Device and method for denitrification and dephosphorization of sewage and sludge reduction by fermentation enhancement

Abstract

The present application belongs to the field of oligocarbon source sewage biological treatment technology, in particular to a device and method for fermentation enhanced sewage denitrification and phosphorus removal and sludge reduction, comprising a main stream sewage treatment system and a side stream sludge fermentation system, wherein the main stream sewage treatment system comprises a sequencing batch reactor of cyclic activated sludge method (CASS); a partition plate with water passing holes is arranged in the sequencing batch reactor, and the sequencing batch reactor is divided into a pre-mixing zone and a main reaction zone by the partition plate with water passing holes; the device has a high-efficiency side stream enhancement effect, the side stream sludge treatment capacity is small (only 3% to 20% of the side stream flow rate is used to treat the sludge), and the treatment time is short (the sludge fermentation time is less than 96 h); no chemicals need to be added, and pH and heating need not be controlled during the fermentation process; only anaerobic fermentation of the refluxed sludge at room temperature can improve the main stream denitrification and phosphorus removal efficiency, reduce the total nitrogen and total phosphorus in the effluent, realize the denitrification and phosphorus removal treatment of oligocarbon source (COD / TN<8) municipal sewage to meet the standards, and has the characteristics of economy and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of biological wastewater treatment technology with low carbon source, specifically a device and method for fermentation-enhanced wastewater denitrification, phosphorus removal, and sludge reduction. Background Technology

[0002] Direct discharge of urban sewage into natural water bodies can induce eutrophication, leading to water pollution and environmental damage. Therefore, nitrogen and phosphorus removal treatment is necessary before discharge. Increasingly stringent sewage discharge standards bring higher treatment difficulty and costs. Meanwhile, municipal sewage nutrient treatment processes often face insufficient carbon sources, particularly in southern my country where urban sewage treatment plants suffer from low organic carbon concentrations and significant C / N ratio imbalances. Traditional sewage treatment processes often require the addition of commercial carbon sources to meet the carbon requirements for denitrification and biological phosphorus removal, significantly increasing sewage treatment costs, sludge production, energy consumption, and secondary pollution. The sewage treatment industry urgently needs to develop and apply green, low-carbon sewage treatment processes suitable for low-carbon water quality to address the problem of insufficient carbon sources in urban sewage treatment.

[0003] Anaerobic fermentation of sludge can transform complex organic matter that is difficult for microorganisms to utilize into easily available small-molecule carbon components, thus realizing the resource utilization of sludge. On the other hand, side-flow fermentation of returned sludge can directly improve the utilization rate of carbon sources in wastewater and reduce the production of excess sludge. Compared with the fermentation of exogenous excess sludge, it can avoid introducing additional nutrient loads, and the fermentation mixture can be fully reused without the need to set up a separation sedimentation tank, which can simplify operation and equipment structure.

[0004] Most reported technologies for enhancing wastewater treatment through sludge fermentation focus on continuous flow wastewater treatment facilities with configurations such as AAO and AO. However, there is little research on the application of side-flow sludge fermentation in sequential wastewater treatment configurations (such as SBR and CASS), and these studies mainly utilize excess sludge or primary sludge for fermentation, with fewer applications using recycled sludge. Furthermore, reported side-flow sludge fermentation processes often employ auxiliary conditions such as alkaline fermentation and mesophilic (35 °C) fermentation, requiring additional chemical additions and energy consumption, which increases operating costs and limits the application prospects of side-flow sludge fermentation technology. Therefore, this invention provides a device and method for enhancing wastewater nitrogen and phosphorus removal and sludge reduction through fermentation. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: The device for fermentation-enhanced wastewater denitrification, phosphorus removal, and sludge reduction includes a mainstream wastewater treatment system and a side-flow return sludge fermentation system. The mainstream wastewater treatment system includes a sequencing batch reactor (SBR) of the circulating activated sludge process (CASS). The SBR is equipped with a baffle plate with water passage holes, which divides the SBR into a premixing zone and a main reaction zone. Both the premixing zone and the main reaction zone are equipped with a stirrer. The premixing zone is equipped with a wastewater inlet pipe, a fermentation mixture inlet pipe, and a return sludge inlet pipe. The wastewater inlet pipe is connected to an inlet pump.

