Side-stream enhanced biological phosphorus removal and phosphorus recovery coupling system and method

Abstract

The application discloses a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system, which comprises a main-flow SBR reactor unit, a side-flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit and a liquid storage tank unit which are sequentially connected; and further comprises a monitoring unit for monitoring the supernatant pH value in the main-flow SBR reactor unit, the side-flow anaerobic fermentation reactor unit and the phosphorus recovery reactor unit and the supernatant DO index in the main-flow SBR reactor unit. The system optimizes the phosphorus recovery conditions and process operation parameters, realizes the dual goals of efficient denitrification and phosphorus removal of sewage and phosphorus resource recovery, reduces the operation cost, and realizes the water resource recycling. The application further discloses a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling method.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically relating to a side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, and also to a side-flow enhanced biological phosphorus removal and phosphorus recovery coupled method. Background Technology

[0002] Phosphorus is a vital non-renewable resource and a key pollutant contributing to eutrophication. Traditional enhanced biological phosphorus removal (EBPR) processes often face challenges such as insufficient influent carbon source and low carbon-to-phosphorus ratio (C / P), resulting in poor phosphorus removal performance. Meanwhile, standalone phosphorus recovery processes are often disconnected from wastewater treatment systems, exhibiting drawbacks such as low phosphorus enrichment, high reagent consumption, and inhibited microbial activity. Side-flow enhanced biological phosphorus removal (S2EBPR) processes, by adding a side-flow anaerobic digester, can achieve carbon source replenishment and sludge reduction; however, how to efficiently couple it with phosphorus recovery processes to achieve synergistic optimization of wastewater treatment and resource recovery remains a current technical challenge.

[0003] The existing process has the following shortcomings: Under the condition of low C / P ratio (20~30) influent, the phosphorus removal effect of the traditional process is poor, and additional carbon source needs to be added to maintain a good phosphorus removal effect; at the same time, the low C / P condition will hinder the phosphorus recovery crystallization reaction, making it difficult to promote phosphorus recovery in a coordinated manner. Summary of the Invention

[0004] The first objective of this invention is to provide a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system that can achieve efficient phosphorus removal from low C / P wastewater, while also enabling efficient phosphorus recovery crystallization reaction, thus achieving process synergy between phosphorus removal and phosphorus recovery.

[0005] The second objective of this invention is to provide a method for coupling side-flow enhanced biological phosphorus removal and phosphorus recovery.

[0006] The first technical solution adopted in this invention is a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system, which includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit and the phosphorus recovery reactor unit and the DO index of the supernatant in the main flow SBR reactor unit.

[0007] The invention is further characterized in that:

[0008] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0009] The mainstream SBR reactor unit includes a mainstream SBR reactor. The upper part of the side wall of the mainstream SBR reactor is provided with the mainstream SBR reactor inlet and the fermentation broth return inlet. The lower part of the side wall of the mainstream SBR reactor is provided with the mainstream SBR reactor outlet and the sludge discharge outlet. The top of the mainstream SBR reactor is equipped with an agitator and an aeration device. The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor. The upper part of the side wall of the side-flow anaerobic fermentation reactor is provided with a side-flow anaerobic fermentation reactor inlet and a supernatant return outlet. The lower part of the side wall of the side-flow anaerobic fermentation reactor is provided with a fermentation liquid return outlet and a return inlet. A second stirrer is installed on the top of the side-flow anaerobic fermentation reactor. The phosphorus recovery reactor unit includes a phosphorus recovery reactor with a conical bottom. A filter screen is installed at the conical bottom of the phosphorus recovery reactor. A supernatant reflux inlet is provided on the upper part of the side wall of the phosphorus recovery reactor, a reflux outlet is provided on the lower part of the side wall of the phosphorus recovery reactor, a crystal outlet is provided at the bottom of the phosphorus recovery reactor, and a first reagent inlet, a second reagent inlet, and a third reagent inlet are also provided at the top of the phosphorus recovery reactor; a third stirrer is installed at the top of the phosphorus recovery reactor. The storage tank unit includes a magnesium salt storage tank for storing magnesium chloride solution, a calcium salt storage tank for storing calcium chloride solution, and an alkaline storage tank for storing sodium hydroxide solution. The fermentation broth reflux inlet is connected to the fermentation broth reflux outlet through the first flow control unit; The sludge discharge port is connected to the inlet of the side-flow anaerobic fermentation reactor through a second flow control unit; The supernatant reflux outlet is connected to the supernatant reflux inlet via a third flow control unit; The return inlet is connected to the return outlet via the fourth flow control unit; The magnesium salt storage tank is connected to the first reagent dosing port through the first reagent dosing unit; The calcium salt storage tank is connected to the second reagent dosing port through the second reagent dosing unit; The alkali solution storage tank is connected to the third reagent dosing port through the third reagent dosing unit; The monitoring unit includes an online monitoring instrument, a first pH sensor, a second pH sensor, and a third pH sensor; the first pH sensor, the second pH sensor, and the third pH sensor are respectively located inside the main flow SBR reactor, the side flow anaerobic fermentation reactor, and the phosphorus recovery reactor; it also includes a DO sensor located inside the main flow SBR reactor; the first pH sensor, the second pH sensor, the third pH sensor, and the DO sensor are all connected to the online monitoring instrument.

[0010] The first flow control unit includes a first pipe, on which a first peristaltic pump, a first flow sensor and a first solenoid valve are installed; the first end of the first pipe is connected to the fermentation broth return inlet and the second end of the first pipe is connected to the fermentation broth return outlet. The second flow control unit includes a second pipeline, on which a second peristaltic pump, a second flow sensor and a second solenoid valve are installed; the first end of the second pipeline is connected to the sludge discharge port and the second end of the second pipeline is connected to the inlet of the side-flow anaerobic fermentation reactor. The third flow control unit includes a third pipeline, on which a third peristaltic pump, a third flow sensor and a third solenoid valve are installed; the first end of the third pipeline is connected to the supernatant return outlet and the second end of the third pipeline is connected to the supernatant return inlet. The fourth flow control unit includes a fourth pipe, on which a fourth peristaltic pump, a fourth flow sensor, and a fourth solenoid valve are installed; the first end of the fourth pipe is connected to the return inlet, and the second end of the fourth pipe is connected to the return outlet. The first reagent dosing unit includes a fifth pipeline, on which a first metering pump and a fifth solenoid valve are installed; the first end of the fifth pipeline is connected to the first reagent dosing port, and the second end of the fifth pipeline is connected to the magnesium salt storage tank. The second reagent dosing unit includes a sixth pipeline, on which a second metering pump and a sixth solenoid valve are installed; the first end of the sixth pipeline is connected to the second reagent dosing port, and the second end of the sixth pipeline is connected to the calcium salt storage tank. The third reagent dosing unit includes a seventh pipeline, on which a third metering pump and a seventh solenoid valve are installed; the first end of the seventh pipeline is connected to the third reagent dosing port, and the second end of the seventh pipeline is connected to the alkali storage tank.

[0011] The aeration device includes a microporous aeration head and an aeration pump connected by a pipe; The microporous aeration head is located at the bottom of the main SBR reactor, and the aeration pump is located at the top outside of the main SBR reactor.

