Device and method for deep nitrogen removal of sewage and in-situ sludge reduction and side stream reaction device thereof

Abstract

The present application relates to a kind of sewage advanced denitrification in situ sludge reduction device and method and its side stream reaction device, the side stream reaction device includes reactor main body;Close to the side wall of the bottom of the reactor main body is provided with feed inlet for sludge and sulfur source to enter;Close to the side wall of the top of the reactor main body is provided with discharge port;The inside of the reactor main body is provided with aeration component;The aeration component includes aeration pipe and the aeration disc on the aeration pipe;The top of the reactor main body is provided with sealing component;The sealing component is provided with exhaust port;The side wall of the reactor main body is provided with stirrer;The side stream reaction device is coupled with AOAO process, without additional carbon source, realizes the sulfur autotrophic heterotrophic denitrification of low C / N sewage, simultaneously sludge in situ efficient reduction, total nitrogen concentration in effluent can be preferably less than 10mg / L, sludge reduction rate is as high as 50% or more, ensure low-carbon sustainable sewage treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a device for deep denitrification of wastewater in situ combined with in-situ sludge reduction, and its side-flow reaction device and method, particularly to a device for deep denitrification of low C / N wastewater in situ combined with in-situ sludge reduction, and its side-flow reaction device and method. Background Technology

[0002] Traditional heterotrophic denitrification processes inevitably produce a large amount of residual sludge. Theoretically, 1 mol NO3... - The reduction requires the transfer of 5 mol e from the oxidation of organic matter. - However, when the carbon-nitrogen ratio is low, the high demand for electron donors often encounters challenges related to insufficient organic matter required for heterotrophic denitrification. To enhance the decomposition and metabolism of heterotrophic denitrifying bacteria and thus achieve higher nitrate removal efficiency, supplementing with an external carbon source is essential. However, due to the inevitable accumulation of additional biomass and microbial metabolites, this method leads to an increased rate of excess sludge production, thereby increasing the difficulty and cost of sludge treatment equipment.

[0003] CN117164115A discloses a device and method for achieving deep denitrification and sludge reduction through continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification anaerobic ammonium oxidation. It mainly achieves denitrification and sludge reduction by coupling in-situ sludge hydrolysis with short-cut denitrification anaerobic ammonium oxidation. However, the autotrophic denitrification is driven by anaerobic ammonium oxidation, resulting in a long start-up period. Furthermore, the sludge reduction of this method is mainly due to the slow growth of autotrophic bacteria, resulting in a limited degree of sludge reduction.

[0004] CN117550740A discloses a wastewater treatment system and method suitable for treating rural sewage. This method couples an A2O-constructed wetland system process and adds carbon slow-release filler, phosphorus strong adsorption-slow release filler, sludge reduction and resource utilization structures to the process to achieve efficient removal and resource utilization of nitrogen and phosphorus. Obviously, it requires an external constructed wetland system for deep denitrification. The device occupies a large area and cannot be implemented within the sewage treatment plant area. Moreover, the addition of carbon slow-release filler, i.e., external carbon source, will lead to the generation of excess sludge.

[0005] Currently, efforts are focused on synergistically combining sulfur autotrophic and heterotrophic denitrification to address the challenges of purely heterotrophic denitrification processes. However, sulfur-oxidizing bacteria (SOBs) take longer to develop than heterotrophic denitrifying bacteria (HDBs), posing a challenge to their synergistic cooperation during denitrification. This leads to sulfur-based denitrification processes typically being used for secondary effluent treatment, usually in conjunction with biological filters to achieve complete nitrate nitrogen removal, but at the cost of increased land area and prolonged start-up time. The growth advantage of HDBs not only hinders SOBs from obtaining sufficient substrate to maintain their catabolism activity and generate sufficient energy for growth, but also results in excessive sludge production. Therefore, developing efficient mixed-nutrient denitrification systems is essential to mitigating the high HDB yield and improving the in-situ enrichment rate of SOBs.

[0006] CN117303558A discloses a method for sulfur autotrophic-heterotrophic synergistic denitrification under low sulfur load conditions. This method involves adding Ca... 2+ and Mg 2+ The microorganisms in the activated sludge in the induced reactor system self-fix and form granular sludge, which improves the retention rate of sulfur autotrophic denitrifying bacteria in the system. This optimizes the complex community structure of sulfur autotrophic and heterotrophic denitrifying bacteria, enabling sulfur autotrophic denitrifying bacteria in the system to synergistically exert nitrogen removal capacity with heterotrophic denitrifying bacteria under low sulfur load. However, it has the drawbacks of limited nitrogen removal improvement and failure to simultaneously achieve in-situ sludge reduction.

[0007] In summary, existing technologies for denitrification and sludge reduction in low C / N wastewater have drawbacks such as large footprint, making them unsuitable for use within sludge treatment plants. Furthermore, the methods employed suffer from the need for additional carbon sources, low denitrification efficiency, and limited sludge reduction. Therefore, achieving deep denitrification of low C / N wastewater combined with efficient in-situ sludge reduction without the need for additional external carbon sources has become an urgent problem to be solved. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a device for deep denitrification of wastewater combined with in-situ sludge reduction, along with its side-flow reaction device and method. By adding the side-flow reaction device at the side-flow point of the AOAO process unit, the apoptosis of heterotrophic denitrifying bacteria in the side-flow reaction device is induced, promoting the growth of sulfur autotrophic bacteria, thereby promoting sulfur autotrophic denitrification. Simultaneously, sludge degradation occurs, which not only facilitates in-situ sludge reduction but also releases endogenous carbon sources to feed the heterotrophic denitrifying bacteria in the mainstream AOAO process, promoting the heterotrophic denitrification process. In other words, without the need for additional external carbon sources, synergistic deep denitrification of sulfur autotrophic and heterotrophic denitrification is achieved, with efficient in-situ sludge reduction, solving the current challenges faced in treating low C / N domestic wastewater.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a side-flow reaction device for deep denitrification of wastewater and in-situ sludge reduction, the side-flow reaction device comprising a reactor body; an inlet is provided on the side wall near the bottom of the reactor body for sludge and sulfur source to enter; and an outlet is provided on the side wall near the top of the reactor body.

[0011] The reactor body is equipped with an aeration component;

[0012] The aeration component includes an aeration pipe and an aeration disc disposed on the aeration pipe;

[0013] A sealing component is provided on the top of the reactor body; an exhaust port is provided on the sealing component;

[0014] A stirrer is installed on the side wall of the reactor body.