[0007] Preferably, the main reaction zone is equipped with a level gauge, a decanter, a drain solenoid valve, an outlet pipe, an aeration disc, and a residual sludge discharge pipe. A sludge return pipeline is installed outside the sequencing batch reactor, and a sludge return pump is installed on the sludge return pipeline to drive sludge return. A high water level and a low water level are set inside the sequencing batch reactor.

[0008] Preferably, the side-flow reflux sludge fermentation system includes a sequencing batch reactor (SBR) and a fermentation mixture storage tank. The SBR is equipped with a stirrer, a side-flow feed pump, a side-flow feed pipe, and a fermentation mixture overflow discharge pipe. One end of the side-flow feed pump is connected to the side-flow feed pipe, and the other end is connected to a branch line of the sludge reflux pipeline.

[0009] Preferably, the fermentation mixture storage tank is equipped with a fermentation mixture feed pump, which is connected to the fermentation mixture water inlet pipe.

[0010] Preferably, the agitator includes a motor, a connecting shaft, and a fixed shaft. The motor is located outside the sequencing batch reactor and is used to drive the connecting shaft to rotate. The bottom end of the connecting shaft is open. The fixed shaft is located inside the connecting shaft and has multiple sets of blades. A hydraulic rod is fixedly connected between the top end of the fixed shaft and the inner wall of the connecting shaft.

[0011] Preferably, a set of connecting rings is fixedly connected to the outer side wall of the fixed shaft, a set of rectangular grooves is provided on the outer side wall of the connecting rings, a round shaft is fixedly connected to the inner wall of the rectangular grooves, the inner wall of the round shaft is a hollow structure, and a rotating shaft is rotatably connected inside the round shaft. The side of the rotating shaft away from the fixed shaft is fixedly connected to the blade, and a rotating component for driving the rotating shaft to rotate is provided on the connecting ring.

[0012] Preferably, the rotating assembly includes a first connecting plate fixedly connected to the side wall of the rotating shaft, the outer side wall of the first connecting plate being rotatably and sealingly connected to the inner wall of the circular shaft, a second connecting plate fixedly connected to the inner wall of the circular shaft, the side of the second connecting plate near the first connecting plate being rotatably and sealingly connected to the outer side wall of the rotating shaft, both the connecting ring and the fixed shaft being hollow, the outer side wall of the fixed shaft being slidably and sealingly connected to the inner wall of the connecting shaft, an air inlet being provided on the top surface of the fixed shaft, a through hole communicating with the interior of the fixed shaft being provided on the inner side wall of the connecting ring, a connecting hole communicating with the interior of the connecting ring being provided on the side of the circular shaft away from the blade, an air outlet being provided on the outer side wall of the circular shaft, the outer side wall of the rotating shaft being rotatably and sealingly connected to the circular shaft, and a torsion spring (not shown in the figure) for driving the rotating shaft to reset being provided on the circular shaft.

[0013] Preferably, a set of fixing blocks corresponding to the rotating shaft are fixedly connected to the inner wall of the connecting ring. The fixing blocks have a hollow structure inside. A magnetic rod is slidably connected to the side of the fixing block near the rotating shaft. A pair of limiting rods are fixedly connected to the side of the magnetic rod near the rotating shaft. A set of annularly distributed slots are opened on the side of the rotating shaft near the fixing blocks. A spring is fixedly connected between the end of the magnetic rod away from the limiting rod and the inner wall of the fixing block. An electromagnet that repels the magnetic rod is fixedly connected to the inner wall of the fixing block.

[0014] A method for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment, employing the aforementioned apparatus for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment, comprises the following steps:

[0015] S1: Two working water levels are set in the main sewage treatment system, namely high water level and low water level. The low water level is the discharge water level. During the anaerobic and aerobic stages, low carbon source (COD / TN=5-8) urban sewage is slowly added to the premixing zone. When the level gauge detects the high water level, the influent pump is turned off to complete the water intake. The agitator is used to mix the sludge and water in the premixing zone and the main reaction zone.

[0016] S2: During the drainage and settling stage, the drainage solenoid valve opens, and the supernatant in the main reaction zone is discharged through the decanter. When the liquid level drops to the low level, the level gauge controls the closure of the drainage solenoid valve to stop drainage.

[0017] S3: The sequencing batch reactor (SBR) operates with intermittent sludge feeding and overflow sludge discharge. During the aerobic stage of the main wastewater treatment system, 3-20% (by volume) of the return liquid is diverted from the sludge return pipeline to the SBR.