[0012] The second technical solution adopted in this invention is a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling method, which uses the above-mentioned system, specifically as follows: Step 1: Use a mainstream SBR reactor and a side-flow anaerobic fermentation reactor to achieve carbon source replenishment and phosphorus enrichment through sludge exchange; Step 2: Add reagents to the phosphorus recovery reactor to achieve phosphorus crystallization and recovery.

[0013] The invention is further characterized in that: Step 1 is as follows: Wastewater with a C / P ratio of 20-30 is received through the inlet of the main SBR reactor, and the treated liquid from the main SBR reactor is discharged through the outlet of the main SBR reactor. Sludge exchange between the main SBR reactor and the side-flow anaerobic fermentation reactor is completed through the first and second pipes. The side-flow anaerobic fermentation reactor is used to receive the return sludge from the main SBR reactor. Under anaerobic conditions, the sludge hydrolysis and fermentation are promoted by the second stirrer to produce VFA, which is a carbon source for biological phosphorus removal of wastewater. At the same time, it promotes the release of phosphorus from the sludge to form a phosphorus-rich supernatant.

[0014] Step 2 specifically involves: using a phosphorus recovery reactor to provide reaction space for phosphorus crystallization; using a third stirrer to ensure thorough mixing of the reagent and the phosphorus-rich supernatant; separating and collecting MAP or HAP crystals through a filter screen set at the diameter change of the cone; periodically collecting the product through the crystal discharge outlet; and sending the supernatant after the reaction back to the side-flow anaerobic fermentation reactor through the supernatant return inlet to continue participating in the process cycle.

[0015] The beneficial effects of this invention are: (1) In view of the shortcomings of traditional processes that have poor phosphorus removal effect under low C / P ratio influent conditions and require additional carbon source addition, the present invention system supplements the mainstream reactor with carbon source through side-flow anaerobic fermentation reactor, so that high-efficiency phosphorus removal of low C / P wastewater can be achieved without additional carbon source addition, which not only improves phosphorus removal performance, but also reduces the operating cost of carbon source addition. (2) In view of the defects of phosphorus recovery crystallization reaction being hindered under low C / P conditions and difficulty in promoting phosphorus recovery and phosphorus removal processes in a coordinated manner, this invention achieves the directional enrichment of phosphorus through side-flow anaerobic fermentation, so that the phosphorus crystallization recovery reaction can be carried out efficiently, and the phosphorus removal and phosphorus recovery processes can be coordinated. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system of the present invention; In the diagram: 1. Mainstream SBR reactor; 1-1. Mainstream SBR reactor inlet; 1-2. Mainstream SBR reactor outlet; 1-3. Fermentation broth reflux inlet; 1-4. Sludge discharge outlet; 2. Side-flow anaerobic fermentation reactor; 2-1. Inlet of the side-flow anaerobic fermentation reactor; 2-2. Fermentation broth reflux outlet; 2-3. Supernatant reflux outlet; 2-4. Reflux inlet; 3. Phosphorus recovery reactor; 3-1. Supernatant reflux inlet; 3-2. Reflux outlet; 3-3. Crystal discharge outlet; 3-4. First reagent addition port; 3-5. Second reagent addition port; 3-6. Third reagent addition port; 3-7. Filter screen; 4. Magnesium salt storage tank; 5. Calcium salt storage tank; 6. Alkali storage tank; 7. Third stirrer; 8. First solenoid valve; 9. First flow sensor; 10. First peristaltic pump; 11. First pH sensor; 12. DO sensor; 13. Online monitoring instrument; 14. First stirrer. 15. Aeration device; 15-1. Microporous aeration head; 15-2. Aeration pump; 16. Second pH sensor, 17. Third pH sensor, 18. Second stirrer, 19. First pipe, 20. Second pipe, 21. Second peristaltic pump, 22. Second flow sensor, 23. Second solenoid valve, 24. Third pipe, 25. Third peristaltic pump, 26. Third flow sensor, 27. Third solenoid valve, 28. Fourth pipe, 29. Fourth solenoid valve, 30. Fourth flow sensor, 31. Fourth peristaltic pump, 32. Seventh solenoid valve, 33. Fifth pipe, 34. First metering pump, 35. Fifth solenoid valve, 36. Sixth pipe, 37. Second metering pump, 38. Sixth solenoid valve, 39. Seventh pipe, 40. Third metering pump. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] This invention provides a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system, such as... Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0019] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0020] The mainstream SBR reactor unit includes a mainstream SBR reactor 1, an inlet 1-1 on the upper side wall of the mainstream SBR reactor 1, a fermentation broth return inlet 1-3 on the upper side wall of the mainstream SBR reactor 1, an outlet 1-2 on the lower side wall of the mainstream SBR reactor 1, from which effluent is discharged, a sludge discharge outlet 1-4 on the lower side wall of the mainstream SBR reactor 1, and an agitator 14 and an aeration device 15 installed on the top of the mainstream SBR reactor 1. The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor 2. The upper part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a side-flow anaerobic fermentation reactor inlet 2-1 and a supernatant return outlet 2-3. The lower part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a fermentation liquid return outlet 2-2 and a return inlet 2-4. A second stirrer 18 is installed on the top of the side-flow anaerobic fermentation reactor 2. The phosphorus recovery reactor unit includes a phosphorus recovery reactor 3 with a conical bottom. A filter screen 3-7 is installed at the conical bottom of the phosphorus recovery reactor 3. A supernatant reflux inlet 3-1 is installed on the upper part of the side wall of the phosphorus recovery reactor 3. A reflux outlet 3-2 is installed on the lower part of the side wall of the phosphorus recovery reactor 3. A crystal outlet 3-3 is installed at the bottom of the phosphorus recovery reactor 3. A first reagent addition port 3-4, a second reagent addition port 3-5, and a third reagent addition port 3-6 are also provided at the top of the phosphorus recovery reactor 3. A third stirrer 7 is installed at the top of the phosphorus recovery reactor 3. The storage tank unit includes a magnesium salt storage tank 4, a calcium salt storage tank 5, and an alkaline solution storage tank 6; The fermentation broth reflux inlet 1-3 is connected to the fermentation broth reflux outlet 2-2 through the first flow control unit; Sludge discharge port 1-4 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor through the second flow control unit; Supernatant reflux outlet 2-3 is connected to supernatant reflux inlet 3-1 through a third flow control unit; The return inlet 2-4 is connected to the return outlet 3-2 through the fourth flow control unit; The magnesium salt storage tank 4 is connected to the first reagent addition port 3-4 via the first reagent addition unit; The calcium salt storage tank 5 is connected to the second reagent addition port 3-5 via the second reagent addition unit; The alkali storage tank 6 is connected to the third reagent addition port 3-6 via the third reagent addition unit; Figure 1 In the process, the sludge from the main SBR reactor 1 flows through a pipe from the sludge discharge port 1-4 to the side-flow anaerobic fermentation reactor inlet 2-1 of the side-flow anaerobic fermentation reactor 2; the fermentation broth from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the fermentation broth return outlet 2-2 to the fermentation broth return inlet 1-3 of the main SBR reactor 1. The supernatant from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the supernatant return outlet 2-3 to the supernatant return inlet 3-1 of the phosphorus recovery reactor 3; the residual liquid from the phosphorus recovery reactor 3 flows through a pipe from the return outlet 3-2 to the return inlet 2-4 of the side-flow anaerobic fermentation reactor 2.

