Sewage treatment system and process

Abstract

The invention discloses a sewage treatment system and process, and relates to the technical field of sewage treatment. The sewage treatment system consists of a main flow system and a side flow system, the mainstream system comprises a resource capturing unit, a pure membrane biochemical treatment unit and a deep treatment unit which are connected in sequence; the sidestream system includes a resource recovery unit. According to the mainstream system, carbon and phosphorus in sewage are removed through a resource capture unit, mud-water separation is achieved, deep nitrogen removal is conducted on the sewage through a pure membrane technology, up-to-standard sewage discharge is achieved, in the OA technology part, the theoretical nitrogen removal amount can reach 100%, COD in the sewage is efficiently removed, and deep nitrogen removal is conducted; the side flow system is used for carrying out anaerobic fermentation on the sludge rich in carbon and phosphorus, phosphorus in the sludge is combined with metal ions or other cations to form precipitates or complexes to be recovered, and carbon in the sludge is fermented to form soluble organic matters to be recovered; according to the sewage treatment system and process, deep denitrification can be effectively considered, and meanwhile carbon and phosphorus resource recycling can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage treatment system and process. Background Art

[0002] As cities develop and population density increases, the amount of urban sewage is also gradually increasing, resulting in insufficient treatment capacity of existing sewage treatment plants. The area of ​​land available for expansion in cities is limited. Conventional sewage treatment processes are not suitable for reconstruction in cities with limited land due to their large land occupation, high operating costs, and long construction periods. In addition, some places have increasingly stringent requirements for the total nitrogen index of the effluent from sewage treatment plants. For example, Beijing, Tianjin, Guangdong, Jiangsu and other regions have successively issued local standards and carried out work to improve the standards, requiring the total nitrogen index of the effluent to be below 10 mg / L, which is a great test for the treatment capacity of existing sewage treatment plants.

[0003] At present, most sewage treatment plants use denitrification filters for nitrogen removal. This process requires the addition of a large amount of organic carbon sources, and the total nitrogen removal is limited, making it difficult to achieve deep nitrogen removal and meet the above-mentioned effluent indicators. Therefore, it is necessary to optimize the existing sewage treatment process and the corresponding sewage treatment system to meet the market demand for fast and efficient, small footprint, low operating cost, simple management, stable effluent, deep nitrogen removal and resource recovery. Summary of the invention

[0004] The technical problem to be solved by the present invention is to optimize the existing sewage treatment process and the corresponding sewage treatment system, and to provide a sewage treatment system and process method which is fast and efficient, occupies a small area, has a low operating cost, is simple to manage, has stable effluent, can deeply remove nitrogen, and can also realize carbon and phosphorus resource recovery and utilization.

[0005] In order to solve the above problems, the present invention proposes the following technical solutions:

[0006] In a first aspect, the present invention provides a sewage treatment system, which is a sewage treatment system for carbon and phosphorus resource recovery formed by a mainstream system and a side stream system; the mainstream system comprises a resource capture unit, a pure membrane biochemical treatment unit and a deep treatment unit connected in sequence; the side stream system comprises a resource recovery unit;

[0007] The resource capture unit is provided with a sewage upper layer area and a sludge sedimentation area, the bottom of the sludge sedimentation area is provided with a sludge outlet, and the top of the sewage upper layer area is provided with a sewage outlet; the sewage outlet is connected to the pure membrane biochemical treatment unit;

[0008] The resource capture unit is a physical sedimentation tank, a biological adsorption tank and / or a chemically enhanced sedimentation tank, wherein the chemically enhanced sedimentation tank is equipped with a reagent delivery device, and the reagent delivery device is used to deliver reagents to the chemically enhanced sedimentation tank; the resource capture unit is used to capture carbon sources and phosphorus sources in sewage;

[0009] The pure membrane biochemical treatment unit comprises an independent tank body and / or a combined tank body;

[0010] The independent pool body is a baffled biofilm pool, in which a plurality of baffles are installed, and a plurality of baffle corridors are formed in the pool body through the baffles, and a three-dimensional immobilized biofilm module is arranged in the baffle corridor;

[0011] The combined pool body comprises a plurality of aerobic biofilm pools and a plurality of anoxic biofilm pools which are interconnected; the aerobic biofilm pools are provided with moving bed biofilm fillers and / or three-dimensional immobilized biofilm modules, and the anoxic biofilm pools are provided with three-dimensional immobilized biofilm modules;

[0012] The resource recovery unit comprises an anaerobic digestion tank, a carbon recovery device and a phosphorus recovery device; the anaerobic digestion tank is connected to the sludge outlet, and the anaerobic digestion tank is also connected to the carbon recovery device and the phosphorus recovery device respectively.

[0013] It can be understood that in the sewage treatment system of the present invention, the resource capture unit is located at the front end of the system and connected to the water inlet pipe; the deep treatment unit is located at the end of the system and connected to the water outlet pipe; the resource recovery unit is located in the system bypass, and its inlet end is connected to the resource capture unit.

[0014] It can be understood that the resource capture unit is a physical sedimentation tank, a biological adsorption tank and / or a chemical enhanced sedimentation tank, which is used to capture carbon sources and phosphorus sources in sewage. Specifically, the carbon and phosphorus resource capture methods can be the following three: ① For the physical sedimentation tank, nothing is added to the tank body, and the organic colloidal substances and suspended particles in the sewage are freely settled by gravity to form primary sludge, thereby capturing the sludge containing carbon and phosphorus;

[0015] ② For the biological adsorption tank, activated sludge is added to the tank body, and sludge microorganisms are used to absorb and aggregate organic colloids, suspended particles and soluble substances in sewage to form biological adsorption sludge, thereby capturing sludge containing carbon and phosphorus;

[0016] ③ Chemically enhanced sedimentation tank, by adding chemical agents (such as metal salts or high molecular polymers) into the tank body, the electrical neutralization, adsorption and bridging effects of the chemical agents are used to capture and gather organic colloids, suspended particles and soluble substances in the sewage to form chemical precipitation sludge, thereby capturing the sludge containing carbon and phosphorus.