[0015] The side-flow reactor of this invention is used to couple with the mainstream AOAO process to achieve deep denitrification through synergistic denitrification of sulfur autotrophs and heterotrophs, as well as in-situ sludge reduction. By installing a stirrer on the side wall of the reactor body, the upper and middle sludge is returned to the bottom, providing sludge agitation to ensure uniform mixing of the sludge and water phases within the device, which is beneficial for sufficient contact between microorganisms and the reaction substrate. Aeration pipes, aeration discs, and exhaust ports are installed inside the device to generate uniform and dense bubbles during aeration, providing a good growth environment for sulfur autotrophic bacteria and promoting their growth to meet the functional bacteria abundance requirements of the mainstream sulfur autotrophic denitrification process. A sealing component is installed to provide an anaerobic environment when O2 is depleted during non-aeration, promoting the denitrification process of sulfur autotrophic bacteria and the degradation of sludge to release endogenous carbon sources for feeding back into the mainstream AOAO process.

[0016] Preferably, the reactor body extends outward from the inlet to form a first feed pipe for sludge to enter.

[0017] Preferably, a second feed pipe extends from the first feed pipe for the entry of the sulfur source.

[0018] Preferably, the reactor body extends outward from the discharge port into a discharge pipe.

[0019] Preferably, the aeration pipe includes a first aeration pipe disposed at the bottom of the reactor body and a second aeration pipe perpendicular to the first aeration pipe, and the first aeration pipe and the second aeration pipe are connected.

[0020] Preferably, the second aeration pipe extends through the sealing component on the side away from the reactor body to connect to the air supply component and supply air to the aeration component.

[0021] Preferably, the air supply component includes a blower.

[0022] Preferably, the sealing component is also provided with an inspection port.

[0023] Secondly, the present invention provides a device for deep denitrification of wastewater and in-situ sludge reduction, the device comprising an AOAO process device and a side-flow reaction device for deep denitrification of wastewater and sludge reduction as described in the first aspect.

[0024] This invention couples the AOAO process device with the side-flow reaction device described in the first aspect. The two work together without the need for additional external carbon sources, achieving deep denitrification of sulfur autotrophic-heterotrophic synergistically in low C / N domestic sewage. At the same time, it achieves efficient in-situ sludge reduction, and the equipment has low operating requirements and low economic cost, which is conducive to practical engineering applications and ensures low-carbon sustainable sewage treatment.

[0025] Preferably, the AOAO process device includes a biological treatment tank and a sedimentation tank; the biological treatment tank includes an anoxic zone I, an aerobic zone I, an anoxic zone II, and an aerobic zone II connected in sequence and interconnected with each other; the sedimentation tank is connected to the side of the biological treatment tank near the aerobic zone II; the sedimentation tank is provided with an outlet and a sludge outlet.

[0026] Preferably, the bottom of the sedimentation tank is connected to the anoxic zone I of the biochemical treatment tank via a first sludge return pipeline.

[0027] Preferably, the bottom of the sedimentation tank is connected to the first feed pipe of the side-flow reaction device via a second sludge return pipe; the discharge pipe of the side-flow reaction device is connected to the anoxic zone II of the biochemical treatment tank via a third sludge return pipe.

[0028] Preferably, the anoxic zone I and anoxic zone II are provided with solid suspended packing material for the aggregation of functional bacteria.

[0029] The present invention preferably provides solid suspended packing material in the anoxic I zone and anoxic II zone, which is conducive to the enrichment of functional bacteria (sulfoautotrophic bacteria and heterotrophic denitrifying bacteria), thereby facilitating the denitrification process and improving nitrogen removal efficiency.

[0030] Preferably, the solid suspension filler includes any one or a combination of at least two of polyurethane sponge filler, high-density polyethylene filler, or porous polypropylene filler, wherein typical but non-limiting combinations include combinations of polyurethane sponge filler and high-density polyethylene filler, combinations of polyurethane sponge filler and porous polypropylene filler, or combinations of high-density polyethylene filler and porous polypropylene filler, etc.

[0031] High-density polyethylene filler refers to polyethylene with a density of 0.941–0.965 g / cm³. 2The polyethylene filler, for example, can be 0.941 g / cm³. 2 0.945g / cm 2 0.950g / cm 2 0.955g / cm 2 0.960 g / cm 2 Or 0.965g / cm 2 wait.

[0032] Thirdly, the present invention provides a method for deep denitrification of wastewater combined with in-situ sludge reduction, wherein the method is carried out using the device for deep denitrification of wastewater combined with in-situ sludge reduction described in the second aspect.

[0033] The method for deep denitrification of wastewater combined with in-situ sludge reduction provided by this invention employs the second aspect of coupling a side-flow reaction device with the AOAO process. Without the need for an external carbon source, it achieves deep denitrification of low C / N wastewater through a synergistic process of sulfur autotrophic-heterotrophic denitrification, improving denitrification efficiency and achieving highly efficient in-situ sludge reduction. This ensures low-carbon and sustainable wastewater treatment.

[0034] Preferably, the method includes the following steps:

[0035] (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained.

[0036] (2) The sulfur source and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction to obtain sludge rich in polymorphic sulfur source and endogenous carbon source.

[0037] (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification.

[0038] The method of this invention is carried out using the apparatus described in the second aspect, namely, adding a side-flow reactor as described in the first aspect to one side of the sedimentation tank in the AOAO process, and introducing a sulfur source into the side-flow reactor to initiate a complex electron transfer pathway, thereby promoting sulfur circulation in the side-flow reactor, and not only oxidizing sulfur to produce SO4. 2- It also promoted sulfur reduction, producing S 2- This provides reduced sulfur as an electron donor for sulfur-autotrophic denitrifying bacteria, thereby achieving sulfur-autotrophic denitrification; simultaneously, S 2- and SO4 2-The presence of sulfur-containing substances can accelerate the degradation of organic components in sludge, producing dissolved organic matter (DOM) and extracellular polymeric substances (EPS). This not only achieves in-situ sludge reduction but also releases endogenous carbon sources. Furthermore, by returning the sludge containing sulfur-autotrophic bacteria, polymorphic sulfur sources, and endogenous carbon sources in the side-flow reactor to the anoxic II zone of the AOAO process, the synergistic deep denitrification process of sulfur autotrophic-heterotrophic is promoted.

[0039] Preferably, the influent flow rate Q of the wastewater in step (1) in The daily output is 10-12L, for example, it can be 10L / day, 10.5L / day, 11L / day, 11.5L / day or 12L / day, etc.

[0040] Preferably, the reflux flow rate Q of the nitrification liquid in step (1) n The influent flow rate Q of the wastewater in The percentage can be 100% to 350%, for example, 100%, 120%, 150%, 180%, 200%, 220%, 250%, 280%, 300%, 320%, or 350%, with 200% to 300% being preferred.

