Sewage denitrification and improvement combined process and device for efficiently utilizing side flow of carbon source in sludge

Abstract

The invention relates to a sewage denitrification lifting combined process and device capable of efficiently utilizing side flow of a carbon source in sludge, a side flow anoxic tank is additionally arranged on the basis of an original sewage treatment process, and the carbon source utilization rate and denitrification efficiency of the side flow tank are improved through external reflux of the sludge; and on the other hand, the extraction efficiency of a carbon source in the sludge is optimized, and a low-temperature and short-residence-time sludge acid production fermentation technology is realized through precise adjustment of pre-concentration and alkali type compounding. According to the sewage denitrification and improvement combined process, the purchasing cost of a chemical carbon source of a traditional denitrification process is saved, rear-end sludge reduction is achieved, unnecessary energy consumption and carbon emission are reduced through organic combination of two process links, meanwhile, the process characteristics of engineering connection and transformation are achieved, and the combined process technology is mature and reliable.

Description

Technical Field

[0001] This invention relates to the fields of sludge treatment and wastewater treatment, and in particular to a combined process and apparatus for wastewater denitrification enhancement that efficiently utilizes carbon sources within sludge via side flow. Background Technology

[0002] Currently, biological treatment is widely considered the most economical and effective method for removing nitrate pollutants from water. Under the action of microorganisms, organic nitrogen and ammonia nitrogen are converted into nitrite and nitrate nitrogen through nitrification, and then nitrate is reduced to nitrogen gas and released into the atmosphere through denitrification. Urban wastewater in my country has relatively low carbon and nitrogen content. To ensure denitrification efficiency, additional carbon sources are usually added, increasing the operating costs of wastewater treatment plants. Because denitrifying bacteria are heterotrophic microorganisms with a rapid growth rate, traditional denitrification processes and their improved versions incur corresponding costs in the external carbon source stage, objectively leading to an increase in sludge volume. Sludge treatment and disposal are increasingly becoming a serious burden on urban wastewater treatment plants. 30% to 50% of the carbon sources added for denitrification, along with the COD of the influent itself, enter the excess sludge. Therefore, sludge treatment and disposal technologies, while adhering to the basic requirements of "reduction, stabilization, and harmlessness," are increasingly emphasizing the need for "resource recovery." There is a lot of research on the utilization of carbon sources in municipal sludge, most of which focuses on the comparison and selection of pretreatment technologies that can efficiently promote sludge hydrolysis, as well as the refined control strategies for acid production processes. The research direction is mainly to reveal the mechanism of new technologies, but there is still a gap in the detailed methods of the engineering application of sludge acid production fermentation and the connection between the process and the transformation of existing sewage treatment processes.

[0003] In view of the above, there is an urgent need to develop a combined wastewater denitrification enhancement process that takes into account both engineering transformation and process integration, and can efficiently utilize the carbon source within the sludge. This process can efficiently obtain energy from sludge treatment and disposal and reduce unnecessary energy consumption and carbon emissions in the wastewater treatment process.

[0004] Patent CN 113060899 B discloses a method for reusing sludge from wastewater treatment plants to generate carbon sources. In this patent, a portion of the sludge from the secondary sedimentation tank / membrane tank is returned to the first tank of the biological nitrogen and phosphorus removal system or the very front end of the biological nitrogen and phosphorus removal system. The pretreatment reaction tank method involves adding any one of the following: oxidant, acid, alkali, oxidant + acid, or oxidant + alkali, to perform preliminary cell wall disruption. The oxidant is hydrogen peroxide, sodium hypochlorite, or ozone. Hydrochloric acid or sulfuric acid is added to control the pH at 2-7, and alkali is added to control the pH at 7-12. However, in this patent, on the one hand, the carbon source conversion path is lengthy, requiring pretreatment, side-flow hydrolysis and acidification, and multi-stage conversion in the main fermentation tank, resulting in low carbon source utilization. Furthermore, the main fermentation tank requires additional denitrification to remove nitrate nitrogen (a complex process). On the other hand, the sludge in the secondary sedimentation tank is diverted to four directions (mainstream fermentation tank, biological system front end, excess sludge tank, and side-flow pretreatment tank), without specifically enhancing the sludge concentration in the denitrification zone, thus limiting denitrification efficiency. In addition, the engineering connections of this patent are complex, and the operation and maintenance costs are high. The pretreatment agents are expensive and may produce toxic byproducts such as chloramines.