[0017] The sludge captured by the resource capture unit enters the resource recovery unit for processing through the sludge outlet.

[0018] A further technical solution is that a mixing zone is provided inside the chemically enhanced sedimentation tank, the mixing zone is connected to a reagent dosing device, a stirring device is provided in the mixing zone, and sewage and reagents are quickly mixed and flocculated in the mixing zone.

[0019] Furthermore, the sludge sedimentation area in the resource capture unit is provided with a scraper, and the captured carbon and phosphorus-containing sludge is finally settled in the sludge hopper of the scraper.

[0020] It can be understood that the sewage is separated into mud and water in the resource capture unit to obtain sludge and primary sewage; the primary sewage enters the pure membrane biochemical treatment unit for treatment from the sewage outlet; and the sludge enters the resource recovery unit for treatment from the sludge outlet.

[0021] A further technical solution is that it also includes a pretreatment tank, the water inlet end of the pretreatment tank is connected to the water inlet pipeline, and the water outlet end is connected to the resource capture unit. The pretreatment tank is used to remove larger suspended matter and impurities in sewage.

[0022] A further technical solution is that the deep treatment unit includes at least one of a filter cloth filter tank, an air flotation tank or a magnetic coagulation sedimentation tank. The sewage passes through the deep treatment unit to achieve deep removal of suspended solids (SS) to ensure that the effluent is stable and meets the discharge standards.

[0023] A further technical solution is that the deep treatment unit also includes a disinfection device, which is located at the rear end of the deep treatment unit and connected to the outlet pipe to kill harmful pathogenic microorganisms in the sewage and deeply improve the outlet water quality.

[0024] A further technical solution is that an aerator is installed at the bottom of the baffled gallery, and the start and stop control of the aerator at the bottom of each baffled gallery is independent. By controlling the start and stop of the aerators at the bottom of different baffled galleries, anoxic and aerobic partition environments can be formed autonomously in the baffled biofilm pool, and the partition volume and sequence can be flexibly adjusted.

[0025] The present invention uses a baffled biofilm pool equipped with a three-dimensional immobilized biofilm module to perform pure membrane biochemical treatment, which has the following advantages:

[0026] Advantage 1: There is no need to preset the order of aerobic and anoxic units. The baffles have divided the reaction tank into several chambers, and the order of anoxic and aerobic can be adjusted according to the quality of the inlet and outlet water.

[0027] For example: After the low C / N influent is treated at the primary level, due to the low organic load of the sewage, the aerator at the bottom of the front chamber of the baffle tank can be opened to form an aerobic-anoxic biofilm treatment process.

[0028] After the high C / N influent is treated in the first stage, due to the high organic load of the sewage, the aerator at the bottom of the chamber at the end of the baffle tank can be opened to form an anoxic-aerobic biofilm treatment process.

[0029] For water quality with extremely high requirements for effluent TN, the AOA process can be combined to adjust the proportion of chambers that open aeration to meet the optimal partitioned hydraulic retention time of the AOA process and form efficient denitrification.

[0030] Advantage 2: The baffles provide convenient conditions for adding carbon sources and water at different points. Multiple carbon source addition points and the volume of each baffle corridor can be set as needed without being affected by the size of the civil engineering pool.

[0031] For example, there are 9 folding plates in a baffled biofilm pool, forming 10 baffled corridors. In theory, 10 points are provided for point-by-point carbon source addition and point-by-point water inlet. The specific addition points can be obtained according to the design calculation book of the multi-stage AO process. According to existing reports, there are generally no more than 3 points, and the proportions of each partition can be the same, or the front area can be large and the end area can be small. This can be easily achieved in the baffled biofilm pool by allocating different volume combinations of 10 baffled corridors.

[0032] It should be noted that the present invention does not limit the order of aerobic treatment and anoxic treatment of the multiple aerobic biofilm pools and the multiple anoxic biofilm pools in the combined pool body. For example, it can be anoxic biofilm pool-aerobic biofilm pool, or aerobic biofilm pool-anoxic biofilm pool, or anoxic biofilm pool-aerobic biofilm pool-anoxic biofilm pool, and so on.

[0033] It can be understood that for the aerobic biofilm pool, a moving bed biofilm filler and / or a three-dimensional immobilized biofilm module can be set to perform aerobic treatment of sewage.

[0034] A further technical solution is that the three-dimensional immobilized biofilm module is suspended and fixed in the biofilm module by a plurality of sheet-like biofilm fillers, and there are intervals between adjacent sheet-like biofilm fillers to form muddy and water channels, which can effectively prevent blockage.

[0035] A further technical solution is that an aeration device is arranged at the bottom of the aerobic biofilm pool.

[0036] It can be understood that the number of the three-dimensional immobilized biofilm modules in the baffled corridor, aerobic biofilm pool and anoxic biofilm pool can be multiple, and the multiple three-dimensional immobilized biofilm modules can be laid flat and stacked to cover the entire pool space. The multiple three-dimensional immobilized biofilm modules can be connected by fasteners, and the interval between adjacent biofilm fillers inside the three-dimensional immobilized biofilm module is about 5-100mm, forming a muddy water channel, and the filler specific surface area is about 20-2000m 2 / m3 The film-forming amount is about 20-260g / m 2 .

[0037] A further technical solution is that a carbon source storage device is provided inside the anoxic biofilm pool to supplement the carbon source for the denitrification treatment of sewage; the carbon recovery device is connected to the carbon source storage device. The dissolved organic matter in the carbon recovery device enters the anoxic biofilm pool to supplement the high-quality carbon source for the denitrification process, thereby improving the efficiency of resource recycling.

