Magnetic enhancement sewage treatment system and treatment process

Abstract

The invention relates to a magnetic enhanced sewage treatment system and a treatment process. The magnetic enhanced sewage treatment system comprises a biochemical tank, a reoxygenation tank, a secondary sedimentation tank, a sludge hydrolysis / activation tank and a magnetic powder feeding device which are connected in sequence. The biochemical tank comprises a pre-anoxic tank, an anaerobic tank, an anoxic tank, an aerobic tank and a facultative tank which are connected in sequence, a nitrification liquid part of the aerobic tank flows back to the anoxic tank, and the facultative tank is connected with the reoxygenation tank. The sludge hydrolysis / activation tank hydrolyzes sludge on sunny days and activates the sludge on rainy days, and the treated sludge flows back to the facultative tank. The magnetic powder adding device is used for adding magnetic powder into the facultative tank in rainy days. Part of sludge obtained at the bottom of the secondary sedimentation tank flows back to the pre-anoxic tank, part of the sludge flows back to the sludge hydrolysis / activation tank, and the other part of the sludge is dehydrated. According to the invention, excessive anaerobic denitrification reaction of sludge in the secondary sedimentation tank is effectively inhibited through the reoxygenation tank, the sludge sedimentation speed of the secondary sedimentation tank is increased by adding magnetic powder into the facultative tank, and the water treatment amount in rainy seasons is increased. According to the invention, dynamic optimization of carbon source utilization efficiency and biological nitrogen and phosphorus removal capability is realized through the sludge hydrolysis / activation pool, and stable operation under different working conditions of sunny days and rainy days is cooperatively guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of water, wastewater, sewage or sludge treatment, and in particular to a magnetically enhanced sewage treatment system and a treatment process. Background Art

[0002] my country's urban sewage treatment facilities have been basically popularized, and great achievements have been made in water environment management. However, the current situation of urban water pollution in my country is still severe, especially the problem of short-term black and smelly water bodies caused by overflow pollution of drainage pipe networks on rainy days is very prominent. The reasons for the overflow of drainage pipe networks on rainy days include inadequate separation of rainwater and sewage, serious leakage of pipe networks, and insufficient rainy day treatment capacity of sewage treatment plants. Therefore, sewage treatment processes with low development and construction costs and operating costs, and which can improve the sewage treatment capacity on rainy days, are of great significance to reducing overflow pollution of urban drainage systems and eliminating the problem of black and smelly urban water bodies on rainy days.

[0003] A 3 The AAO process is also commonly known as the improved AAO process. It adds a pre-anoxic tank to the AAO process. In the pre-anoxic tank, the return sludge is mixed with a small amount of sewage to be treated. The denitrifying bacteria use the carbon source in the water to be treated under anoxic conditions to convert the nitrate nitrogen brought by the return sludge into N2 for discharge, thereby reducing the nitrate nitrogen concentration in the subsequent anaerobic tank, which is beneficial for the release of phosphorus and absorption of organic carbon sources by polyphosphate bacteria in the anaerobic tank, thereby improving the denitrification and phosphorus removal efficiency of the entire biochemical pool. Therefore, AAO 3 The O process is a wastewater treatment process for nitrogen and phosphorus removal that has been widely used in recent years. 3 The O process has the disadvantages of long hydraulic retention time, large pool volume, large aeration volume, and high construction and operating costs.

[0004] The adsorption regeneration aeration sewage treatment process system is mainly composed of a sludge activation tank, an adsorption tank, and a sedimentation tank. The sewage to be treated and the activated sludge are both sent to the adsorption tank. After being fully mixed, the organic matter in the sewage is removed by the flocculation and adsorption of the sludge. Then the mixed liquid enters the sedimentation tank. After the mud and water are separated in the sedimentation tank, the clean water is discharged, part of the sludge is discharged into the sludge activation tank, and the other part of the sludge is discharged as residual sludge. In the sludge activation tank, aeration is used to oxidize the adsorbed organic matter by the sludge, and the microorganisms are starved, so that the sludge has stronger adsorption performance in the adsorption tank. The adsorption regeneration process has a high removal rate for organic matter, but the removal effect of nitrogen and phosphorus is very poor, so it is rarely used in urban sewage treatment.

[0005] The invention patent with application number 202410054522.3 discloses a AAAOF sewage treatment system and process. Although the process utilizes the adsorption effect of sludge in section F, it is difficult to further increase the amount of water treated on rainy days. In addition, the effluent of the AAAOF process is in the anoxic section. The too low dissolved oxygen in the anoxic section may cause excessive anaerobic reaction of the sludge in the secondary sedimentation tank, thereby reducing the sedimentation effect of the sludge and causing the effluent quality of the secondary sedimentation tank to deteriorate. Therefore, it is necessary to further increase the amount of water treated on rainy days and avoid the problem of deterioration of the effluent quality of the secondary sedimentation tank due to excessive anaerobic reaction of the sludge in the secondary sedimentation tank. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In order to solve the problems that the treatment capacity of the sewage treatment process in the prior art cannot be further improved on rainy days, and that the sludge may undergo excessive anaerobic reaction in the secondary sedimentation tank, resulting in deterioration of the water quality of the secondary sedimentation tank effluent, the present invention provides a magnetically enhanced sewage treatment system and treatment process.

[0008] (II) Technical solution

[0009] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0010] The present invention provides a magnetically enhanced sewage treatment system, comprising a biochemical tank, a reoxygenation tank, a secondary sedimentation tank and a sludge hydrolysis / activation tank connected in sequence, and a magnetic powder dosing device;

[0011] The biochemical pool includes a pre-anoxic pool, an anaerobic pool, an anoxic pool, an aerobic pool and an anaerobic pool connected in sequence; the nitrification liquid at the end of the aerobic pool partially flows back to the anoxic pool;

[0012] The aeration tank is connected to the reoxygenation tank;

[0013] The sludge hydrolysis / activation tank hydrolyzes the sludge on a sunny day and activates the sludge on a rainy day; the sludge that has been hydrolyzed or activated is returned to the aerobic tank;

[0014] The magnetic powder adding device is used to add magnetic powder to the aerobic tank on rainy days;

[0015] Part of the sludge obtained from the bottom of the secondary sedimentation tank is returned to the pre-anoxic tank, part is returned to the sludge hydrolysis / activation tank, and the other part is dehydrated.

[0016] The magnetic enhanced sewage treatment system as described above preferably further comprises a magnetic powder recovery device connected to the anoxic tank, and the sludge portion is transported to the magnetic powder recovery device;

[0017] The magnetic powder dosing device adds 0.5-2g / L of magnetic powder to the aeration tank;

[0018] The magnetic powder is Fe3O4 nano magnetic powder with a particle size of 20-200nm.

[0019] The magnetically enhanced sewage treatment system as described above preferably further comprises water inlet pipes respectively connected to the pre-anoxic tank, the anaerobic tank and the anoxic tank, and the sewage inlet enters the pre-anoxic tank, the anaerobic tank and the anoxic tank respectively through the water inlet pipes;

[0020] The water inlet pipeline is provided with a water inlet main valve and a water inlet main flow meter;

[0021] A pre-anoxic pool water inlet valve and a pre-anoxic pool water inlet flowmeter are also provided on the water inlet pipeline connected to the pre-anoxic pool;

[0022] An anaerobic tank water inlet valve and an anaerobic tank water inlet flowmeter are also provided on the water inlet pipeline connected to the anaerobic tank;

[0023] The water inlet pipe connected to the anoxic pool is also provided with an anoxic pool water inlet valve and an anoxic pool water inlet flowmeter;

[0024] The pre-anoxic tank is also provided with a pre-anoxic tank return sludge flowmeter, and the anoxic tank is also provided with an anoxic tank return sludge flowmeter.

[0025] In the magnetically enhanced sewage treatment system as described above, preferably, a pre-anoxic tank agitator is provided in the pre-anoxic tank, an anaerobic tank agitator is provided in the anaerobic tank, and an anoxic tank agitator is provided in the anoxic tank;

[0026] The aerobic pool is provided with an aerobic pool online dissolved oxygen meter, an aerobic pool online ammonia nitrogen monitor and an online sludge concentration monitor;

[0027] The aerobic tank is provided with an online ammonia nitrogen monitor for the aerobic tank, an online dissolved oxygen meter for the aerobic tank and an aerobic tank agitator;

[0028] An online dissolved oxygen meter for the reoxygenation tank is arranged in the reoxygenation tank;

[0029] The sludge hydrolysis / activation tank is provided with a sludge hydrolysis / activation tank online dissolved oxygen meter and a sludge hydrolysis / activation tank agitator.

[0030] The magnetically enhanced sewage treatment system as described above preferably further comprises a return excess sludge pumping station, wherein the sludge obtained from the bottom of the secondary sedimentation tank enters the return excess sludge pumping station; the return excess sludge pumping station is provided with a first sludge return pump, a second sludge return pump and an excess sludge pump;

[0031] Part of the sludge is returned to the pre-anoxic tank through the first sludge return pump, part of it is returned to the sludge hydrolysis / activation tank through the second sludge return pump, part of it is transported to the magnetic powder recovery device through the residual sludge pump, and the other part is transported to the sludge dewatering system through the residual sludge pump for dewatering treatment.

[0032] The magnetically enhanced sewage treatment system as described above preferably further comprises an aeration device, wherein the aeration device comprises an aeration pipe assembly and a blower assembly;

[0033] The aeration pipe assembly comprises aeration pipes respectively arranged at the bottom of the aerobic tank, the anoxic tank, the reoxygenation tank and the sludge hydrolysis / activation tank;

[0034] The blower assembly comprises an aerobic tank blower, a facultative aerobic tank blower and a sludge hydrolysis / activation tank blower, the aerobic tank blower is connected to the aeration pipe at the bottom of the aerobic tank, the facultative aerobic tank blower is connected to the aeration pipe at the bottom of the facultative aerobic tank and the aeration pipe at the bottom of the reoxygenation tank, and the sludge hydrolysis / activation tank blower is connected to the aeration pipe at the bottom of the sludge hydrolysis / activation tank;

[0035] The aeration pipe at the bottom of the aeration tank and the aeration pipe at the bottom of the reoxygenation tank are also provided with an aeration tank air valve and a reoxygenation tank air valve respectively.