[0005] Patent CN 113929210 A discloses a device and method for enhancing the utilization of carbon sources and deep denitrification in mainstream urban wastewater through side-flow sludge fermentation to produce acid. 2 The outlet pipe (1.5) of the O system is connected to the secondary sedimentation tank (3), and the internal return pipe (1.6) is connected to A. 2 The O system is connected to the anoxic biofilm reaction zone (1.3). In this patent, the acidified mixture needs to be transferred through the sludge storage tank before being added, and it is only used as a supplementary electron donor. It does not directly enhance the core denitrification area, so the denitrification efficiency is still limited. Moreover, the system is complicated to start up: it requires enrichment of anaerobic ammonia-oxidizing bacteria (relative abundance ≥0.1%), and the biofilm cultivation is difficult. Summary of the Invention

[0006] The purpose of this invention is to provide a combined process and device for wastewater denitrification enhancement that efficiently utilizes carbon sources in sludge through side flow, thereby achieving efficient extraction of carbon sources from sludge, improving the utilization rate of carbon sources in sludge and the denitrification efficiency of wastewater, and reducing energy consumption and carbon emissions.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides a combined wastewater denitrification enhancement process for efficient utilization of carbon sources in sludge via side flow, comprising the following steps: S1: Introduce wastewater into the wastewater carbon source side-flow high-efficiency utilization system: it sequentially enters the wastewater treatment biological reaction tank and the wastewater treatment aerobic reaction tank for COD (chemical oxygen demand) removal and denitrification and phosphorus removal; after being treated in the wastewater treatment aerobic reaction tank, part of the wastewater enters the aerobic reaction tank O2, and the other part first enters the side-flow high-efficiency anoxic tank A2 for further denitrification, and then flows into the aerobic reaction tank O2 for further COD removal; S2: Wastewater treated by the aerobic reaction tank (O2) enters the sludge sedimentation and thickening system: First, sludge is obtained by preliminary sedimentation in the secondary sedimentation tank. Part of the sludge is returned to the side-flow high-efficiency anoxic tank (A2) to increase the sludge concentration therein. The other part of the sludge is concentrated in the gravity thickening tank and centrifugal thickener in sequence to make the sludge reach the concentration required for hydrolysis and acidification. S3: Sludge that reaches the concentration required for hydrolysis and acidification enters the sludge carbon source extraction system: First, sludge is pretreated by alkaline hydrolysis in the sludge hydrolysis tank, and then it enters the sludge acid-producing fermentation tank for acid-producing fermentation treatment of high-concentration hydrolyzed sludge. The fermented sludge obtained from the acid-producing fermentation treatment is processed by a plate and frame dewatering machine to prepare liquid sludge carbon source. S4: The carbon source in the liquid sludge is added to the wastewater treatment reaction tank through the influent carbon source replenishment pipe, and at the same time, the carbon source in the liquid sludge is added to the side-flow high-efficiency anoxic tank A2 through the A2 tank carbon source addition pipe.

[0008] Preferably, the process comprising the wastewater treatment biological reaction tank and the wastewater treatment aerobic reaction tank is AAO or AO or a derivative thereof.

[0009] More preferably, the AAO process refers to the anaerobic-anoxic-aerobic process, and the AO process refers to the anoxic-aerobic process.

[0010] Preferably, the aerobic reaction tank O2 is an independent aerobic reaction tank or is obtained by modifying and separating a wastewater treatment aerobic reaction tank.

[0011] Preferably, the flow measurement ratio of the side-flow high-efficiency anoxic tank A2 is 25%~75%, and the sludge return ratio is 50%~100%.

[0012] More preferably, the flow ratio refers to the proportion of water diverted from the main system to the side-flow high-efficiency anoxic pool A2.

[0013] More preferably, the mainstream system refers to the traditional system in which wastewater sequentially enters the wastewater treatment biological reaction tank, the wastewater treatment aerobic reaction tank, the aerobic reaction tank O2, and the sludge sedimentation and thickening system.

[0014] More preferably, the sludge return ratio refers to the proportion of sludge returned from the sedimentation tank (i.e., the secondary sedimentation tank) to the side-flow high-efficiency anoxic tank A2.

[0015] Preferably, the concentration required for the sludge to reach the level of hydrolysis and acidification refers to a water content of 95wt% to 90wt% in the sludge.

[0016] Preferably, the sludge acidification fermentation tank operates at a temperature of 20℃~60℃, and the sludge retention time is 5~10 days.