[0038] A further technical solution is that an anaerobic digestion mixer is provided in the anaerobic digestion tank.

[0039] In a second aspect, the present invention further provides a sewage treatment process, comprising the following steps:

[0040] S1, sewage enters the resource capture unit through the water inlet pipe, and captures carbon and phosphorus substances through physical free sedimentation and / or biological adsorption flocculation and / or chemical enhanced electrical neutralization and adsorption bridging to obtain sludge and primary sewage;

[0041] S2, sending the sludge to a resource recovery unit, performing anaerobic fermentation in an anaerobic digestion tank to obtain soluble organic matter and nitrogen and phosphorus precipitates, wherein the soluble organic matter is collected in a carbon recovery device, and the nitrogen and phosphorus precipitates are collected in a phosphorus recovery device;

[0042] S3, sending the primary sewage to a pure membrane biochemical treatment unit for aerobic degradation, nitrification and denitrification treatment, etc., to obtain secondary sewage;

[0043] S4, sending the secondary sewage to the deep treatment unit for treatment, and then discharging the effluent after testing it is qualified.

[0044] Its further technical scheme is that in the step S2, the sludge is sent to the resource recovery unit, the water content of the sludge is within 90%, the temperature of anaerobic fermentation is 35-45°C, the fermentation time is 1-5 days, and the pH is above 5.0. Specifically, acidic fermentation or alkaline fermentation can be selected to inhibit the reproduction of gas-producing microorganisms, thereby ensuring that the fermentation product is a fermentation liquid containing soluble organic matter, which is a high-quality carbon source; the pH of the acidic supernatant obtained by fermentation is adjusted to neutral or slightly alkaline, and a composite precipitation of phosphorus and cations such as ammonium and metals can be obtained, which is the recovered phosphorus source.

[0045] In step S1 of the present invention, the capture of carbon-phosphorus substances can be achieved by at least one of the following methods:

[0046] 1) The organic colloidal substances and suspended particles in the sewage are allowed to settle freely under the action of gravity to form primary sludge, thereby capturing a large amount of carbon and phosphorus in the sewage.

[0047] 2) By adding activated sludge into sewage, sludge microorganisms are used to absorb and aggregate organic colloids, suspended particles and soluble substances in sewage to form biological adsorption sludge, thereby achieving large-scale capture of carbon and phosphorus in sewage.

[0048] 3) By adding chemicals into the sewage, the chemicals can destabilize, colloidal and agglomerate the organic colloids and suspended particles in the sewage into large flocs through electrical neutralization, adsorption and bridging. The flocs can also adsorb soluble substances, eventually forming chemical precipitation sludge, thereby achieving large-scale capture of carbon and phosphorus in the sewage.

[0049] In step S2 of the present invention, the sludge undergoes hydrolysis, acidification and fermentation reactions in an anaerobic digester. The generated fermentation liquid contains soluble organic matter, including volatile fatty acids (VFA), etc., which are collected in a carbon recovery device. At the same time, during the anaerobic digestion process, with the hydrolysis of protein and the breakage of sludge cells, the nitrogen and phosphorus elements entrained in and outside the sludge cells are released. By adding agents, adjusting pH and other means, the released phosphorus combines with agents (iron salts, aluminum salts, calcium salts, etc.) to form phosphate precipitates or complexes. When the nitrogen and phosphorus substances reach a certain concentration, phosphate precipitates or complexes, such as Fe-P, Al-P, Ca-P, Mg-P, NH4-P, etc., are collected in a phosphorus recovery device.

[0050] It is understandable that for the sludge obtained by physical sedimentation tanks and biological adsorption tanks, additional chemicals, such as alkali, metal salts, etc., need to be added when recovering resources after anaerobic fermentation to promote the sludge to release ammonium and phosphorus, and combine them with the chemicals to form precipitates for recovery; for the sludge obtained by chemical enhanced sedimentation tanks, since chemicals such as iron salts, aluminum salts, calcium salts, etc. have been added during the sludge capture and enrichment stage, there will be residual chemicals in the captured sludge. Therefore, no additional chemicals are required during anaerobic digestion.

[0051] In the present invention, the dissolved organic matter in the carbon recovery device can be used as a supplementary carbon source for the denitrification process of the anoxic biofilm pool in the pure membrane biochemical treatment unit to achieve carbon resource recycling; or further recovered as an important organic carbon source for producing alternative fuels, microbial fats and oils, and synthesizing biodegradable plastics.

[0052] In the present invention, the phosphate precipitate or complex in the phosphorus recovery device can be used as raw materials for industrial or agricultural production and processing, thereby realizing resource recovery and utilization of phosphorus in sewage.

[0053] In step S3 of the present invention, the primary sewage enters the pure membrane biochemical treatment unit for aerobic degradation, nitrification and denitrification to obtain secondary sewage. Aerobic microorganisms use oxygen to decompose organic matter in sewage into carbon dioxide and water, and at the same time convert ammonia nitrogen in sewage into nitrate nitrogen through nitrification, thereby achieving efficient removal of organic pollutants and ammonia nitrogen in sewage; at the same time, denitrifying bacteria attached to the surface of the biofilm filler can convert nitrate nitrogen in sewage into nitrogen gas through denitrification, thereby achieving deep removal of total nitrogen and reducing total nitrogen in effluent.

[0054] It should be noted that when the carbon source in the anoxic treatment is insufficient, the dissolved organic matter in the carbon recovery device is used as an additional carbon source for the anoxic biofilm pool for use in the denitrification process.

[0055] In step S4 of the present invention, the secondary sewage is treated by the deep treatment unit and then enters the disinfection device for disinfection. After disinfection, the effluent is tested and discharged as qualified.

[0056] A further technical solution is that in step S1, the sewage first enters a pretreatment unit through a water inlet pipe to remove suspended matter and impurities in the sewage, and then enters a resource capture unit for mud-water separation.