[0041] The present invention further optimizes the reflux flow rate Q of the nitrification liquid. n The influent flow rate Q of the wastewater in A flow rate of 100% to 350% is beneficial to ensure that the nitrates generated in the system can be fully denitrified in the anoxic zone I; if the reflux rate of the nitrifying liquid Q n The flow rate is too small, resulting in only a small amount of nitrate nitrogen participating in the denitrification process, leading to low nitrogen removal efficiency; if the reflux flow rate Q of the nitrification liquid is too small... n If the concentration is too high, excessive dissolved oxygen will flow back to the anoxic zone through the nitrification liquid, disrupting the anoxic environment for denitrification.

[0042] Preferably, the sludge phase in step (1) also includes recirculation to the anoxic zone I and / or discharge.

[0043] Preferably, the reflux rate Q of the sludge phase returned to the anoxic zone I in step (1) is... s The influent flow rate Q of the wastewater in It can be 50% to 80%, for example, 50%, 60%, 70% or 80%, etc.

[0044] Preferably, the inflow rate of the sludge phase transported to the side-flow reactor in step (2) is Q. t The daily intake is 0.14 to 0.18 L, for example, it can be 0.14 L / day, 0.15 L / day, 0.16 L / day, 0.17 L / day or 0.18 L / day, etc.

[0045] Preferably, the sulfur source in step (2) includes a thiosulfate solution and / or a solution containing S.2- A salt solution, preferably a thiosulfate solution.

[0046] Preferably, the sulfur source includes a sodium thiosulfate solution.

[0047] This invention preferably uses a thiosulfate solution as the sulfur source, compared to sulfur-containing solutions. 2- Salt solutions containing sulfur, especially thiosulfate solutions, have low toxicity, high solubility, and are readily utilized by microorganisms as reaction substrates; while solutions containing sulfur... 2- S in salt solution 2- It inhibits biological reactions, resulting in low denitrification efficiency. Compared to elemental sulfur and pyrite, thiosulfate solution is readily available and has high bioavailability, while elemental sulfur and pyrite are both solids with low bioavailability, and the reaction produces H2S, which is highly toxic.

[0048] Preferably, the polymorphic sulfur source in step (2) includes S 2- S2O3 2- or S 0 Any one or at least two of the above, wherein typical but non-limiting combinations include S 2- S2O3 2- and S 0 Combinations, S 2- S2O3 2- and S 0 Combinations, etc., where S 0 bio-sulfur bio-S 0 .

[0049] The method described in this invention introduces a sulfur source into the side-flow reaction device to promote sulfur cycling, which can supply polymorphic sulfur electrons and promote deep denitrification in the mainstream AOAO process.

[0050] Preferably, when the nitrate nitrogen concentration C of the aqueous phase in step (1) is... 水相硝态氮 When the concentration is <20 mg / L, the amount of sulfur source Q added in step (2) is... a =160Q in mg / day.

[0051] Preferably, when the concentration C of nitrate nitrogen in the aqueous phase of step (1) is... 水相硝态氮 When the concentration is ≥20 mg / L, the amount of sulfur source Q added in step (2) is... a =C 出水硝态氮 ×8×Q in mg / day.

[0052] The present invention further preferably uses the nitrate nitrogen concentration C of the effluent. 出水硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q inmg / day, when the concentration of nitrate nitrogen in the effluent is C 出水硝态氮 When the concentration of sulfur source is ≥20 mg / L, the dosage of the sulfur source Qa = C 出水硝态氮 ×8×Q in mg / day; that is, when the nitrate nitrogen concentration in the effluent is high, the amount of sulfur source added is increased, thereby promoting the reaction in the side-flow reactor, and further promoting the synergistic deep denitrification of sulfur autotrophic-heterotrophic in the AOAO process, thus improving the denitrification efficiency.

[0053] Preferably, the hydraulic residence time of the side-flow reaction device in step (2) is 1 to 5 days, for example, it can be 1 day, 2 days, 3 days, 4 days or 5 days.

[0054] The present invention further preferably uses a hydraulic retention time of 1 to 5 days for the side-flow reaction device, which is beneficial to sludge reduction and stable proliferation of sulfur autotrophic bacteria. If the hydraulic retention time of the side-flow reaction device is too short, it will lead to insufficient release of endogenous carbon in the sludge and loss of sulfur autotrophic bacteria with sludge discharge. If the hydraulic retention time of the side-flow reaction device is too long, it will lead to an excessively large reactor footprint.

[0055] Preferably, the aeration component in the side-flow reaction device described in step (2) adopts an intermittent aeration method.

[0056] Preferably, under aeration, the concentration of dissolved oxygen in the side-flow reaction device described in step (2) is 0.8 to 1.2 mg / L, for example, it can be 0.8 mg / L, 0.9 mg / L, 1.0 mg / L, 1.1 mg / L or 1.2 mg / L.

[0057] Preferably, the flow rate of sludge returned to the anoxic II zone in step (3) is 0.14 to 0.18 L / day, for example, it can be 0.14 L / day, 0.15 L / day, 0.16 L / day, 0.17 L / day or 0.18 L / day, etc.

[0058] As a further preferred technical solution of the present invention, refer to Figure 1 The process flow shown includes the following steps:

[0059] (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained.

[0060] (2) The sulfur source and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction to obtain sludge rich in polymorphic sulfur source and endogenous carbon source.

[0061] (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification.

[0062] In step (1), the influent flow rate Q of the wastewater is... in The reflux rate is 10-12 L / day; the reflux rate of the nitrification liquid is Q. n The influent flow rate Q of the wastewater in 100% to 350%; the flow direction of the sludge phase also includes recirculation to the anoxic zone I and / or discharge; the recirculation flow rate Q of the sludge phase recirculated to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 50-80%;

[0063] In step (2), the inflow rate of the sludge phase transported to the side-flow reactor is Q. t The concentration is 0.14–0.18 L / day; the sulfur source includes thiosulfate solution and / or sulfur-containing solutions. 2- A salt solution; the polymorphic sulfur source includes S 2- S2O3 2- or S 0 Any one or at least two of the following; when the nitrate nitrogen concentration C of the aqueous phase, i.e., the effluent, in step (1) is... 水相硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q in mg / day; when the concentration of nitrate nitrogen in the aqueous phase, i.e., the effluent, in step (1) is C 水相硝态氮 When the sulfur source concentration is ≥20 mg / L, the dosage Q is... a =C 出水硝态氮 ×8×Q in mg / day;

[0064] In step (3), the flow rate of sludge returned to the anoxic II zone is 0.14 to 0.18 L / day.