[0021] The monitoring unit includes an online monitoring instrument 13, a first pH sensor 11, a second pH sensor 16, and a third pH sensor 17; the first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 are respectively installed inside the main flow SBR reactor 1, the side flow anaerobic fermentation reactor 2, and the phosphorus recovery reactor 3; it also includes a DO sensor 12 installed inside the main flow SBR reactor 1; the first pH sensor 11, the second pH sensor 16, the third pH sensor 17, and the DO sensor 12 are all connected to the online monitoring instrument 13.

[0022] The first flow control unit includes a first pipe 19, on which a first peristaltic pump 10, a first flow sensor 9 and a first solenoid valve 8 are installed; the first end of the first pipe 19 is connected to the fermentation liquid return inlet 1-3, and the second end of the first pipe 19 is connected to the fermentation liquid return outlet 2-2. The second flow control unit includes a second pipe 20, on which a second peristaltic pump 21, a second flow sensor 22 and a second solenoid valve 23 are installed; the first end of the second pipe 20 is connected to the sludge discharge port 1-4, and the second end of the second pipe 20 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor. The third flow control unit includes a third pipe 24, on which a third peristaltic pump 25, a third flow sensor 26 and a third solenoid valve 27 are installed; the first end of the third pipe 24 is connected to the supernatant return outlet 2-3, and the second end of the third pipe 24 is connected to the supernatant return inlet 3-1. The fourth flow control unit includes a fourth pipe 28, on which a fourth peristaltic pump 31, a fourth flow sensor 30 and a fourth solenoid valve 29 are installed; the first end of the fourth pipe 28 is connected to the return inlet 2-4, and the second end of the fourth pipe 28 is connected to the return outlet 3-2. The first reagent dosing unit includes a fifth pipeline 33, on which a first metering pump 34 and a fifth solenoid valve 35 are installed; the first end of the fifth pipeline 33 is connected to the first reagent dosing port 3-4, and the second end of the fifth pipeline 33 is connected to the magnesium salt storage tank 4. The second reagent dosing unit includes a sixth pipeline 36, on which a second metering pump 37 and a sixth solenoid valve 38 are installed; the first end of the sixth pipeline 36 is connected to the second reagent dosing port 3-5, and the second end of the sixth pipeline 36 is connected to the calcium salt storage tank 5. The third reagent dosing unit includes a seventh pipeline 39, on which a third metering pump 40 and a seventh solenoid valve 32 are installed; the first end of the seventh pipeline 39 is connected to the third reagent dosing port 3-6, and the second end of the seventh pipeline 39 is connected to the alkali storage tank 6.

[0023] The aeration device 15 includes a microporous aeration head 15-1 and an aeration pump 15-2 connected by a pipe; The microporous aeration head 15-1 is installed at the bottom of the main SBR reactor 1, and the aeration pump 15-2 is installed on the top outside of the main SBR reactor 1.

[0024] In the side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system of this invention, the main SBR reactor 1 is made of cylindrical transparent plexiglass with an effective volume of 4.6L; The side-flow anaerobic fermentation reactor 2 is made of rectangular transparent plexiglass with an effective volume of 5.52L. It has no aeration device at the bottom to maintain the anaerobic environment.

[0025] The phosphorus recovery reactor 3 consists of a cylindrical reaction zone (effective volume 0.8L) and a conical crystal collection zone (effective volume 0.2L), and is made of transparent plexiglass.

[0026] Magnesium salt storage tank, calcium salt storage tank, and alkali storage tank respectively store magnesium chloride solution, calcium chloride solution, and sodium hydroxide solution.

[0027] The monitoring unit includes an online monitoring instrument 13 (the online monitoring instrument 13 is a Hangzhou Meiyi Supmea MDX500 multi-parameter water quality analyzer), a first pH sensor 11, a second pH sensor 16, and a third pH sensor 17. The first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 are installed with their probes immersed in the middle of the supernatant of the main flow reactor 1, the middle of the supernatant of the side-flow anaerobic fermentation reactor 2, and the reaction zone of the phosphorus recovery reactor 3, respectively. A DO sensor 12 is installed with its probe immersed in the middle of the supernatant of the main flow reactor 1. The online monitoring instrument 13 connects the first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 to the DO sensor 12 to monitor pH and DO levels in real time.

[0028] This invention also provides a side-flow enhanced biological phosphorus removal and phosphorus recovery coupling method, which uses the above-mentioned system, specifically as follows: Step 1: Carbon source replenishment and phosphorus enrichment are achieved through sludge exchange using a mainstream SBR reactor 1 and a side-flow anaerobic fermentation reactor 2. Step 1 is as follows: Wastewater with a C / P ratio of 20-30 is received through the inlet 1-1 of the main SBR reactor 1, and the treated liquid of the main SBR reactor 1 is discharged through the outlet 1-2 of the main SBR reactor. The sludge exchange between the main SBR reactor 1 and the side-flow anaerobic fermentation reactor 2 is completed through the first pipe 19 and the second pipe 20. The side-flow anaerobic fermentation reactor 2 is used to receive the return sludge from the main SBR reactor 1. Under anaerobic conditions, the sludge hydrolysis and fermentation are promoted by the second stirrer 18 to produce VFA, which is a carbon source for biological phosphorus removal of wastewater. At the same time, it promotes the release of phosphorus from the sludge to form a phosphorus-rich supernatant.

[0029] Step 2: Add reagents to phosphorus recovery reactor 3 to achieve phosphorus crystallization and recovery.

[0030] Step 2 is as follows: Phosphorus recovery reactor 3 is used to provide space for phosphorus crystallization reaction, and third stirrer 7 is used to ensure that the reagent and phosphorus-rich supernatant are fully mixed; MAP or HAP crystals are separated and collected through the filter screen set at the diameter change of the cone, and the product is collected periodically through crystal outlet 3-3. The supernatant after reaction is sent back to the side flow anaerobic fermentation reactor 2 through supernatant return inlet 3-1 to continue to participate in the process cycle.

[0031] The system of this invention runs 4 cycles per day, each cycle lasting 6 hours. The specific process is as follows: S1: (00:00) Artificially dispensed water is injected into the main SBR reactor 1 through the inlet 1-1 of the main SBR reactor. At this time, the first agitator 14 and the aeration device 15 are in the closed state; the second agitator 18 is turned on. S2: (00:30) Stop artificial water injection into the main SBR reactor 1; at the same time, start the first agitator 14; S3: (02:00) Turn on the aeration device 15; S4: (03:30) Turn off the second mixer 18; S5: (04:30) Turn on the third peristaltic pump 25; S6: (04:31) Turn on the second mixer 18, turn off the third peristaltic pump 25, turn on the third mixer 7, and turn on the first metering pump 34, the second metering pump 37, and the third metering pump 40. S7: (05:00) Turn off the aeration device 15 and the first agitator 14; S8: (05:01) Turn off the third mixer 7; S9: (05:31) Turn on the fourth peristaltic pump 31; S10: (05:32) Turn off the fourth peristaltic pump 31; S11: (05:35) Open the main SBR reactor outlet 1-2; S12: (05:50) Close the main SBR reactor outlet 1-2; S13: (05:55) Turn off the second stirrer 18, turn on the second peristaltic pump 21, and turn on the first peristaltic pump 10; S14: (06:00) Turn off the second peristaltic pump 21 and the first peristaltic pump 10. The first cycle ends and the next cycle begins.