[0018] S4: As the liquid level in the sequencing batch anaerobic digester rises, the upper fermentation mixture is discharged through overflow and stored in the fermentation mixture storage tank. In the anaerobic stage of the main wastewater treatment system, the fermentation mixture feed pump returns all the fermentation mixture to the premixing zone. The sludge fermentation time of the sequencing batch anaerobic digester is 24-96 hours.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The device in this invention has a high efficiency of side flow enhancement, a small side flow sludge treatment volume (only 3-20% of the side flow return sludge is treated) and a short treatment time (sludge fermentation time <96 h). The fermentation process does not require the addition of chemicals, pH control or heating. It can improve the mainstream nitrogen and phosphorus removal efficiency and reduce the total nitrogen and total phosphorus in the effluent by relying solely on the anaerobic fermentation of the return sludge at room temperature. It can achieve the standard nitrogen and phosphorus removal treatment of urban sewage with low carbon source (COD / TN<8), and has the characteristics of economy and high efficiency.

[0021] 2. The device in the invention can effectively reduce the production of excess sludge by more than 30%, realize the resource utilization of sludge, reduce the aeration demand, and has green and low-carbon advantages.

[0022] 3. The present invention adopts a sequencing batch reactor using the circulating activated sludge process, which has similar operating characteristics to ordinary sequencing batch reactors, but can improve the continuity of influent and the nitrogen and phosphorus removal effect; compared with continuous flow reactors, it has the advantages of not needing to set up sludge sedimentation tanks, small footprint, simple structure, and flexible operation.

[0023] 4. The side-flow return sludge fermentation system of the present invention directly uses the return sludge-water mixture for fermentation, without the need for sludge concentration and sedimentation; all sludge fermentation liquid is reused, without the need for sludge-water separation, thus avoiding the need for centrifuges and sedimentation tanks. It has the advantages of simple structure and easy implementation, which can effectively reduce the volume of anaerobic devices and save equipment production and operating costs.

[0024] 5. The multi-blade agitator used in this invention can flexibly and quickly adjust the blade angle according to the sludge concentration, improve the mixing effect, ensure the homogeneity of liquid at all depths, and avoid sludge-water separation. Attached Figure Description

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram of the device structure in this invention;

[0027] Figure 2 This is a graph showing the changes in total nitrogen, total phosphorus, and COD concentrations in the influent and effluent of Example 1;

[0028] Figure 3This is a graph showing the changes in total nitrogen, total phosphorus, and COD concentrations in the influent and effluent of Example 2;

[0029] Figure 4 This is a graph showing the changes in total nitrogen, total phosphorus, and COD concentrations in the influent and effluent under the non-side-flow fermentation conditions of this invention;

[0030] Figure 5 This is a schematic diagram of the stirring phase in this invention;

[0031] Figure 6 This is a schematic diagram of the internal structure of the connecting shaft and the fixed shaft in this invention;

[0032] Figure 7 yes Figure 6 Enlarged view of point A;

[0033] Figure 8 This is a schematic diagram of the internal structure of the circular shaft in this invention;

[0034] Figure 9 This is a front view of the rotating shaft in this invention;

[0035] Figure 10 This is a flowchart of the method in this invention.

[0036] In the diagram: 1. Premixing zone; 1.1. Agitator; 1.2. Wastewater inlet pipe; 1.3. Fermentation liquor inlet pipe; 1.4. Return sludge inlet pipe; 1.5. Baffle with water passage holes; 1.6. Inlet pump; 2. Main reaction zone; 2.1. Level gauge; 2.2. High water level; 2.3. Low water level; 2.4. Decanter; 2.5. Drain solenoid valve; 2.6. Outlet pipe; 2.7. Aerator; 2.8. Aeration disc; 2.9. Excess sludge discharge pipe; 2.10. Sludge return pump; 3. Sequencing batch anaerobic fermentation 3.1 Side-flow feed pump; 3.2 Side-flow feed pipe; 3.3 Fermentation mixture overflow discharge pipe; 4. Fermentation mixture storage tank; 4.1 Fermentation mixture feed pump; 5. Connecting shaft; 6. Fixed shaft; 7. Paddle; 8. Hydraulic rod; 9. Connecting ring; 10. Connecting hole; 11. Rectangular groove; 12. Round shaft; 13. Rotating shaft; 14. First connecting plate; 15. Slot; 16. Second connecting plate; 17. Fixing block; 18. Electromagnet; 19. Magnetic rod; 20. Through hole; 21. Air outlet; 22. Air inlet. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0038] Example 1: As Figure 1 , Figure 2 and Figure 4As shown in the embodiment of the present invention, a device for enhanced nitrogen and phosphorus removal and sludge reduction in wastewater through fermentation includes a main wastewater treatment system and a side-flow return sludge fermentation. The sequencing batch reactor is a rectangular water tank, which is divided into a premixing zone 1 and a main reaction zone 2 by a baffle with water passage holes. The ratio of the working volumes of the two zones is 1:5 to 1:10. Both zones are equipped with a stirrer 1.1 to achieve sludge-water mixing. The premixing zone 1 is equipped with a wastewater inlet pipe 1.2, a fermentation mixture inlet pipe 1.3, and a return sludge inlet pipe 1.4. The wastewater inlet pipe 1.2 is connected to an inlet pump 1.6.

