Post-sludge internal carbon source denitrification nitrogen and phosphorus removal sewage treatment system and method

Abstract

The invention belongs to the technical field of sewage treatment, and relates to a sewage treatment system and method for denitrification nitrogen and phosphorus removal of a carbon source in rear sludge, and the sewage treatment system comprises an anaerobic tank, an aerobic tank and an anoxic tank which are connected in sequence; a sludge-water separation area is arranged at the tail end of the anaerobic tank, the top of the sludge-water separation area is communicated with the aerobic tank, and the bottom of the sludge-water separation area is communicated with the anoxic tank through a sludge distribution pipe; the aerobic tank is provided with a liquid discharge pipe; the anoxic tank is internally provided with a clarification separator, a sludge-water distributor and an anoxic tank aerator, the sludge-water distributor is connected with a sludge flow distribution pipe and a liquid discharge pipe, and the sludge-water distributor is also provided with a nozzle for spraying mixed liquid towards two sides of the clarification separator; a flexible control area is arranged in the anoxic tank, the anoxic tank aerator is located in the flexible control area, and the anoxic tank aerator sprays air upwards to enable mixed liquid in the anoxic tank to flow upwards; a sludge collecting pipe is also arranged at the bottom of the anoxic tank and is connected with a sludge discharge pipe and a sludge return pipe for returning to the anaerobic tank, so that the sludge in the anoxic tank returns to the anaerobic tank.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a sewage treatment system and method for denitrification, denitrification and dephosphorization by post-sludge internal carbon source. Background Art

[0002] At present, most domestic sewage treatment plants in China use anaerobic-anoxic-aerobic process or anaerobic-aerobic process to treat sewage. In the anaerobic-anoxic-aerobic process, sewage flows through anaerobic tanks, anoxic tanks and aerobic tanks in sequence. Under anaerobic conditions, the polyphosphate bacteria in the sludge release phosphorus; under anoxic conditions, denitrifying bacteria use the organic carbon source in the sewage to denitrify; under aerobic conditions, nitrifying bacteria nitrify the ammonia nitrogen in the sewage to form nitrified liquid, which flows back to the anoxic tank.

[0003] Generally, the reaction time of anaerobic tanks is short, and the reaction time of anoxic tanks is shorter than that of aerobic tanks, so that most of the original carbon sources in the sewage cannot be effectively utilized. Only a small part of the carbon sources in the sewage can be used, so a large amount of external carbon sources need to be added. At the same time, since the organic carbon sources in the sewage stay in the aerobic tank for a long time, they are wasted by aerobic digestion, which increases oxygen consumption and leads to increased electricity consumption. In addition, the reflux of nitrification liquid is relatively large, generally 100%-300%, which increases power consumption and ultimately leads to increased operating costs. Summary of the invention

[0004] The present invention provides a wastewater treatment system with post-sludge internal carbon source denitrification, denitrification and dephosphorization to solve the technical problem of high wastewater treatment cost in the prior art; and also provides a wastewater treatment method with post-sludge internal carbon source denitrification, denitrification and dephosphorization to solve the technical problem.

[0005] In order to solve the above problems, the present invention provides a post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system adopts the following technical scheme: a post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system, comprising an anaerobic tank, an aerobic tank and an anoxic tank connected in sequence; The anaerobic tank is provided with at least two partitions arranged in an up-down staggered manner so that the sewage can flow back and forth up and down. The end of the anaerobic tank is provided with a mud-water separation zone. The top of the mud-water separation zone is connected with the aerobic tank so that the low-concentration mud-water mixture separated initially can enter the aerobic tank. The bottom of the mud-water separation zone is connected with the anoxic tank through a sludge distribution pipe so that the high-concentration mud-water mixture can enter the anoxic tank, thereby realizing the mud-water distribution in the anaerobic tank. A drainage pipe from the aerobic pool to the anoxic pool is provided in the aerobic pool to discharge the nitrified liquid after the reaction in the aerobic pool into the anoxic pool; The anoxic tank is provided with a clarifier separator for separating mud and water, a mud-water distributor, and anoxic tank aerator. The clarifier separator has a side inlet for mixed liquid to enter and a bottom outlet for the sinking sludge to flow back into the anoxic tank. A water collecting tank for collecting clean water is provided in the middle of the top of the clarifier separator. The mud and water distributor is connected to the sludge distribution pipe and the drainage pipe, so that the high-concentration mud and water mixed liquid at the bottom of the anaerobic tank and the nitrified liquid in the aerobic tank are mixed in the mud and water distributor. The mud and water distributor is also provided with nozzles for spraying the mixed liquid toward both sides of the clarifier separator. The anoxic tank is provided with a flexible control area located on both sides of the clarifier separator. The anoxic tank aerator is located at the bottom of the flexible control area. The anoxic tank aerator is a medium-pore aerator or a large-pore aerator. The anoxic tank aerator sprays upward to make the mixed liquid in the anoxic tank flow upward. By controlling the air volume of the anoxic tank aerator, the flexible control area can be switched to an aerobic state or an anoxic state. A sludge collecting pipe is also provided at the bottom of the anoxic tank, to which a sludge discharge pipe and a sludge return pipe connected to the side where sewage enters the anaerobic tank are connected, so that the sludge in the anoxic tank can flow back to the anaerobic tank.