[0032] The core reaction equipment in the side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system of this invention is as follows: The main SBR reactor 1 is the core site for nitrogen and phosphorus removal from wastewater. The first agitator 14 is used to mix materials in the anaerobic stage to ensure that PAOs (polyphosphate-accumulating organisms) fully release phosphorus and absorb carbon sources. The aeration device 15 is used to provide oxygen in the aerobic stage to meet the needs of nitrification by nitrifying bacteria and excessive phosphorus absorption by PAOs. The main SBR reactor inlet 1-1 receives wastewater, and the main SBR reactor outlet 1-2 discharges treated effluent that meets the standards (all indicators of the effluent meet the requirements of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002)). The sludge exchange between the main SBR reactor 1 and the side-flow anaerobic fermentation reactor 2 is completed through the first pipe 19 and the second pipe 20, which synergistically completes the carbon source replenishment and phosphorus enrichment.

[0033] The side-flow anaerobic fermentation reactor 2 receives the return sludge from the main SBR reactor 1. Under anaerobic conditions, the second stirrer 18 promotes the hydrolysis and fermentation of the sludge, producing VFA (volatile fatty acids) to supplement the carbon source. At the same time, it promotes the release of phosphorus from the sludge to form a phosphorus-rich supernatant. The mass exchange with the main SBR reactor 1 optimizes the C / P ratio of the main influent. The connection with the phosphorus recovery reactor 3 enables the transport of the phosphorus-rich supernatant and the return of the supernatant after the reaction.

[0034] Phosphorus recovery reactor 3 provides space for phosphorus crystallization reaction, and the third stirrer 7 ensures thorough mixing of the reagents and phosphorus-rich supernatant. The conical crystal collection zone separates and collects MAP or HAP crystals through a filter screen at the cone's diameter change. Crystal outlet 3-3 facilitates periodic product collection, and supernatant return inlet 3-1 returns the supernatant after reaction to the side-flow anaerobic fermentation reactor 2 for continued process circulation. The main SBR reactor 1 and the side-flow anaerobic fermentation reactor 2 achieve carbon source replenishment and phosphorus enrichment through sludge exchange. The side-flow anaerobic fermentation reactor 2 supplies phosphorus-rich supernatant to the phosphorus recovery reactor 3, which recovers phosphorus crystals through reagent addition.

[0035] Auxiliary equipment: The reagent dosing equipment includes: magnesium salt storage tank 4, calcium salt storage tank 5, and alkali storage tank 6, which respectively provide the reaction reagents required for MAP method, HAP method, and alkalinity control. Based on the pH data of the monitoring unit, the reagent dosage is calculated according to the ion molar ratio and the reagents are added through the first metering pump 34, the second metering pump 37, and the third metering pump 40 to ensure phosphorus recovery efficiency.

[0036] Flow control unit: The peristaltic pump provides power for material conveying between various devices, the flow sensor monitors the flow data in the pipeline in real time, and the solenoid valve automatically adjusts the flow according to preset parameters to ensure the stability of the hydraulic retention time (HRT) of the main SBR reactor 1 and the HRT of the side-flow anaerobic fermentation reactor 2, and to ensure the consistency of process parameters.

[0037] Monitoring Unit: Each pH sensor provides real-time feedback on the pH value of each reactor, providing a basis for alkali addition; the DO sensor ensures that the DO in the main reactor is maintained at 2.0~5.5mg / L during the aerobic stage, ensuring the stable operation of the entire system.

[0038] This invention system leverages the carbon source replenishment advantages of the S2EBPR process and the resource recovery advantages of phosphorus recovery via crystallization. Through a synergistic mechanism of "mainstream purification - sidestream enrichment - phosphorus recovery - supernatant recirculation," it achieves simultaneous optimization of wastewater nitrogen and phosphorus removal and phosphorus resource recovery. In the mainstream SBR reactor, during the anaerobic stage, PAOs decompose poly-P within the organism, releasing phosphorus and absorbing carbon sources to synthesize PHA. During the aerobic stage, PAOs utilize the energy from PHA to excessively absorb phosphorus, and nitrifying bacteria convert NH4+ into phosphorus. + -N is oxidized to NO3 - -N; In the side-flow anaerobic fermentation reactor, the returned sludge undergoes hydrolysis and fermentation to produce VFA, while simultaneously releasing phosphorus to form a phosphorus-rich supernatant, supplementing the mainstream carbon source and improving phosphorus recovery efficiency; In phosphorus recovery reactor 3, the pH and ion molar ratio are adjusted by precisely adding magnesium / calcium salts and alkaline solution to ensure PO4 3- -P and Mg 2+ / Ca 2+ NH4 + MAP / HAP crystals are formed to achieve phosphorus resource recovery.

[0039] Example 1 S2EBPR+PR Coupling Process Construction and Operation Experimental Setup: A mainstream SBR reactor with a cylindrical structure and an effective volume of 4.6 L was constructed using transparent plexiglass. A side-flow anaerobic fermentation reactor with a cuboid structure and an effective volume of 5.52 L was also constructed using transparent plexiglass. A phosphorus recovery reactor was constructed, consisting of a cylindrical reaction zone (effective volume 0.8 L) and a conical bottom crystal collection zone (effective volume 0.2 L), both constructed using transparent plexiglass. All reactors were connected via inlet, outlet, and return pipes made of silicone tubing.

[0040] Sludge acclimatization: Sludge taken from the biological tank of the Fourth Reclaimed Water Plant in Xi'an was inoculated into the mainstream SBR reactor and the side-flow anaerobic fermentation reactor, respectively. The initial concentration of mainstream MLSS was 2000 mg / L, and the initial concentration of side-flow MLSS was 3950 mg / L; the acclimatization period was 30 days.

[0041] Influent configuration: Influent is configured according to C / P=30, with a total carbon source concentration of 325 mg / L, containing acid-hydrolyzed casein (71.15 mg / L), glucose (75.00 mg / L), anhydrous sodium acetate (96.25 mg / L), and sodium propionate (64.30 mg / L). The phosphorus source is KH2PO4 (43.87 mg / L), the nitrogen source is NH4Cl (95.53 mg / L), and the macroelements are yeast extract (8.00 mg / L) and MgCl2. 6H2O (219.00 mg / L), MgSO4 The concentrations of H₂O (14.00 mg / L), KCl (98.00 mg / L), and CaCl₂ (46.00 mg / L) were found in the following amounts: H₃BO₃ (0.06 mg / L) and Na₂MoO₄. 2H2O (0.03mg / L), KI (0.02mg / L), CuSO4 5H₂O (0.06 mg / L), CoCl₂ 6H2O (0.06 mg / L), ZnSO4 7H2O (0.30 mg / L), MnSO4 H2O (0.34 mg / L), FeSO4 7H2O (0.30 mg / L). The influent was prepared according to a C / P=20 configuration, with a total carbon source concentration of 216 mg / L, containing acid-hydrolyzed casein (47.43 mg / L), glucose (50.00 mg / L), anhydrous sodium acetate (64.17 mg / L), and sodium propionate (2.87 mg / L). The concentrations of phosphorus source, nitrogen source, macroelements, and microelements were completely consistent with the C / P=30 configuration.