[0039] The main reaction zone 2 is equipped with a level gauge 2.1, a decanter 2.4, a drain solenoid valve 2.5, an outlet pipe 2.6, an aerator 2.7, an aeration disc 2.8, and a residual sludge discharge pipe 2.9. A sludge return pipeline is installed outside the sequencing batch reactor, and a sludge return pump 2.10 is installed on the sludge return pipeline to drive sludge return. The sequencing batch reactor is equipped with a high water level 2.2 and a low water level 2.3.

[0040] The side-flow return sludge fermentation system includes a sequencing batch reactor (SBR) anaerobic digester 3 and a fermentation mixture storage tank 4. The SBR anaerobic digester 3 is equipped with a stirrer 1.1, a side-flow feed pump 3.1, a side-flow feed pipe, and a fermentation mixture overflow discharge pipe 3.3. One end of the side-flow feed pump 3.1 is connected to the side-flow feed pipe 3.2, and the other end is connected to a branch line of the sludge return pipeline.

[0041] The fermentation mixture storage tank 4 is equipped with a fermentation mixture feed pump 4.1, which is connected to the fermentation mixture water inlet pipe 1.3.

[0042] The mainstream wastewater treatment system operates cyclically with continuous influent and intermittent effluent, with a treatment cycle of 8-12 hours. Each cycle consists of four stages: an anaerobic stage of 2-3 hours, an aerobic stage of 4-6 hours, a sedimentation stage of 1-2 hours, and a effluent settling stage of 1 hour. The hydraulic retention time (HRT) of the mainstream wastewater treatment system is 15-25 hours. The sludge age of the system is 10-20 days. The circulating sludge flow rate is 50-100% of the influent flow rate.

[0043] The main wastewater treatment system is equipped with two working water levels: a high water level and a low water level 2.3. The low water level 2.3 is the drainage water level. During the anaerobic and aerobic stages, low-carbon source municipal wastewater is slowly added to the premixing zone 1. When the level gauge 2.1 detects the high water level 2.2, the influent pump 1.6 is shut off to complete the influent process. During the drainage settling stage, the drainage solenoid valve 2.5 is opened, and the supernatant from the main reaction zone 2 is discharged through the decanter 2.4. When the water level drops to the low water level 2.3, the level gauge 2.1 controls the closure of the drainage solenoid valve 2.5, stopping the drainage. The anaerobic digester 3 operates with intermittent sludge feeding and overflow sludge discharge. During the aerobic stage of the main wastewater treatment system, 3-20% (by volume) of the return liquid is diverted from the sludge return pipeline to the sequencing batch reactor (SBR) anaerobic digester 3. As the liquid level in the SBR 3 rises, the upper fermentation mixture is discharged via overflow and stored in the fermentation mixture storage tank 4. During the anaerobic stage of the main wastewater treatment system, the fermentation mixture feed pump 4.1 returns all the fermentation mixture to the premixing zone 1. The sludge fermentation time in the SBR anaerobic digester 3 is 24-96 hours, the daily treatment flow rate is -1000 L, the hydraulic retention time is 15 hours, the sludge retention time is 17 days, the return sludge flow rate accounts for 100% of the influent flow rate, the side flow flow rate accounts for 3% of the return flow rate, and the side flow sludge retention time is 1.5 days.