[0017] Preferably, the agent used in the sludge alkaline pretreatment in the sludge hydrolysis tank is a mixture of calcium alkali and non-calcium alkali, wherein the calcium alkali is one or more of calcium oxide, calcium hydroxide, and calcium peroxide, and the non-calcium alkali is one or more of sodium hydroxide and potassium hydroxide.

[0018] Preferably, when the calcium base is calcium hydroxide, the molar ratio of the calcium base to the non-calcium base compound is (1-9):1, and the dosage of the calcium base is 2wt%-6wt% of the dry sludge.

[0019] Preferably, the organic acid content of the carbon source in the liquid sludge accounts for 50% to 80% of the BOD5 (five-day biochemical oxygen demand), the C / N ratio (carbon-nitrogen ratio) is greater than 16, and the C / P ratio (carbon-phosphorus ratio) is greater than 200.

[0020] Preferably, the pressing pressure range of the plate and frame dewatering machine is 0.5-2.0 MPa.

[0021] The present invention also provides an apparatus for the wastewater denitrification enhancement combined process for the efficient utilization of carbon sources in the sludge side flow, comprising a wastewater carbon source side flow efficient utilization system, a sludge sedimentation and concentration system, and a sludge carbon source extraction system. The wastewater internal carbon source side-flow high-efficiency utilization system includes a wastewater treatment biological reaction tank, a wastewater treatment aerobic reaction tank, an aerobic reaction tank (O2), a side-flow high-efficiency anoxic tank (A2), a deep denitrification inlet pipeline, a first return pipe, and an outlet pipe; the sludge sedimentation and thickening system includes a secondary sedimentation tank, a second return pipe, a first sludge inlet pipe, a gravity thickener, a second sludge inlet pipe, a centrifugal thickener, and a third sludge inlet pipe; the sludge internal carbon source extraction system includes a sludge hydrolysis tank, a hydrolyzed sludge inlet pipe, a sludge acidification fermentation tank, a sludge discharge pipe, a plate and frame dewatering machine, an inlet carbon source replenishment pipe, and an A2 tank carbon source addition pipe; The wastewater treatment aerobic reactor is connected to the side-flow high-efficiency anoxic tank A2 via a deep denitrification inlet pipe. The side-flow high-efficiency anoxic tank A2 is connected to the aerobic reactor O2 via a first return pipe, and the aerobic reactor O2 is connected to the secondary sedimentation tank via an outlet pipe. The secondary sedimentation tank is connected to the side-flow high-efficiency anoxic tank A2 via a second return pipe and to the gravity thickener via a first sludge inlet pipe. The gravity thickener is connected to the centrifugal thickener via a second sludge inlet pipe. The centrifugal thickener is connected to the sludge hydrolysis tank via a third sludge inlet pipe. The sludge hydrolysis tank is connected to the sludge acidification fermentation tank via a hydrolyzed sludge inlet pipe, and the sludge acidification fermentation tank is connected to the plate and frame dewatering machine via a sludge discharge pipe. The plate and frame dewatering machine is connected to the wastewater treatment bioreactor via an inlet carbon source replenishment pipe and to the side-flow high-efficiency anoxic tank A2 via the carbon source addition pipe of tank A2.

[0022] Preferably, the wastewater denitrification enhancement combined process for efficient utilization of carbon sources in sludge via side flow includes the following steps: S1: In the wastewater carbon source side-flow high-efficiency utilization system, wastewater enters the wastewater treatment biological reaction tank and the wastewater treatment aerobic reaction tank for COD removal and denitrification and phosphorus removal. After being treated by the wastewater treatment aerobic reaction tank, part of the wastewater enters the aerobic reaction tank O2; the other part enters the A2 tank (i.e., the side-flow high-efficiency anoxic tank A2) through the deep denitrification inlet pipe for further denitrification. Finally, it flows into the O2 tank (i.e., the aerobic reaction tank O2) through the first return pipe for further COD removal, ensuring the quality of the effluent.

[0023] S2: The treated mixed liquor enters the sludge sedimentation and thickening system from the O2 tank. After preliminary sedimentation in the secondary sedimentation tank, part of the sludge is returned to the A2 tank to increase the sludge concentration, and part enters the gravity thickening tank and centrifugal thickener for further thickening to achieve the sludge concentration required for hydrolysis and acidification.

[0024] S3: The sludge after mechanical concentration (centrifugal concentration) enters the sludge carbon source extraction system through the third sludge inlet pipe. After the sludge is pretreated by alkaline hydrolysis in the sludge hydrolysis tank, it enters the sludge acid fermentation tank to start the acid fermentation of high-concentration hydrolyzed sludge. The fermented sludge is dewatered by a plate and frame dewatering machine to prepare liquid sludge carbon source.