[0036] The present invention also provides a sewage treatment process using the magnetically enhanced sewage treatment system, wherein the magnetically enhanced sewage treatment system includes a sunny day mode and a rainy day mode;

[0037] Assuming that the design water inflow on a sunny day is Q, when the water inflow is less than 1.3Q, the magnetic enhanced sewage treatment system operates in the sunny day mode; when the water inflow is greater than or equal to 1.3Q, the magnetic enhanced sewage treatment system operates in the rainy day mode;

[0038] When the magnetic enhanced wastewater treatment system is operated in sunny weather mode, the wastewater treatment process includes the following steps:

[0039] S1: The sewage to be treated enters the pre-anoxic tank, anaerobic tank and facultative aerobic tank respectively;

[0040] S2: The sewage in the pre-anoxic tank is mixed with the returned sludge to undergo denitrification, and the effluent enters the anaerobic tank;

[0041] S3: The water undergoes phosphorus dissolution reaction in the anaerobic tank, and the effluent enters the anoxic tank;

[0042] S4: The influent of the anoxic tank and the nitrified liquid returned from the aerobic tank undergo denitrification and denitrification reactions, and the effluent enters the aerobic tank;

[0043] S5: Nitrification and phosphorus absorption reactions are carried out in the aerobic tank, and part of the terminal nitrification liquid flows back to the anoxic tank, and part enters the facultative anoxic tank;

[0044] S6: The sewage raw water in the aerobic tank, the nitrification liquid from the aerobic tank and the hydrolyzed sludge are mixed to simultaneously carry out nitrification reaction, denitrification reaction and simultaneous nitrification and denitrification phosphorus removal reaction;

[0045] S7: The effluent from the aerobic tank enters the reoxygenation tank for treatment;

[0046] S8: The effluent from the reoxygenation tank is separated into mud and water in the secondary sedimentation tank, the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station;

[0047] S9: Part of the sludge from the return residual sludge pumping station is returned to the pre-anoxic tank, part is returned to the sludge hydrolysis / activation tank, and the other part is dehydrated;

[0048] S10: The sludge is hydrolyzed in the sludge hydrolysis / activation tank under anoxic conditions and then returned to the anoxic tank;

[0049] When the magnetic enhanced wastewater treatment system is operated in rainy day mode, the wastewater treatment process includes the following steps:

[0050] A1: The sewage to be treated enters the pre-anoxic tank, anaerobic tank and facultative aerobic tank respectively;

[0051] A2: The sewage in the pre-anoxic tank is mixed with the returned sludge to undergo denitrification, and the effluent enters the anaerobic tank;

[0052] A3: The water undergoes phosphorus desorption reaction in the anaerobic tank, and the effluent enters the anoxic tank;

[0053] A4: The influent of the anoxic pool and the nitrified liquid returned from the aerobic pool undergo denitrification and denitrification reactions, and the effluent enters the aerobic pool;

[0054] A5: Nitrification and phosphorus absorption reactions take place in the aerobic pool, with part of the terminal nitrification liquid returning to the anoxic pool and part entering the facultative aerobic pool;

[0055] A6: Magnetic powder is added to the aerobic tank through a magnetic powder dosing device. The sewage in the aerobic tank, the nitrification liquid from the aerobic tank, the activated sludge and the magnetic powder are mixed to simultaneously carry out nitrification reaction, magnetic enhanced denitrification reaction and simultaneous nitrification, denitrification and phosphorus removal reaction;

[0056] A7: The effluent from the aeration tank enters the reoxygenation tank for treatment;

[0057] A8: The effluent from the reoxygenation tank is separated into mud and water in the secondary sedimentation tank, the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station;

[0058] A9: Part of the sludge from the return excess sludge pumping station is returned to the pre-anoxic tank, part is returned to the sludge hydrolysis / activation tank, and the other part is transported to the magnetic powder recovery device to recover the magnetic powder. The recovered magnetic powder is added to the anoxic tank, and the remaining sludge is dehydrated;

[0059] A10: The sludge is activated in the sludge hydrolysis / activation tank and then returned to the aeration tank.

[0060] In the above-mentioned sewage treatment process, preferably, when the magnetic enhanced sewage treatment system is operated in sunny day mode, in step S1, the water inflow of the pre-anoxic tank is 0.1Q-0.3Q; the water inflow of the anaerobic tank is 0.6Q-0.8Q; the water inflow of the facultative anoxic tank is 0.1Q-0.4Q;

[0061] In step S5, the reflux flow rate of the terminal nitrification liquid part returning to the anoxic tank is 1.0 times to 2.0 times the inlet flow rate of the pre-anoxic tank;

[0062] In step S9, the sludge return rate of the pre-anoxic tank is 0.4Q-0.7Q;

[0063] In step S10, the sludge return rate of the aerobic tank is 0.1Q-0.2Q;

[0064] When the magnetic enhanced sewage treatment system operates in rainy day mode, the treated water volume of the magnetic enhanced sewage treatment system is 1.3Q-3.0Q;

[0065] In step A1, the water inflow of the pre-anoxic tank is 0.2Q-0.3Q; the water inflow of the anaerobic tank is 0.7Q-0.8Q; the water inflow of the facultative aerobic tank is 0.3Q-2.0Q;

[0066] In step A5, the reflux ratio of the terminal nitrification liquid part back to the anoxic tank is 1.0Q-2.0Q;

[0067] In step A9, the sludge return rate of the pre-anoxic tank is 0.4Q-0.5Q;

[0068] In step A10, the sludge return rate of the aerobic tank is 0.2Q-0.5Q.

[0069] In the sewage treatment process as described above, preferably, when the magnetic enhanced sewage treatment system is operated in sunny day mode or rainy day mode, the concentration of dissolved oxygen in the aerobic tank is 2.0 mg / L-3.0 mg / L, the concentration of dissolved oxygen in the facultative oxygen tank is 0.5 mg / L-1.5 mg / L, and the concentration of dissolved oxygen in the reoxygenation tank is 2.0 mg / L-3.0 mg / L;

[0070] In step A6, the magnetic powder adding device adds magnetic powder to the aeration tank in an amount of 0.5-2 g / L;

[0071] In step A10, when the sludge is activated in the sludge hydrolysis / activation tank, the dissolved oxygen concentration in the sludge hydrolysis / activation tank is 2.0 mg / L-3.0 mg / L;

[0072] When the magnetic enhanced sewage treatment system is operated in sunny day mode, the hydraulic retention time in the pre-anoxic tank is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank is 1.0h-2.0h, the hydraulic retention time in the anoxic tank is 2.0h-3.0h, the hydraulic retention time in the aerobic tank is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank is 1.5h-3.0h, the hydraulic retention time in the reoxygenation tank is 5min-10min, and the total hydraulic retention time is 9.0h-16.0h;

[0073] When the magnetic enhanced sewage treatment system is operated in sunny day mode, the hydraulic retention time of sludge hydrolysis in the sludge hydrolysis / activation tank is 2h-4h, and the sludge ratio from the return residual sludge pump station to the sludge hydrolysis / activation tank is 20%-50%;

[0074] When the magnetic enhanced sewage treatment system is operated in rainy day mode, the hydraulic retention time in the pre-anoxic tank is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank is 1.0h-2.0h, the hydraulic retention time in the anoxic tank is 2.0h-3.0h, the hydraulic retention time in the aerobic tank is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank is 0.5h-1.0h, the hydraulic retention time in the reoxygenation tank is 2min-4min, and the total hydraulic retention time is 8.0h-14.0h;

[0075] When the magnetically enhanced sewage treatment system of the sewage treatment system is operated in rainy day mode, the hydraulic retention time of sludge activation in the sludge hydrolysis / activation tank is 1.5h-2h, and the sludge ratio returned from the return residual sludge pumping station to the sludge hydrolysis / activation tank is 20%-50%.

[0076] (III) Beneficial effects

[0077] First, the present invention is provided with a magnetic powder adding device for adding magnetic powder to the anoxic tank. Adding magnetic powder to the anoxic tank on rainy days can form magnetically enhanced activated sludge flocs with the magnetic powder as the core. The outside of the magnetically enhanced activated sludge flocs is in an aerobic state, and the inside is in an anoxic state, which can form an aerobic-anoxic environment under the microscopic environment. The micromagnetic field of the magnetic powder can increase the activity of microorganisms, thereby improving the denitrification and phosphorus removal efficiency of microorganisms. The density of the magnetically enhanced activated sludge is significantly improved, and the sludge settling rate of the secondary sedimentation tank can be increased by more than 3 times, thereby solving the problem of insufficient water treatment in the rainy season and increasing the water treatment volume by 3 times.

[0078] Secondly, the present invention also sets a sludge hydrolysis / activation tank in the magnetically enhanced sewage treatment system, realizes the dynamic optimization of carbon source utilization efficiency and biological denitrification and phosphorus removal capacity, and synergistically ensures stable operation under different working conditions on sunny and rainy days. The sludge hydrolysis / activation tank hydrolyzes the sludge on sunny days, hydrolyzes the difficult-to-degrade organic matter adsorbed by the sludge into small molecular organic matter, provides more carbon sources for denitrification for the anoxic tank and the anoxic tank, and improves the utilization rate of the carbon source. Sludge hydrolysis can also enable the nitrate nitrogen remaining in the sludge to complete the denitrification reaction, reduce the concentration of nitrate nitrogen refluxed to the anoxic tank, is conducive to the removal of phosphorus, and can also improve the denitrification efficiency of the biochemical tank. On rainy days, the sludge hydrolysis / activation tank is used to activate the sludge, convert the remaining ammonia nitrogen oxygen in the sludge into nitrate nitrogen, and in the activated sludge, the microbial metabolism is accelerated, and it is in a hungry state, and the flocculation and adsorption capacity of the sludge is enhanced.