[0042] Process operating parameters: water temperature controlled at 18±0.5℃, pH of main flow and side flow controlled at 7.0±0.2, DO of the main flow SBR reactor maintained at 3.0±0.5mg / L during the aerobic stage, agitator speed of the main flow SBR reactor 250r / min, agitator speed of the side flow anaerobic fermentation reactor 120r / min, agitator speed of the phosphorus recovery reactor 150r / min; influent flow rate of the main flow SBR reactor 9.2L / d, exchange flow rate between the main flow SBR reactor and the side flow anaerobic fermentation reactor 1.84L / d, hydraulic retention time (HRT) of the main flow SBR reactor 12h, sludge retention time (SRT) of the main flow SBR reactor 15d, hydraulic retention time of the side flow anaerobic fermentation reactor 72h; Phosphorus recovery method: Magnetic struvite (MAP) method; pH adjuster: 1 mol / L NaOH solution is used as the pH adjuster to control the pH at 9.8 ± 0.1; Magnesium source: Magnesium chloride hexahydrate (MgCl2) A 1 mol / L stock solution was prepared using 6H₂O as the magnesium source, and the dosage was calculated based on a P / Mg molar ratio of 1:1.45. During the phosphorus recovery reaction, samples were taken every 5 minutes to determine the PO₄⁻ content in the supernatant. 3- -P, NH4 + -N concentration was used to observe the crystallization reaction process; after the reaction was completed, the crystallized product in the conical collection area was collected, washed three times with ultrapure water, and dried in a 40℃ forced-air drying oven for 48 hours.

[0043] After stable operation, samples were collected daily from the influent and effluent of the main SBR reactor, the supernatant of the side-flow anaerobic fermentation reactor, and the influent and effluent of the phosphorus recovery reactor. Various indicators were monitored: COD: determined using the potassium dichromate oxidation method, digested using a Hach digester, and detected by a UV-Vis spectrophotometer (DR6000); PO4: 3- -P: Determined using the molybdenum-antimony spectrophotometric method and detected by a UV-Vis spectrophotometer; NH4 + -N: Determined using Nessler's reagent spectrophotometry and detected by UV-Vis spectrophotometer; TN: Determined using potassium persulfate oxidation method and detected by UV-Vis spectrophotometer; Actual phosphorus recovery rate: Calculated from the PO4 in the phosphorus recovery reactor. 3- -P removal rate and PO4 in system influent 3- The ratio of total -P. Purity of the recovered product struvite (MAP): determined by acid dissolution method, 10 mg of dried product was dissolved in 100 ml of 3 mol / L HCl solution, and the NH4+ content in the solution was measured. + -N concentration, MAP purity is NH4 + -N concentration multiplied by 2.4541.

[0044] Results: COD removal rate was 85.2%, PO4 removal rate was [missing information]. 3--P removal rate was 93.5%, TN removal rate was 70.8%, and NH4 removal rate was... + -N removal rate was 98.6%, and actual phosphorus recovery rate was 56.8%. The purity of the recovered product, struvite (MAP), was 19.8%.

[0045] Operating Results: Under low C / P influent conditions of C / P=30 and C / P=20, the coupled system of this invention achieves in-situ carbon source supplementation to the mainstream SBR reactor through a side-flow anaerobic fermentation reactor, eliminating the need for additional carbon source addition throughout the process. This effectively solves the problem of poor phosphorus removal caused by carbon source scarcity under low C / P conditions in traditional processes. At C / P=30, PO4... 3- The phosphorus removal rate reached 93.5%, maintaining a high phosphorus removal efficiency of 92.6% even at a C / P=20. At a C / P=30, the COD removal rate was 85.2%, the TN removal rate was 70.8%, and the NH4+ removal rate was... + When the removal rate of -N is 98.6% and C / P=20, the removal rate of COD is 85.5%, the removal rate of TN is 67.8%, and the removal rate of NH4 is... + The nitrogen removal rate was 91.2%, and the effluent met the national standards. This achieved efficient nitrogen and phosphorus removal from low C / P wastewater, while eliminating the need for additional carbon source addition costs. Water resources were recycled by relying on the supernatant reflux and other circulation designs within the process. To address the shortcomings of phosphorus recovery crystallization reaction being hindered under low C / P conditions and the difficulty in synergizing with phosphorus removal processes, the coupled system of this invention achieves targeted phosphorus enrichment through side-flow anaerobic fermentation. Combined with reagent addition and pH control of the phosphorus recovery reactor, the phosphorus crystallization recovery reaction proceeds efficiently. At C / P=30, the system's actual phosphorus recovery rate reaches 56.8% and MAP purity is 19.8%. Even at C / P=20, the phosphorus recovery rate remains at a good level of 51.2%. The phosphorus enrichment effect and crystallization reaction are not significantly affected by further reduction in carbon source. The system stably achieves synergistic effects of phosphorus removal and recovery under both low C / P gradients, achieving the dual goals of wastewater treatment and phosphorus resource recovery. This also verifies that the minimum influent C / P ratio for maintaining good phosphorus removal and recovery effects is 20, and the synergistic effect can be stably exerted under low carbon source conditions with a C / P ratio of 20-30.

[0046] Example 2 Side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, such as Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0047] Example 3 Side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, such as Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0048] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0049] Example 4 Side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, such as Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0050] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0051] The mainstream SBR reactor unit includes a mainstream SBR reactor 1, an inlet 1-1 on the upper side wall of the mainstream SBR reactor 1, a fermentation broth return inlet 1-3 on the upper side wall of the mainstream SBR reactor 1, an outlet 1-2 on the lower side wall of the mainstream SBR reactor 1 from which effluent is discharged, a sludge discharge outlet 1-4 on the lower side wall of the mainstream SBR reactor 1, and an agitator 14 and an aeration device 15 installed on the top of the mainstream SBR reactor 1. The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor 2. The upper part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a side-flow anaerobic fermentation reactor inlet 2-1 and a supernatant return outlet 2-3. The lower part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a fermentation liquid return outlet 2-2 and a return inlet 2-4. A second stirrer 18 is installed on the top of the side-flow anaerobic fermentation reactor 2. The phosphorus recovery reactor unit includes a phosphorus recovery reactor 3 with a conical bottom. A filter screen 3-7 is installed at the conical bottom of the phosphorus recovery reactor 3. A supernatant reflux inlet 3-1 is installed on the upper part of the side wall of the phosphorus recovery reactor 3. A reflux outlet 3-2 is installed on the lower part of the side wall of the phosphorus recovery reactor 3. A crystal outlet 3-3 is installed at the bottom of the phosphorus recovery reactor 3. A first reagent addition port 3-4, a second reagent addition port 3-5, and a third reagent addition port 3-6 are also provided at the top of the phosphorus recovery reactor 3. A third stirrer 7 is installed at the top of the phosphorus recovery reactor 3. The storage tank unit includes a magnesium salt storage tank 4, a calcium salt storage tank 5, and an alkaline solution storage tank 6; The fermentation broth reflux inlet 1-3 is connected to the fermentation broth reflux outlet 2-2 through the first flow control unit; Sludge discharge port 1-4 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor through the second flow control unit; Supernatant reflux outlet 2-3 is connected to supernatant reflux inlet 3-1 through a third flow control unit; The return inlet 2-4 is connected to the return outlet 3-2 through the fourth flow control unit; The magnesium salt storage tank 4 is connected to the first reagent addition port 3-4 via the first reagent addition unit; The calcium salt storage tank 5 is connected to the second reagent addition port 3-5 via the second reagent addition unit; The alkali storage tank 6 is connected to the third reagent addition port 3-6 via the third reagent addition unit; Figure 1 In the process, the sludge from the main SBR reactor 1 flows through a pipe from the sludge discharge port 1-4 to the side-flow anaerobic fermentation reactor inlet 2-1 of the side-flow anaerobic fermentation reactor 2; the fermentation broth from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the fermentation broth return outlet 2-2 to the fermentation broth return inlet 1-3 of the main SBR reactor 1. The supernatant from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the supernatant return outlet 2-3 to the supernatant return inlet 3-1 of the phosphorus recovery reactor 3; the residual liquid from the phosphorus recovery reactor 3 flows through a pipe from the return outlet 3-2 to the return inlet 2-4 of the side-flow anaerobic fermentation reactor 2.