[0025] S4: The carbon source in the liquid sludge is added to the wastewater treatment reactor and the A2 tank through the influent carbon source replenishment pipe and the A2 tank carbon source addition pipe.

[0026] This invention presents a combined wastewater denitrification enhancement process that efficiently utilizes carbon sources within sludge via side flow. It comprises three mutually reinforcing process systems, achieving improved wastewater denitrification through the efficient utilization of carbon sources within the sludge. The principle behind this process effect is as follows: (1) The existing wastewater treatment system was modified by adding an anoxic side-flow tank A2 as the core area for denitrification, which further reduced the nitrate nitrogen concentration in the wastewater. By increasing the sludge return from the secondary sedimentation tank to the A2 tank, the sludge concentration in the side-flow anoxic tank was increased, which further improved the denitrification efficiency and formed a high-efficiency utilization system for carbon sources in the wastewater. The carbon sources added to the A2 tank and the influent system are both carbon sources from the sludge.

[0027] (2) Carbon source extraction from sludge is achieved through alkaline acid-producing fermentation technology. A combination of calcium and non-calcium alkali is used for sludge hydrolysis and alkaline fermentation control. Calcium alkali reacts with phosphate to form a precipitate, which simultaneously serves as the framework for sludge dewatering, achieving simultaneous phosphorus removal and efficient dewatering. The addition of non-calcium alkali improves hydrolysis efficiency and increases the proportion of acetic acid in the fermentation broth, fully tapping the sludge's acid-producing fermentation potential and improving the C / N ratio and internal carbon source utilization efficiency. Therefore, the required operating temperature range can be as low as 20℃, and the required sludge retention time is short. By rationally controlling the ratio of alkali types, the organic acid content of the carbon source in the liquid sludge accounts for 50%~80% of BOD5, and the C / N ratio is greater than 16. No denitrification treatment of the carbon source in the liquid sludge is required, and the wastewater treatment process can directly absorb the total nitrogen in the fermentation broth.

[0028] (3) The main function of the sludge sedimentation and thickening system is to increase the sludge concentration in the anoxic tank A2 by a certain proportion of recirculation, thereby achieving efficient denitrification. On the other hand, the mechanical thickening of sludge further increases the sludge concentration, improves the efficiency of sludge hydrolysis and acidification, and reduces the land occupation and operation and maintenance costs of the carbon source extraction system in the sludge.

[0029] In summary, (1) the present invention achieves precise and efficient utilization by adding carbon sources at two points: the carbon source in the liquid sludge is added to the two core denitrification areas of the A2 tank and the biological reaction tank through the carbon source addition pipe in the A2 tank and the carbon source replenishment pipe in the influent, without having to go through a long conversion path (avoiding the problems of low carbon source utilization and complicated steps), which greatly improves the carbon source utilization efficiency and further ensures the denitrification effect.

[0030] (2) The present invention enhances denitrification by high proportion of sludge return: the sludge settled in the secondary sedimentation tank is directly returned to the A2 tank at a high proportion of 50%~100% through the second return pipe, which can specifically increase the sludge concentration in the core denitrification area of ​​the A2 tank, effectively enhance the denitrification efficiency, and avoid the problem of insufficient sludge concentration and limited denitrification efficiency in the denitrification zone caused by sludge diversion to multiple directions.

[0031] (3) The present invention uses calcium base to react with phosphate to generate precipitate. While efficiently removing phosphorus, the generated precipitate can be directly used as a dehydration skeleton without adding a large amount of highly corrosive agents. This avoids the risks of high agent cost, easy equipment corrosion and the generation of toxic byproducts such as chloramines, and balances the phosphorus removal effect with the economy and safety of system operation and maintenance.

[0032] (4) This invention improves hydrolysis efficiency by using non-calcium alkali, so that the sludge fermentation temperature can be as low as 20°C and the sludge retention time can be shortened to 5-10 days. It does not require the harsh conditions of maintaining high pH, ​​thus avoiding the problems of high energy consumption and complex control, significantly reducing energy consumption and operation difficulty, and improving fermentation efficiency.