[0079] Thirdly, the present invention also oxygenates the effluent from the aerobic tank by setting up a reoxygenation tank, thereby increasing the concentration of dissolved oxygen in the effluent from the aerobic tank, which can effectively inhibit excessive anaerobic denitrification of sludge in the secondary sedimentation tank and avoid affecting the sedimentation effect and the effluent quality from the secondary sedimentation tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is a structural schematic diagram of the magnetically enhanced sewage treatment system in the present invention.

[0081] [Description of Reference Numerals]

[0082] 1: Pre-anoxic tank; 2: Anaerobic tank; 3: Anoxic tank; 4: Aerobic tank; 5: Facultative aerobic tank; 6: Reoxygenation tank; 7: Secondary sedimentation tank; 8: Return residual sludge pump station; 9: Sludge hydrolysis / activation tank; 10: Inlet main valve; 11: Pre-anoxic tank inlet valve; 12: Anaerobic tank inlet valve; 13: Facultative aerobic tank inlet valve; 14: Nitrate liquid return pump; 15: First sludge return pump; 16: Second sludge return pump; 17: Residual sludge pump; 18: Aerobic tank blower; 19: Facultative aerobic tank blower; 20: Sludge hydrolysis / activation tank blower; 21: Facultative aerobic tank air valve; 22: Reoxygenation tank air valve; 23: Total inlet flow meter; 24: Pre-anoxic tank inlet flow meter ; 25: Anaerobic tank inlet flow meter; 26: Facultative aerobic tank inlet flow meter; 27: Pre-anoxic tank return sludge flow meter; 28: Facultative aerobic tank return sludge flow meter; 29: Aerobic tank online dissolved oxygen meter; 30: Aerobic tank online ammonia nitrogen monitor; 31: Online sludge concentration monitor; 32: Facultative ammonia nitrogen monitor; 33: Facultative aerobic tank online dissolved oxygen meter; 34: Reoxygenation tank online dissolved oxygen meter; 35: Sludge hydrolysis / activation tank online dissolved oxygen meter; 36: Pre-anoxic tank mixer; 37: Anaerobic tank mixer; 38: Anoxic tank mixer; 39: Facultative aerobic tank mixer; 40: Sludge hydrolysis / activation tank mixer; 41: Magnetic powder dosing device; 42: Magnetic powder recovery device. DETAILED DESCRIPTION

[0083] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with specific implementation methods.

[0084] like Figure 1 As shown, the present invention provides a magnetically enhanced sewage treatment system, comprising a biochemical tank, a reoxygenation tank 6, a secondary sedimentation tank 7 and a sludge hydrolysis / activation tank 9, which are connected in sequence, and a magnetic powder dosing device 41.

[0085] The biochemical pool includes a pre-anoxic pool 1, an anaerobic pool 2, an anoxic pool 3, an aerobic pool 4 and an anaerobic pool 5 which are connected in sequence. The nitrification liquid at the end of the aerobic pool 4 flows back to the anoxic pool 3, and the anaerobic pool 5 is connected to the reoxygenation pool 6.

[0086] The sludge hydrolysis / activation tank 9 performs hydrolysis treatment on the sludge on sunny days and performs activation treatment on the sludge on rainy days. The sludge that has been hydrolyzed or activated is returned to the aeration tank 5 .

[0087] The magnetic powder adding device 41 is used to add magnetic powder to the aeration tank 5 on rainy days.

[0088] Part of the sludge obtained at the bottom of the secondary sedimentation tank 7 is returned to the pre-anoxic tank 1, part is returned to the sludge hydrolysis / activation tank 9, and the other part enters the sludge dehydration system for dehydration treatment.

[0089] The present invention oxygenates the effluent from the anoxic tank by arranging a reoxygenation tank, thereby increasing the concentration of dissolved oxygen in the effluent from the anoxic tank, and can effectively inhibit excessive anaerobic denitrification of sludge in the secondary sedimentation tank, thereby avoiding affecting the sedimentation effect and the effluent quality from the secondary sedimentation tank.

[0090] The present invention also provides a magnetic powder adding device for adding magnetic powder to the anoxic tank. Adding magnetic powder to the anoxic tank on rainy days can form magnetically enhanced activated sludge flocs with the magnetic powder as the core. The outside of the magnetically enhanced activated sludge flocs is in an aerobic state, and the inside is in an anoxic state, which can form an aerobic-anoxic environment under the microscopic environment. The micromagnetic field of the magnetic powder can increase the activity of microorganisms, thereby improving the denitrification and phosphorus removal efficiency of microorganisms. The density of the magnetically enhanced activated sludge is significantly improved, and the sludge settling speed of the secondary sedimentation tank can be increased by more than 3 times, thereby solving the problem of insufficient water treatment in the rainy season and increasing the water treatment volume by 3 times.

[0091] The sludge hydrolysis / activation pool in the present invention realizes the dynamic optimization of carbon source utilization efficiency and biological denitrification and phosphorus removal capacity, and synergistically ensures stable operation under different working conditions on sunny and rainy days. The sludge hydrolysis / activation pool hydrolyzes the sludge on a sunny day, hydrolyzes the difficult-to-degrade organic matter adsorbed by the sludge into small molecular organic matter, provides more carbon sources for denitrification for the anoxic pool and the anoxic pool, and improves the utilization rate of the carbon source. Sludge hydrolysis can also complete the denitrification reaction of the nitrate nitrogen remaining in the sludge, reduce the concentration of nitrate nitrogen returned to the anoxic pool, is conducive to the removal of phosphorus, and can also improve the denitrification efficiency of the biochemical pool. The AAAOF sewage treatment process of the prior art, although the adsorption effect of sludge is utilized in the F section, the researchers of the present invention have found through long-term research that the microorganisms in the return sludge are still in a "full" state, and the flocculation and adsorption capacity of the return sludge is limited. Therefore, the amount of water treated on rainy days is limited, and the upper limit can only reach 2.4 times the amount of water on sunny days. Based on this problem, the present invention uses a sludge hydrolysis / activation tank to activate the sludge on rainy days, converting the remaining ammonia nitrogen oxygen in the sludge into nitrate nitrogen. In the activated sludge, the metabolism of microorganisms is accelerated and they are in a hungry state. The flocculation and adsorption capacity of the sludge is enhanced, and the treated water volume can reach three times the water volume on a sunny day.

[0092] Preferably, the magnetic enhanced sewage treatment system further comprises a magnetic powder recovery device 42 connected to the oxygenation tank 5, and the sludge is partially transported to the magnetic powder recovery device 42. The magnetic powder addition device 41 adds 0.5-2 g / L of magnetic powder to the oxygenation tank 5, and the magnetic powder is preferably Fe3O4 nano magnetic powder with a particle size of 20-200 nm, or other magnetic powder carrier materials.

[0093] Magnetic powder has the following two functions: First, magnetic powder has a micromagnetic field, which can improve the activity of microorganisms and improve the biological denitrification and phosphorus removal effect. Second, magnetic powder has the effect of strengthening flocculation, which can form magnetically strengthened activated sludge, greatly increase the sludge density, and increase the sedimentation speed of the secondary sedimentation tank by more than 3 times, thus solving the problem of insufficient treatment capacity of the secondary sedimentation tank in the rainy season.

[0094] Preferably, the magnetically enhanced sewage treatment system further comprises an inlet pipe connected to the pre-anoxic tank 1, the anaerobic tank 2 and the anoxic tank 5 respectively, and the sewage inlet can be divided into three routes, and enters the pre-anoxic tank 1, the anaerobic tank 2 and the anoxic tank 5 respectively through the inlet pipe. A total inlet valve 10 and a total inlet flow meter 23 are arranged on the inlet pipe, a pre-anoxic tank inlet valve 11 and a pre-anoxic tank inlet flow meter 24 are also arranged on the inlet pipe connected to the pre-anoxic tank 1, an anaerobic tank inlet valve 12 and an anaerobic tank inlet flow meter 25 are also arranged on the inlet pipe connected to the anaerobic tank 2, an anaerobic tank inlet valve 13 and an anaerobic tank inlet flow meter 26 are also arranged on the inlet pipe connected to the anoxic tank 5, a pre-anoxic tank return sludge flow meter 27 is also arranged in the pre-anoxic tank 1, and an anaerobic tank return sludge flow meter 28 is also arranged in the anoxic tank 5.

[0095] Preferably, a pre-anoxic tank mixer 36 is provided in the pre-anoxic tank 1, an anaerobic tank mixer 37 is provided in the anaerobic tank 2, and an anoxic tank mixer 38 is provided in the anoxic tank 3. An aerobic tank online dissolved oxygen meter 29, an aerobic tank online ammonia nitrogen monitor 30, and an online sludge concentration monitor 31 are provided in the aerobic tank 4, an aerobic tank online ammonia nitrogen monitor 32, an aerobic tank online dissolved oxygen meter 33, and an aerobic tank mixer 39 are provided in the facultative aerobic tank 5, a reoxygenation tank online dissolved oxygen meter 34 is provided in the reoxygenation tank 6, and a sludge hydrolysis / activation tank online dissolved oxygen meter 35 and a sludge hydrolysis / activation tank mixer 40 are provided in the sludge hydrolysis / activation tank 9. The function of the above-mentioned mixers is to mix the sludge and sewage evenly to prevent the sludge from settling.