[0057] The sewage treatment process provided by the present invention utilizes a resource capture unit to perform physical precipitation, biological adsorption and / or chemical enhanced precipitation on carbon and phosphorus in sewage to achieve carbon and phosphorus resource capture. Various types of microorganisms are attached to the biofilm filler in the pure membrane biochemical treatment unit, which can efficiently remove pollutants such as organic matter and ammonia nitrogen in sewage and deeply remove total nitrogen in sewage. The deep treatment unit can deeply remove suspended matter in sewage. A sewage treatment system and method with high efficiency, small footprint, low operating cost, simple management, stable effluent, deep denitrification and resource recovery is formed.

[0058] The resource capture unit used in the present invention can remove more than 50% of COD in raw water and more than 80% of TP in raw water, thereby achieving the capture of carbon and phosphorus.

[0059] In the present invention, the carbon and phosphorus-containing sludge captured by the resource capture unit can be subjected to anaerobic digestion. During the anaerobic digestion process, the sludge is hydrolyzed and fermented to produce soluble organic matter, which can be used as a backup carbon source for the system, thereby maximizing the recycling of carbon sources in the influent and reducing the amount of external carbon sources. At the same time, the anaerobic digestion process releases nitrogen and phosphorus substances, and after chemical capture, phosphorus can be combined with metal ions or other cations to form precipitation or complexes for recovery.

[0060] The pure membrane biochemical treatment unit of the present invention adopts a pure membrane system, which can form multiple aerobic-anoxic treatment modes. The aerobic section has a low gas-water ratio, low oxygen demand, and saves aeration energy consumption. At the same time, the pure membrane system has no sludge return, saving sludge return energy consumption, and does not require a mud-water separation unit, so it occupies a small area, is simple to operate and maintain, and has low operating costs.

[0061] The present invention adopts a resource capture unit combined with a biofilm system, and the overall system sludge production rate is extremely low, saving sludge treatment costs.

[0062] In the present invention, the OA process can be flexibly adopted according to actual conditions, and the nitrification liquid all enters the anoxic section without nitrification liquid reflux. Theoretically, the denitrification rate is as high as 100%, and the operating power consumption is low.

[0063] Compared with the prior art, the technical effects achieved by the present invention include:

[0064] The sewage treatment system provided by the present invention is a sewage treatment system for recovering carbon and phosphorus resources formed by a mainstream system and a side stream system; the mainstream system uses a resource capture unit to preliminarily enrich the carbon and phosphorus in the sewage, and then aerobic degradation, nitrification and denitrification are carried out in a pure membrane biochemical treatment unit to efficiently remove COD and deep denitrification in the sewage, and finally SS in the sewage is removed by a deep treatment unit to achieve sewage discharge that meets standards; the side stream system mainly performs anaerobic fermentation on the carbon and phosphorus sludge enriched in the resource capture unit, and the digested phosphorus can be recovered in the form of phosphate precipitation or complex such as Fe-P, Al-P, Ca-P, Mg-P, NH4-P, etc., to avoid the loss of phosphorus; the digested carbon forms soluble organic matter for recovery, and the sewage treatment system of the present invention can effectively take into account deep denitrification while realizing carbon and phosphorus resource recovery and utilization.

[0065] The sewage treatment system of the present invention adopts a pure membrane process combined with a front-end resource capture unit for sewage treatment. The overall residual sludge volume of the system is extremely low, and the oxygen demand of the aerobic section of the pure membrane process is small. At the same time, the pure membrane process has no sludge return, does not require a mud-water separation unit, has a short process, occupies a small area, and is easy to operate and maintain. In addition, the pure membrane process biofilm filler is modularly designed, can be flexibly assembled, and is convenient for construction and construction with a short cycle.

[0066] In the sewage treatment system of the present invention, the dissolved organic carbon source recovered by the side stream system can be used as a denitrification supplementary carbon source for deep denitrification, thereby maximizing the utilization of the influent carbon source. The recovered phosphorus can be used as a production and processing raw material, etc., thereby achieving effective utilization of phosphorus.

[0067] The sewage treatment system of the present invention has a wide range of applications and can be flexibly designed to adopt multi-stage OA, AO or AOA processes according to different sewage quality conditions. When the OA process is selected, no nitrification liquid reflux is required. Theoretically, the denitrification rate is as high as 100%, and the operating power consumption is low.

[0068] The sewage treatment process provided by the present invention first captures carbon and phosphorus in sewage, and settles suspended colloidal substances in sewage into sludge containing carbon and phosphorus by physical precipitation, biological adsorption or chemical means, which can remove more than 50% of COD in raw water and more than 80% of TP in raw water, thereby achieving carbon and phosphorus capture. The carbon and phosphorus resources in the sludge are respectively recovered by anaerobic fermentation of the sludge, thereby achieving carbon and phosphorus resource recycling; the sewage is further subjected to pure membrane biochemical treatment and deep treatment, and COD and deep nitrogen removal are efficiently removed, thereby effectively achieving sewage discharge standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0070] Figure 1 This is a schematic diagram of the structure of the sewage treatment system provided in Example 1 of the present invention.

[0071] Figure 2 This is a process flow chart of the sewage treatment process provided in Example 1 of the present invention.

[0072] Figure 3 This is a process flow chart of the sewage treatment process provided in Example 2 of the present invention.

[0073] Figure 4 This is a schematic diagram of the structure of the sewage treatment system provided in Example 2 of the present invention.