[0033] (5) The organic acid content in the produced liquid carbon source is 50%~80%, and the C / N ratio is >16, so it can be directly reused without additional denitrification; at the same time, there is no need to enrich anaerobic ammonia oxidizing bacteria (requiring relative abundance ≥0.1%) or cultivate biofilm (avoiding the problem of complex and difficult system startup), simplifying the system operation process, reducing startup difficulty, and improving the convenience and practicality of carbon source reuse.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) The wastewater denitrification enhancement combined process of the present invention, which utilizes the carbon source in the sludge side flow efficiently, achieves efficient extraction of carbon source in the sludge through the synergistic effect of the wastewater carbon source side flow efficient utilization system, sludge sedimentation and concentration system and sludge carbon source extraction system. This not only improves the carbon source utilization rate of sludge and the denitrification efficiency of wastewater, but also reduces energy consumption and carbon emissions.

[0035] (2) The wastewater denitrification enhancement combined process of the present invention, which utilizes the carbon source in the sludge in the side flow, further reduces the nitrate nitrogen concentration in the wastewater by setting up a separate side flow anoxic tank, thereby improving the denitrification effect of the wastewater treatment process; at the same time, a return pipeline is set up between the side flow anoxic tank and the secondary sedimentation tank, so that part of the sludge obtained from the sedimentation in the secondary sedimentation tank is returned to the side flow anoxic tank, increasing the sludge concentration in the side flow anoxic tank and achieving efficient denitrification; the sludge hydrolysis and alkaline fermentation are controlled by the combination of calcium alkali and non-calcium alkali, achieving efficient acid production and phosphorus removal, while significantly reducing the water content of the dewatered sludge.

[0036] (3) The wastewater denitrification enhancement combined process of the present invention, which utilizes the carbon source in the sludge side flow for high efficiency, achieves direct reuse of the carbon source in the fermentation liquid without denitrification by reasonably controlling the hydrolysis and acid production process. The internal carbon source has higher denitrification efficiency than chemical carbon source.

[0037] (4) The wastewater denitrification enhancement combined process of the present invention, which utilizes the carbon source in the sludge side flow efficiently, realizes the wastewater denitrification process of utilizing the carbon source in the sludge side flow efficiently through the modification of the side flow tank and aerobic tank of the wastewater treatment process. It is suitable for engineering application and modification. The operation process of low-temperature fermentation of sludge is low-carbon and environmentally friendly, and optimizes the investment and construction cost of the overall combined process.

[0038] (5) This invention improves the quality of carbon source in liquid sludge by optimizing the acid-producing fermentation process of sludge, and reasonably connects and transforms the technology with the existing sewage treatment process. The amount of carbon source added in sludge can be flexibly adjusted according to the influent water quality and denitrification effect, filling the gap in the field of sewage denitrification process with efficient side flow utilization of carbon source in sludge. Attached Figure Description

[0039] Figure 1 This is a flowchart of the combined process of the present invention; In the diagram: 1-Sewage internal carbon source side-flow high-efficiency utilization system; 1.1-Sewage treatment biological reaction tank, 1.2-Sewage treatment aerobic reaction tank, 1.3-Aerobic reaction tank O2, 1.4-Side-flow high-efficiency anoxic tank A2, 1.5-Deep denitrification inlet pipe, 1.6-First return pipe, 1.7-Outlet pipe; 2-Sludge sedimentation and thickening system; 2.1-Second sedimentation tank, 2.2-Second return pipe, 2.3-First sludge inlet pipe, 2.4-Gravity thickener, 2.5-Second sludge inlet pipe, 2.6-Centrifuge thickener, 2.7-Third sludge inlet pipe; 3-Sludge internal carbon source extraction system; 3.1-Sludge hydrolysis tank, 3.2-Hydrolyzed sludge inlet pipe, 3.3-Sludge acidification fermentation tank, 3.4-Sludge discharge pipe, 3.5-Plate and frame dewatering machine, 3.6-Inlet carbon source replenishment pipe, 3.7-A2 tank carbon source addition pipe. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0041] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0042] Example 1 A combined wastewater denitrification enhancement process that efficiently utilizes carbon sources within sludge via side flow includes the following steps: (1) Introduce wastewater into the wastewater carbon source side flow high-efficiency utilization system 1: it enters the wastewater treatment biological reaction tank 1.1 and the wastewater treatment aerobic reaction tank 1.2 in sequence for COD removal and denitrification and phosphorus removal. After being treated by the wastewater treatment aerobic reaction tank 1.2, part of the wastewater enters the aerobic reaction tank O21.3, and the other part first enters the side flow high-efficiency anoxic tank A21.4 for further denitrification, and then flows into the aerobic reaction tank O21.3 for further COD removal; (2) Wastewater treated by aerobic reaction tank O21.3 enters sludge sedimentation and thickening system 2: First, sludge is obtained by preliminary sedimentation treatment in secondary sedimentation tank 2.1. Part of the sludge is returned to the side flow high-efficiency anoxic tank A21.4 to increase the sludge concentration therein. The other part of the sludge is concentrated in gravity thickening tank 2.4 and centrifugal thickener 2.6 in sequence to make the sludge reach the concentration required for hydrolysis and acidification. (3) The sludge that reaches the concentration required for hydrolysis and acidification enters the sludge carbon source extraction system 3: First, the sludge is pretreated by alkaline hydrolysis in the sludge hydrolysis tank 3.1, and then it enters the sludge acid fermentation tank 3.3 for acid fermentation treatment of high-concentration hydrolyzed sludge. The fermented sludge obtained by acid fermentation treatment is processed by the plate and frame dewatering machine 3.5 to prepare liquid sludge carbon source. (4) The carbon source in the liquid sludge is added to the wastewater treatment reaction tank 1.1 through the influent carbon source replenishment pipe 3.6, and the carbon source in the liquid sludge is added to the side flow high-efficiency anoxic tank A21.4 through the A2 tank carbon source addition pipe 3.7.