[0006] The anaerobic tank uses at least two partitions that are staggered up and down to make the sewage flow back and forth, so that the sewage is in a suspended state, thereby replacing the mechanical stirring method used in traditional anaerobic tanks, realizing the unpowered movement of the anaerobic tank and saving energy consumption. The sewage in the anaerobic tank flows back and forth up and down, increasing the anaerobic reaction time, allowing the polysaccharide-accumulating bacteria and polyphosphate-accumulating bacteria to fully adsorb, absorb, transfer and store the dissolved organic matter in the sewage in the sludge bacteria, greatly reducing the dissolved organic matter in the sewage, achieving the full phosphorus release of polyphosphate-accumulating bacteria, and creating good reaction conditions for subsequent aerobic nitrification and phosphorus removal, so that the aerobic tank forms a dominant bacterial community with autotrophic nitrifying bacteria, achieving efficient degradation of ammonia nitrogen, and greatly improving the nitrification effect and efficiency. At the same time, due to the low concentration of organic matter in the low-concentration mud and water mixture, the reaction time and oxygen consumption are greatly reduced during carbonization in the aerobic tank, achieving energy saving and consumption reduction.

[0007] The mud-water separation area diverts the low-concentration mud-water mixture at the top and the high-concentration mud-water mixture at the bottom. The high-concentration mud-water mixture directly enters the anoxic tank, where the organic carbon source stored in the sludge is fully utilized to denitrify the nitrified liquid, thereby achieving efficient denitrification without the need for an external carbon source.

[0008] The anoxic tank has flexible control zones located on both sides of the clarification separator, which can improve the system's ammonia nitrogen and total nitrogen's impact load resistance and ensure that ammonia nitrogen and total nitrogen meet the standards stably. A medium-pore aerator or a large-pore aerator is set in the flexible control zone. On the one hand, the flexible control zone can be switched to an aerobic state or an anoxic state by controlling the gas volume of the medium-pore aerator or the large-pore aerator. If the system has incomplete ammonia nitrogen conversion, the flexible control zone can be switched to an aerobic state for nitrification, and then switched to an anoxic environment for denitrification, so as to achieve stable ammonia nitrogen and total nitrogen standards; on the other hand, since the anoxic tank aerator is a medium-pore aerator or a large-pore aerator, the oxygen utilization rate is low and the bubbles are large, forming a water flow state of internal circulation of gas upflow.

[0009] By setting a clarification separator, a mud-water distributor and anoxic tank aerator in the anoxic tank, the four functions of mud-water mixing, reaction, sedimentation and sludge self-reflux in the anoxic tank are realized, and the oxygen content in the sewage can be controlled.

[0010] By using the sludge return pipe, the sludge containing polysaccharide-accumulating bacteria, denitrifying bacteria and polyphosphate-accumulating bacteria in the starved endogenous reaction state after the internal carbon source stored in the anoxic tank is fully utilized can be returned to the anaerobic tank, where it can be mixed and contacted with the untreated sewage, and the organic carbon source in the sewage can be adsorbed and stored. Then, the sludge can be returned to the anoxic tank to be used as a denitrification carbon source, thereby achieving efficient and full utilization of the carbon source in the sewage and saving operating costs.

[0011] Through aerobic pre-position, anoxic post-position, and the use of the triple effects of denitrifying bacteria to fully release phosphorus under anaerobic conditions, store internal carbon sources, and redistribute and transfer the stored internal carbon sources, the carbon source in the anoxic tank can be fully utilized, and efficient denitrification can be achieved without adding or adding a small amount of external carbon source, so that the carbon source in the sewage is fully and effectively utilized without waste, while reducing the increased electricity bill due to oxidation and consumption of carbon sources. In addition, since the sewage is first aerobically nitrified to convert ammonia nitrogen into nitrate and then flows into the back-end anoxic denitrification, there is no need to set up a large-flow nitrification liquid reflux, which greatly saves electricity consumption and improves sewage treatment efficiency.

[0012] As a further improvement, at least two of the partitions divide the interior of the anaerobic tank into a head chamber, a middle chamber and a terminal chamber, and the volume of the terminal chamber is larger than the volume of the head chamber and the middle chamber to reduce the flow rate of sewage in the terminal chamber, thereby forming the mud-water separation zone in the terminal chamber.

[0013] As a further improvement, the mud-water distributor is a horizontal liquid distribution pipe, the two ends of which are respectively connected to the sludge distribution pipe and the drainage pipe, and the bottom of the liquid distribution pipe is provided with the nozzle.

[0014] As a further improvement, a baffle is provided in the anoxic tank, which is located below the bottom outlet of the clarifier separator. The baffle is used to block the mixed liquid from flowing upward, and a reflux gap is formed between the baffle and the clarifier separator for sludge to flow back into the anoxic tank.

[0015] As a further improvement, the cross section of the baffle is triangular, and the top corner of the baffle extends into the bottom outlet.

[0016] As a further improvement, the aerobic pool is provided with biological fillers for nitrifying bacteria to attach to. The biological fillers are used for the attachment and growth of nitrifying bacteria with a long growth and reproduction cycle, and together with the activated sludge containing suspended polyphosphate bacteria in the pool, form a mud film symbiotic reaction environment, thereby increasing the number of nitrifying bacteria in the aerobic pool, solving the contradiction between the sludge age of nitrifying bacteria and polyphosphate bacteria, and realizing the functions of membrane nitrification and mud phosphorus removal, which not only ensures efficient biological nitrification, but also realizes efficient biological phosphorus removal.

[0017] As a further improvement, the aerobic pool is provided with a bracket and an aerobic pool aerator, the aerobic pool aerator and the biological filler are fixed on the bracket, the aerobic pool aerator is a microporous aerator; the biological filler and the microporous aerator are combined through the bracket to form a module. The aerobic pool aerator and the biological filler are fixed on the bracket, and can be lifted and lowered as a whole, which is convenient for layout and maintenance.

[0018] As a further improvement, the post-sludge carbon source denitrification, denitrification and phosphorus removal sewage treatment system includes a fan, an air supply main, a first air supply branch pipe and a second air supply branch pipe. The first air supply branch pipe and the second air supply branch pipe are both connected to the air supply main pipe. The first air supply main pipe is connected to the aerator of the aerobic tank, and the second air supply branch pipe is connected to the aerator of the anoxic tank.