[0052] The monitoring unit includes an online monitoring instrument 13, a first pH sensor 11, a second pH sensor 16, and a third pH sensor 17; the first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 are respectively installed inside the main flow SBR reactor 1, the side flow anaerobic fermentation reactor 2, and the phosphorus recovery reactor 3; it also includes a DO sensor 12 installed inside the main flow SBR reactor 1; the first pH sensor 11, the second pH sensor 16, the third pH sensor 17, and the DO sensor 12 are all connected to the online monitoring instrument 13.

[0053] Example 5 Side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, such as Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0054] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0055] The mainstream SBR reactor unit includes a mainstream SBR reactor 1, an inlet 1-1 on the upper side wall of the mainstream SBR reactor 1, a fermentation broth return inlet 1-3 on the upper side wall of the mainstream SBR reactor 1, an outlet 1-2 on the lower side wall of the mainstream SBR reactor 1, from which effluent is discharged, a sludge discharge outlet 1-4 on the lower side wall of the mainstream SBR reactor 1, and an agitator 14 and an aeration device 15 installed on the top of the mainstream SBR reactor 1. The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor 2. The upper part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a side-flow anaerobic fermentation reactor inlet 2-1 and a supernatant return outlet 2-3. The lower part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a fermentation liquid return outlet 2-2 and a return inlet 2-4. A second stirrer 18 is installed on the top of the side-flow anaerobic fermentation reactor 2. The phosphorus recovery reactor unit includes a phosphorus recovery reactor 3 with a conical bottom. A filter screen 3-7 is installed at the conical bottom of the phosphorus recovery reactor 3. A supernatant reflux inlet 3-1 is installed on the upper part of the side wall of the phosphorus recovery reactor 3. A reflux outlet 3-2 is installed on the lower part of the side wall of the phosphorus recovery reactor 3. A crystal outlet 3-3 is installed at the bottom of the phosphorus recovery reactor 3. A first reagent addition port 3-4, a second reagent addition port 3-5, and a third reagent addition port 3-6 are also provided at the top of the phosphorus recovery reactor 3. A third stirrer 7 is installed at the top of the phosphorus recovery reactor 3. The storage tank unit includes a magnesium salt storage tank 4, a calcium salt storage tank 5, and an alkaline solution storage tank 6; The fermentation broth reflux inlet 1-3 is connected to the fermentation broth reflux outlet 2-2 through the first flow control unit; Sludge discharge port 1-4 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor through the second flow control unit; Supernatant reflux outlet 2-3 is connected to supernatant reflux inlet 3-1 through a third flow control unit; The return inlet 2-4 is connected to the return outlet 3-2 through the fourth flow control unit; The magnesium salt storage tank 4 is connected to the first reagent addition port 3-4 via the first reagent addition unit; The calcium salt storage tank 5 is connected to the second reagent addition port 3-5 via the second reagent addition unit; The alkali storage tank 6 is connected to the third reagent addition port 3-6 via the third reagent addition unit; Figure 1 In the process, the sludge from the main SBR reactor 1 flows through a pipe from the sludge discharge port 1-4 to the side-flow anaerobic fermentation reactor inlet 2-1 of the side-flow anaerobic fermentation reactor 2; the fermentation broth from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the fermentation broth return outlet 2-2 to the fermentation broth return inlet 1-3 of the main SBR reactor 1. The supernatant from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the supernatant return outlet 2-3 to the supernatant return inlet 3-1 of the phosphorus recovery reactor 3; the residual liquid from the phosphorus recovery reactor 3 flows through a pipe from the return outlet 3-2 to the return inlet 2-4 of the side-flow anaerobic fermentation reactor 2.

[0056] The monitoring unit includes an online monitoring instrument 13, a first pH sensor 11, a second pH sensor 16, and a third pH sensor 17; the first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 are respectively installed inside the main flow SBR reactor 1, the side flow anaerobic fermentation reactor 2, and the phosphorus recovery reactor 3; it also includes a DO sensor 12 installed inside the main flow SBR reactor 1; the first pH sensor 11, the second pH sensor 16, the third pH sensor 17, and the DO sensor 12 are all connected to the online monitoring instrument 13.

[0057] The first flow control unit includes a first pipe 19, on which a first peristaltic pump 10, a first flow sensor 9 and a first solenoid valve 8 are installed; the first end of the first pipe 19 is connected to the fermentation liquid return inlet 1-3, and the second end of the first pipe 19 is connected to the fermentation liquid return outlet 2-2. The second flow control unit includes a second pipe 20, on which a second peristaltic pump 21, a second flow sensor 22 and a second solenoid valve 23 are installed; the first end of the second pipe 20 is connected to the sludge discharge port 1-4, and the second end of the second pipe 20 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor. The third flow control unit includes a third pipe 24, on which a third peristaltic pump 25, a third flow sensor 26 and a third solenoid valve 27 are installed; the first end of the third pipe 24 is connected to the supernatant return outlet 2-3, and the second end of the third pipe 24 is connected to the supernatant return inlet 3-1. The fourth flow control unit includes a fourth pipe 28, on which a fourth peristaltic pump 31, a fourth flow sensor 30 and a fourth solenoid valve 29 are installed; the first end of the fourth pipe 28 is connected to the return inlet 2-4, and the second end of the fourth pipe 28 is connected to the return outlet 3-2. The first reagent dosing unit includes a fifth pipeline 33, on which a first metering pump 34 and a fifth solenoid valve 35 are installed; the first end of the fifth pipeline 33 is connected to the first reagent dosing port 3-4, and the second end of the fifth pipeline 33 is connected to the magnesium salt storage tank 4. The second reagent dosing unit includes a sixth pipeline 36, on which a second metering pump 37 and a sixth solenoid valve 38 are installed; the first end of the sixth pipeline 36 is connected to the second reagent dosing port 3-5, and the second end of the sixth pipeline 36 is connected to the calcium salt storage tank 5. The third reagent dosing unit includes a seventh pipeline 39, on which a third metering pump 40 and a seventh solenoid valve 32 are installed; the first end of the seventh pipeline 39 is connected to the third reagent dosing port 3-6, and the second end of the seventh pipeline 39 is connected to the alkali storage tank 6.