[0096] Preferably, the magnetic enhanced sewage treatment system further comprises a return excess sludge pump station 8, the sludge obtained at the bottom of the secondary sedimentation tank 7 enters the return excess sludge pump station 8, and the return excess sludge pump station 8 is provided with a first sludge return pump 15, a second sludge return pump 16 and an excess sludge pump 17. A part of the sludge is returned to the pre-anoxic tank 1 through the first sludge return pump 15, a part is returned to the sludge hydrolysis / activation tank 9 through the second sludge return pump 16, a part is transported to the magnetic powder recovery device 42 through the excess sludge pump 17, and the other part is transported to the sludge dewatering system through the excess sludge pump 17 for dewatering treatment.

[0097] Preferably, the magnetic enhanced sewage treatment system further comprises an aeration device, and the aeration device comprises an aeration pipe assembly and a blower assembly. The aeration pipe assembly comprises aeration pipes respectively arranged at the bottom of the aerobic tank 4, the facultative aerobic tank 5, the reoxygenation tank 6 and the sludge hydrolysis / activation tank 9, and the blower assembly comprises an aerobic tank blower 18, a facultative aerobic tank blower 19 and a sludge hydrolysis / activation tank blower 20, the aerobic tank blower 18 is connected to the aeration pipe at the bottom of the aerobic tank 4, the facultative aerobic tank blower 19 is connected to the aeration pipe at the bottom of the facultative aerobic tank 5 and the aeration pipe at the bottom of the reoxygenation tank 6, and the sludge hydrolysis / activation tank blower 20 is connected to the aeration pipe at the bottom of the sludge hydrolysis / activation tank 9. The aeration pipe at the bottom of the facultative aerobic tank 5 and the aeration pipe at the bottom of the reoxygenation tank 6 are also provided with a facultative aerobic tank air valve 21 and a reoxygenation tank air valve 22, respectively.

[0098] The aeration volume of each pool can be adjusted by the automatic control system sending instructions to the blower according to the dissolved oxygen concentration of the aerobic pool, anaerobic pool, reoxygenation pool, and sludge hydrolysis / activation pool.

[0099] The present invention also provides a sewage treatment process using the magnetically enhanced sewage treatment system, wherein the magnetically enhanced sewage treatment system includes a sunny day mode and a rainy day mode.

[0100] Assuming that the design water inflow on a sunny day is Q, when the water inflow is less than 1.3Q, the magnetically enhanced sewage treatment system operates in sunny day mode; when the water inflow is greater than or equal to 1.3Q, the magnetically enhanced sewage treatment system operates in rainy day mode.

[0101] When the magnetic enhanced wastewater treatment system is operated in sunny weather mode, the wastewater treatment process includes the following steps:

[0102] S1: The sewage to be treated enters the pre-anoxic tank 1, the anaerobic tank 2 and the facultative aerobic tank 5 respectively.

[0103] S2: The sewage in the pre-anoxic tank 1 is mixed with the returned sludge, and the denitrifying bacteria use the carbon source in the sewage to convert the remaining nitrate in the returned sludge into nitrogen gas, undergoing a denitrification reaction, and the effluent enters the anaerobic tank 2.

[0104] S3: The anaerobic tank 2 undergoes a water phosphorus release reaction. Microorganisms in the anaerobic tank absorb organic carbon sources in the sewage, accumulate phosphorus and release phosphorus. The effluent enters the anoxic tank 3.

[0105] S4: the influent of the anoxic pool 3 and the nitrified liquid returned from the aerobic pool 4 undergo denitrification and denitrification reactions. The denitrifying bacteria utilize the carbon source absorbed in the anaerobic pool to perform denitrification and denitrification reactions in the anoxic pool, and the nitrate nitrogen is converted into nitrogen gas. The effluent enters the aerobic pool 4.

[0106] S5: Nitrification reaction and phosphorus absorption reaction are carried out in the aerobic tank 4. Nitrifying bacteria oxidize ammonia nitrogen into nitrate nitrogen under sufficient dissolved oxygen conditions, and polyphosphate bacteria undergo phosphorus absorption reaction, thereby removing ammonia nitrogen and phosphorus. The terminal nitrification liquid is partially returned to the anoxic tank 3 through the nitrification liquid reflux pump 14, and partially enters the facultative anoxic tank 5.

[0107] S6: The sewage raw water in the anoxic tank 5, the nitrified liquid from the aerobic tank 4 and the hydrolyzed sludge are mixed, and nitrification, denitrification and simultaneous nitrification, denitrification and phosphorus removal reactions are carried out simultaneously. In the nitrification reaction, nitrifying bacteria continue to convert ammonia nitrogen into nitrate nitrogen. In the denitrification reaction, the microorganisms inside the activated sludge mass are in anoxic state, and the denitrifying bacteria use the carbon source brought in from the anoxic section to convert nitrate into nitrogen gas. In the simultaneous nitrification and denitrification reaction, in the anoxic zone, under low dissolved oxygen conditions, the synchronous nitrification and denitrification bacteria in the activated sludge are more active, directly using ammonia nitrogen and nitrite to carry out simultaneous nitrification, denitrification and phosphorus removal, converting ammonia nitrogen and nitrite nitrogen into nitrogen gas, and absorbing phosphorus, thereby completing the simultaneous removal of ammonia nitrogen and total nitrogen and total phosphorus.

[0108] S7: The effluent from the aeration tank 5 enters the reoxygenation tank 6 for treatment.

[0109] S8: The effluent from the reoxygenation tank 6 is separated into mud and water by the secondary sedimentation tank 7, the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station 8.

[0110] S9: A portion of the sludge from the return residual sludge pumping station 8 is returned to the pre-anoxic tank 1, a portion is returned to the sludge hydrolysis / activation tank 9, and the remaining portion is dehydrated.

[0111] S10: The sludge is hydrolyzed in the sludge hydrolysis / activation tank 9 under anoxic conditions, i.e. without turning on the blower for aeration, and then returned to the aerobic tank 5. The return of sludge from the aerobic tank can increase the microbial biomass in the aerobic tank and provide part of the carbon source to the aerobic tank, thereby improving the treatment efficiency.

[0112] When the magnetic enhanced wastewater treatment system is operated in rainy day mode, the wastewater treatment process includes the following steps:

[0113] A1: The sewage to be treated enters the pre-anoxic tank 1, the anaerobic tank 2 and the facultative aerobic tank 5 respectively.

[0114] A2: The sewage in the pre-anoxic tank 1 is mixed with the returned sludge to undergo a denitrification reaction. The denitrifying bacteria use the carbon source in the sewage to convert the remaining nitrate in the returned sludge into nitrogen gas, and the effluent enters the anaerobic tank 2.

[0115] A3: The anaerobic tank 2 undergoes a water phosphorus release reaction. Microorganisms in the anaerobic tank absorb organic carbon sources in the sewage, accumulate phosphorus and release phosphorus. The effluent enters the anoxic tank 3.

[0116] A4: The influent of the anoxic tank 3 and the nitrified liquid returned from the aerobic tank 4 undergo denitrification and denitrification reactions. The denitrifying bacteria utilize the carbon source absorbed in the anaerobic tank to perform denitrification and denitrification reactions in the anoxic tank, and the nitrate nitrogen is converted into nitrogen gas. The effluent enters the aerobic tank 4.

[0117] A5: Nitrification reaction and phosphorus absorption reaction are carried out in the aerobic tank 4. Nitrifying bacteria oxidize ammonia nitrogen into nitrate nitrogen under sufficient dissolved oxygen conditions, and polyphosphate bacteria undergo phosphorus absorption reaction, thereby removing ammonia nitrogen and phosphorus. Part of the terminal nitrification liquid flows back to the anoxic tank 3, and part enters the facultative anoxic tank 5.

[0118] A6: Magnetic powder is added to the anoxic tank 5 through the magnetic powder adding device 41. The sewage raw water in the anoxic tank 5, the nitrification liquid from the aerobic tank 4, the activated sludge and the magnetic powder are mixed, and nitrification reaction, magnetic enhanced denitrification reaction and simultaneous nitrification, denitrification and phosphorus removal reaction are carried out simultaneously. Fe3O4 nano magnetic powder has a good flocculation effect. The magnetic powder can enhance the function of the activated sludge biological flocculation adsorption tank, has good adsorption performance, and can efficiently remove organic pollutants, suspended matter and TP entering the sewage from the anoxic tank. After adding magnetic powder, the anoxic tank can quickly form a magnetic enhanced activated sludge floc with magnetic powder as the core. The outside of the magnetic enhanced activated sludge floc is in an aerobic state, and the inside is in an anoxic state, which can form an aerobic-anoxic environment under the microscopic environment; the micromagnetic field of the magnetic powder can increase the activity of microorganisms, thereby improving the efficiency of microbial denitrification and phosphorus removal; the density of the magnetic enhanced activated sludge is large, which can increase the sludge settling speed of the secondary sedimentation tank by 3 times or more, thereby solving the problem of insufficient treatment capacity of the secondary sedimentation tank in the rainy season.

[0119] The facultative oxygen pool can simultaneously complete nitrification, denitrification and simultaneous nitrification, denitrification and phosphorus removal reactions: in the nitrification reaction, nitrifying bacteria continue to convert ammonia nitrogen into nitrate nitrogen. In the denitrification reaction, the microorganisms inside the magnetically enhanced activated sludge group are in an anoxic state. The denitrifying bacteria use the carbon source brought in from the facultative oxygen section to convert nitrate into nitrogen gas. In the simultaneous nitrification and denitrification reaction, in the facultative oxygen zone, under low dissolved oxygen conditions, the simultaneous nitrification and denitrification bacteria in the magnetically enhanced activated sludge will be more active, directly using ammonia nitrogen and nitrite to undergo simultaneous nitrification, denitrification and phosphorus removal, converting ammonia nitrogen and nitrite nitrogen into nitrogen gas and absorbing phosphorus, thereby completing the simultaneous removal of ammonia nitrogen, total nitrogen and total phosphorus.

[0120] A7: The effluent from the aeration tank 5 enters the reoxygenation tank 6 for treatment.

[0121] A8: The effluent from the reoxygenation tank 6 is separated into mud and water by the secondary sedimentation tank 7, the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station 8.