[0019] The post-sludge internal carbon source denitrification denitrification and phosphorus removal wastewater treatment method provided by the present invention adopts the following technical scheme: a post-sludge internal carbon source denitrification denitrification and phosphorus removal wastewater treatment method, using a post-sludge internal carbon source denitrification denitrification and phosphorus removal wastewater treatment system, comprising the following steps: Step 1, sewage and sludge returned from the anoxic tank flow back and forth in the anaerobic tank to mix, the sludge-accumulating bacteria and phosphate-accumulating bacteria in the sludge absorb and store the organic carbon source in the sewage, and the phosphate-accumulating bacteria release phosphorus, and the sewage and sludge are initially separated in the mud-water separation area. After the initial separation, the low-concentration mud-water mixture at the top enters the aerobic tank, and the high-concentration mud-water mixture at the bottom enters the anoxic tank after separation; Step 2: After the low-concentration mud-water mixture enters the aerobic tank, nitrifying bacteria are used to nitrify and decompose the ammonia nitrogen in the mixture, so that the ammonia nitrogen is converted into nitrate and nitrite, and polyphosphate bacteria absorb phosphorus under aerobic conditions. After the reaction in the aerobic tank, the nitrified liquid flows to the anoxic tank by gravity; Step 3, the nitrification liquid of the aerobic tank and the high-concentration mud-water mixture of the anaerobic tank enter the mud-water distributor for mixing, and then are sprayed to both sides of the clarifier separator through the nozzle, and mixed with the sludge returned from the clarifier separator. In the anoxic environment, the denitrifying bacteria use the organic carbon source stored in the sludge to denitrify, so that the nitrate and nitrite in the sewage are converted into nitrogen gas; the mixed liquid after the anoxic reaction flows upward to the clarifier separator for mud-water separation, and the clear water is discharged through the sump at the top of the clarifier separator; the sludge in the clarifier separator flows back to the bottom of the anoxic tank, a part of it reacts with the mixed liquid sprayed from the mud-water distributor, a part of it flows back to the anaerobic tank, and a part of it is discharged through the sludge discharge pipe.

[0020] As a further improvement, biological fillers are fixed in the aerobic pool, which provide a place for nitrifying bacteria to attach and grow, and together with the activated sludge containing suspended polyphosphate bacteria in the pool, form a mud film symbiotic reaction environment, thereby achieving physical separation of nitrifying bacteria and polyphosphate bacteria, and achieving biofilm nitrification and activated sludge dephosphorization.

[0021] The beneficial effects of the present invention are: 1. The anaerobic tank uses at least two partitions that are staggered up and down to make the sewage flow back and forth, so that the sewage is in a suspended state, thereby replacing the mechanical stirring method used in traditional anaerobic tanks, realizing the unpowered movement of the anaerobic tank and saving energy consumption. The sewage in the anaerobic tank flows back and forth up and down, increasing the anaerobic reaction time, allowing the polysaccharide-accumulating bacteria and polyphosphate-accumulating bacteria to fully adsorb, absorb, transfer and store the dissolved organic matter in the sewage in the sludge bacteria, greatly reducing the dissolved organic matter in the sewage, achieving the full phosphorus release of polyphosphate-accumulating bacteria, and creating good reaction conditions for subsequent aerobic nitrification and phosphorus removal, so that the aerobic tank forms a dominant bacterial community with autotrophic nitrifying bacteria, achieving efficient degradation of ammonia nitrogen, and greatly improving the nitrification effect and efficiency. At the same time, due to the low concentration of organic matter in the low-concentration mud and water mixture, the reaction time and oxygen consumption are greatly reduced during carbonization in the aerobic tank, achieving energy saving and consumption reduction.

[0022] The mud-water separation area diverts the low-concentration mud-water mixture at the top and the high-concentration mud-water mixture at the bottom. The high-concentration mud-water mixture directly enters the anoxic tank, where the organic carbon source stored in the sludge is fully utilized to denitrify the nitrified liquid, thereby achieving efficient denitrification without the need for an external carbon source.

[0023] The anoxic tank has flexible control zones located on both sides of the clarification separator, which can improve the system's ammonia nitrogen and total nitrogen's impact load resistance and ensure that ammonia nitrogen and total nitrogen meet the standards stably. A medium-pore aerator or a large-pore aerator is set in the flexible control zone. On the one hand, the flexible control zone can be switched to an aerobic state or an anoxic state by controlling the gas volume of the medium-pore aerator or the large-pore aerator. If the system has incomplete ammonia nitrogen conversion, the flexible control zone can be switched to an aerobic state for nitrification, and then switched to an anoxic environment for denitrification, so as to achieve stable ammonia nitrogen and total nitrogen standards; on the other hand, since the anoxic tank aerator is a medium-pore aerator or a large-pore aerator, the oxygen utilization rate is low and the bubbles are large, forming a water flow state of internal circulation of gas upflow.

[0024] By setting a clarification separator, a mud-water distributor and anoxic tank aerator in the anoxic tank, the four functions of mud-water mixing, reaction, sedimentation and sludge self-reflux in the anoxic tank are realized, and the oxygen content in the sewage can be controlled.

[0025] By using the sludge return pipe, the sludge containing polysaccharide-accumulating bacteria, denitrifying bacteria and polyphosphate-accumulating bacteria in the starved endogenous reaction state after the internal carbon source stored in the anoxic tank is fully utilized can be returned to the anaerobic tank, where it can be mixed and contacted with the untreated sewage, and the organic carbon source in the sewage can be adsorbed and stored. Then, the sludge can be returned to the anoxic tank to be used as a denitrification carbon source, thereby achieving efficient and full utilization of the carbon source in the sewage and saving operating costs.

