denitrification of sewage and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: In step 1, the particle size of the elemental sulfur is 5-8 mm; the particle size of the limestone is 3-5 mm; and the particle size of the gravel is 8-16 mm.

5. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: The sewage in the sewage container (5) in step 1 is the inlet water of the secondary sedimentation tank of the sewage treatment plant.

6. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: In step 2, the trace nutrients added to the upflow elemental sulfur bioreactor (1) include EDTA, ZnSO4, CaCl2, MnCl2·4H2O, FeSO4, (NH4)2MoO4, CuSO4·5H2O and CoCl2·6H2O.

7. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: The content of trace nutrients added to the upflow elemental sulfur bioreactor (1) described in step 2 is: EDTA: 50.0 g / L; ZnSO4: 22.0 g / L; CaCl2: 5.54 g / L; MnCl2·4H2O: 5.06 g / L; FeSO4: 4.99 g / L; (NH4)2MoO4: 1.10 g / L; CuSO4·5H2O: 1.57 g / L; CoCl2·6H2O: 1.61 g / L.

8. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: The alkali solution in step 2 is a NaHCO3 solution, and the concentration of the alkali solution in the upward-flow elemental sulfur bioreactor (1) is 50-200 mg / L.

9. The method for low-temperature, high-efficiency, low-carbon denitrification of sewage and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: The nitrate in step 2 is KNO3, and the nitrate concentration in the upward-flow elemental sulfur bioreactor (1) is 10-100 mg / L.

10. The method for wastewater low-temperature, high-efficiency, low-carbon denitrification and simultaneous ammonium recovery mediated by sulfur disproportionation according to claim 1, characterized in that: The hydraulic retention time for continuous sewage treatment in step three is set as follows: the hydraulic retention time from 0 to 60 days is 20 hours, the hydraulic retention time from 60 to 200 days is 10 hours, the hydraulic retention time from 200 to 250 days is 5 hours, the hydraulic retention time from 250 to 280 days is 2.5 hours, and the hydraulic retention time from 280 to 320 days is 1 hour.

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