[0122] A9: Part of the sludge from the return residual sludge pump station 8 is returned to the pre-anoxic tank 1, part is returned to the sludge hydrolysis / activation tank 9, and the other part is transported to the magnetic powder recovery device 42 to recover the magnetic powder. The recovered magnetic powder is added to the anoxic tank 5, and the remaining sludge is dehydrated.

[0123] A10: The sludge is activated in the sludge hydrolysis / activation tank 9 and then returned to the aeration tank 5.

[0124] Preferably, when the magnetic enhanced sewage treatment system is operated in sunny day mode, in step S1, the water inflow of the pre-anoxic tank 1 is 0.1Q-0.3Q; the water inflow of the anaerobic tank 2 is 0.6Q-0.8Q; the water inflow of the anoxic tank 5 is 0.1Q-0.4Q. In step S5, the return flow rate of the terminal nitrification liquid part back to the anoxic tank 3 is 1.0 times-2.0 times the water inflow rate of the pre-anoxic tank 1, in step S9, the sludge return flow rate of the pre-anoxic tank 1 is 0.4Q-0.7Q, and in step S10, the sludge return flow rate of the anoxic tank 5 is 0.1Q-0.2Q.

[0125] When the magnetically enhanced sewage treatment system is operated in rainy day mode, the treated water volume of the magnetically enhanced sewage treatment system is 1.3Q-3.0Q. In step A1, the water inflow of the pre-anoxic tank 1 is 0.2Q-0.3Q; the water inflow of the anaerobic tank 2 is 0.7Q-0.8Q; the water inflow of the anoxic tank 5 is 0.3Q-2.0Q. In step A5, the reflux ratio of the terminal nitrification liquid part to the anoxic tank 3 is 1.0Q-2.0Q. In step A9, the sludge return volume of the pre-anoxic tank 1 is 0.4Q-0.5Q. In step A10, the sludge return volume of the anoxic tank 5 is 0.2Q-0.5Q.

[0126] When the magnetically enhanced sewage treatment system operates in sunny day mode or rainy day mode, the concentration of dissolved oxygen in the aerobic tank 4 is 2.0 mg / L-3.0 mg / L, the concentration of dissolved oxygen in the facultative oxygen tank 5 is 0.5 mg / L-1.5 mg / L, and the concentration of dissolved oxygen in the reoxygenation tank 6 is 2.0 mg / L-3.0 mg / L.

[0127] In step A6, the magnetic powder dosing device 41 adds magnetic powder to the aeration tank 5 at a dosage of 0.5-2 g / L. In step A10, when the sludge is activated in the sludge hydrolysis / activation tank 9, the dissolved oxygen concentration in the sludge hydrolysis / activation tank 9 is 2.0 mg / L-3.0 mg / L.

[0128] When the magnetic enhanced sewage treatment system is operated in sunny day mode, the hydraulic retention time in the pre-anoxic tank 1 is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank 2 is 1.0h-2.0h, the hydraulic retention time in the anoxic tank 3 is 2.0h-3.0h, the hydraulic retention time in the aerobic tank 4 is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank 5 is 1.5h-3.0h, the hydraulic retention time in the reoxygenation tank 6 is 5min-10min, and the total hydraulic retention time is 9.0h-16.0h. The total hydraulic retention time is the sum of the retention time of the sewage in the pre-anoxic tank 1, the anaerobic tank 2, the anoxic tank 3, the aerobic tank 4, the facultative aerobic tank 5 and the reoxygenation tank 6.

[0129] When the magnetically enhanced sewage treatment system operates in sunny day mode, the hydraulic retention time of sludge hydrolysis in the sludge hydrolysis / activation tank 9 is 2h-4h, and the sludge ratio returned from the return residual sludge pump station 8 to the sludge hydrolysis / activation tank 9 is 20%-50%.

[0130] When the magnetically enhanced sewage treatment system of the sewage treatment system is operated in rainy day mode, the hydraulic retention time in the pre-anoxic tank 1 is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank 2 is 1.0h-2.0h, the hydraulic retention time in the anoxic tank 3 is 2.0h-3.0h, the hydraulic retention time in the aerobic tank 4 is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank 5 is 0.5h-1.0h, the hydraulic retention time in the reoxygenation tank 6 is 2min-4min, and the total hydraulic retention time is 8.0h-14.0h.

[0131] When the magnetically enhanced sewage treatment system of the sewage treatment system operates in rainy day mode, the hydraulic retention time of sludge activation in the sludge hydrolysis / activation tank 9 is 1.5h-2h, and the sludge ratio returned from the return residual sludge pump station 8 to the sludge hydrolysis / activation tank 9 is 20%-50%.

[0132] In order to further clarify the scheme of the present invention and its technical advancement, the following is a description in conjunction with specific embodiments and technical effects.

[0133] Example 1

[0134] This embodiment provides a sewage treatment process, and a simulation experiment is carried out with the water quality of a sewage treatment plant, and the design flow rate Q=60L / d. The total residence time of the water in the biochemical tank and the reoxygenation tank is 12.6h, of which the residence time of the pre-anoxic tank is 0.5h, the residence time of the anaerobic tank is 1h, the hydraulic retention time of the anoxic tank is 2.5h, the hydraulic retention time of the aerobic tank is 6h, the hydraulic retention time of the facultative aerobic tank is 2.5h, the hydraulic retention time of the reoxygenation tank is 0.1h, and the hydraulic retention time of the sludge hydrolysis tank is 2.0h. The hydraulic retention time in the secondary sedimentation tank is 4h. The system operates in sunny day mode:

[0135] Adjust the valve of the pre-anoxic tank, 0.1Q sewage enters the pre-anoxic tank, the sewage mixes and reacts with the return sludge, and the effluent from the pre-anoxic tank enters the anaerobic tank.

[0136] Adjust the water inlet valve of the anaerobic tank, 0.7Q sewage enters the anaerobic tank and is fully mixed with the mixed liquid entering the pre-anoxic tank, and the effluent from the anaerobic tank enters the anoxic tank.

[0137] In the anoxic tank, the effluent from the anaerobic tank is mixed with the nitrified liquid returned from the aerobic tank. The denitrifying bacteria use the carbon source in the sewage to complete the denitrification reaction and remove TN. The effluent from the anoxic tank enters the aerobic tank.

[0138] Adjust the air supply of the aerobic pool blower to control the dissolved oxygen in the aerobic pool at 2.0mg / L-3.0mg / L. Nitrifying bacteria use the dissolved oxygen in the aerobic pool to undergo nitrification reaction, oxidizing ammonia nitrogen into nitrate nitrogen. Adjust the flow rate of the nitrification liquid reflux pump. 1.0Q of nitrification liquid in the aerobic pool will flow back to the anoxic pool, and the rest of the nitrification liquid will flow to the facultative aerobic pool.

[0139] Adjust the water inlet valve of the aerobic pool, and 0.2Q of sewage enters the aerobic pool to mix with the nitrification liquid from the aerobic pool and 0.1Q of sludge from the sludge hydrolysis pool. Adjust the air supply of the blower in the aerobic pool to control the dissolved oxygen in the aerobic pool at 0.5mg / L-1.5mg / L. Nitrification, denitrification, and simultaneous nitrification, denitrification, and phosphorus removal reactions are completed in the aerobic pool at the same time.

[0140] The effluent from the aeration tank enters the reoxygenation tank, where the dissolved oxygen concentration of the mixed liquor is increased to 2.0mg-3.0mg / L, and the effluent is discharged to the secondary sedimentation tank.

[0141] In the secondary sedimentation tank, after the sedimentation sludge and water are separated, the supernatant is discharged and the sludge is discharged to the return residual sludge pumping station.

[0142] The sludge return pump in the return residual sludge pumping station transports part of the sludge to the pre-anoxic tank through the first sludge return pump, and the sludge return volume is 0.5Q. Part of the sludge is transported to the sludge hydrolysis / activation tank through the second sludge return pump, and the return volume is 0.1Q. The remaining sludge is discharged to the sludge dewatering system through the residual sludge pump.

[0143] In sunny day mode, the sludge hydrolysis / activation tank operates as a sludge hydrolysis tank, and the hydrolyzed sludge is returned to the aeration tank.

[0144] In this embodiment, the pollutant removal effect is shown in Table 1:

[0145] Table 1 Statistics of pollutants and their removal effects in Example 1

[0146] index COD <![CDATA[BOD5]]> <![CDATA[NH3-N]]> TN TP SS Influent (mg / L) 220 102 26 31 2.2 202 Outlet water (mg / L) 14.54 2.16 1.84 13.63 0.46 15.8 Removal rate 93.39％ 97.88％ 92.92％ 56.03％ 79.09％ 92.18％

[0147] In the effluent of Example 1, except for SS, the other pollutant indicators are better than the first-level A standard.

[0148] Comparative Example 1

[0149] This embodiment provides a traditional A 3 The sewage treatment process of O was simulated with the water quality of a sewage treatment plant, and the design flow rate Q = 60L / d. The total retention time of the biochemical pool is 12.6h, of which the retention time of the pre-anoxic pool is 0.6h, the retention time of the anaerobic pool is 1h, the hydraulic retention time of the anoxic pool is 2.5h, and the hydraulic retention time of the aerobic pool is 8.5h. The hydraulic retention time in the secondary sedimentation tank is 4h.

[0150] Adjust the water inlet valve of the pre-anoxic tank so that 0.3 times the sewage enters the pre-anoxic tank and mixes with 0.6Q of return sludge.

[0151] Adjust the water inlet valve of the anaerobic tank so that 0.7Q of sewage enters the anaerobic tank and mixes with the effluent from the pre-anoxic tank.

[0152] The effluent from the anaerobic tank enters the anoxic tank and mixes with the nitrified liquid returned from the aerobic tank. In the anoxic tank, the denitrifying bacteria use the carbon source in the sewage to complete the denitrification reaction and remove TN. The effluent from the anoxic tank enters the aerobic tank.