[0026] Through aerobic pre-position, anoxic post-position, and the use of the triple effects of denitrifying bacteria to fully release phosphorus under anaerobic conditions, store internal carbon sources, and redistribute and transfer the stored internal carbon sources, the carbon source in the anoxic tank can be fully utilized, and efficient denitrification can be achieved without adding or adding a small amount of external carbon source, so that the carbon source in the sewage is fully and effectively utilized without waste, while reducing the increased electricity bill due to oxidation and consumption of carbon sources. In addition, since the sewage is first aerobically nitrified to convert ammonia nitrogen into nitrate and then flows into the back-end anoxic denitrification, there is no need to set up a large-flow nitrification liquid reflux, which greatly saves electricity consumption and improves sewage treatment efficiency.

[0027] 2. Biological fillers provide a place for nitrifying bacteria with long growth and reproduction cycles to attach and grow, and together with the activated sludge containing suspended polyphosphate bacteria in the pool, they form a mud film symbiotic reaction environment, which increases the number of nitrifying bacteria in the aerobic pool, solves the contradiction between the sludge age of nitrifying bacteria and polyphosphate bacteria, and realizes membrane nitrification and mud phosphorus removal functions, ensuring both efficient biological nitrification and efficient biological phosphorus removal.

[0028] 3. The aerator of the aerobic pool and the biological filler are fixed on the bracket and can be lifted up and lowered as a whole, which is convenient for layout and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 It is a schematic diagram of the wastewater treatment system with denitrification, denitrification and dephosphorization using carbon sources in post-sludge; Figure 2 for Figure 1 Cross-sectional view of the middle distribution pipe; Figure 3 This is a schematic diagram of the planar distribution of the anoxic zone and the flexible control zone in the anoxic pool.

[0030] Description of reference numerals: 1. Anaerobic tank; 2. Aerobic tank; 3. Anoxic tank; 4. First baffle; 5. Second baffle; 6. Head chamber; 7. Middle chamber; 8. End chamber; 9. Sludge distribution pipe; 10. Sludge pump; 11. Sewage inlet pipe; 12. Bracket; 13. Biological filler; 14. Aerobic tank aerator; 15. Drain pipe; 16. Anoxic tank aerator; 17. Separation cylinder; 18. Guide plate; 19. , bottom opening; 20, side inlet; 21, water collecting trough; 22, drain pipe; 23, baffle; 24, liquid distribution pipe; 25, nozzle; 26, mud collecting pipe; 27, sludge return pipe; 28, mud discharge pipe; 29, return pump; 30, mud discharge pump; 31, fan; 32, air supply main pipe; 33, first air supply branch pipe; 34, second air supply branch pipe; 35, anoxic zone; 36, flexible control zone. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0033] Embodiments of the wastewater treatment system for post-sludge internal carbon source denitrification and dephosphorization provided by the present invention: like Figures 1 to 3 As shown, the post-sludge internal carbon source denitrification, denitrification and phosphorus removal sewage treatment system (hereinafter referred to as the sewage treatment system) includes an anaerobic tank 1, an aerobic tank 2 and an anoxic tank 3 which are connected in sequence.

[0034] The anaerobic tank 1 provides anaerobic conditions for sewage treatment. A first baffle 4 and a second baffle 5 are sequentially installed in the anaerobic tank 1 along the flow direction of the sewage. The top of the first baffle 4 is fixedly installed on the top of the anaerobic tank 1, and there is a gap between the bottom and the bottom of the anaerobic tank 1. The bottom of the second baffle 5 is fixedly installed on the bottom of the anaerobic tank 1, and there is a gap between the top and the top of the anaerobic tank 1. The sewage flows up and down in the anaerobic tank 1. The first baffle 4 and the second baffle 5 divide the internal space of the anaerobic tank 1 into three chambers. Of course, in other embodiments, the number of baffles can be increased as needed, as long as any two adjacent baffles are staggered up and down, the sewage can flow up and down.

[0035] Each chamber of the anaerobic tank 1 is divided into a head end chamber 6, a middle chamber 7 and a terminal chamber 8 along the flow direction of the sewage, wherein the number of the middle chambers 7 is adjusted according to the number of baffles. The size and volume of the head end chamber 6 and the middle chamber 7 are the same, and the size and volume of the terminal chamber 8 are twice that of the head end chamber 6 and the middle chamber 7. Since the size and volume of the terminal chamber 8 are larger, the flow rate of the sewage in the terminal chamber 8 is lower than the flow rate of the sewage in the head end chamber 6 and the middle chamber 7.

[0036] Since the sewage flows back and forth in the anaerobic tank 1, mud and water are mixed and stirred. The flow rate of sewage in the head chamber 6 and the middle chamber 7 is controlled at 3-5m / h, and the sludge can be fully mixed with the sewage, and due to the fast flow rate, sludge deposition can be avoided. The flow rate of sewage in the terminal chamber 8 is controlled at 2-2.5m / h. Since the flow rate of sewage in the terminal chamber 8 is slow, the mud and water mixture can be separated in the terminal chamber 8, that is, a mud and water separation zone is formed in the terminal chamber 8, and the sludge sinks for initial separation. After the initial separation, the low-concentration mud and water mixture at the top flows directly into the aerobic tank 2 by gravity. The bottom of the mud and water separation zone is connected to a sludge distribution pipe 9, which is connected to the anoxic tank 3. A sludge pump 10 is installed on the sludge distribution pipe 9, and the high-concentration mud and water mixture at the bottom is transported to the anoxic tank 3.

[0037] The anaerobic tank 1 is connected with a sewage inlet pipe 11 . Specifically, the sewage inlet pipe 11 is in communication with a head end chamber 6 of the anaerobic tank 1 .