[0074] Reference numerals

[0075] Resource capture unit 10, agent delivery device 11, chemical enhanced sedimentation tank 12, stirring device 13, mixing area 121, sedimentation area 122, sludge outlet 1221, sewage outlet 1211;

[0076] Pure membrane biochemical treatment unit 20, aerobic biofilm pool 21, anoxic biofilm pool 22, baffled biofilm pool 23;

[0077] Baffle gallery 231, aerator 232;

[0078] Moving bed biofilm filler 2, agitator 3, perforated aeration tube 4, three-dimensional immobilized biofilm module 5;

[0079] Deep processing unit 30, disinfection device 6;

[0080] Resource recovery unit 40 , anaerobic digestion tank 41 , carbon recovery device 8 , phosphorus recovery device 9 , anaerobic digestion mixer 7 . DETAILED DESCRIPTION

[0081] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Similar component numbers in the drawings represent similar components. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0083] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms.

[0084] In the following embodiments, the sewage treatment system and sewage treatment method provided by the present invention are introduced by using a chemically enhanced sedimentation tank as a resource capture unit and a pure membrane biochemical treatment unit as a combined tank body of an aerobic biofilm tank and an anoxic biofilm tank connected to each other.

[0085] In other embodiments, the resource capture unit may be a combination of at least one of a physical sedimentation tank, a biological adsorption tank, and / or a chemically enhanced sedimentation tank.

[0086] In other embodiments, the pure membrane biochemical treatment unit may be a single independent baffled biofilm pool, or may be a plurality of aerobic biofilm pools and a plurality of anoxic biofilm pools connected to each other.

[0087] Example 1

[0088] See also Figure 1 , which is a schematic diagram of the structure of the sewage treatment system provided by the present invention. As can be seen from the figure, the sewage treatment system provided by the present invention is a sewage treatment system for carbon and phosphorus resource recovery formed by a mainstream system and a side stream system. The mainstream system includes a resource capture unit 10, a pure membrane biochemical treatment unit 20 and a deep treatment unit 30 connected in sequence; the side stream system includes a resource recovery unit 40.

[0089] In the sewage treatment system of the present invention, the resource capture unit 10 is located at the front end of the system and connected to the water inlet pipe; the deep treatment unit 30 is located at the end of the system and connected to the water outlet pipe; the resource recovery unit 40 is located in the system bypass, and its inlet end is connected to the resource capture unit 10. The following is a detailed introduction to each unit:

[0090] In this embodiment, the resource capture unit 10 is a chemically enhanced sedimentation tank 12, which is equipped with a reagent dosing device 11, and the reagent dosing device 11 is used to dosing reagents into the chemically enhanced sedimentation tank 12; the chemically enhanced sedimentation tank 12 includes a mixing zone 121 and a sedimentation zone 122, and a sludge outlet 1221 is provided at the bottom of the chemically enhanced sedimentation tank 12, and a sewage outlet 1211 is provided at the top of the chemically enhanced sedimentation tank 12. The mixing zone 121 is connected to the reagent dosing device 11, and the mixing zone 121 is provided with a stirring device 13, and the sewage and the reagent are quickly mixed and flocculated in the mixing zone 121. The sedimentation zone 122 is provided with a scraper, and the captured carbon and phosphorus-containing sludge is finally settled in the sludge bucket of the scraper.

[0091] In a specific implementation, the agent includes a coagulant and a flocculant, wherein the coagulant can be an iron salt, an aluminum salt and / or a calcium salt, and the flocculant can be polyacrylamide.

[0092] In this embodiment, sewage enters the chemical enhanced sedimentation tank 12 from the water inlet pipe, and undergoes electrical neutralization, adsorption bridging and other reactions with the added reagents in the mixing zone 121, so that the suspended colloidal substances in the sewage are destabilized, collided and condensed, and the condensed colloidal substances are settled as floccules (sludge) containing carbon and phosphorus. The mud and water are separated in the sedimentation zone 122 to obtain sludge and primary sewage; the primary sewage enters the pure membrane biochemical treatment unit 20 for treatment from the sewage outlet end 1211; the sludge enters the resource recovery unit 40 for treatment from the sludge outlet end 1221.

[0093] This embodiment adopts a chemically enhanced primary treatment process, which can remove more than 50% of COD in the raw water and more than 80% of TP in the raw water, while achieving the capture of carbon and phosphorus.

[0094] The resource recovery unit 40 includes an anaerobic digester 41 , a carbon recovery device 8 and a phosphorus recovery device 9 ; the anaerobic digester 41 is connected to the sludge outlet 1221 , and the anaerobic digester 41 is also connected to the carbon recovery device 8 and the phosphorus recovery device 9 , respectively.

[0095] The sludge produced by the chemical enhanced sedimentation tank 12 enters the anaerobic digestion tank 41 from the sludge outlet port 1221, and the sludge is fermented, hydrolyzed and acidified to produce volatile fatty acids (VFA), which are collected in the carbon recovery device 8. At the same time, during the anaerobic digestion process, with the hydrolysis of protein and the breakage of sludge cells, the nitrogen and phosphorus elements entrained inside and outside the sludge cells are released, and combined with the added reagents to form phosphate precipitation. When the nitrogen and phosphorus substances reach a certain concentration, phosphorus combines with metal ions or other cations to form precipitation or complexes, etc., which are collected in the phosphorus recovery device 9.

[0096] An anaerobic digestion mixer 7 is provided in the anaerobic digestion tank 41 .

[0097] The volatile fatty acids in the carbon recovery device 8 can be used as a supplementary carbon source for the anoxic biofilm pool 22 during the denitrification process or as an important organic carbon source for producing alternative fuels, microbial fats and oils, and synthesizing biodegradable plastics, thereby achieving maximum resource utilization of carbon sources in sewage.

[0098] The phosphate precipitate or complex in the phosphorus recovery device 9 can be used as raw materials for industrial or agricultural production and processing, thereby realizing resource utilization of phosphorus in sewage.

[0099] The pure membrane biochemical treatment unit 20 includes an aerobic biofilm pool 21 and an anoxic biofilm pool 22 connected in sequence. The aerobic biofilm pool 21 is connected to the sewage outlet 1211 , and the anoxic biofilm pool is connected to the deep treatment unit 30 .