[0065] Compared with the prior art, the present invention has at least the following beneficial effects:

[0066] (1) The side-flow reaction device for deep denitrification of wastewater and in-situ sludge reduction provided by the present invention promotes the return of sludge from the middle and upper parts to the bottom by adding a stirrer on the side wall of the reactor body, and provides sludge disturbance to ensure that the sludge phase and water phase in the device are mixed evenly, which is more conducive to the full contact between microorganisms and reaction substrates; at the same time, the design of aeration components and sealing components allows aeration to provide dissolved oxygen required for the growth of sulfur autotrophic bacteria, and sealing to provide an anaerobic environment for the sulfur autotrophic denitrification process, providing a growth environment for sulfur autotrophic bacteria, thereby promoting the sulfur autotrophic denitrification process in low C / N wastewater, and accelerating the degradation of organic components in sludge. It not only achieves in-situ sludge reduction, but also releases endogenous carbon sources to supply heterotrophic denitrifying bacteria in the anoxic zone of the AOAO mainstream process for heterotrophic denitrification.

[0067] (2) The wastewater deep denitrification and in-situ sludge reduction device provided by the present invention adds the side flow reaction device at the side flow of the AOAO process device and couples the two to treat low C / N wastewater. It can achieve deep denitrification and in-situ sludge reduction at the same time. The device is simple to operate, occupies a small area, and is conducive to practical application.

[0068] (3) The method for deep denitrification of wastewater combined with in-situ sludge reduction provided by the present invention is to couple the above-mentioned side-flow reaction device with the AOAO process, and introduce a sulfur source into the side-flow reaction device to promote sulfur cycling, generate polymorphic sulfur sources, and promote the sulfur autotrophic denitrification process; at the same time, it degrades the organic components in the sludge, realizes sludge reduction and releases endogenous carbon sources; and then feeds the sludge treated by the side-flow reaction device back to the AOAO process, so that the heterotrophic denitrifying bacteria in the anoxic zone of the AOAO process can not only use the carbon sources in the wastewater for denitrification, but also use the sulfur autotrophic bacteria, polymorphic sulfur sources and endogenous carbon sources supplied by the sludge treated by the side-flow reaction device to carry out sulfur autotrophic-heterotrophic denitrification synergistic deep denitrification, thereby improving the denitrification efficiency; and finally achieve the effect of deep denitrification of low C / N wastewater combined with in-situ sludge reduction, with the total nitrogen concentration in the effluent being less than 10 mg / L and the sludge reduction rate being as high as 50% or more. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the process flow of the method for deep denitrification of wastewater combined with in-situ sludge reduction provided by the present invention.

[0070] Figure 2 This is a schematic diagram of the side-flow reaction device for deep denitrification of wastewater and in-situ sludge reduction provided by the present invention;

[0071] Figure 3 This is a trend graph showing the change of ammonia nitrogen concentration in the influent and effluent over time in the methods provided in Examples 1-2 and Comparative Examples 1-2 of the present invention.

[0072] Figure 4 This is a trend graph showing the change of nitrate nitrogen concentration in the effluent over time according to the methods provided in Examples 1-2 and Comparative Examples 1-2 of the present invention.

[0073] Figure 5 This is a trend graph showing the change of effluent COD concentration over time in the methods provided in Examples 1-2 and Comparative Examples 1-2 of the present invention.

[0074] Figure 6 This is a graph showing the change in the concentration of suspended solids in the mixture as a function of the amount of organic matter consumed in the methods provided in Embodiment 1 and Comparative Example 1 of the present invention.

[0075] Figure 7 The S in the side-flow reaction device in the method provided in Embodiment 1 of the present invention is...2- SO4 2- And a graph showing changes in COD concentration;

[0076] Figure 8 This is a transmission electron microscope image of the sludge phase in the method provided in Embodiment 1 of the present invention;

[0077] Figure 9 In the side-flow reaction device described in the method provided in Embodiment 1 of the present invention, the DOM protein component flows with S 2- Concentration trend graph;

[0078] Figure 10 In the side-flow reaction device described in the method provided in Embodiment 1 of the present invention, the DOM protein component is carried by SO4. 2- Concentration trend graph;

[0079] Figure 11 This is a graph showing the change in the total concentration of extracellular polymeric components in the feed and discharge sludge of the side-flow reaction device described in Embodiment 1 of the present invention.

[0080] Figure 12 This is a diagram showing the horizontal community distribution of bacteria in the side-flow reaction device and the AOAO process described in Embodiment 1 and Comparative Example 1 of the present invention.

[0081] In the diagram: 1. Reactor body; 2. Feed inlet; 3. First feed pipe; 4. Second feed pipe; 5. Discharge outlet; 6. Discharge pipe; 7. Aeration components; 8. Aeration pipe; 801. First aeration pipe; 802. Second aeration pipe; 9. Aeration disc; 10. Sealing components; 11. Agitator; 12. Exhaust port; 13. Inspection port. Detailed Implementation

[0082] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0083] In the following examples and comparative examples, sodium acetate, glucose and peptone were used as a composite carbon source, and ammonium chloride and potassium dihydrogen phosphate were used as N and P pollutants in simulated domestic sewage, wherein the influent C / N ratio of the simulated domestic sewage was 2.

[0084] The aeration components of the side-flow reaction device described in the following examples and comparative examples adopt an intermittent aeration mode, with an aeration time of 5 minutes every 4 hours. During operation, the dissolved oxygen in the device is controlled to maintain a concentration of 0.8–1.2 mg / L by controlling the gas flow rate.

[0085] The AOAO process apparatus used in the following embodiments and comparative examples includes a biological treatment tank and a sedimentation tank; the biological treatment tank includes an anoxic zone I, an aerobic zone I, an anoxic zone II, and an aerobic zone II that are connected in sequence and communicate with each other; the sedimentation tank is connected to the side of the biological treatment tank near the aerobic zone II; the sedimentation tank is provided with an outlet and a sludge outlet.

[0086] The bottom of the sedimentation tank is connected to the anoxic zone I of the biochemical treatment tank via a first sludge return pipeline.

[0087] The bottom of the sedimentation tank is connected to the first feed pipe of the side-flow reaction device through a second sludge return pipe; the discharge pipe of the side-flow reaction device is connected to the anoxic zone II of the biochemical treatment tank through a third sludge return pipe.

[0088] The hypoxia-deficient zone I and hypoxia-deficient zone II are equipped with polyurethane sponge fillers.