[0038] A biofilm aeration device is placed in the aerobic pool 2, and the biofilm aeration device includes a support 12, a biological filler 13, and an aerobic pool aerator 14. The support 12 includes a column supported on the bottom of the aerobic pool 2 and an upper crossbar and a lower crossbar fixed on the column.

[0039] The upper end of the biological filler 13 is fixed on the upper crossbar, and the lower end is fixed on the lower crossbar. The biological filler 13 provides an attachment surface for microorganisms, so that the microorganisms form a biofilm on the surface of the biological filler 13. Here, the biological filler 13 is mainly used to enrich nitrifying bacteria and increase the number of nitrifying bacteria in the aerobic pool 2.

[0040] The aerobic pool aerator 14 is a microporous aerator. The oxygen provided by the aerobic pool aerator 14 puts the aerobic pool 2 in an aerobic state. The oxygen also stirs the sewage in the aerobic pool 2 during the rising process. The aerobic pool aerator 14 integrates oxygen supply and stirring.

[0041] The biofilm aeration device is placed in the aerobic tank 2 to form a module, which can be lifted out and lowered as a whole to facilitate replacement and maintenance.

[0042] The aerobic pool 2 is connected with a drain pipe 15 , and the drain pipe 15 discharges the nitrified liquid after the reaction in the aerobic pool 2 into the anoxic pool 3 .

[0043] The anoxic pool 3 is provided with a clarifier separator, a muddy water distributor, and anoxic pool aerator 16. Figure 3 As shown, the anoxic tank 3 has an anoxic zone 35 in the middle and flexible control zones 36 located on both sides of the anoxic zone 35. The clarifier separator and the muddy water distributor are located in the anoxic zone 35, and the anoxic tank aerator 16 is located in the flexible control zone 36.

[0044] The clarifier separator is located at the center of the anoxic tank 3, and the clarifier separator includes a separation cylinder 17 and a guide plate 18. The separation cylinder 17 includes a straight cylinder portion at the top and a conical cylinder portion at the bottom. The straight cylinder portion and the conical cylinder portion are connected and the insides are interconnected. The diameter of the conical cylinder portion gradually decreases from top to bottom, and there is a bottom opening 19 at the lower end of the conical cylinder portion. The upper part of the straight cylinder portion is fixedly installed on the upper part of the anoxic tank 3. A side inlet 20 connecting the inside and outside of the straight cylinder portion is provided on the bottom side of the straight cylinder portion. The mixed liquid enters the straight cylinder portion through the side inlet 20, and the sludge sinks into the conical cylinder portion. There are multiple side inlets 20 and they are arranged at intervals around the straight cylinder portion.

[0045] The bottom of the guide plate 18 is fixedly mounted on the separation cylinder 17 , and the bottom of the guide plate 18 is located below the side inlet 20 . The guide plate 18 is arranged tilted from top to bottom and toward the axis of the separation cylinder 17 , and can guide the mixed liquid to flow toward the side inlet 20 .

[0046] A water collecting tank 21 is installed in the middle position of the top of the separation cylinder 17. Specifically, the water collecting tank 21 can be fixed by a structure such as multiple support rods. A drain pipe 22 is connected to the water collecting tank 21. The drain pipe 22 extends to the outside of the anoxic pool 3 and can discharge the clean water in the water collecting tank 21.

[0047] A baffle 23 is arranged below the separation cylinder 17. The cross-section of the baffle 23 is triangular. The top corner of the baffle 23 extends into the bottom opening 19. A reflux gap is formed between the baffle 23 and the conical cylinder part for the sludge in the conical cylinder part to enter the anoxic tank 3. The baffle 23 can block the mixed liquid to prevent the mixed liquid in the anoxic tank 3 from directly entering the separation cylinder 17 vertically upward.

[0048] The muddy water distributor is located below the clarifier separator. Here, the muddy water distributor is a liquid distribution pipe 24, which is open at both ends, one end is connected to the sludge distribution pipe 9, and the other end is connected to the drainage pipe 15. A nozzle 25 is provided at the bottom of the liquid distribution pipe 24 to spray the mixed liquid. Specifically, both sides of the bottom of the liquid distribution pipe 24 have nozzles 25, and the nozzles 25 are inclined toward both sides of the clarifier separator, so that the muddy water mixed liquid is sprayed toward both sides of the clarifier separator.

[0049] The anoxic tank aerator 16 is a medium-pore aerator or a large-pore aerator. There are two anoxic tank aerators 16, which are placed on both sides of the clarifier separator. The anoxic tank aerator 16 mainly stirs and supplements with oxygen supply. The liquid distribution pipe 24 sprays the mixed liquid to both sides of the clarifier separator, and the anoxic tank aerator 16 sprays gas upward, so that the mixed liquid on both sides of the clarifier separator can flow upward. After the mixed liquid flows upward, it can enter the separation cylinder 17 through the side inlet 20 of the separation cylinder 17 to separate mud and water. The sludge of the clarifier separator sinks and then flows back to the anoxic tank 3 through the reflux seam. The clean water is collected by the water collection tank 21 and discharged through the drain pipe 22. The sludge returned from the clarifier separator to the anoxic tank 3, part of which sinks to the bottom of the anoxic tank 3, and the other part is mixed again with the mixed liquid sprayed by the liquid distribution pipe 24 and flows upward again.