[0100] In some embodiments, the aerobic biofilm pool 21 is provided with a moving bed biofilm filler 2 and / or a three-dimensional immobilized biofilm module 5 .

[0101] In this embodiment, a moving bed biofilm filler 2 is provided in the aerobic biofilm pool 21 .

[0102] In the present invention, the moving bed biofilm filler 2 is a suspended biofilm filler. The sewage passes through the microorganisms attached to the surface of the biofilm filler, and under the action of aeration and oxygenation, the degradation of organic pollutants is achieved. At the same time, the moving bed biofilm filler 2 has the advantages of large specific surface area, large amount of microorganism attachment, and high organic pollutant removal load. The aerobic biofilm pool 21 of this embodiment is also provided with an agitator 3, which has the function of enhancing the fluidization of the suspended biofilm filler and preventing clogging.

[0103] In this embodiment, an aeration device, specifically a perforated aeration pipe 4, is provided at the bottom of the aerobic biofilm pool 21.

[0104] The effluent of the aerobic biofilm pool 21 enters the anoxic biofilm pool 22. In this embodiment, the anoxic biofilm pool 22 is provided with a plurality of three-dimensional immobilized biofilm modules 5. The sewage passes through the sheet-like biofilm filler attached to the surface of the three-dimensional immobilized biofilm module 5. Under the action of denitrifying bacteria, all the nitrified liquid in the incoming water can be denitrified to achieve deep removal of total nitrogen. When the carbon source is insufficient, the dissolved organic matter recovered in the carbon recovery device can be added to supplement the high-quality carbon source, and the total nitrogen in the effluent can reach less than 2.0 mg / L.

[0105] The three-dimensional immobilized biofilm module 5 is specifically composed of a plurality of sheet-like biofilm fillers fixed in the biofilm module by hanging, and there are intervals between adjacent sheet-like biofilm fillers to form muddy and water channels, which can effectively prevent blockage.

[0106] According to the volume of the anoxic biofilm pool 22, the number of the three-dimensional immobilized biofilm modules 5 can be multiple, and the multiple three-dimensional immobilized biofilm modules 5 are arranged flat and stacked to cover the entire pool space. The multiple three-dimensional immobilized biofilm modules 5 are connected by fasteners, and the interval between adjacent biofilm fillers inside the three-dimensional immobilized biofilm module 5 is about 5-100mm, forming a muddy water channel, and the filler specific surface area is about 20-2000m 2 / m 3 The film-forming amount is about 20-260g / m 2 The anoxic biofilm pool using the above fixed bed biofilm reactor configuration parameters has an ammonia nitrogen removal load of about 0.01-0.1 kg NH3-N / (kg MLSS·d), and a BOD removal load of about 0.02-0.3 kg BOD / (kg MLSS·d).

[0107] In this embodiment, the interval between adjacent biofilm fillers in the three-dimensional immobilized biofilm module 5 is about 20 mm, forming a muddy water channel, and the filler specific surface area is about 500 m 2 / m 3 , the film amount is about 150g / m 2 .

[0108] Most of the existing sewage treatment plants use the traditional AAO sewage treatment process. The carbon source in the influent is used by the microorganisms in the biochemical stage, which leads to an increase in the amount of mud produced in the system. Denitrification needs to be carried out through reflux, and the denitrification efficiency is not high. This embodiment uses a combination of pure membrane method and OA method in the main process. All nitrified liquid enters the anoxic stage, and there is no nitrified liquid reflux. The denitrification rate is as high as 100%, and the operating power consumption is low; at the same time, there is no need for a mud-water separation unit, the process is short, the operation and maintenance are simple, the footprint is small, and the amount of residual sludge is extremely low.

[0109] In a specific implementation, the deep treatment unit 30 includes at least one of a filter cloth filter tank, an air flotation tank or a magnetic coagulation sedimentation tank.

[0110] The deep treatment unit 30 of this embodiment includes a filter cloth filter tank. The sewage passes through the deep treatment unit to achieve deep removal of suspended solids (SS) to ensure that the effluent is stable and meets the discharge standards.

[0111] In this embodiment, the deep treatment unit 30 also includes a disinfection device 6, which is located at the rear end of the deep treatment unit 30 and connected to the outlet pipe for killing harmful pathogenic microorganisms in the sewage and deeply improving the outlet water quality.

[0112] In other embodiments, the resource capture unit 10 further includes a pretreatment tank (not shown), the water inlet of the pretreatment tank is connected to the water inlet pipe, and the water outlet is connected to the chemical enhanced sedimentation tank 12. The pretreatment tank is used to remove larger suspended matter and impurities in sewage.

[0113] The sewage treatment system provided in this embodiment has the advantages of high treatment efficiency, small footprint, low operating cost, simple management, stable effluent, deep denitrification and resource recovery.

[0114] See also Figure 2 , which is a process flow chart of the sewage treatment process provided by an embodiment of the present invention. This embodiment provides a sewage treatment process based on the above-mentioned sewage treatment system, which specifically includes the following steps:

[0115] S1, sewage enters the mixing zone of the chemical enhanced sedimentation tank through the water inlet pipe, and the reagent dosing device adds reagents to the sewage in the mixing zone. After the sewage and the reagents are evenly mixed, certain components such as carbon and phosphorus in the sewage are electrically neutralized, adsorbed and bridged with the reagents to destabilize, colloidal substances suspended in the sewage, colloidal substances ...

[0116] It can be understood that the carbon and phosphorus in the sewage are captured through chemical treatment in the chemical enhanced sedimentation tank, and the sewage settles to the sedimentation area to form carbon and phosphorus rich sludge, and the upper layer of the sediment is primary sewage.