[0153] Adjust the air supply of the aerobic tank blower to control the dissolved oxygen in the aerobic tank at 2.0mg / L~3.0mg / L. Part of the mixed liquor in the aerobic tank is discharged to the secondary sedimentation tank, and the other part is refluxed to the anoxic tank with a reflux rate of 2.0Q.

[0154] The effluent from the aerobic tank is separated into mud and water in the secondary sedimentation tank, the supernatant is discharged, and the sludge is discharged to the return residual sludge pump station.

[0155] At the return residual sludge pumping station, a portion of the sludge (0.6Q) is returned to the pre-anoxic tank through the sludge return pump, and the remaining sludge is discharged to the sludge dewatering system.

[0156] In this embodiment, the pollutant removal effect is shown in Table 2:

[0157] Table 2 Statistics of pollutants and their removal effects in comparative example 1

[0158] index COD <![CDATA[BOD5]]> <![CDATA[NH3-N]]> TN TP SS Influent (mg / L) 220 102 26 31 2.2 202 Outlet water (mg / L) 15.57 2.33 1.08 15.59 0.56 16.6 Removal rate 92.92％ 97.72％ 95.85％ 49.71％ 74.55％ 91.78％

[0159] It can be seen from Table 2 that TN, TP and SS of Comparative Example 1 can meet the Class I B emission standard, and the remaining pollutants can meet the Class I A emission standard.

[0160] By comparing the treatment effects of Example 1 and Comparative Example 1, it can be seen that the treatment process of the present invention is operated in sunny mode, and the effluent quality is better than that of the traditional A 3 O process is good.

[0161] Example 2

[0162] This embodiment provides a sewage treatment process, and a simulation experiment is carried out with the water quality of a sewage treatment plant. The design flow rate Q=60L / d on sunny days, and the treatment capacity on rainy days is 180L / d. The total retention time of the biochemical pool is 10.7h, of which the retention time of the pre-anoxic pool is 0.5h, the retention time of the anaerobic pool is 1h, the hydraulic retention time of the anoxic pool is 2.5h, the hydraulic retention time of the aerobic pool is 6h, the hydraulic retention time of the facultative aerobic pool is 0.7h, the hydraulic retention time of the reoxygenation pool is 3min, and the hydraulic retention time of the sludge activation pool is 2.0h. The hydraulic retention time in the secondary sedimentation tank is 1.33h. The system operates in rainy day mode.

[0163] Adjust the valve of the pre-anoxic tank, 0.3Q sewage enters the pre-anoxic tank, the sewage mixes and reacts with the return sludge, and the effluent from the pre-anoxic tank enters the anaerobic tank.

[0164] Adjust the water inlet valve of the anaerobic tank, 0.7Q sewage enters the anaerobic tank and is fully mixed with the mixed liquid entering the pre-anoxic tank, and the effluent from the anaerobic tank enters the anoxic tank.

[0165] In the anoxic tank, the effluent from the anaerobic tank is mixed with the nitrified liquid returned from the aerobic tank. The denitrifying bacteria use the carbon source in the sewage to complete the denitrification reaction and remove TN. The effluent from the anoxic tank enters the aerobic tank.

[0166] Adjust the air supply of the aerobic pool blower to control the dissolved oxygen in the aerobic pool at 2.0mg / L-3.0mg / L. Adjust the flow rate of the nitrification liquid return pump, so that 1.0Q of the nitrification liquid in the aerobic pool flows back to the anoxic pool, and the rest of the nitrification liquid flows to the facultative aerobic pool.

[0167] Start the magnetic powder dosing device, the magnetic powder dosing amount is 1g / L, the magnetic powder is Fe3O4 nano magnetic powder with an average particle size of 20nm; adjust the water inlet valve of the aerobic pool, 2.0Q sewage enters the aerobic pool and mixes with the nitrification liquid from the aerobic pool, 0.5Q sludge from the sludge hydrolysis pool and magnetic powder. Adjust the air supply of the blower of the aerobic pool to control the dissolved oxygen in the aerobic pool at 0.5mg / L-1.5mg / L.

[0168] The effluent from the aeration tank enters the reoxygenation tank, where the dissolved oxygen concentration of the mixed liquor is increased to 2.0mg~3.0mg / L, and the effluent is discharged to the secondary sedimentation tank.

[0169] The supernatant of the secondary sedimentation tank is discharged, and the sludge is discharged to the return residual sludge pump station. The first sludge return pump in the return residual sludge pump station transports part of the sludge to the pre-anoxic tank, and the sludge return volume is 0.5Q. Part of the sludge is transported to the sludge hydrolysis / activation tank through the second sludge return pump, and the return volume is 0.5Q. Another part of the sludge is discharged to the magnetic powder recovery device through the residual sludge pump. The magnetic powder recovered by the magnetic powder recovery device is transported to the anoxic tank for recycling, and the remaining sludge is sent to the sludge dewatering system.

[0170] The sludge hydrolysis / activation tank is operated as a sludge activation tank. The sludge activation tank blower is turned on for aeration. The dissolved oxygen is controlled at 2.0mg / L-3.0mg / L. The sludge regenerated in the sludge activation tank is returned to the aeration tank.

[0171] In this embodiment, the pollutant removal effect is shown in Table 3:

[0172] Table 3 Statistics of pollutants and their removal effects in Example 2

[0173]

[0174]

[0175] It can be seen from Table 3 that, in the effluent of Example 2, except for SS, all other indicators are better than the first-level A standard.

[0176] Example 3

[0177] This embodiment provides a sewage treatment process, which is different from Embodiment 2 in that the system operates in rainy day mode, the total retention time of the biochemical pool is 12 hours, and the amount of water treated is 2.6 times that of sunny days. The retention time of the pre-anoxic pool is 1 hour, the retention time of the anaerobic pool is 2 hours, the hydraulic retention time of the anoxic pool is 2 hours, the hydraulic retention time of the aerobic pool is 6 hours, the hydraulic retention time of the facultative aerobic pool is 1.0 hour, the hydraulic retention time of the reoxygenation pool is 5 minutes, and the hydraulic retention time of the sludge activation pool is 2 hours. The hydraulic retention time in the secondary sedimentation tank is 1.6 hours.

[0178] Adjust the valve of the pre-anoxic tank, 0.2Q sewage enters the pre-anoxic tank, the sewage mixes and reacts with the return sludge, and the effluent from the pre-anoxic tank enters the anaerobic tank.

[0179] Adjust the water inlet valve of the anaerobic tank, 0.8Q sewage enters the anaerobic tank and is fully mixed with the mixed liquid entering the pre-anoxic tank, and the effluent from the anaerobic tank enters the anoxic tank.

[0180] Adjust the air supply of the aerobic pool blower to control the dissolved oxygen in the aerobic pool at 2.0mg / L-3.0mg / L. Adjust the flow rate of the nitrification liquid return pump, so that 2.0Q of the nitrification liquid in the aerobic pool flows back to the anoxic pool, and the rest of the nitrification liquid flows to the facultative aerobic pool.

[0181] Start the magnetic powder dosing device, the magnetic powder dosage is 0.5g / L, the magnetic powder is Fe3O4 nano magnetic powder with an average particle size of 50nm; adjust the water inlet valve of the aerobic tank, 1.6Q sewage enters the aerobic tank and is mixed with the nitrification liquid from the aerobic tank, 0.5Q sludge from the sludge hydrolysis tank and magnetic powder.

[0182] In this embodiment, the pollutant removal effect is shown in Table 4:

[0183] Table 4 Statistics of pollutants and their removal effects in Example 3

[0184] index COD <![CDATA[BOD5]]> <![CDATA[NH3-N]]> TN TP SS Influent (mg / L) 144 71 14.8 20.1 1.52 152 Outlet water (mg / L) 19.63 7.82 4.75 11.98 0.46 15.54 Removal rate 86.37％ 88.99％ 67.91％ 40.40％ 69.74％ 89.78％

[0185] It can be seen from Table 4 that, in the effluent of Example 3, except for SS, all other indicators are better than the first-level A standard.

[0186] Example 4

[0187] This embodiment provides a sewage treatment process, which is different from the embodiment 2 in that the total retention time of the biochemical pool is 11.1 hours, the water volume treated is 2.8 times that of a sunny day, the retention time of the pre-anoxic pool is 0.8 hours, the retention time of the anaerobic pool is 1.5 hours, the hydraulic retention time of the anoxic pool is 3 hours, the hydraulic retention time of the aerobic pool is 5 hours, the hydraulic retention time of the facultative aerobic pool is 0.8 hours, the hydraulic retention time of the reoxygenation pool is 4 minutes, and the hydraulic retention time of the sludge activation pool is 1.6 hours. The system operates in rainy day mode.

[0188] Adjust the valve of the pre-anoxic tank, 0.25Q sewage enters the pre-anoxic tank, the sewage mixes with the return sludge, and the effluent of the pre-anoxic tank enters the anaerobic tank. Adjust the inlet valve of the anaerobic tank, 0.75Q sewage enters the anaerobic tank, and is fully mixed with the mixed liquid entering the pre-anoxic tank, and the effluent of the anaerobic tank enters the anoxic tank. The dosage of magnetic powder is 2g / L, and the magnetic powder is Fe3O4 nano magnetic powder with an average particle size of 200nm.

[0189] In this embodiment, the pollutant removal effect is shown in Table 5:

[0190] Table 5 Statistics of pollutants and their removal effects in Example 4

[0191] index COD <![CDATA[BOD5]]> <![CDATA[NH3-N]]> TN TP SS Influent (mg / L) 126 63.3 13.1 16.4 1.43 126 Outlet water (mg / L) 19.52 8.24 4.38 10.38 0.43 15.54 Removal rate 84.51％ 86.98％ 66.56％ 36.71％ 69.93％ 87.67％

[0192] It can be seen from Table 5 that, in the effluent of Example 4, except for SS, all indicators are better than the first-level A standard.