[0050] A sludge collecting pipe 26 is arranged at the bottom of the anoxic tank 3, and the sludge sinking in the anoxic tank 3 enters the sludge collecting pipe 26. The sludge collecting pipe 26 is connected to a sludge return pipe 27 and a sludge discharge pipe 28. A reflux pump 29 is installed on the sludge return pipe 27. One end of the sludge return pipe 27 is connected to the sludge collecting pipe 26, and the other end is connected to the head end chamber 6 of the anaerobic tank 1, so as to return the sludge in the anoxic tank 3 to the anaerobic tank 1. A sludge discharge pump 30 is installed on the sludge discharge pipe 28, and the sludge discharge pump 30 can directly discharge the sludge in the sludge collecting pipe 26.

[0051] The sewage treatment system includes a fan 31, an air supply main pipe 32, a first air supply branch pipe 33, and a second air supply branch pipe 34. The air supply main pipe 32 is connected to the fan 31, and the first air supply branch pipe 33 and the second air supply branch pipe 34 are respectively connected to the air supply main pipe 32. The first air supply branch pipe 33 extends into the aerobic tank 2 and is connected to the aerator 14 of the aerobic tank; the second air supply branch pipe 34 extends into the anoxic tank 3 and is connected to the aerator 16 of the anoxic tank.

[0052] The sewage treatment system also includes an online monitoring device, including an online pH meter, OPR meter, and MLSS meter arranged in the anaerobic tank 1; an online pH meter, DO meter, and MLSS meter arranged in the aerobic tank 2; and an online DO meter, OPR meter, and MLSS meter arranged in the anoxic tank 3.

[0053] The online pH meter of anaerobic tank 1 mainly monitors the pH value of sewage in order to adjust the acid and alkali to meet the anaerobic reaction conditions. The ORP meter mainly monitors the redox potential value in anaerobic tank 1 in order to adjust and ensure the anaerobic environment. The MLSS meter mainly monitors the sludge concentration in anaerobic tank 1 in order to adjust the sludge concentration to meet the carbon source adsorption and sufficient phosphorus release in the sludge.

[0054] The online pH meter of aerobic tank 2 mainly monitors the pH value of the mixed liquid in order to adjust the acid and alkali to meet the nitrification reaction conditions. The DO meter mainly monitors the dissolved oxygen value in aerobic tank 2 in order to adjust and ensure the aerobic environment. The MLSS meter mainly monitors the sludge concentration in aerobic tank 2 in order to adjust the sludge concentration to meet the requirements of sufficient phosphorus absorption by aerobic sludge.

[0055] The online DO meter of the anoxic tank 3 mainly monitors the dissolved oxygen value in the anoxic tank 3 so as to regulate and ensure the anoxic environment. The MLSS meter mainly monitors the sludge concentration in the anoxic tank 3 so as to regulate the sludge concentration to meet the carbon source denitrification, denitrification and phosphorus removal in the anoxic sludge.

[0056] The working process of the sludge treatment system of the present invention is as follows: Step 1: Sewage enters the head end chamber 6 of the anaerobic tank 1 from the sewage inlet pipe 11, and sludge transported by the sludge return pipe 27 enters at the same time as the sewage. When the sewage and sludge flow in the head end chamber 6 and the middle chamber 7, the sewage and sludge are stirred by the return flow to fully mix the sewage and sludge. The polysaccharide-accumulating bacteria and polyphosphate-accumulating bacteria in the sludge absorb and store the organic carbon source in the sewage under the anaerobic environment and the condition of a relatively high organic carbon source, and the polyphosphate-accumulating bacteria fully release phosphorus. The mixed liquid of sewage and sludge is separated in the terminal chamber 8, and the low-concentration mud-water mixed liquid at the top flows into the aerobic tank 2 by gravity, and the high-concentration mud-water mixed liquid at the bottom enters the distribution pipe 24 of the anoxic tank 3 through the sludge distribution pipe 9.

[0057] Step 2: After the low-concentration mud-water mixture of the anaerobic tank 1 enters the aerobic tank 2, a biofilm symbiotic environment is formed in the aerobic tank 2 through the biofilm aeration device set in the aerobic tank 2, that is, nitrifying bacteria are attached to the biological filler 13, and polyphosphate bacteria are suspended in the aerobic tank 2 and sink after absorbing phosphorus. The oxygen provided by the aerator 14 of the aerobic tank puts the aerobic tank 2 in an aerobic state. The ammonia nitrogen in the mixed solution is treated by the nitrifying bacteria growing on the biological filler 13, and the ammonia nitrogen is converted into nitrate and nitrite through nitrification decomposition. At the same time, the polyphosphate bacteria suspended in the sludge absorb excessive phosphorus under aerobic conditions. The nitrified liquid formed after the reaction in the aerobic tank enters the liquid distribution pipe 24 of the anoxic tank 3 through the drain pipe 15.

[0058] Step 3: The nitrification liquid entering the distribution pipe 24 and the high-concentration mixed liquid of the anaerobic tank 1 are mixed in the distribution pipe 24 and distributed to the anoxic tank 3 through the nozzle 25. Mixed with the sludge sinking in the clarification separator, in an anaerobic environment, the denitrifying bacteria use the organic carbon source in the sludge to denitrify, convert nitrates and nitrites in the sewage into nitrogen, and further absorb phosphorus, consume the organic carbon source stored in the sludge, and simultaneously achieve sewage denitrification and phosphorus removal and sludge regeneration. The mixed liquid after the anoxic reaction flows upward to the separation cylinder 17 for mud and water separation, and the clean water is discharged through the water collection tank 21 and the drain pipe 22. The sludge flows back to the bottom of the anoxic tank 3, a part of it reacts with the mixed liquid sprayed from the distribution pipe 24 for anoxic reaction, a part is discharged through the mud collection pipe 26 and the mud discharge pipe 28, and a part is transported to the water inlet end of the anaerobic tank 1 through the sludge return pipe 27.