[0044] like Figure 2 The system effluent COD concentration was <25 mg / L, ammonia nitrogen concentration was <2 mg N / L, total phosphorus concentration was 0.6 mg P / L, total nitrogen concentration was 7.8 mg N / L, and total nitrogen removal rate was 58%; the treatment effect compared with the control group without sludge return side-flow fermentation ( Figure 4 Compared with the control group (total phosphorus concentration of 1.4 mg P / L, total nitrogen concentration of 11.4 mg N / L, and total nitrogen removal rate of 39%), the nitrogen and phosphorus removal effects were significantly enhanced. The system's residual sludge production was 58.8 g SS / d, which was significantly lower than the control group's 164.7 g SS / d, resulting in a sludge reduction of 64%.

[0045] In summary, the device method of this invention has the effect of enhancing nitrogen and phosphorus removal and sludge reduction in the treatment of urban wastewater with low carbon sources, and can achieve the national Class A standard for total nitrogen, ammonia nitrogen, total phosphorus and COD in the effluent without the need for external carbon source addition.

[0046] Example 2: Figure 1 and Figure 3As shown in the comparison with Example 1, another embodiment of the present invention is as follows: Due to temperature fluctuations, the temperature of urban sewage drops in autumn and winter, resulting in lower sludge activity, which is not conducive to nitrogen and phosphorus removal and sludge fermentation. The example uses primary effluent from a sewage treatment plant in autumn and winter (November) as the treatment target, with a total nitrogen concentration of 22.6 mg N / L, an average total phosphorus concentration of 7.3 mg P / L, an average TCOD concentration of 173 mg / L, a COD / TN ratio of 6.7, and an average water temperature of 18℃.

[0047] The fermentation-enhanced wastewater denitrification, phosphorus removal, and sludge reduction equipment used, such as... Figure 1 As shown, the daily treatment flow rate is -1000L, the hydraulic retention time is 18 h, the sludge retention time is 18 d, the return sludge flow rate accounts for 100% of the influent flow rate; the side flow flow rate accounts for 10% of the return flow rate, and the side flow sludge retention time is 1.5 d.

[0048] The structure of the dual-sequence batch recirculation sludge side-flow fermentation device for enhanced wastewater nitrogen and phosphorus removal and sludge reduction is as follows: Figure 1 As shown, the daily treatment flow rate is 1000 L, the hydraulic retention time is 18 h, the sludge retention time is 18 d, the return sludge flow rate accounts for 100% of the influent flow rate; the side flow flow rate accounts for 10% of the return flow rate, and the side flow sludge retention time is 1.5 d.

[0049] like Figure 3 The system effluent COD concentration was <25 mg / L, ammonia nitrogen concentration was <2 mg N / L, total phosphorus concentration was 0.7 mg P / L, and total nitrogen concentration was 9.4 mg N / L; the system's excess sludge production was 94.4 g SS / d, significantly lower than the control group's 164.7 g SS / d, resulting in a sludge reduction of 42%.

[0050] In summary, the device of this invention has a significant effect on sludge reduction in the treatment of urban sewage with low temperature and low carbon source. It can achieve the national Class A standard for total nitrogen, ammonia nitrogen and COD in effluent without the need for external carbon source addition, with total nitrogen concentration below 10 mgN / L and total phosphorus concentration below 1 mgP / L.

[0051] Example 3: Figures 5 to 9As shown, the agitator 1.1 includes a motor, a connecting shaft 5, and a fixed shaft 6. The motor is located outside the sequencing batch reactor and is used to drive the connecting shaft 5 to rotate. The bottom end of the connecting shaft 5 is open. The fixed shaft 6 is located inside the connecting shaft 5 and is equipped with multiple sets of blades 7. A hydraulic rod 8 is fixedly connected between the top end of the fixed shaft 6 and the inner wall of the connecting shaft 5. In this application, when mixing the mud and water in the premixing zone 1 and the main reaction zone 2, the motor can drive the connecting shaft 5 to rotate. At this time, the connecting shaft 5 will drive the fixed shaft 6 to rotate, thereby allowing the blades 7 to mix the mud and water. During the mixing process, the hydraulic rod 8 can be used to control the fixed shaft 6 to move up and down, thereby changing the position of the blades 7 and allowing the blades 7 to mix the mud and water more efficiently.

[0052] A set of connecting rings 9 are fixedly connected to the outer wall of the fixed shaft 6. A set of rectangular grooves 11 are opened on the outer wall of the connecting rings 9. A round shaft 12 is fixedly connected to the inner wall of the rectangular grooves 11. The inner wall of the round shaft 12 is hollow, and a rotating shaft 13 is rotatably connected inside the round shaft 12. The side of the rotating shaft 13 away from the fixed shaft 6 is fixedly connected to the blade 7. A rotating component for driving the rotating shaft 13 to rotate is provided on the connecting rings 9. When mixing mud and water, the rotating component can be used to control the rotation of the rotating shaft 13. At this time, the blade 7 will also rotate, so that the flow field changes continuously and scours different areas, thereby effectively eliminating the dead zone caused by the fixed flow field and achieving a more thorough and uniform mixing.