[0043] like Figure 1 As shown, the apparatus used in the process of this embodiment 1 includes a wastewater carbon source side-flow high-efficiency utilization system 1, a sludge sedimentation and concentration system 2, and a sludge carbon source extraction system 3. The wastewater internal carbon source side-flow high-efficiency utilization system 1 includes a wastewater treatment biological reaction tank 1.1, a wastewater treatment aerobic reaction tank 1.2, an aerobic reaction tank O2 1.3, a side-flow high-efficiency anoxic tank A2 1.4, a deep denitrification inlet pipe 1.5, a first return pipe 1.6, and an outlet pipe 1.7; the sludge sedimentation and thickening system 2 includes a secondary sedimentation tank 2.1, a second return pipe 2.2, a first sludge inlet pipe 2.3, a gravity thickener 2.4, a second sludge inlet pipe 2.5, a centrifugal thickener 2.6, and a third sludge inlet pipe 2.7; the sludge internal carbon source extraction system 3 includes a sludge hydrolysis tank 3.1, a hydrolyzed sludge inlet pipe 3.2, a sludge acidification fermentation tank 3.3, a sludge discharge pipe 3.4, a plate and frame dewatering machine 3.5, an inlet carbon source replenishment pipe 3.6, and an A2 tank carbon source addition pipe 3.7; The wastewater treatment aerobic reactor 1.2 is connected to the side-flow high-efficiency anoxic reactor A21.4 via a deep denitrification inlet pipe 1.5; the side-flow high-efficiency anoxic reactor A21.4 is connected to the aerobic reactor O21.3 via a first return pipe 1.6, and the aerobic reactor O21.3 is connected to the secondary sedimentation tank 2.1 via an outlet pipe 1.7; the secondary sedimentation tank 2.1 is connected to the side-flow high-efficiency anoxic reactor A21.4 via a second return pipe 2.2, and is also connected to the gravity thickener 2.4 via a first sludge inlet pipe 2.3; the gravity thickener 2.4 is connected to... The second sludge inlet pipe 2.5 is connected to the centrifugal thickener 2.6; the centrifugal thickener 2.6 is connected to the sludge hydrolysis tank 3.1 through the third sludge inlet pipe 2.7; the sludge hydrolysis tank 3.1 is connected to the sludge acidification fermentation tank 3.3 through the hydrolyzed sludge inlet pipe 3.2; the sludge acidification fermentation tank 3.3 is connected to the plate and frame dewatering machine 3.5 through the sludge discharge pipe 3.4; the plate and frame dewatering machine 3.5 is connected to the wastewater treatment biological reaction tank 1.1 through the inlet carbon source replenishment pipe 3.6, and is also connected to the side-flow high-efficiency anoxic tank A21.4 through the A2 tank carbon source addition pipe 3.7.