[0117] S2, sending the sludge to an anaerobic digester for anaerobic fermentation to obtain volatile fatty acids and nitrogen and phosphorus precipitates, wherein the volatile fatty acids are collected in a carbon recovery device, and the nitrogen and phosphorus precipitates are collected in a phosphorus recovery device.

[0118] Specifically, the sludge is sent to the anaerobic digester, the moisture content of the sludge in the anaerobic digester is controlled within 90%, and the acidic fermentation or alkaline fermentation at medium temperature (35-45°C) is carried out, the pH is controlled above 5.0, and the organic load is 4-10kgCOD / m 3·d. It has been verified that under this parameter, the volatile fatty acids produced by anaerobic digestion are as high as 2-8g / L, and the carbon source recovery rate is between 50-80%; at the same time, after nitrogen and phosphorus precipitation, the concentration can reach 1-3g / L, and the phosphorus recovery rate in the phosphorus recovery device is between 50-80%.

[0119] It can be understood that the carbon and phosphorus-containing sludge is subjected to anaerobically digested, and the sludge is hydrolyzed and fermented during the anaerobic digestion process to produce VFA, which is collected in the carbon recovery device; at the same time, with the hydrolysis of protein and the breakage of sludge cells during the anaerobic digestion process, the nitrogen and phosphorus elements entrained in and outside the sludge cells are released, and by adjusting the pH and other methods, the released phosphorus can be combined with the added metal salts such as iron salts, aluminum salts, calcium salts or other cationic salts to form phosphate (Fe-P, Al-P, Ca-P, Mg-P, NH4-P) precipitates or complexes, which are collected in the phosphorus recovery device.

[0120] In the present invention, no additional agent needs to be added during the anaerobic digestion of sludge.

[0121] S3, sending the primary sewage to an aerobic biofilm tank for aerobic degradation and nitrification treatment to obtain secondary sewage.

[0122] In this embodiment, the aerobic biofilm pool adopts membrane process treatment, which utilizes microorganisms attached to the surface of suspended or fixed biofilm fillers combined with oxygen to decompose organic matter in the primary sewage into carbon dioxide and water, and at the same time converts ammonia nitrogen in the primary sewage into nitrate nitrogen through nitrification, thereby achieving efficient removal of organic pollutants and ammonia nitrogen in the sewage.

[0123] S4, sending the secondary sewage to an anoxic biofilm tank for denitrification treatment to obtain tertiary sewage.

[0124] In this embodiment, the anoxic biofilm pool uses a membrane process to treat the wastewater, using the denitrifying bacteria attached to the surface of the fixed biofilm filler to convert nitrate nitrogen in the sewage into nitrogen gas through denitrification, thereby achieving deep removal of total nitrogen. When the carbon source is insufficient, volatile fatty acids recovered by the carbon recovery device can be added to supplement the high-quality carbon source.

[0125] S5, sending the tertiary sewage to the deep treatment unit for treatment, and then discharging the effluent after testing it is qualified.

[0126] In this embodiment, the tertiary sewage after treatment in the anoxic biofilm tank enters the deep treatment unit, and the deep removal of suspended matter in the sewage is achieved through facilities such as filter cloth filter, flotation tank or magnetic coagulation sedimentation tank.

[0127] In this embodiment, the sewage after deep unit treatment is collected through a collection pipe and enters a disinfection facility, and the effluent meets the discharge standards after disinfection.

[0128] See also Figure 2In this embodiment 2, after the sewage enters through the water inlet pipe, it first enters the pretreatment unit to remove suspended matter and impurities in the sewage, and then enters the chemical enhanced sedimentation tank, aerobic biofilm tank, anoxic biofilm tank and deep treatment tank, and finally achieves the effluent discharge meeting the standards. Table 1 shows the pollutant treatment effect of each unit when the sewage treatment system of this embodiment is used for sewage treatment.

[0129] Table 1 Pollutant treatment effects of each unit of the sewage treatment system of this embodiment

[0130]

[0131] Furthermore, the sludge separated from the above sewage in the chemical enhanced sedimentation tank enters the anaerobic digestion tank for anaerobic fermentation, and the total solid content of the sludge is 10kgCOD / m 3 . The fermentation process adopts medium temperature (35-45℃) acidic fermentation, and the pH is controlled between 5.0 and 6.0. After 4 days of fermentation, the dissolved organic matter in the supernatant reaches the highest concentration of 7g / L, and the carbon source recovery rate reaches 70%. The recovered carbon source is added to the anoxic biofilm pool for carbon source supplementation and enhanced denitrification. The addition concentration is 100mg / L and the dilution ratio is 1:70. Nitrogen and phosphorus are recovered by adjusting the pH of the fermentation supernatant to obtain phosphate precipitates or complexes, and the recovery rate reaches 50%.

[0132] Example 2

[0133] The sewage treatment system and sewage treatment method provided in this embodiment are based on the embodiment 1, and use the chemical enhanced sedimentation tank as the resource capture unit and the pure membrane biochemical treatment unit as an independent tank body of the baffled biofilm tank.

[0134] See also Figure 3 and Figure 4 The difference between this embodiment and embodiment 1 is that the pure membrane biochemical treatment unit 20 is specifically a baffled biofilm pool 23.

[0135] In this embodiment, the baffled biofilm pool 23 contains a total of 9 baffled corridors 231, and 5 layers of three-dimensional immobilized biofilm modules 5 are placed in the baffled corridors 231. Aerators 232 are evenly distributed at the bottom of each baffled corridor 231, among which the aerators 232 at the bottom of the first 6 baffled corridors 231 are in an open state, and the aerators 232 at the bottom of the last 3 baffled corridors 231 are in a closed state, thereby controlling the formation of aerobic and anoxic zones in the baffled biofilm pool 23, and performing an aerobic-anoxic process. In this embodiment, the volume ratio of the aerobic zone to the anoxic zone is 2: 1. The dissolved oxygen organic matter produced by the anaerobic digestion tank 41 can be used as a carbon source for the anoxic zone. In this embodiment, the carbon source addition points are set in the 7th and 8th corridors.