[0059] In step 3, by controlling the gas volume of the anoxic tank aerator 16, the flexible control zone 36 can be switched to an aerobic state or an anoxic state. If the system has incomplete ammonia nitrogen conversion, the flexible control zone 36 can be switched to an aerobic state for nitrification, and then switched to an anoxic environment for denitrification, so as to achieve stable compliance of ammonia nitrogen and total nitrogen.

[0060] The whole sewage treatment process takes 15 hours, the hydraulic retention time of anaerobic tank 1 is 3 hours, the hydraulic retention time of aerobic tank 2 is 4 hours, and the hydraulic retention time of anoxic tank 3 is 8 hours. The sludge return ratio inside anoxic tank 3 is 100%; the sludge return ratio of anoxic tank 3 to anaerobic tank 1 is 100%-150%, and the distribution ratio of anaerobic tank 1 to aerobic tank 2 and anoxic tank 3 is (1-2): 1. The online pH meter installed in the inlet section of anaerobic tank 1 monitors the pH value in anaerobic tank 1 to maintain it at 6-7, and the ORP meter and MLSS meter installed in the middle section monitor the ORP value in anaerobic tank 1 to maintain -150mv-50mv, and the MLSS control range is 4000-5000mg / L. The online pH meter installed in the middle section of aerobic pool 2 monitors the pH value in aerobic pool 2 to maintain at 6.5-7.5. The DO meter and MLSS meter installed in the rear section monitor the DO value in aerobic pool 2 to maintain at 1-2mg / L, and the MLSS control range is 1000-2000mg / L. The online DO meter and MLSS meter installed in the middle section of anoxic pool 3 monitors the DO value in anoxic pool 3 to maintain at 0.2-0.5mg / L, and the MLSS control range is 5000-6000mg / L.

[0061] After the above process treatment, the water quality data of the inlet and outlet water are as follows (the unit is mg / L):

[0062] The effluent quality is better than the Class A discharge standard, and the wastewater denitrification and phosphorus removal effects are significant.

[0063] In other embodiments, the shape of the mud and water distributor can be changed, for example, it can be cylindrical with openings on both sides for the nitrification liquid of the aerobic tank 2 and the high-concentration mud and water mixture of the anaerobic tank 1 to enter, and nozzles 25 are provided on both sides of the bottom for the mixed liquid to be sprayed out.

[0064] Embodiments of the wastewater treatment method for denitrification, denitrification and dephosphorization with post-sludge carbon source provided by the present invention: A method for treating wastewater by denitrification, denitrification and dephosphorization with a post-sludge internal carbon source, using the above-mentioned wastewater treatment system by denitrification, denitrification and dephosphorization with a post-sludge internal carbon source, comprises the following steps: Step 1, sewage and sludge returned from the anoxic tank flow back and forth in the anaerobic tank to mix, the sludge-accumulating bacteria and phosphate-accumulating bacteria in the sludge absorb and store the organic carbon source in the sewage, and the phosphate-accumulating bacteria release phosphorus, and the sewage and sludge are initially separated in the mud-water separation area. After the initial separation, the low-concentration mud-water mixture at the top enters the aerobic tank, and the high-concentration mud-water mixture at the bottom enters the anoxic tank after separation; Step 2: After the low-concentration mud-water mixture enters the aerobic tank, nitrifying bacteria are used to nitrify and decompose the ammonia nitrogen in the mixture, so that the ammonia nitrogen is converted into nitrate and nitrite, and polyphosphate bacteria absorb phosphorus under aerobic conditions. After the reaction in the aerobic tank, the nitrified liquid flows to the anoxic tank by gravity; Step 3, the nitrified liquid in the aerobic tank and the high-concentration mud-water mixture in the anaerobic tank enter the mud-water distributor for mixing, and then are sprayed to both sides of the clarifier separator through the nozzle, and mixed with the sludge returned from the clarifier separator. In the anoxic environment, the denitrifying bacteria use the organic carbon source stored in the sludge to denitrify, so that the nitrate and nitrite in the sewage are converted into nitrogen gas; the mixed liquid after the anoxic reaction flows upward to the clarifier separator for mud-water separation, and the clear water is discharged through the sump at the top of the clarifier separator; the sludge in the clarifier separator flows back to the bottom of the anoxic tank, a part of it reacts with the mixed liquid sprayed from the mud-water distributor, a part of it flows back to the anaerobic tank, and a part of it is discharged through the sludge discharge pipe.

[0065] Among them, in step 2, biological fillers are fixed in the aerobic pool, and the biological fillers are used for nitrifying bacteria to attach and grow, and together with the activated sludge containing suspended polyphosphate bacteria in the pool, a mud film symbiotic reaction environment is formed, thereby realizing the physical separation of nitrifying bacteria and polyphosphate bacteria, and achieving biofilm nitrification and activated sludge dephosphorization.