[0193] In Example 2 to Example 4, due to the addition of magnetic powder, the setting of a reoxygenation tank, and the activation treatment of the sludge, a magnetically enhanced activated sludge system was formed, which greatly improved the nitrogen and phosphorus removal effects of the aerobic tank and the sedimentation effect of the secondary sedimentation tank. Therefore, the treatment capacity in the rainy season reached 3 times the design scale in the dry season. Compared with the AAAOF treatment process in the prior art, the treated water volume can be increased by 25%, and the effluent water quality has been further improved compared with the AAAOF process in the prior art. All indicators, especially TP, have reached the Class A emission standard.

[0194] Comparative Example 2

[0195] This comparative example provides a sewage treatment process, and a simulation experiment is conducted on the water quality of a sewage treatment plant. The design flow rate Q on sunny days is 60L / d, the treatment capacity on rainy days is 120L / d, and the total retention time in the biochemical tank and the reoxygenation tank is 12.6h, of which the retention time of the pre-anoxic tank is 0.5h; the retention time of the anaerobic tank is 1h; the hydraulic retention time of the anoxic tank is 2.5h; the hydraulic retention time of the aerobic tank is 6h; the hydraulic retention time of the facultative aerobic tank is 2.5h; the hydraulic retention time of the reoxygenation tank is 0.1h; and the hydraulic retention time of the sludge activation tank is 2.0h. The hydraulic retention time of the secondary sedimentation tank is 2h. The system operates in rainy day mode.

[0196] Adjust the valve of the pre-anoxic tank, 0.3Q sewage enters the pre-anoxic tank, the sewage mixes and reacts with the return sludge, and the effluent from the pre-anoxic tank enters the anaerobic tank.

[0197] Adjust the water inlet valve of the anaerobic tank, 0.7Q sewage enters the anaerobic tank and is fully mixed with the mixed liquid entering the pre-anoxic tank, and the effluent from the anaerobic tank enters the anoxic tank.

[0198] In the anoxic tank, the effluent from the anaerobic tank is mixed with the nitrified liquid returned from the aerobic tank. The denitrifying bacteria use the carbon source in the sewage to complete the denitrification reaction and remove TN. The effluent from the anoxic tank enters the aerobic tank.

[0199] Adjust the air supply of the aerobic pool blower to control the dissolved oxygen in the aerobic pool at 2.0mg / L-3.0mg / L. Nitrifying bacteria use the dissolved oxygen in the aerobic pool to nitrify and oxidize ammonia nitrogen into nitrate nitrogen. Adjust the flow rate of the nitrification liquid return pump. 1.0Q of the nitrification liquid in the aerobic pool will flow back to the anoxic pool, and the rest of the nitrification liquid will flow to the facultative aerobic pool.

[0200] Adjust the water inlet valve of the aerobic tank, so that 1.0Q sewage enters the aerobic tank and mixes with the nitrification liquid from the aerobic tank and 0.5Q sludge from the sludge hydrolysis tank; adjust the air supply of the blower in the aerobic tank to control the dissolved oxygen in the aerobic tank at 0.5mg / L-1.5mg / L.

[0201] The effluent from the aeration tank enters the reoxygenation tank, where the dissolved oxygen concentration of the mixed liquor is increased to 2.0mg~3.0mg / L, and the effluent is discharged to the secondary sedimentation tank.

[0202] In the secondary sedimentation tank, after the sedimentation mud and water are separated, the supernatant is discharged; the sludge is discharged to the return residual sludge pumping station.

[0203] The No. 1 sludge return pump in the return residual sludge pumping station transports part of the sludge to the pre-anoxic tank, and the sludge return volume is 0.5Q; part of the sludge is transported to the sludge hydrolysis / activation tank through the No. 2 sludge return pump, and the return volume is 0.5Q; the remaining sludge is discharged to the sludge dewatering system through the residual sludge pump.

[0204] In rainy day mode, the sludge hydrolysis / activation tank operates as a sludge activation tank, that is, the sludge activation tank blower is turned on for aeration, and the dissolved oxygen is controlled at 2.0mg / L-3.0mg / L. The residual ammonia nitrogen in the sludge is oxidized into nitrate nitrogen; at the same time, the metabolism of microorganisms is accelerated under aerobic conditions, and eventually the microorganisms are in a hungry state, thereby enhancing the flocculation and adsorption capacity of the sludge. This process is the sludge regeneration process. The sludge regenerated in the sludge activation tank is returned to the aerobic tank.

[0205] In this comparative example, the pollutant removal effect is shown in Table 6:

[0206] Table 6 Statistics of pollutants and their removal effects in comparative example 2

[0207] index COD <![CDATA[BOD5]]> <![CDATA[NH3-N]]> TN TP SS Influent (mg / L) 153 73 15.2 20.3 1.8 156 Outlet water (mg / L) 20.88 8.18 4.43 11.16 0.81 19.2 Removal rate 86.35％ 88.79％ 70.86％ 45.02％ 55.28％ 87.69％

[0208] It can be seen from Table 6 that when comparative example 2 is operated in rainy season mode, TP and SS can only reach the first-level B standard, while the other indicators are better than the first-level A standard.

[0209] The rainy day treatment capacity of Comparative Example 2 can only reach twice that of the sunny day mode and cannot be further improved. Except for SS, TP can only reach the Class I B emission standard. Overall, the effluent water quality cannot fully reach the Class I A emission standard as in Examples 2-4.

[0210] In addition, under the condition that the difference in influent water quality is not large, in the process of treating sewage for two consecutive months in Examples 2-4, there was no deterioration in the effluent water quality in the secondary sedimentation tank. However, the AAAOF treatment process in the prior art had deterioration in the effluent water quality of the secondary sedimentation tank three times in the process of running for two consecutive months. Specifically, on the 15th day, 38th day and 55th day, sludge in the secondary sedimentation tank floated, the effluent was turbid, and the TP content was >0.8 mg / L. After the water quality deteriorated, it needed to be adjusted or stopped, and the sewage treatment capacity was reduced or lost during this period.

[0211] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetically enhanced sewage treatment system, characterized in that: It comprises a biochemical tank, a reoxygenation tank (6), a secondary sedimentation tank (7) and a sludge hydrolysis / activation tank (9) which are connected in sequence, and a magnetic powder dosing device (41); The biochemical pool comprises a pre-anoxic pool (1), an anaerobic pool (2), an anoxic pool (3), an aerobic pool (4) and an anaerobic pool (5) which are connected in sequence; the nitrification liquid at the end of the aerobic pool (4) partially flows back to the anoxic pool (3); The anoxic tank (5) is connected to the reoxygenation tank (6); The sludge hydrolysis / activation tank (9) performs hydrolysis treatment on the sludge on sunny days and performs activation treatment on the sludge on rainy days; the sludge that has been hydrolyzed or activated is returned to the aeration tank (5); The magnetic powder adding device (41) is used to add magnetic powder to the oxygen-absorbing tank (5) on rainy days; Part of the sludge obtained at the bottom of the secondary sedimentation tank (7) is returned to the pre-anoxic tank (1), part is returned to the sludge hydrolysis / activation tank (9), and the remaining part is dehydrated.

2. The magnetic enhanced sewage treatment system according to claim 1, characterized in that: It also includes a magnetic powder recovery device (42) connected to the anoxic tank (5), and the sludge portion is transported to the magnetic powder recovery device (42); The magnetic powder adding device (41) adds 0.5-2 g / L of magnetic powder to the oxygenation tank (5); The magnetic powder is Fe3O4 nano magnetic powder with a particle size of 20-200nm.

3. The magnetically enhanced sewage treatment system according to claim 1, characterized in that: It also includes water inlet pipes respectively connected to the pre-anoxic tank (1), the anaerobic tank (2) and the anoxic tank (5), and sewage water enters the pre-anoxic tank (1), the anaerobic tank (2) and the anoxic tank (5) respectively through the water inlet pipes; The water inlet pipeline is provided with a water inlet main valve (10) and a water inlet total flow meter (23); A pre-anoxic pool water inlet valve (11) and a pre-anoxic pool water inlet flowmeter (24) are also provided on the water inlet pipeline connected to the pre-anoxic pool (1); An anaerobic tank water inlet valve (12) and an anaerobic tank water inlet flowmeter (25) are also provided on the water inlet pipeline connected to the anaerobic tank (2); The water inlet pipe connected to the anoxic pool (5) is also provided with an anoxic pool water inlet valve (13) and an anoxic pool water inlet flowmeter (26); The pre-anoxic tank (1) is also provided with a pre-anoxic tank return sludge flowmeter (27), and the anoxic tank (5) is also provided with an anoxic tank return sludge flowmeter (28).

4. The magnetically enhanced sewage treatment system according to claim 1, characterized in that: The pre-anoxic tank (1) is provided with a pre-anoxic tank agitator (36), the anaerobic tank (2) is provided with an anaerobic tank agitator (37), and the anoxic tank (3) is provided with an anoxic tank agitator (38); The aerobic tank (4) is provided with an aerobic tank online dissolved oxygen meter (29), an aerobic tank online ammonia nitrogen monitor (30) and an online sludge concentration monitor (31); The aerobic tank (5) is provided with an online ammonia nitrogen monitor (32) for the aerobic tank, an online dissolved oxygen meter (33) for the aerobic tank, and a stirrer (39) for the aerobic tank; The reoxygenation tank (6) is provided with a reoxygenation tank online dissolved oxygen meter (34); The sludge hydrolysis / activation tank (9) is provided with a sludge hydrolysis / activation tank online dissolved oxygen meter (35) and a sludge hydrolysis / activation tank agitator (40).