[0044] In this embodiment, the concentration of the residual sludge after mechanical thickening is 50 g / L (i.e., moisture content 95%). Alkali (calcium alkali dosage is 2 wt% of the dry sludge basis) is added for hydrolysis pretreatment of the sludge. The SCOD dissolution concentration of the sludge filtrate is 20.2 ± 0.9 g / L (SCOD refers to soluble COD). Further acid-producing fermentation treatment is performed on the hydrolyzed sludge, with a sludge retention time of 5 days and a fermentation temperature greater than 20℃. The resulting fermentation broth has an organic acid concentration of 15.8 ± 0.6 g / L and a total nitrogen concentration of 0.85 g / L. For a wastewater treatment plant with a daily treatment capacity of 100,000 tons, to remove 5 mg / L of nitrate nitrogen, based on a C / N ratio of 4.57, 14.65 m³ of 20% sodium acetate (liquid) is required. 3 This means the BOD5 consumption of carbon sources is 2285 kg / d. A wastewater treatment plant with a daily treatment capacity of 100,000 tons produces 100 t of sludge daily (at 80% moisture content). The fermentation broth produced by dewatering 95% moisture content sludge to 80% yields 300 t / d, resulting in a daily organic acid production of 4740 kg / d. This achieves complete coverage of chemical carbon source addition. Based on a price of 1200 yuan / t for 20% sodium acetate, this saves 17,000 yuan per day in chemical carbon source purchase costs.

[0045] Example 2 The process method in this embodiment is mostly the same as in Example 1, except that the sludge concentration required for hydrolysis acidification is changed to 90%.

[0046] Example 3 The process method in this embodiment is mostly the same as in Example 1, except that the amount of calcium alkali added in the alkali agent is changed to 6 wt% of the dry sludge.

[0047] Example 4 The process method in this embodiment is mostly the same as that in Example 1, except that the fermentation temperature is changed to 60°C.

[0048] Example 5 The process method in this embodiment is mostly the same as that in Example 1, except that the sludge retention time is changed to 10°C.

[0049] Based on Examples 1-5, the wastewater denitrification enhancement combined process of the present invention, which efficiently utilizes carbon sources within the sludge in the sideflow, adds a sideflow anoxic tank to the original wastewater treatment process and improves the carbon source utilization rate and denitrification efficiency of the sideflow tank through sludge external recirculation. Furthermore, it optimizes the extraction efficiency of carbon sources within the sludge by precisely adjusting pre-concentration and alkali type compounding to achieve low-temperature, short-retention-time sludge acidification fermentation technology. This wastewater denitrification enhancement combined process not only saves on the purchase cost of chemical carbon sources in traditional denitrification processes and reduces downstream sludge volume, but also reduces unnecessary energy consumption and carbon emissions in both process stages. It also possesses the characteristics of engineering integration and modification, and the combined process technology is mature and reliable.

[0050] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A combined wastewater denitrification enhancement process for efficient utilization of carbon sources in sludge via side flow, characterized in that, Includes the following steps: S1: Introduce wastewater into the wastewater carbon source side-flow high-efficiency utilization system (1): sequentially enter the wastewater treatment biological reaction tank (1.1) and the wastewater treatment aerobic reaction tank (1.2) for COD removal and denitrification and phosphorus removal; after being treated in the wastewater treatment aerobic reaction tank (1.2), part of the wastewater enters the aerobic reaction tank O2 (1.3), and the other part first enters the side-flow high-efficiency anoxic tank A2 (1.4) for further denitrification, and then flows into the aerobic reaction tank O2 (1.3) for further COD removal; S2: Wastewater treated by the aerobic reaction tank O2 (1.3) enters the sludge sedimentation and thickening system (2): First, sludge is obtained by preliminary sedimentation treatment in the secondary sedimentation tank (2.1). Part of the sludge is returned to the side flow high-efficiency anoxic tank A2 (1.4) to increase the sludge concentration therein. The other part of the sludge is concentrated in the gravity thickening tank (2.4) and centrifugal thickener (2.6) in sequence to make the sludge reach the concentration required for hydrolysis and acidification. S3: Sludge that reaches the concentration required for hydrolysis and acidification enters the sludge carbon source extraction system (3): First, sludge is pretreated by alkaline hydrolysis in the sludge hydrolysis tank (3.1), and then enters the sludge acid-producing fermentation tank (3.3) for acid-producing fermentation treatment of high-concentration hydrolyzed sludge. The fermented sludge obtained by acid-producing fermentation treatment is processed by plate and frame dewatering machine (3.5) to prepare liquid sludge carbon source. S4: The carbon source in the liquid sludge is added to the wastewater treatment reaction tank (1.1) through the influent carbon source replenishment pipe (3.6), and the carbon source in the liquid sludge is added to the side flow high-efficiency anoxic tank A2 (1.4) through the A2 tank carbon source addition pipe (3.7).

2. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The process consisting of the wastewater treatment biological reaction tank (1.1) and the wastewater treatment aerobic reaction tank (1.2) is AAO or AO or a derivative process.

3. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The flow measurement ratio of the side-flow high-efficiency anoxic tank A2 (1.4) is 25%~75%, and the sludge return ratio is 50%~100%.

4. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The concentration required for the sludge to reach hydrolysis and acidification refers to a water content of 95wt%~90wt% in the sludge.

5. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The sludge acidification fermentation tank (3.3) operates at a temperature of 20℃~60℃ and has a sludge retention time of 5~10 days.

6. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The sludge pretreatment in the sludge hydrolysis tank (3.1) uses a mixture of calcium alkali and non-calcium alkali, wherein the calcium alkali is one or more of calcium oxide, calcium hydroxide, and calcium peroxide, and the non-calcium alkali is one or more of sodium hydroxide and potassium hydroxide.

7. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 6, is characterized in that... When the calcium base is calcium hydroxide, the molar ratio of the calcium base to the non-calcium base compound is (1-9):1, and the dosage of the calcium base is 2wt%-6wt% of the dry sludge.

8. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The organic acids in the carbon source of the liquid sludge account for 50% to 80% of BOD5, the C / N ratio is greater than 16, and the C / P ratio is greater than 200.

9. The combined wastewater denitrification and enhancement process for efficient utilization of carbon sources in sludge via side flow, as described in claim 1, is characterized in that... The pressing pressure range of the plate and frame dewatering machine (3.5) is 0.5-2.0 MPa.

10. An apparatus for a combined wastewater denitrification and upgrading process for efficient utilization of carbon sources in sludge via side flow as described in any one of claims 1-9, characterized in that, It includes a wastewater carbon source side-flow high-efficiency utilization system (1), a sludge sedimentation and concentration system (2), and a sludge carbon source extraction system (3). The wastewater internal carbon source side-flow high-efficiency utilization system (1) includes a wastewater treatment biological reaction tank (1.1), a wastewater treatment aerobic reaction tank (1.2), an aerobic reaction tank O2 (1.3), a side-flow high-efficiency anoxic tank A2 (1.4), a deep denitrification inlet pipe (1.5), a first return pipe (1.6), and an outlet pipe (1.7); the sludge sedimentation and thickening system (2) includes a secondary sedimentation tank (2.1), a second return pipe (2.2), a first sludge inlet pipe (2.3), a gravity thickener (2.4), a second sludge inlet pipe (2.5), a centrifugal thickener (2.6), and a third sludge inlet pipe (2.7); the sludge internal carbon source extraction system (3) includes a sludge hydrolysis tank (3.1), a hydrolyzed sludge inlet pipe (3.2), a sludge acidification fermentation tank (3.3), a sludge discharge pipe (3.4), a plate and frame dewatering machine (3.5), an inlet carbon source replenishment pipe (3.6), and an A2 tank carbon source addition pipe (3.7); The wastewater treatment aerobic reactor (1.2) is connected to the side-flow high-efficiency anoxic reactor A2 (1.4) via a deep denitrification inlet pipe (1.5); the side-flow high-efficiency anoxic reactor A2 (1.4) is connected to the aerobic reactor O2 (1.3) via a first return pipe (1.6), and the aerobic reactor O2 (1.3) is connected to the secondary sedimentation tank (2.1) via an outlet pipe (1.7); the secondary sedimentation tank (2.1) is connected to the side-flow high-efficiency anoxic reactor A2 (1.4) via a second return pipe (2.2), and is connected to the gravity thickener (2.4) via a first sludge inlet pipe (2.3); the gravity thickener (2.4) is connected to the first... The second sludge inlet pipe (2.5) is connected to the centrifugal thickener (2.6); the centrifugal thickener (2.6) is connected to the sludge hydrolysis tank (3.1) through the third sludge inlet pipe (2.7); the sludge hydrolysis tank (3.1) is connected to the sludge acidification fermentation tank (3.3) through the hydrolyzed sludge inlet pipe (3.2); the sludge acidification fermentation tank (3.3) is connected to the plate and frame dewatering machine (3.5) through the sludge discharge pipe (3.4); the plate and frame dewatering machine (3.5) is connected to the wastewater treatment biological reaction tank (1.1) through the inlet carbon source replenishment pipe (3.6), and is connected to the side-flow high-efficiency anoxic tank A2 (1.4) through the A2 tank carbon source addition pipe (3.7).

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