[0058] Example 6 Side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, such as Figure 1 As shown, it includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

[0059] The mainstream SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

[0060] The mainstream SBR reactor unit includes a mainstream SBR reactor 1, an inlet 1-1 on the upper side wall of the mainstream SBR reactor 1, a fermentation broth return inlet 1-3 on the upper side wall of the mainstream SBR reactor 1, an outlet 1-2 on the lower side wall of the mainstream SBR reactor 1, from which effluent is discharged, a sludge discharge outlet 1-4 on the lower side wall of the mainstream SBR reactor 1, and an agitator 14 and an aeration device 15 installed on the top of the mainstream SBR reactor 1. The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor 2. The upper part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a side-flow anaerobic fermentation reactor inlet 2-1 and a supernatant return outlet 2-3. The lower part of the side wall of the side-flow anaerobic fermentation reactor 2 is provided with a fermentation liquid return outlet 2-2 and a return inlet 2-4. A second stirrer 18 is installed on the top of the side-flow anaerobic fermentation reactor 2. The phosphorus recovery reactor unit includes a phosphorus recovery reactor 3 with a conical bottom. A filter screen 3-7 is installed at the conical bottom of the phosphorus recovery reactor 3. A supernatant reflux inlet 3-1 is installed on the upper part of the side wall of the phosphorus recovery reactor 3. A reflux outlet 3-2 is installed on the lower part of the side wall of the phosphorus recovery reactor 3. A crystal outlet 3-3 is installed at the bottom of the phosphorus recovery reactor 3. A first reagent addition port 3-4, a second reagent addition port 3-5, and a third reagent addition port 3-6 are also provided at the top of the phosphorus recovery reactor 3. A third stirrer 7 is installed at the top of the phosphorus recovery reactor 3. The storage tank unit includes a magnesium salt storage tank 4, a calcium salt storage tank 5, and an alkaline solution storage tank 6; The fermentation broth reflux inlet 1-3 is connected to the fermentation broth reflux outlet 2-2 through the first flow control unit; Sludge discharge port 1-4 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor through the second flow control unit; Supernatant reflux outlet 2-3 is connected to supernatant reflux inlet 3-1 through a third flow control unit; The return inlet 2-4 is connected to the return outlet 3-2 through the fourth flow control unit; The magnesium salt storage tank 4 is connected to the first reagent addition port 3-4 via the first reagent addition unit; The calcium salt storage tank 5 is connected to the second reagent addition port 3-5 via the second reagent addition unit; The alkali storage tank 6 is connected to the third reagent addition port 3-6 via the third reagent addition unit; Figure 1 In the process, the sludge from the main SBR reactor 1 flows through a pipe from the sludge discharge port 1-4 to the side-flow anaerobic fermentation reactor inlet 2-1 of the side-flow anaerobic fermentation reactor 2; the fermentation broth from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the fermentation broth return outlet 2-2 to the fermentation broth return inlet 1-3 of the main SBR reactor 1. The supernatant from the side-flow anaerobic fermentation reactor 2 flows through a pipe from the supernatant return outlet 2-3 to the supernatant return inlet 3-1 of the phosphorus recovery reactor 3; the residual liquid from the phosphorus recovery reactor 3 flows through a pipe from the return outlet 3-2 to the return inlet 2-4 of the side-flow anaerobic fermentation reactor 2.

[0061] The monitoring unit includes an online monitoring instrument 13, a first pH sensor 11, a second pH sensor 16, and a third pH sensor 17; the first pH sensor 11, the second pH sensor 16, and the third pH sensor 17 are respectively installed inside the main flow SBR reactor 1, the side flow anaerobic fermentation reactor 2, and the phosphorus recovery reactor 3; it also includes a DO sensor 12 installed inside the main flow SBR reactor 1; the first pH sensor 11, the second pH sensor 16, the third pH sensor 17, and the DO sensor 12 are all connected to the online monitoring instrument 13.

[0062] The first flow control unit includes a first pipe 19, on which a first peristaltic pump 10, a first flow sensor 9 and a first solenoid valve 8 are installed; the first end of the first pipe 19 is connected to the fermentation liquid return inlet 1-3, and the second end of the first pipe 19 is connected to the fermentation liquid return outlet 2-2. The second flow control unit includes a second pipe 20, on which a second peristaltic pump 21, a second flow sensor 22 and a second solenoid valve 23 are installed; the first end of the second pipe 20 is connected to the sludge discharge port 1-4, and the second end of the second pipe 20 is connected to the inlet 2-1 of the side-flow anaerobic fermentation reactor. The third flow control unit includes a third pipe 24, on which a third peristaltic pump 25, a third flow sensor 26 and a third solenoid valve 27 are installed; the first end of the third pipe 24 is connected to the supernatant return outlet 2-3, and the second end of the third pipe 24 is connected to the supernatant return inlet 3-1. The fourth flow control unit includes a fourth pipe 28, on which a fourth peristaltic pump 31, a fourth flow sensor 30 and a fourth solenoid valve 29 are installed; the first end of the fourth pipe 28 is connected to the return inlet 2-4, and the second end of the fourth pipe 28 is connected to the return outlet 3-2. The first reagent dosing unit includes a fifth pipeline 33, on which a first metering pump 34 and a fifth solenoid valve 35 are installed; the first end of the fifth pipeline 33 is connected to the first reagent dosing port 3-4, and the second end of the fifth pipeline 33 is connected to the magnesium salt storage tank 4. The second reagent dosing unit includes a sixth pipeline 36, on which a second metering pump 37 and a sixth solenoid valve 38 are installed; the first end of the sixth pipeline 36 is connected to the second reagent dosing port 3-5, and the second end of the sixth pipeline 36 is connected to the calcium salt storage tank 5. The third reagent dosing unit includes a seventh pipeline 39, on which a third metering pump 40 and a seventh solenoid valve 32 are installed; the first end of the seventh pipeline 39 is connected to the third reagent dosing port 3-6, and the second end of the seventh pipeline 39 is connected to the alkali storage tank 6.

[0063] The aeration device 15 includes a microporous aeration head 15-1 and an aeration pump 15-2 connected by a pipe.

[0064] The microporous aeration head 15-1 is installed at the bottom of the main SBR reactor 1, and the aeration pump 15-2 is installed on the top outside of the main SBR reactor 1.

Claims

1. A side-flow enhanced biological phosphorus removal and phosphorus recovery coupled system, characterized in that, It includes a main flow SBR reactor unit, a side flow anaerobic fermentation reactor unit, a phosphorus recovery reactor unit, and a storage tank unit connected in sequence; it also includes a monitoring unit for monitoring the pH value of the supernatant in the main flow SBR reactor unit, the side flow anaerobic fermentation reactor unit, the phosphorus recovery reactor unit, and the DO index of the supernatant in the main flow SBR reactor unit.

2. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system according to claim 1, characterized in that, The main SBR reactor unit is connected to the side-flow anaerobic fermentation reactor unit through two sets of flow control units; the side-flow anaerobic fermentation reactor unit is connected to the phosphorus recovery reactor unit through two sets of flow control units; and the phosphorus recovery reactor unit is connected to the storage tank unit through three sets of reagent dosing units.

3. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system according to claim 2, characterized in that, The mainstream SBR reactor unit includes a mainstream SBR reactor (1), with a mainstream SBR reactor inlet (1-1) and a fermentation broth return inlet (1-3) provided on the upper side wall of the mainstream SBR reactor (1), and a mainstream SBR reactor outlet (1-2) and a sludge discharge outlet (1-4) provided on the lower side wall of the mainstream SBR reactor (1); a stirrer (14) and an aeration device (15) are installed on the top of the mainstream SBR reactor (1). The side-flow anaerobic fermentation reactor unit includes a side-flow anaerobic fermentation reactor (2). The upper part of the side wall of the side-flow anaerobic fermentation reactor (2) is provided with a side-flow anaerobic fermentation reactor inlet (2-1) and a supernatant return outlet (2-3). The lower part of the side wall of the side-flow anaerobic fermentation reactor (2) is provided with a fermentation liquid return outlet (2-2) and a return inlet (2-4). A second stirrer (18) is installed on the top of the side-flow anaerobic fermentation reactor (2). The phosphorus recovery reactor unit includes a phosphorus recovery reactor (3) with a conical bottom. A filter screen (3-7) is provided at the conical bottom of the phosphorus recovery reactor (3). A supernatant reflux inlet (3-1) is provided on the upper part of the side wall of the phosphorus recovery reactor (3). A reflux outlet (3-2) is provided on the lower part of the side wall of the phosphorus recovery reactor (3). A crystal outlet (3-3) is provided at the bottom of the phosphorus recovery reactor (3). A first reagent addition port (3-4), a second reagent addition port (3-5), and a third reagent addition port (3-6) are also provided on the top of the phosphorus recovery reactor (3). A third stirrer (7) is installed on the top of the phosphorus recovery reactor (3). The storage tank unit includes a magnesium salt storage tank (4) for storing magnesium chloride solution, a calcium salt storage tank (5) for storing calcium chloride solution, and an alkaline storage tank (6) for storing sodium hydroxide solution. The fermentation broth reflux inlet (1-3) is connected to the fermentation broth reflux outlet (2-2) through the first flow control unit; The sludge discharge port (1-4) is connected to the inlet (2-1) of the side-flow anaerobic fermentation reactor through the second flow control unit; The supernatant reflux outlet (2-3) is connected to the supernatant reflux inlet (3-1) through a third flow control unit; The return inlet (2-4) is connected to the return outlet (3-2) through the fourth flow control unit; The magnesium salt storage tank (4) is connected to the first reagent addition port (3-4) through the first reagent addition unit; The calcium salt storage tank (5) is connected to the second reagent dosing port (3-5) through the second reagent dosing unit; The alkali storage tank (6) is connected to the third reagent addition port (3-6) through the third reagent addition unit; The monitoring unit includes an online monitoring instrument (13), a first pH sensor (11), a second pH sensor (16), and a third pH sensor (17); the first pH sensor (11), the second pH sensor (16), and the third pH sensor (17) are respectively located inside the main flow SBR reactor (1), the side flow anaerobic fermentation reactor (2), and the phosphorus recovery reactor (3); it also includes a DO sensor (12) located inside the main flow SBR reactor (1); the first pH sensor (11), the second pH sensor (16), the third pH sensor (17), and the DO sensor (12) are all connected to the online monitoring instrument (13).

4. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system according to claim 3, characterized in that, The first flow control unit includes a first pipe (19), on which a first peristaltic pump (10), a first flow sensor (9) and a first solenoid valve (8) are provided; the first end of the first pipe (19) is connected to the fermentation liquid return inlet (1-3), and the second end of the first pipe (19) is connected to the fermentation liquid return outlet (2-2); The second flow control unit includes a second pipe (20), on which a second peristaltic pump (21), a second flow sensor (22) and a second solenoid valve (23) are installed; the first end of the second pipe (20) is connected to the sludge discharge port (1-4), and the second end of the second pipe (20) is connected to the inlet (2-1) of the side-flow anaerobic fermentation reactor; The third flow control unit includes a third pipe (24), on which a third peristaltic pump (25), a third flow sensor (26) and a third solenoid valve (27) are installed; the first end of the third pipe (24) is connected to the supernatant return outlet (2-3), and the second end of the third pipe (24) is connected to the supernatant return inlet (3-1); The fourth flow control unit includes a fourth pipe (28), on which a fourth peristaltic pump (31), a fourth flow sensor (30) and a fourth solenoid valve (29) are installed; the first end of the fourth pipe (28) is connected to the return inlet (2-4), and the second end of the fourth pipe (28) is connected to the return outlet (3-2); The first reagent dosing unit includes a fifth pipeline (33), on which a first metering pump (34) and a fifth solenoid valve (35) are installed; the first end of the fifth pipeline (33) is connected to the first reagent dosing port (3-4), and the second end of the fifth pipeline (33) is connected to the magnesium salt storage tank (4); The second agent dosing unit includes a sixth pipe (36), on which a second metering pump (37) and a sixth solenoid valve (38) are installed; the first end of the sixth pipe (36) is connected to the second agent dosing port (3-5), and the second end of the sixth pipe (36) is connected to the calcium salt storage tank (5); The third reagent dosing unit includes a seventh pipe (39), on which a third metering pump (40) and a seventh solenoid valve (32) are installed; the first end of the seventh pipe (39) is connected to the third reagent dosing port (3-6), and the second end of the seventh pipe (39) is connected to the alkali storage tank (6).

5. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling system according to claim 3, characterized in that, The aeration device (15) includes a microporous aeration head (15-1) and an aeration pump (15-2) connected by a pipe. The microporous aeration head (15-1) is located at the bottom of the main SBR reactor (1), and the aeration pump (15-2) is located on the top outside of the main SBR reactor (1).

6. A method for coupling side-flow enhanced biological phosphorus removal and phosphorus recovery, characterized in that, The system described in claim 1 is specifically used as follows: Step 1: Use a mainstream SBR reactor (1) and a side-flow anaerobic fermentation reactor (2) to achieve carbon source replenishment and phosphorus enrichment through sludge exchange; Step 2: Add reagents to the phosphorus recovery reactor (3) to achieve phosphorus crystallization recovery.

7. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling method according to claim 6, characterized in that, Step 1 is as follows: wastewater with a C / P ratio of 20 to 30 is received through the inlet (1-1) of the main SBR reactor (1), and the liquid treated by the main SBR reactor (1) is discharged through the outlet (1-2). The sludge exchange between the main SBR reactor (1) and the side-flow anaerobic fermentation reactor (2) is completed through the first pipe (19) and the second pipe (20). The side-flow anaerobic fermentation reactor (2) is used to receive the return sludge from the main SBR reactor (1). Under anaerobic conditions, the sludge hydrolysis and fermentation are promoted by the second stirrer (18) to produce VFA as a carbon source for biological phosphorus removal of wastewater. At the same time, the sludge releases phosphorus to form a phosphorus-rich supernatant.

8. The side-flow enhanced biological phosphorus removal and phosphorus recovery coupling method according to claim 6, characterized in that, Step 2 is as follows: Use the phosphorus recovery reactor (3) to provide space for phosphorus crystallization reaction, use the third stirrer (7) to ensure that the reagent and the phosphorus-rich supernatant are fully mixed; separate and collect MAP or HAP crystals through the filter screen set at the diameter change of the cone, collect the product periodically through the crystal outlet (3-3), and send the supernatant after reaction back to the side flow anaerobic fermentation reactor (2) through the supernatant return inlet (3-1) to continue to participate in the process cycle.

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