[0089] I. Implementation Examples

[0090] Example 1

[0091] This embodiment provides a method for deep denitrification of wastewater combined with in-situ sludge reduction. The method involves adding a device such as... at the side flow of the AOAO process unit. Figure 2 The side-flow reaction apparatus shown is used in the process;

[0092] The side-flow reaction device includes a reactor body 1; an inlet 2 is provided on the side wall near the bottom of the reactor body 1 for sludge and sulfur source to enter, the sulfur source being a Na2S2O3 solution; a first feed pipe 3 extends outward from the inlet 2 from the reactor body 1 for sludge to enter; a second feed pipe 4 extends from the first feed pipe 3 for sulfur source to enter; an outlet 5 is provided on the side wall near the top of the reactor body 1; an outlet pipe 6 extends outward from the outlet 5 from the reactor body 1; an aeration component 7 is provided inside the reactor body 1; the aeration component 7 includes an aeration pipe 8 and an aeration disc 9 disposed on the aeration pipe 8; the aeration pipe 8 includes an aeration disc 9 disposed on the aeration pipe 8. The reactor body 1 has a first aeration pipe 801 at the bottom and a second aeration pipe 802 perpendicular to the first aeration pipe 801, and the first aeration pipe 801 and the second aeration pipe 802 are connected; a sealing component 10 is provided at the top of the reactor body 1, and the sealing component 10 is a top sealing cover; the second aeration pipe 802 extends through the sealing component 10 away from the reactor body 1 to connect to an air supply component to supply air to the aeration component 7, and the air supply component is a blower; an exhaust port 12 is provided on the sealing component 10; an agitator 11 is provided on the side wall of the reactor body 1; the agitator 11 is a hydraulic agitator; and an inspection port 13 is also provided on the sealing component 10.

[0093] The method includes the following steps:

[0094] (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained.

[0095] (2) The Na2S2O3 solution and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction, and sludge rich in polymorphic sulfur sources and endogenous carbon sources is obtained.

[0096] (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification.

[0097] In step (1), the average ammonia nitrogen concentration of the influent wastewater is 86.6 mg / L; the influent flow rate of the wastewater is Q. in The reflux rate is 11 L / day; the reflux rate of the nitrification liquid is Q. n The influent flow rate Q of the wastewater in 250%; the flow direction of the sludge phase also includes recirculation to the anoxic zone I and discharge; the recirculation flow rate Q of the sludge phase recirculated to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 80%;

[0098] In step (2), the inflow rate of the sludge phase transported to the side-flow reactor is Q. t The concentration is 0.16 L / day; the hydraulic residence time of the side-flow reaction device is 5 days; the polymorphic sulfur source includes S 2- S2O3 2- and bio-S 0 When the nitrate nitrogen concentration C of the aqueous phase, i.e., the effluent, in step (1) is... 水相硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q in mg / day; when the concentration of nitrate nitrogen in the aqueous phase, i.e., the effluent, in step (1) is C 水相硝态氮 When the sulfur source concentration is ≥20 mg / L, the dosage Q is... a =C 出水硝态氮 ×8×Q in mg / day;

[0099] In step (3), the flow rate of sludge returned to the anoxic II zone is 0.16 L / day.

[0100] Example 2

[0101] This embodiment provides a method for deep denitrification of wastewater combined with in-situ sludge reduction, and the method is carried out using the same apparatus as in Embodiment 1;

[0102] The method includes the following steps:

[0103] (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained.

[0104] (2) The Na2S2O3 solution and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction, and sludge rich in polymorphic sulfur sources and endogenous carbon sources is obtained.

[0105] (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification.

[0106] In step (1), the average ammonia nitrogen concentration of the influent wastewater is 42.1 mg / L; the influent flow rate of the wastewater is Q. in The reflux rate is 10L / day; the reflux rate of the nitrification liquid is Q. n The influent flow rate Q of the wastewater in 300%; the flow direction of the sludge phase also includes recirculation to the anoxic zone I and discharge; the recirculation flow rate Q of the sludge phase recirculated to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 70%;

[0107] In step (2), the inflow rate of the sludge phase transported to the side-flow reactor is Q. t The concentration is 0.14 L / day; the hydraulic residence time of the side-flow reaction device is 4 days; the polymorphic sulfur source includes S 2- S2O3 2- and bio-S 0 When the nitrate nitrogen concentration C of the aqueous phase, i.e., the effluent, in step (1) is... 水相硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q in mg / day; when the concentration of nitrate nitrogen in the aqueous phase, i.e., the effluent, in step (1) is C 水相硝态氮 When the sulfur source concentration is ≥20 mg / L, the dosage Q is... a =C 出水硝态氮 ×8×Q in mg / day;

[0108] In step (3), the flow rate of sludge returned to the anoxic II zone is 0.14 L / day.

[0109] Example 3

[0110] This embodiment provides a method for deep denitrification of wastewater combined with in-situ sludge reduction, and the method is carried out using the same apparatus as in Embodiment 1;

[0111] The method includes the following steps:

[0112] (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained.

[0113] (2) The Na2S2O3 solution and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction, and sludge rich in polymorphic sulfur sources and endogenous carbon sources is obtained.

[0114] (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification.

[0115] In step (1), the average ammonia nitrogen concentration of the influent wastewater is 60.3 mg / L; the influent flow rate of the wastewater is Q. in The reflux rate is 12L / day; the reflux rate of the nitrification liquid is Q. n The influent flow rate Q of the wastewater in 200%; the flow direction of the sludge phase also includes recirculation to the anoxic zone I and discharge; the recirculation flow rate Q of the sludge phase recirculated to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 60%;

[0116] In step (2), the inflow rate of the sludge phase transported to the side-flow reactor is Q. t The concentration is 0.18 L / day; the hydraulic residence time of the side-flow reaction device is 4 days; the polymorphic sulfur source includes S 2- S2O3 2- and bio-S 0 When the nitrate nitrogen concentration C of the aqueous phase, i.e., the effluent, in step (1) is... 水相硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q in mg / day; when the concentration of nitrate nitrogen in the aqueous phase, i.e., the effluent, in step (1) is C 水相硝态氮 When the sulfur source concentration is ≥20 mg / L, the dosage Q is... a =C 出水硝态氮 ×8×Q in mg / day;

[0117] In step (3), the flow rate of sludge returned to the anoxic II zone is 0.18 L / day.

[0118] Example 4

[0119] This embodiment provides a method for deep denitrification of wastewater in conjunction with in-situ sludge reduction. Except for the use of Na2S solution as the sulfur source, the method is the same as that in Example 1.

[0120] Example 5

[0121] This embodiment provides a method for deep denitrification of wastewater in conjunction with in-situ sludge reduction. Except for the hydraulic retention time of the side-flow reaction device being 0.5 days, the method is the same as that in Embodiment 1.

[0122] Example 6

[0123] This embodiment provides a method for deep denitrification of wastewater in conjunction with in-situ sludge reduction. Except for the hydraulic retention time of the side-flow reaction device being 7 days, the method is the same as that in Embodiment 1.