[0053] The rotating assembly includes a first connecting plate 14 fixedly connected to the side wall of the rotating shaft 13. The outer side wall of the first connecting plate 14 is rotatably and sealingly connected to the inner wall of the circular shaft 12. A second connecting plate 16 is fixedly connected to the inner wall of the circular shaft 12. The side of the second connecting plate 16 closest to the first connecting plate 14 is rotatably and sealingly connected to the outer side wall of the rotating shaft 13. The connecting ring 9 and the fixed shaft 6 are both hollow structures. The outer side wall of the fixed shaft 6 is slidably and sealingly connected to the inner wall of the connecting shaft 5. An air inlet 22 is provided on the top surface of the fixed shaft 6. A through hole 20 communicating with the interior of the fixed shaft 6 is provided on the inner side wall of the connecting ring 9. A connecting hole 10 communicating with the interior of the connecting ring 9 is provided on the side of the circular shaft 12 away from the blade 7. An air outlet 21 is provided on the outer side wall of the circular shaft 12. The outer side wall of the rotating shaft 13 is rotatably and sealingly connected to the circular shaft 12. A torsion spring (not shown in the figure) is provided on the circular shaft 12 to drive the rotating shaft 13 to reset.

[0054] In this application, when the fixed shaft 6 is moved upward by the hydraulic rod 8, the gas in the connecting shaft 5 enters the fixed shaft 6 through the air inlet 22. At this time, the gas passes through the through hole 20, the inside of the connecting ring 9 and the air inlet 22, and finally enters the round shaft 12. The gas pushes the first connecting plate 14, causing the first connecting plate 14 to drive the rotating shaft 13 to rotate, thereby causing the blade 7 to rotate. When the fixed shaft 6 moves downward, the gas will no longer push the first connecting plate 14. At this time, the torsion spring will drive the rotating shaft 13 to reset, thus allowing the blade 7 to rotate.

[0055] The inner wall of the connecting ring 9 is fixedly connected to a set of fixed blocks corresponding to the rotating shaft 13. The fixed blocks are hollow inside. A magnetic rod 19 is slidably connected to the side of the fixed block near the rotating shaft 13. A pair of limiting rods are fixedly connected to the side of the magnetic rod 19 near the rotating shaft 13. A set of annularly distributed slots 15 are opened on the side of the rotating shaft 13 near the fixed block. A spring is fixedly connected between the end of the magnetic rod 19 away from the limiting rod and the inner wall of the fixed block. An electromagnet 18 that repels the magnetic rod 19 is fixedly connected to the inner wall of the fixed block. When the sludge concentration is detected to increase in this application, the fixed shaft 6 can be moved upward to allow gas to enter the circular shaft 12 and drive the rotating shaft 13 to rotate 90 degrees. Then, the electromagnet 18 is activated to push the magnetic rod 19, thereby allowing the locking rod to engage with the slot 15. At this time, the rotating shaft 13 will be fixed, thereby adjusting the angle of the blade 7 by 90 degrees and fixing it, increasing the stirring force of the blade 7, and preventing "mud-water separation" or "hollowing out" in high-viscosity fluid.

[0056] like Figure 10 As shown, a method for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment is disclosed. This method utilizes the aforementioned apparatus for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment, and includes the following steps:

[0057] S1: Two working water levels are set in the main sewage treatment system, namely high water level and low water level 2.3. The low water level 2.3 is the discharge water level. During the anaerobic and aerobic stages, low carbon source (COD / TN=5-8) urban sewage is slowly added to the premixing zone 1. When the level gauge 2.1 detects the high water level 2.2, the influent pump 1.6 is turned off to complete the water intake. The agitator 1.1 is used to mix the sludge and water in the premixing zone 1 and the main reaction zone 2.

[0058] S2: During the drainage and settling stage, the drainage solenoid valve 2.5 is opened, and the supernatant in the main reaction zone 2 is discharged through the decanter 2.4. When the liquid level drops to the low water level 2.3, the level gauge 2.1 controls the closure of the drainage solenoid valve 2.5 to stop drainage.