[0136] The sewage treatment process of this embodiment is the same as that of Embodiment 1, and will not be described in detail.

[0137] Table 2 shows the pollutant treatment effect of each unit when the sewage treatment system of this embodiment is used for sewage treatment.

[0138] Table 2 Pollutant treatment effects of each unit of the sewage treatment system of this embodiment

[0139]

[0140] Furthermore, the sludge in this embodiment enters the anaerobic digester for anaerobic fermentation, and the total solid content of the sludge is 10 kgCOD / m 3 . The fermentation process uses alkaline fermentation to inhibit gas production. Sodium bicarbonate is used to adjust the pH to 9.0-10.0 during the fermentation process. After 4 days of fermentation, the dissolved organic matter in the supernatant reaches the highest concentration of 7g / L, and the carbon source recovery rate reaches 70%. The recovered carbon source is added to the anoxic biofilm pool for carbon source supplementation and enhanced denitrification. The addition concentration is 100mg / L and the dilution ratio is 1:70. Nitrogen and phosphorus are recovered by adjusting the pH of the fermentation supernatant to obtain phosphate precipitates or complexes, with a recovery rate of 60%.

[0141] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0142] The above is a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A sewage treatment system, characterized in that: A wastewater treatment system for carbon and phosphorus resource recovery is formed by a mainstream system and a side stream system; the mainstream system comprises a resource capture unit, a pure membrane biochemical treatment unit and a deep treatment unit connected in sequence; the side stream system comprises a resource recovery unit; The resource capture unit is provided with a sewage upper layer area and a sludge sedimentation area, the bottom of the sludge sedimentation area is provided with a sludge outlet, and the top of the sewage upper layer area is provided with a sewage outlet; the sewage outlet is connected to the pure membrane biochemical treatment unit; The resource capture unit is a physical sedimentation tank, a biological adsorption tank and / or a chemically enhanced sedimentation tank, wherein the chemically enhanced sedimentation tank is equipped with a reagent delivery device, and the reagent delivery device is used to deliver reagents to the chemically enhanced sedimentation tank; the resource capture unit is used to capture carbon sources and phosphorus sources in sewage; The pure membrane biochemical treatment unit comprises an independent tank body and / or a combined tank body; The independent pool body is a baffled biofilm pool, in which a plurality of baffles are installed, and a plurality of baffle corridors are formed in the pool body through the baffles, and a three-dimensional immobilized biofilm module is arranged in the baffle corridor; The combined pool body comprises a plurality of aerobic biofilm pools and a plurality of anoxic biofilm pools which are interconnected; the aerobic biofilm pools are provided with moving bed biofilm fillers and / or three-dimensional immobilized biofilm modules, and the anoxic biofilm pools are provided with three-dimensional immobilized biofilm modules; The resource recovery unit comprises an anaerobic digestion tank, a carbon recovery device and a phosphorus recovery device; the anaerobic digestion tank is connected to the sludge outlet, and the anaerobic digestion tank is also connected to the carbon recovery device and the phosphorus recovery device respectively.

2. The sewage treatment system according to claim 1, characterized in that: It also includes a pre-treatment pool, wherein the water inlet end of the pre-treatment pool is connected to the water inlet pipeline, and the water outlet end of the pre-treatment pool is connected to the resource capture unit.

3. The sewage treatment system according to claim 1, characterized in that: A carbon source storage device is arranged inside the anoxic biofilm pool, and the carbon recovery device is connected to the carbon source storage device.

4. The sewage treatment system according to claim 1, characterized in that: The deep processing unit also includes a disinfection device, which is located at the rear end of the deep processing unit and connected to the water outlet pipe.

5. The sewage treatment system according to claim 1, characterized in that: An aerator is installed at the bottom of the baffle gallery, and the start and stop control of the aerator at the bottom of each baffle gallery is independent.

6. The sewage treatment system according to claim 1, characterized in that: The three-dimensional immobilized biofilm module is composed of a plurality of sheet-like biofilm fillers suspended and fixed in the biofilm module, and there are intervals between adjacent sheet-like biofilm fillers.

7. A sewage treatment process, characterized in that: The following steps are involved: S1, sewage enters the resource capture unit through the water inlet pipe, and captures carbon and phosphorus substances through physical free sedimentation and / or biological adsorption flocculation and / or chemical enhanced electrical neutralization and adsorption bridging to obtain sludge and primary sewage; S2, sending the sludge to a resource recovery unit, performing anaerobic fermentation in an anaerobic digestion tank to obtain soluble organic matter and nitrogen and phosphorus precipitates, wherein the soluble organic matter is collected in a carbon recovery device, and the nitrogen and phosphorus precipitates are collected in a phosphorus recovery device; S3, sending the primary sewage to a pure membrane biochemical treatment unit for aerobic degradation, nitrification and denitrification treatment, etc., to obtain secondary sewage; S4, sending the secondary sewage to the deep treatment unit for treatment, and then discharging the effluent after testing it is qualified.

8. The sewage treatment process according to claim 7, characterized in that: In the step S2, the dissolved organic matter in the carbon recovery device is sent to the pure membrane biochemical treatment unit as a supplementary carbon source for the denitrification treatment in step S3.

9. The sewage treatment process according to claim 7, characterized in that: The step S4 also includes that the secondary sewage is treated by the deep treatment unit and then enters a disinfection device for disinfection, and the effluent is tested and discharged after being qualified after disinfection.

10. The sewage treatment process according to claim 7, characterized in that: In step S2, the sludge is sent to a resource recovery unit, the water content of the sludge is within 90%, the temperature of anaerobic fermentation is 35-45°C, the fermentation time is 1-5 days, and the pH is above 5.0.

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