[0124] II. Comparative Example

[0125] Comparative Example 1

[0126] This comparative example provides a method for deep denitrification of wastewater in conjunction with in-situ sludge reduction. Except for the use of an AOAO process device without a side-flow reaction device, the method is the same as in Example 1.

[0127] Comparative Example 2

[0128] This comparative example provides a method for deep denitrification of wastewater in conjunction with in-situ sludge reduction. Except for the use of an AOAO process device without a side-flow reaction device, the method is the same as in Example 2.

[0129] Comparative Example 3

[0130] This comparative example provides a method for deep denitrification of wastewater combined with in-situ sludge reduction. Except for the use of an AOAO process device without a side-flow reaction device, the method is the same as in Example 3.

[0131] III. Tests and Results

[0132] ① Verify the characteristics of deep denitrification:

[0133] i. After the system has been running for 80 days, the influent and effluent ammonia nitrogen concentrations and effluent nitrate nitrogen concentrations in the above embodiments and comparative examples were recorded. The ammonia nitrogen removal rate and total nitrogen removal rate were calculated after the system had been running for 80 days. The results are shown in Table 1.

[0134] Table 1

[0135]

[0136]

[0137] As shown in Table 1:

[0138] (1) As can be seen from Examples 1 to 3, the method of the present invention is carried out by using a device that couples a side-flow reaction device with an AOAO process device, and by introducing a specific sulfur source into the side-flow reaction device and using specific operating parameters, a deep denitrification effect is achieved, the denitrification efficiency is improved, the ammonia nitrogen removal rate is as high as 96.4% or more, and the total nitrogen removal rate is as high as 72.9% or more.

[0139] (2) As can be seen from Examples 1 and 4, since the sulfur source used in Example 4 is Na2S solution, the ammonia nitrogen oxidation process and heterotrophic denitrification process are inhibited, and the ammonia nitrogen removal rate is only 95.2% and the total nitrogen removal rate is only 82.7%. Therefore, it can be seen that the present invention further preferably uses thiosulfate solution as sulfur source, which further improves the denitrification efficiency.

[0140] (3) As can be seen from Examples 1 and 5-6, the short hydraulic residence time of the side-flow reaction device in Example 5 resulted in limited proliferation of sulfur autotrophic denitrifying bacteria, and the total nitrogen removal rate was only 77.8%. The long hydraulic residence time of the side-flow reaction device in Example 6 resulted in excessive device volume, but no improvement in denitrification efficiency. Therefore, it can be seen that the present invention further optimizes the hydraulic residence time of the side-flow reaction device to 1-5 days, which further improves the deep denitrification effect.

[0141] (4) As can be seen from Example 1 and Comparative Examples 1 to 3, since no side-flow reaction device was added in Comparative Examples 1 to 3, the ammonia nitrogen removal rate was significantly reduced. This shows that the method of the present invention couples the AOAO process with the corresponding side-flow reaction device for wastewater treatment, realizes the synergistic denitrification of sulfur autotrophic heterotrophic denitrification, and improves the denitrification efficiency.

[0142] ii. Simultaneously plot the trend graphs of influent and effluent ammonia nitrogen concentration and effluent nitrate nitrogen concentration over time in Examples 1-2 and Comparative Examples 1-2. The results are as follows: Figure 3 and Figure 4 As shown;

[0143] Depend on Figure 3 and Figure 4 It can be seen that the ammonia nitrogen concentration and nitrate nitrogen concentration in Example 1 are significantly lower than those in Comparative Example 1, and the ammonia nitrogen concentration and nitrate nitrogen concentration in Example 2 are significantly lower than those in Comparative Example 2. This further illustrates that by adding a corresponding side-flow reaction device at the side-flow of the AOAO process, the present invention improves the removal rate of ammonia nitrogen and nitrate nitrogen in wastewater and achieves a deep denitrification effect.

[0144] ②Verify efficient organic matter removal:

[0145] The influent organic matter (COD) concentration and effluent COD concentration in Examples 1-2 and Comparative Examples 1-2 were tested, and the COD removal rate was calculated.

[0146] The results are as follows: In Example 1, the influent COD concentration was 200.4 mg / L and the effluent COD concentration was 15.4 mg / L, with a COD removal rate of 92.3%; while in Comparative Example 1, the influent COD concentration was 200.4 mg / L and the effluent COD concentration was 17.0 mg / L, with a COD removal rate of 91.5%. Compared to Comparative Example 1, the effluent COD concentration in Example 1 decreased by 9.4%. In Example 2, the influent COD concentration was 102.7 mg / L and the effluent COD concentration was 11.6 mg / L, with a COD removal rate of 88.7%; while in Comparative Example 2, the influent COD concentration was 102.7 mg / L and the effluent COD concentration was 18.1 mg / L, with a COD removal rate of 82.4%. Compared to Comparative Example 2, the effluent COD concentration in Example 2 decreased by 35.9%.

[0147] Simultaneously, the changes in COD concentration of the influent and effluent over time were recorded in Example 1 and Comparative Example 1, as well as Example 2 and Comparative Example 2, and trend graphs were plotted. The results are as follows: Figure 5 As shown;

[0148] Depend on Figure 5 It can be seen that, compared with Comparative Example 1, the effluent COD concentration in Example 1 is significantly lower, and compared with Comparative Example 2, the effluent COD concentration in Example 2 is also significantly reduced, indicating that the carbon source in the wastewater is efficiently utilized, and the efficient removal of organic matter by the AOAO process is achieved, that is, the heterotrophic denitrification process is enhanced.

[0149] This demonstrates that by adding the aforementioned side-flow reaction device at the side-flow point of the AOAO process during the low C / N wastewater treatment process, not only is the sulfur autotrophic denitrification process realized, but the heterotrophic denitrification process is also enhanced, achieving bidirectional promotion of autotrophic and heterotrophic processes.

[0150] ③ Verify efficient in-situ sludge reduction:

[0151] The cumulative calculation of the variation of the mixed liquor suspended solids concentration (MLSS) in Example 1 and Comparative Example 1 with the increase and consumption of organic matter (COD) in the system was performed, and the results are as follows: Figure 6 As shown;

[0152] Depend on Figure 6 It can be seen that the apparent sludge growth rate in Example 1 was 0.0962g. MLSS / g COD In Comparative Example 1, the apparent sludge growth rate was 0.2499 g. MLSS / g CODThis indicates that the addition of the side-flow reaction device achieves deep denitrification through synergistic autotrophic and heterotrophic denitrification of sulfur, while promoting efficient reduction of in-situ sludge, with an in-situ sludge reduction rate of up to 61.5%.

[0153] The in-situ sludge reduction rate in Examples 2 and 3 was tested using the same method. The in-situ sludge reduction rate in Example 2 was as high as 58.5%, and the in-situ sludge reduction rate in Example 3 was as high as 52.2%.