[0059] S3: The sequencing batch anaerobic digester 3 operates with intermittent sludge feeding and overflow sludge discharge. During the aerobic stage of the main wastewater treatment system, 3-20% (by volume) of the return liquid is diverted from the sludge return pipeline to the sequencing batch anaerobic digester 3.

[0060] S4: As the liquid level in the sequencing batch anaerobic digester 3 rises, the upper fermentation mixture is discharged through overflow and stored in the fermentation mixture storage tank 4. In the anaerobic stage of the main wastewater treatment system, the fermentation mixture feed pump 4.1 returns all the fermentation mixture to the premixing zone 1. The sludge fermentation time of the sequencing batch anaerobic digester 3 is 24-96 h.

[0061] Working principle: Urban wastewater with low carbon source is slowly added to the premixing zone 1. When the level gauge 2.1 detects a high water level 2.2, the inlet pump 1.6 is shut off to complete the water intake. During the drainage and settling stage, the drainage solenoid valve 2.5 opens, and the supernatant in the main reaction zone 2 is discharged through the decanter 2.4. When the water level drops to the low water level 2.3, the level gauge 2.1 controls the closure of the drainage solenoid valve 2.5, stopping the drainage. The sequencing batch reactor 3 operates using intermittent sludge feeding and overflow sludge discharge. In the aerobic stage of the main wastewater treatment system, 3-20% (by volume) of the return liquid is diverted from the sludge return pipeline to the sequencing batch reactor (SBR) anaerobic digester 3. As the liquid level in the SBR 3 rises, the upper fermentation mixture is discharged through overflow and stored in the fermentation mixture storage tank 4. In the anaerobic stage of the main wastewater treatment system, the fermentation mixture feed pump 4.1 returns all the fermentation mixture to the premixing zone 1. The sludge fermentation time in the SBR anaerobic digester 3 is 24-96 hours, the daily treatment flow rate is -1000 L, the hydraulic retention time is 15 hours, the sludge retention time is 17 days, the return sludge flow rate accounts for 100% of the influent flow rate, the side flow flow rate accounts for 3% of the return flow rate, and the side flow sludge retention time is 1.5 days.

[0062] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0063] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A device for fermentation-enhanced wastewater nitrogen and phosphorus removal and sludge reduction, comprising a main wastewater treatment system and a side-flow return sludge fermentation system, wherein the main wastewater treatment system comprises a sequencing batch reactor of the circulating activated sludge process; Its features The sequencing batch reactor is equipped with a baffle plate (1.5) with water passage holes, and the sequencing batch reactor is divided into a premixing zone (1) and a main reaction zone (2) by the baffle plate (1.5) with water passage holes. Both the premixing zone (1) and the main reaction zone (2) are equipped with a stirrer (1.1). The premixing zone (1) is equipped with a sewage inlet pipe (1.2), a fermentation mixture inlet pipe (1.3), and a return sludge inlet pipe (1.4). The sewage inlet pipe (1.2) is connected to an inlet pump (1.6). The side-flow return sludge fermentation system includes a sequencing batch reactor (3) and a fermentation mixture storage tank (4). The sequencing batch reactor (3) is equipped with a stirrer (1.1), a side-flow feed pump (3.1), a side-flow feed pipe (3.2), and a fermentation mixture overflow discharge pipe (3.3). One end of the side-flow feed pump (3.1) is connected to the side-flow feed pipe (3.2), and the other end is connected to a branch line of the sludge return pipeline. The fermentation mixture storage tank (4) is equipped with a fermentation mixture feed pump (4.1), which is connected to the fermentation mixture water inlet pipe (1.3). The stirrer (1.1) includes a motor, a connecting shaft (5) and a fixed shaft (6). The motor is located outside the CASS reactor and is used to drive the connecting shaft (5) to rotate. The bottom end of the connecting shaft (5) is open. The fixed shaft (6) is located inside the connecting shaft (5). Multiple sets of blades (7) are provided on the fixed shaft (6). A hydraulic rod (8) is fixedly connected between the top end of the fixed shaft (6) and the inner wall of the connecting shaft (5). A set of connecting rings (9) are fixedly connected to the outer wall of the fixed shaft (6). A set of rectangular grooves (11) are opened on the outer wall of the connecting rings (9). A round shaft (12) is fixedly connected to the inner wall of the rectangular grooves (11). The inner wall of the round shaft (12) is hollow, and a rotating shaft (13) is rotatably connected inside the round shaft (12). The side of the rotating shaft (13) away from the fixed shaft (6) is fixedly connected to the blade (7). A rotating component for driving the rotating shaft (13) to rotate is provided on the connecting rings (9). The rotating assembly includes a first connecting plate (14) fixedly connected to the side wall of the rotating shaft (13). The outer side wall of the first connecting plate (14) is rotatably and sealingly connected to the inner wall of the round shaft (12). A second connecting plate (16) is fixedly connected to the inner wall of the round shaft (12). The side of the second connecting plate (16) closest to the first connecting plate (14) is rotatably and sealingly connected to the outer side wall of the rotating shaft (13). The connecting ring (9) and the fixed shaft (6) are both hollow structures. The outer side wall of the fixed shaft (6) is connected to the inner wall of the connecting shaft (5). The fixed shaft (6) is provided with an air inlet (22) on its top surface. The inner side wall of the connecting ring (9) is provided with a through hole (20) that communicates with the inside of the fixed shaft (6). The side of the round shaft (12) away from the blade (7) is provided with a connecting hole (10) that communicates with the inside of the connecting ring (9). The outer side wall of the round shaft (12) is provided with an air outlet (21). The outer side wall of the rotating shaft (13) is sealed and rotatably connected to the round shaft (12). A torsion spring is provided on the round shaft (12) to drive the rotating shaft (13) to reset.