[0066] In addition, in the description of this specification, “plurality” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system, characterized in that: It includes anaerobic tank, aerobic tank and anoxic tank connected in sequence; The anaerobic tank is provided with at least two partitions arranged in an up-down staggered manner so that the sewage can flow back and forth up and down. The end of the anaerobic tank is provided with a mud-water separation zone. The top of the mud-water separation zone is connected with the aerobic tank so that the low-concentration mud-water mixture separated initially can enter the aerobic tank. The bottom of the mud-water separation zone is connected with the anoxic tank through a sludge distribution pipe so that the high-concentration mud-water mixture can enter the anoxic tank, thereby realizing the mud-water distribution in the anaerobic tank. A drainage pipe from the aerobic pool to the anoxic pool is provided in the aerobic pool to discharge the nitrified liquid after the reaction in the aerobic pool into the anoxic pool; The anoxic tank is provided with a clarifier separator for separating mud and water, a mud-water distributor, and anoxic tank aerator. The clarifier separator has a side inlet for mixed liquid to enter and a bottom outlet for the sinking sludge to flow back into the anoxic tank. A water collecting tank for collecting clean water is provided in the middle of the top of the clarifier separator. The mud and water distributor is connected to the sludge distribution pipe and the drainage pipe, so that the high-concentration mud and water mixed liquid at the bottom of the anaerobic tank and the nitrified liquid in the aerobic tank are mixed in the mud and water distributor. The mud and water distributor is also provided with nozzles for spraying the mixed liquid toward both sides of the clarifier separator. The anoxic tank is provided with a flexible control area located on both sides of the clarifier separator. The anoxic tank aerator is located at the bottom of the flexible control area. The anoxic tank aerator is a medium-pore aerator or a large-pore aerator. The anoxic tank aerator sprays upward to make the mixed liquid in the anoxic tank flow upward. By controlling the air volume of the anoxic tank aerator, the flexible control area can be switched to an aerobic state or an anoxic state. A sludge collecting pipe is also provided at the bottom of the anoxic tank, to which a sludge discharge pipe and a sludge return pipe connected to the side where sewage enters the anaerobic tank are connected, so that the sludge in the anoxic tank can flow back to the anaerobic tank.

2. The post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system according to claim 1 is characterized in that: At least two of the partitions divide the interior of the anaerobic tank into a head end chamber, a middle chamber and a terminal chamber. The volume of the terminal chamber is larger than that of the head end chamber and the middle chamber to reduce the flow rate of sewage in the terminal chamber, thereby forming the mud-water separation zone in the terminal chamber.

3. The post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system according to claim 1, characterized in that: The mud-water distributor is a horizontal liquid distribution pipe, the two ends of which are respectively connected to the sludge distribution pipe and the liquid discharge pipe, and the bottom of the liquid distribution pipe is provided with the nozzle.

4. The post-sludge internal carbon source denitrification, denitrification and dephosphorization sewage treatment system according to claim 1, 2 or 3, characterized in that: A baffle is provided in the anoxic tank, and the baffle is located below the bottom outlet of the clarifier separator. The baffle is used to block the mixed liquid from flowing upward, and a reflux gap is formed between the baffle and the clarifier separator for sludge to flow back into the anoxic tank.

5. The post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system according to claim 4 is characterized in that: The cross section of the baffle is triangular, and the top corner of the baffle extends into the bottom outlet.

6. The post-sludge internal carbon source denitrification, denitrification and dephosphorization sewage treatment system according to claim 1, 2 or 3, characterized in that: The aerobic pool is provided with biological fillers for nitrifying bacteria to attach to.

7. The post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system according to claim 6, characterized in that: The aerobic pool is provided with a support and an aerobic pool aerator. The aerobic pool aerator and the biological filler are fixed on the support. The aerobic pool aerator is a microporous aerator. The biological filler and the microporous aerator are combined through the support to form a module.

8. The post-sludge internal carbon source denitrification denitrification and phosphorus removal sewage treatment system according to claim 7, characterized in that: The post-sludge internal carbon source denitrification, denitrification and dephosphorization sewage treatment system comprises a fan, an air supply main, a first air supply branch pipe and a second air supply branch pipe. The first air supply branch pipe and the second air supply branch pipe are both connected to the air supply main pipe. The first air supply main pipe is connected to the aerator of the aerobic tank, and the second air supply branch pipe is connected to the aerator of the anoxic tank.

9. A method for treating wastewater by denitrification, denitrification and dephosphorization with post-sludge carbon source, characterized in that: The post-sludge internal carbon source denitrification and dephosphorization sewage treatment system according to claim 1 comprises the following steps: Step 1, sewage and sludge returned from the anoxic tank flow back and forth in the anaerobic tank to mix, the sludge-accumulating bacteria and phosphate-accumulating bacteria in the sludge absorb and store the organic carbon source in the sewage, and the phosphate-accumulating bacteria release phosphorus, and the sewage and sludge are initially separated in the mud-water separation area. After the initial separation, the low-concentration mud-water mixture at the top enters the aerobic tank, and the high-concentration mud-water mixture at the bottom enters the anoxic tank after separation; Step 2: After the low-concentration mud-water mixture enters the aerobic tank, nitrifying bacteria are used to nitrify and decompose the ammonia nitrogen in the mixture, so that the ammonia nitrogen is converted into nitrate and nitrite, and polyphosphate bacteria absorb phosphorus under aerobic conditions. After the reaction in the aerobic tank, the nitrified liquid flows to the anoxic tank by gravity; Step 3, the nitrification liquid of the aerobic tank and the high-concentration mud-water mixture of the anaerobic tank enter the mud-water distributor for mixing, and then are sprayed to both sides of the clarifier separator through the nozzle, and mixed with the sludge returned from the clarifier separator. In the anoxic environment, the denitrifying bacteria use the organic carbon source stored in the sludge to denitrify, so that the nitrate and nitrite in the sewage are converted into nitrogen gas; the mixed liquid after the anoxic reaction flows upward to the clarifier separator for mud-water separation, and the clear water is discharged through the sump at the top of the clarifier separator; the sludge in the clarifier separator flows back to the bottom of the anoxic tank, a part of it reacts with the mixed liquid sprayed from the mud-water distributor, a part of it flows back to the anaerobic tank, and a part of it is discharged through the sludge discharge pipe.

10. The method for treating wastewater by denitrification, denitrification and dephosphorization with post-sludge internal carbon source according to claim 9, characterized in that: The aerobic pool is fixed with biological fillers for nitrifying bacteria to attach and grow, and together with the activated sludge containing suspended polyphosphate bacteria in the pool, forms a mud film symbiotic reaction environment, thereby achieving physical separation of nitrifying bacteria and polyphosphate bacteria, and achieving biofilm nitrification and activated sludge dephosphorization.

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