[0154] ④ Verify the polymorphic sulfur electrons and endogenous carbon supply:

[0155] The S at the inlet and outlet of the side-flow reaction device described in Test Example 1 2- SO4 2- And COD concentration, the results are as follows Figure 7 As shown;

[0156] Depend on Figure 7 It can be seen that at the feed inlet S of the side-flow reaction device 2- Concentration of 0 mg / L, SO4 2- The concentration is 500 mg / L, and the discharge port S of the device... 2- Concentrations can reach 18.0 mg / L, SO4 2- The concentration can reach 1400 mg / L, indicating that the introduction of a sulfur source into the side-flow reactor promotes sulfur circulation within the reactor, and not only carries out sulfur oxidation (SO4) 2- The generation of sulfur (S) also promotes sulfur reduction (S). 2- (the generation of); at the same time, such as Figure 8 As shown, bio-sulfur (bio-S) was observed in the sludge phase. 0 The electrons are discharged outside the biofilm, indicating that the addition of the side-flow reaction device generates polymorphic sulfur electrons, which flow back to the anoxic II zone as donors for sulfur autotrophic denitrification.

[0157] Moreover, the COD concentration at the inlet of the side-flow reaction device is about 18 mg / L, and the COD concentration at the outlet can reach 105 mg / L, which is 82.9% higher than the COD concentration. This indicates that the degradation of organic matter in the sludge not only promotes the reduction of organic solids in the sludge, but also facilitates the self-sufficiency of organic carbon source in low C / N wastewater, that is, returning it to the heterotrophic denitrifying bacteria in the anoxic II zone to utilize the organic carbon source supplied by the device for heterotrophic denitrification.

[0158] In summary, the side-flow reaction device can supply polymorphic sulfur electrons and endogenous carbon source donors, thus enabling deep denitrification and sludge reduction to be synergistically achieved in the mainstream AOAO process.

[0159] ⑤ Verify the reduction of organic components in in-situ sludge:

[0160] Synchronous fluorescence spectroscopy was used to observe the DOM protein composition in the side-flow reactor as a function of S. 2- and SO4 2- The trend of increasing concentration is shown in the following figures. Figure 9 (S 2- )and Figure 10 (SO4 2- As shown in the figure;

[0161] Depend on Figure 9 and Figure 10 It can be seen that: with S 2- and SO4 2- The increase in concentration led to a significant increase in DOM protein components observed by synchronous fluorescence spectroscopy, indicating that endogenous organic matter was effectively converted into protein-like DOM that can be degraded by microorganisms, and further utilized by heterotrophic denitrifying bacteria to enhance endogenous denitrification.

[0162] Simultaneously, the influence of the multi-state sulfur source generation process on the changes in extracellular polymer concentration in the sludge before and after the side-flow reactor was investigated, and the results are as follows: Figure 11 As shown;

[0163] Depend on Figure 11 It is known that the total concentration of extracellular polymeric substances in the feed sludge of the side-flow reactor is 30.3 mg / g. MLSS (Total concentration of polysaccharides, proteins, and DNA) The total concentration of extracellular polymers in the discharged sludge was 14.9 mg / g. MLSS The total concentration of polysaccharides, proteins, and DNA decreased by 50.8%, which explains... Figure 7 The reason for the increase in COD concentration is that the extracellular polymers in the sludge responded positively to the introduction of polymorphic sulfur sources and ultimately fed back to the AOAO anoxic II zone in the form of DOM, promoting the heterotrophic denitrification process in the anoxic II zone.

[0164] ⑥ Verify the stable formation of denitrifying bacterial communities:

[0165] The bacterial genus-level community structure of the lateral flow reaction device, anoxic zone I, aerobic zone I, anoxic zone II, and aerobic zone II described in Example 1 and Comparative Example 1 was investigated, and the abundance of the corresponding bacteria was tested using 16S rRNA gene sequencing; the results are as follows. Figure 12 As shown;

[0166] Thiobacillus and Sulfurimonas are two representative sulfur-oxidizing bacteria (SOBs) that play a key role in reducing nitrates and nitrites in the mainstream AOAO in Example 1 by oxidizing the polymorphic sulfur source provided in the side-flow reactor. Thaurea is a unique bacterium that can utilize carbon and sulfur sources to generate electrons for nitrate reduction. Dokdonella, Ferruginibacter, and Terrimonas are representative heterotrophic denitrifying bacteria (HDBs) that can utilize carbon sources for denitrification.

[0167] Depend on Figure 12 It can be seen that in the side-flow reaction device, the relative abundance of Thiobacillus and Thiomonas is 12.2% and 2.7%, respectively, while the average abundance of Terreosomes and Thiomonas in the mainstream AOAO of Example 1 is 6.2% and 0.9%, respectively. Compared with the total relative abundance of Thiobacillus and Thiomonas in Comparative Example 1, which is less than 0.2%, the accumulation of Thiobacillus and Thiomonas in Example 1 is higher.

[0168] In Example 1 and Comparative Example 1, the relative abundance of Tauella in the mainstream AOAO was 0.36% and 0.19%, respectively. It can be seen that the abundance of bacteria related to carbon-driven denitrification was higher in Example 1, which is similar to SOB.

[0169] The relative abundances of *Gynostemma pentaphyllum*, *Isophytes* and *Monopterus* in the mainstream AOAO of Example 1 were 6.5%, 3.9% and 5.5%, respectively, which were 3.1%, 1.3% and 3.2% higher than those in Comparative Example 1. This indicates that HDB more effectively utilizes potential endogenous carbon sources and provides sufficient material and energy for anabolism.

[0170] The main SOBs and HDBs are mostly facultative bacteria, and the presence of molecular oxygen in the surrounding environment promotes ATP production, thereby stimulating their growth. Therefore, the proportion of bacteria in the aerobic zone is higher than in the anoxic zone. However, a significant difference in the growth trends of SOBs and HDBs was observed in the lateral flow reactor, due to the presence of sufficient sulfur electron donors and exposure to various electron acceptors (i.e., NO3-). -In terms of dissolved oxygen (SOB), SOB has more opportunities to multiply in the device; in contrast, HDB exhibits obvious decay characteristics and a decrease in relative abundance in the absence of exogenous carbon sources, which further leads to sludge reduction. This also promotes a large increase in SOB in the equipment, thereby stabilizing the stable growth of SOB in the mainstream AOAO process in Example 1. That is, the main growth site of SOB is in the side-flow reactor, while the main growth site of HDB is in the mainstream AOAO process. This also promotes the formation of the sulfur autotrophic-heterotrophic deep denitrification mode and the stable realization of in-situ sludge reduction.