2. The device for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment according to claim 1, characterized in that... The main reaction zone (2) is equipped with a level gauge (2.1), a decanter (2.4), a drain solenoid valve (2.5), an outlet pipe (2.6), an aerator (2.7), an aeration disc (2.8), and a residual sludge discharge pipe (2.9). A sludge return pipeline is installed outside the sequencing batch reactor, and a sludge return pump (2.10) is installed on the sludge return pipeline to drive sludge return. A high water level (2.2) and a low water level (2.3) are set inside the sequencing batch reactor.

3. The device for enhanced nitrogen and phosphorus removal and sludge reduction in fermentation-enhanced wastewater treatment according to claim 1, characterized in that... The inner wall of the connecting ring (9) is fixedly connected to a set of fixing blocks (17) corresponding to the rotating shaft (13). The fixing blocks (17) are hollow inside. A magnetic rod (19) is slidably connected to the side of the fixing block (17) near the rotating shaft (13). A pair of limiting rods are fixedly connected to the side of the magnetic rod (19) near the rotating shaft (13). A set of annularly distributed slots (15) are opened on the side of the rotating shaft (13) near the fixing block (17). A spring is fixedly connected between the end of the magnetic rod (19) away from the limiting rod and the inner wall of the fixing block (17). An electromagnet (18) that repels the magnetic rod (19) is fixedly connected to the inner wall of the fixing block (17).

4. A method for enhanced nitrogen and phosphorus removal and sludge reduction in fermented wastewater, wherein the method employs the apparatus for enhanced nitrogen and phosphorus removal and sludge reduction in fermented wastewater as described in claim 3, characterized in that... The method includes the following steps: S1: Two working water levels are set in the main sewage treatment system, namely high water level and low water level (2.3). The low water level (2.3) is the drainage water level. During the anaerobic and aerobic stages, the low carbon source urban sewage is slowly added to the premixing zone (1). When the level gauge (2.1) detects the high water level (2.2), the influent pump (1.6) is turned off to complete the water intake. The agitator (1.1) is used to mix the mud and water in the premixing zone (1) and the main reaction zone (2). S2: During the drainage and settling stage, the drainage solenoid valve (2.5) is opened, and the supernatant in the main reaction zone (2) is discharged through the decanter (2.4). When the liquid level drops to the low water level (2.3), the level gauge (2.1) controls the closure of the drainage solenoid valve (2.5) to stop drainage; S3: The sequencing batch anaerobic digester (3) operates by intermittent sludge feeding and overflow sludge discharge. During the aerobic stage of the main wastewater treatment system, 3-20% of the volume of the return liquid is diverted from the sludge return pipeline to the sequencing batch anaerobic digester (3). S4: As the liquid level of the sequencing batch anaerobic digester (3) rises, the upper fermentation mixture is discharged through overflow and stored in the fermentation mixture storage tank (4). In the anaerobic stage of the main wastewater treatment system, the fermentation mixture feed pump (4.1) returns all the fermentation mixture to the premixing zone (1). The sludge fermentation time of the sequencing batch anaerobic digester (3) is 24-96 h.

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