5. The magnetically enhanced sewage treatment system according to claim 2, characterized in that: It also includes a return excess sludge pump station (8), wherein the sludge obtained from the bottom of the secondary sedimentation tank (7) enters the return excess sludge pump station (8); the return excess sludge pump station (8) is provided with a first sludge return pump (15), a second sludge return pump (16) and an excess sludge pump (17); Part of the sludge is returned to the pre-anoxic tank (1) through the first sludge return pump (15), part of it is returned to the sludge hydrolysis / activation tank (9) through the second sludge return pump (16), part of it is transported to the magnetic powder recovery device (42) through the residual sludge pump (17), and the other part of it is transported to the sludge dewatering system through the residual sludge pump (17) for dewatering treatment.

6. The magnetically enhanced sewage treatment system according to claim 1, characterized in that: Also included is an aeration device, the aeration device comprising an aeration pipe assembly and a blower assembly; The aeration pipe assembly comprises aeration pipes respectively arranged at the bottom of the aerobic tank (4), the anoxic tank (5), the reoxygenation tank (6) and the sludge hydrolysis / activation tank (9); The blower assembly comprises an aerobic tank blower (18), an anaerobic tank blower (19) and a sludge hydrolysis / activation tank blower (20), wherein the aerobic tank blower (18) is connected to the aeration pipe at the bottom of the aerobic tank (4), the anaerobic tank blower (19) is connected to the aeration pipe at the bottom of the anaerobic tank (5) and the aeration pipe at the bottom of the reoxygenation tank (6), and the sludge hydrolysis / activation tank blower (20) is connected to the aeration pipe at the bottom of the sludge hydrolysis / activation tank (9); The aeration pipe at the bottom of the aeration tank (5) and the aeration pipe at the bottom of the reoxygenation tank (6) are also provided with an aeration tank air valve (21) and a reoxygenation tank air valve (22) respectively.

7. A sewage treatment process using the magnetically enhanced sewage treatment system according to any one of claims 1 to 6, characterized in that: The magnetically enhanced sewage treatment system includes sunny day mode and rainy day mode; Assuming that the design water inflow on a sunny day is Q, when the water inflow is less than 1.3Q, the magnetic enhanced sewage treatment system operates in the sunny day mode; when the water inflow is greater than or equal to 1.3Q, the magnetic enhanced sewage treatment system operates in the rainy day mode; When the magnetic enhanced wastewater treatment system is operated in sunny weather mode, the wastewater treatment process includes the following steps: S1: The wastewater to be treated enters the pre-anoxic tank (1), the anaerobic tank (2) and the facultative aerobic tank (5) respectively; S2: The sewage in the pre-anoxic tank (1) is mixed with the returned sludge to undergo denitrification, and the effluent enters the anaerobic tank (2); S3: The anaerobic tank (2) undergoes a water-phosphorus reaction, and the effluent enters the anoxic tank (3); S4: The influent of the anoxic tank (3) and the nitrified liquid returned from the aerobic tank (4) undergo denitrification and denitrification reactions, and the effluent enters the aerobic tank (4); S5: Nitrification reaction and phosphorus absorption reaction are carried out in the aerobic tank (4), and part of the terminal nitrification liquid flows back to the anoxic tank (3), and part enters the facultative anoxic tank (5); S6: The sewage raw water in the aerobic tank (5), the nitrification liquid from the aerobic tank (4) and the hydrolyzed sludge are mixed to simultaneously carry out nitrification reaction, denitrification reaction and simultaneous nitrification and denitrification phosphorus removal reaction; S7: The effluent from the aerobic tank (5) enters the reoxygenation tank (6) for treatment; S8: The effluent from the reoxygenation tank (6) is separated into mud and water in the secondary sedimentation tank (7), the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station (8); S9: a portion of the sludge from the return excess sludge pump station (8) is returned to the pre-anoxic tank (1), a portion is returned to the sludge hydrolysis / activation tank (9), and the remaining portion is dehydrated; S10: The sludge is hydrolyzed in the sludge hydrolysis / activation tank (9) under anoxic conditions and then returned to the anoxic tank (5); When the magnetic enhanced wastewater treatment system is operated in rainy day mode, the wastewater treatment process includes the following steps: A1: The wastewater to be treated enters the pre-anoxic tank (1), the anaerobic tank (2) and the facultative aerobic tank (5) respectively; A2: The sewage in the pre-anoxic tank (1) is mixed with the returned sludge to undergo denitrification, and the effluent enters the anaerobic tank (2); A3: The anaerobic tank (2) undergoes a water-phosphorus reaction, and the effluent enters the anoxic tank (3); A4: The influent of the anoxic tank (3) and the nitrified liquid returned from the aerobic tank (4) undergo denitrification and denitrification reactions, and the effluent enters the aerobic tank (4); A5: Nitrification and phosphorus absorption reactions are carried out in the aerobic tank (4), and part of the terminal nitrification liquid flows back to the anoxic tank (3), and part enters the facultative aerobic tank (5); A6: Magnetic powder is added to the aerobic tank (5) through the magnetic powder adding device (41), and the sewage raw water in the aerobic tank (5), the nitrification liquid from the aerobic tank (4), the activated sludge and the magnetic powder are mixed to simultaneously carry out nitrification reaction, magnetic enhanced denitrification reaction and simultaneous nitrification, denitrification and phosphorus removal reaction; A7: The effluent from the aerobic tank (5) enters the reoxygenation tank (6) for treatment; A8: The effluent from the reoxygenation tank (6) is separated into mud and water in the secondary sedimentation tank (7), the supernatant is discharged, and the bottom sludge is discharged into the return residual sludge pump station (8); A9: A portion of the sludge from the return excess sludge pump station (8) is returned to the pre-anoxic tank (1), a portion is returned to the sludge hydrolysis / activation tank (9), and the remaining portion is transported to the magnetic powder recovery device (42) to recover the magnetic powder. The recovered magnetic powder is added to the anoxic tank (5), and the remaining sludge is dehydrated; A10: The sludge is activated in the sludge hydrolysis / activation tank (9) and then returned to the aeration tank (5).

8. The sewage treatment process according to claim 7, characterized in that: When the magnetic enhanced sewage treatment system is operated in sunny day mode, in step S1, the water inflow of the pre-anoxic tank (1) is 0.1Q-0.3Q; the water inflow of the anaerobic tank (2) is 0.6Q-0.8Q; the water inflow of the facultative aerobic tank (5) is 0.1Q-0.4Q; In step S5, the reflux flow rate of the terminal nitrification liquid part returning to the anoxic tank (3) is 1.0 to 2.0 times the inlet flow rate of the pre-anoxic tank (1); In step S9, the sludge return rate of the pre-anoxic tank (1) is 0.4Q-0.7Q; In step S10, the sludge return rate of the aerobic tank (5) is 0.1Q-0.2Q; When the magnetic enhanced sewage treatment system operates in rainy day mode, the treated water volume of the magnetic enhanced sewage treatment system is 1.3Q-3.0Q; In step A1, the water inflow of the pre-anoxic tank (1) is 0.2Q-0.3Q; the water inflow of the anaerobic tank (2) is 0.7Q-0.8Q; the water inflow of the facultative aerobic tank (5) is 0.3Q-2.0Q; In step A5, the reflux ratio of the terminal nitrification liquid part back to the anoxic tank (3) is 1.0Q-2.0Q; In step A9, the sludge return rate of the pre-anoxic tank (1) is 0.4Q-0.5Q; In step A10, the sludge return rate of the aerobic tank (5) is 0.2Q-0.5Q.

9. The sewage treatment process according to claim 7, characterized in that: When the magnetic enhanced sewage treatment system is operated in sunny day mode or rainy day mode, the concentration of dissolved oxygen in the aerobic tank (4) is 2.0 mg / L-3.0 mg / L, the concentration of dissolved oxygen in the facultative oxygen tank (5) is 0.5 mg / L-1.5 mg / L, and the concentration of dissolved oxygen in the reoxygenation tank (6) is 2.0 mg / L-3.0 mg / L; In step A6, the magnetic powder adding device (41) adds magnetic powder to the oxygenation tank (5) at a magnetic powder adding amount of 0.5-2 g / L; In step A10, when the sludge is activated in the sludge hydrolysis / activation tank (9), the dissolved oxygen concentration in the sludge hydrolysis / activation tank (9) is 2.0 mg / L-3.0 mg / L; When the magnetically enhanced sewage treatment system is operated in sunny day mode, the hydraulic retention time in the pre-anoxic tank (1) is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank (2) is 1.0h-2.0h, the hydraulic retention time in the anoxic tank (3) is 2.0h-3.0h, the hydraulic retention time in the aerobic tank (4) is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank (5) is 1.5h-3.0h, the hydraulic retention time in the reoxygenation tank (6) is 5min-10min, and the total hydraulic retention time is 9.0h-16.0h; When the magnetically enhanced sewage treatment system is operated in sunny mode, the hydraulic retention time of sludge hydrolysis in the sludge hydrolysis / activation tank (9) is 2h-4h, and the sludge ratio returned from the return excess sludge pump station (8) to the sludge hydrolysis / activation tank (9) is 20%-50%; When the magnetically enhanced sewage treatment system of the sewage treatment system is operated in rainy day mode, the hydraulic retention time in the pre-anoxic tank (1) is 0.5h-1.0h, the hydraulic retention time in the anaerobic tank (2) is 1.0h-2.0h, the hydraulic retention time in the anoxic tank (3) is 2.0h-3.0h, the hydraulic retention time in the aerobic tank (4) is 4.0h-7.0h, the hydraulic retention time in the facultative aerobic tank (5) is 0.5h-1.0h, the hydraulic retention time in the reoxygenation tank (6) is 2min-4min, and the total hydraulic retention time is 8.0h-14.0h; When the magnetically enhanced sewage treatment system of the sewage treatment system is operated in rainy day mode, the hydraulic retention time of sludge activation in the sludge hydrolysis / activation tank (9) is 1.5h-2h, and the sludge ratio returned from the return residual sludge pump station (8) to the sludge hydrolysis / activation tank (9) is 20%-50%.

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