[0171] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for deep denitrification of wastewater combined with in-situ sludge reduction, characterized in that, The method includes the following steps: (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained. (2) The sulfur source and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction to obtain sludge rich in polymorphic sulfur source and endogenous carbon source. (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification; The method employs the following device for deep wastewater denitrification combined with in-situ sludge reduction: The device for deep denitrification of wastewater and in-situ sludge reduction includes an AOAO process device and the following side-flow reaction device for deep denitrification of wastewater and in-situ sludge reduction. The side-flow reaction device includes a reactor body; an inlet is provided on the side wall near the bottom of the reactor body for sludge and sulfur source to enter; and an outlet is provided on the side wall near the top of the reactor body. The reactor body is equipped with an aeration component; The aeration component includes an aeration pipe and an aeration disc disposed on the aeration pipe; A sealing component is provided on the top of the reactor body; an exhaust port is provided on the sealing component; A stirrer is installed on the side wall of the reactor body; The aeration pipe includes a first aeration pipe disposed at the bottom of the reactor body and a second aeration pipe perpendicular to the first aeration pipe, and the first aeration pipe and the second aeration pipe are connected. The second aeration pipe extends through the sealing component on the side away from the reactor body to connect to the air supply component and supply air to the aeration component; The sealing component is also provided with an inspection port; The AOAO process device includes a biological treatment tank and a sedimentation tank; the biological treatment tank includes an anoxic zone I, an aerobic zone I, an anoxic zone II, and an aerobic zone II that are connected in sequence and communicate with each other; the sedimentation tank is connected to the side of the biological treatment tank near the aerobic zone II; the sedimentation tank is provided with an outlet and a sludge outlet.

2. The method according to claim 1, characterized in that, The reactor body extends outward from the inlet to form a first feed pipe for sludge to enter.

3. The method according to claim 2, characterized in that, A second feed pipe extends from the first feed pipe for the sulfur source to enter.

4. The method according to claim 1, characterized in that, The reactor body extends outward from the discharge port into a discharge pipe.

5. The method according to claim 1, characterized in that, The bottom of the sedimentation tank is connected to the anoxic zone I of the biochemical treatment tank via a first sludge return pipeline.

6. The method according to claim 1, characterized in that, The bottom of the sedimentation tank is connected to the first feed pipe of the side-flow reactor via a second sludge return pipe; the discharge pipe of the side-flow reactor is connected to the anoxic zone II of the biochemical treatment tank via a third sludge return pipe.

7. The method according to claim 1, characterized in that, The anoxic zone I and anoxic zone II are equipped with solid suspended packing material for the aggregation of functional bacteria.

8. The method according to claim 7, characterized in that, The solid suspension filler includes any one or a combination of at least two of polyurethane sponge fillers, high-density polyethylene fillers, or porous polypropylene fillers.

9. The method according to claim 1, characterized in that, The influent flow rate Q of the wastewater in step (1) in It is 10~12L / day.

10. The method according to claim 1, characterized in that, The reflux flow rate Q of the nitrification liquid in step (1) n The influent flow rate Q of the wastewater in 100%~350%.

11. The method according to claim 10, characterized in that, The reflux flow rate Q of the nitrification liquid in step (1) n The influent flow rate Q of the wastewater in 200%~300%.

12. The method according to claim 1, characterized in that, The flow direction of the sludge phase in step (1) also includes recirculation to the anoxic zone I and / or discharge.

13. The method according to claim 1, characterized in that, The reflux rate Q of the sludge phase returned to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 50-80%.

14. The method according to claim 1, characterized in that, The inflow rate of the sludge phase transported to the side-flow reactor in step (2) is Q. t It is 0.14~0.18L / day.

15. The method according to claim 1, characterized in that, The sulfur source in step (2) includes a thiosulfate solution and / or a solution containing S. 2- A salt solution.

16. The method according to claim 15, characterized in that, The sulfur source in step (2) is a thiosulfate solution.

17. The method according to claim 1, characterized in that, The polymorphic sulfur source in step (2) includes S 2- S2O3 2- or S 0 Any one or at least two of them.

18. The method according to claim 1, characterized in that, When the nitrate nitrogen concentration C of the aqueous phase in step (1) 水相硝态氮 When the concentration is <20 mg / L, the amount of sulfur source Q added in step (2) is... a =160Q in mg / day.

19. The method according to claim 1, characterized in that, When the concentration C of nitrate nitrogen in the aqueous phase in step (1) 水相硝态氮 When the concentration is ≥20 mg / L, the amount of sulfur source added in step (2) is Q. a =C 出水硝态氮 ×8×Q in mg / day.

20. The method according to claim 1, characterized in that, The flow rate of sludge returned to the anoxic II zone in step (3) is 0.14~0.18L / day.

21. The method according to claim 1, characterized in that, The method includes the following steps: (1) Wastewater is first fed into the aerobic zone to undergo nitrification to obtain nitrified liquid, and then returned to the anoxic I zone for heterotrophic denitrification. After sedimentation, sludge phase and water phase are obtained. (2) The sulfur source and the sludge phase described in step (1) are transported to the side-flow reaction device to carry out sulfur autotrophic denitrification and sludge degradation reaction to obtain sludge rich in polymorphic sulfur source and endogenous carbon source. (3) The sludge rich in polymorphic sulfur sources and endogenous carbon sources described in step (2) is returned to the anoxic II zone to carry out sulfur autotrophic-heterotrophic denitrification synergistic denitrification; In step (1), the influent flow rate Q of the wastewater is... in The reflux rate is 10-12 L / day; the reflux rate of the nitrification liquid is Q. n The influent flow rate Q of the wastewater in 100%~350%; the flow direction of the sludge phase also includes recirculation to the anoxic zone I and / or discharge; the recirculation flow rate Q of the sludge phase recirculated to the anoxic zone I in step (1) s The influent flow rate Q of the wastewater in 50-80%; In step (2), the inflow rate of the sludge phase transported to the side-flow reactor is Q. t The concentration is 0.14~0.18 L / day; the sulfur source includes thiosulfate solution and / or sulfur-containing solutions. 2- A salt solution; the polymorphic sulfur source includes S 2- S2O3 2- or S 0 Any one or at least two of the following; when the nitrate nitrogen concentration C of the aqueous phase in step (1) is... 水相硝态氮 When the concentration of sulfur source is <20 mg / L, the dosage Q of the sulfur source is... a =160Q in mg / day; when the concentration of nitrate nitrogen in the aqueous phase of step (1) is C 水相硝态氮 When the sulfur source concentration is ≥20 mg / L, the dosage Q is... a =C 出水硝态氮 ×8×Q in mg / day; In step (3), the flow rate of sludge returned to the anoxic II zone is 0.14~0.18L / day.

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