Improved garbage transfer station leachate treatment integrated equipment

Abstract

An improved leachate treatment integrated device for a garbage transfer station belongs to the technical field of sewage treatment and garbage leachate treatment, and is characterized in that a water producing pump, a water producing tank, a fan, a dosing device and an electric control cabinet are arranged in an equipment room. The internal structure is compact, functions are complete, and operation regulation and control are intelligent. The system regulation and control modes of water inlet, backflow, dosing, cooling and the like in the equipment are diversified, the biochemical treatment efficiency can be effectively improved, and through point water inlet, multi-stage AO, multi-point backflow, air pipe communication, intelligent control and the like, the addition amount of an external carbon source and the aeration air volume of a fan can be effectively reduced, and the total nitrogen can be efficiently removed, so that the energy conservation, consumption reduction, cost reduction and efficiency improvement of a project are realized; the device is low-carbon equipment in the field of leachate treatment.

Description

An improved integrated equipment for leachate treatment in waste transfer stations Technical Field

[0001] This utility model relates to an improved integrated equipment for treating leachate from a waste transfer station, belonging to the technical field of wastewater treatment and landfill leachate treatment. Background Technology

[0002] Wastewater generated from waste transfer operations is native landfill leachate. Leachate from waste transfer stations has a complex composition, containing large amounts of organic matter, suspended solids, ammonia nitrogen, COD, heavy metal ions, and pathogens, and its concentration fluctuates significantly. Therefore, the characteristics of leachate from transfer stations are: small volume, dispersed distribution, large variations in water quality, and obvious seasonality in both quantity and quality. The pollutants it contains are complex and difficult to biodegrade.

[0003] Currently, waste transfer stations handle waste through either fixed civil engineering facilities or containerized integrated treatment equipment. Conventional treatment processes include physicochemical oil separation / air flotation + biological anaerobic / aerobic / secondary sedimentation tank / MBR + advanced membrane / evaporation treatment, with effluent meeting standards before being discharged into the municipal sewage network.

[0004] A 2 The O+MBR biological treatment process is widely used in landfill leachate treatment. Based on the high filtration performance of the membrane, the sludge concentration in the membrane tank can typically reach 15-30 g / L. Sludge recirculation from the membrane tank significantly increases the sludge concentration in the upstream biological treatment stage, thereby reducing the overall tank volume and footprint of the biological treatment stage. However, in practical applications, A 2 The O+MBR process has drawbacks such as large dosage of external carbon source, high energy consumption, difficulty in total nitrogen removal, and low treatment efficiency. These are particularly evident in containerized integrated treatment equipment, where most designs are relatively simple, equipment configurations are relatively crude, and operation relies on manual control, resulting in poor treatment effects. Summary of the Invention

[0005] This invention solves the technical problems existing in the prior art, thereby providing an improved integrated equipment for leachate treatment in waste transfer stations.

[0006] The existing technical problems are solved by the following technical solution: an improved integrated equipment for leachate treatment in waste transfer stations, comprising a treatment area and an equipment room. The treatment area has a primary anoxic tank, a primary aerobic tank, a secondary anoxic tank, a secondary aerobic tank, a tertiary anoxic tank, a tertiary aerobic tank, and an MBR membrane tank arranged sequentially. The primary, secondary, and tertiary anoxic tanks are equipped with agitators; the primary, secondary, and tertiary aerobic tanks are equipped with aerators; the MBR membrane tank is equipped with a membrane module; and the tertiary aerobic tank and the MBR membrane tank are equipped with sludge return pumps. The equipment room is equipped with a permeate pump, a permeate tank, a blower, a dosing device, and an electrical control cabinet. The treatment area is equipped with an online dissolved oxygen meter, an online thermometer, an online sludge concentration meter, and an online level gauge.

[0007] The beneficial effects of this utility model are as follows: The improved integrated equipment for leachate treatment in waste transfer stations features a compact internal structure, comprehensive functions, and intelligent operation and control. The equipment offers diverse control methods for its internal water inlet, reflux, chemical dosing, and cooling systems, effectively improving biochemical treatment efficiency. Furthermore, through point-to-point water inlet, multi-stage AO (Automatic Aeration), multi-point reflux, duct interconnection, and intelligent control, it effectively reduces the amount of external carbon source added and the aeration air volume of the blower, efficiently removing total nitrogen. This achieves energy saving, cost reduction, and efficiency improvement, making it a low-carbon device in the field of leachate treatment. In addition, it can be flexibly connected with other peripheral process units or equipment according to other leachate treatment process routes, effectively nested in any position within physicochemical treatment, advanced treatment, or other units, and can be combined according to the actual project conditions. Moreover, this equipment can also be applied to the treatment of other high-concentration, recalcitrant, or low C / N organic wastewater, achieving significant treatment results. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. As shown in the figures:

[0009] Figure 1 is a schematic diagram of the structure of this utility model.

[0010] 1. Submersible mixer; 2. Aeration pipe; 3. Membrane module; 4. First sludge return pump; 5. Second sludge return pump; 6. Permeate pump; 7. Permeate tank; 8. Membrane tank blower; 9. Aerobic blower; 10. Carbon source dosing; 11. Defoaming dosing; 12. Phosphorus removal dosing; 13. Online dissolved oxygen meter; 14. Online thermometer; 15. Online sludge concentration meter; 16. Online level gauge; 17. Equipment room; 18. Membrane grid; 18. Inlet electromagnetic flow meter; 20. Inlet electric regulating valve; 21. Sludge return electromagnetic flow meter; 22. Sludge return electric regulating valve; 23. Duct connection electric regulating valve; 24. Aeration calorific gas flow meter; 25. Aeration electric regulating valve; 26. Carbon source dosing electromagnetic flow meter; 27. Carbon source dosing electric regulating valve; 28. Electric sludge discharge valve; 29. ​​Cooling tower; 30. Plate heat exchanger; 31. Circulation pump; 32. Cooling system electric valve; 33. Touch screen. Detailed Implementation

[0011] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0012] Example 1: As shown in Figure 1, an improved integrated leachate treatment equipment for a waste transfer station is provided. Equipment room 17 is equipped with a permeate pump 6, a permeate tank 7, a membrane tank blower 8, an aerobic blower 9, a carbon source dosing device 10, an antifoaming dosing device 11, a phosphorus removal dosing device 12, and a touch screen 33. The MBR membrane tank contains a membrane module 3 and a first sludge return pump 4. Aeration pipes 2 are provided in the primary aerobic tank O1, the secondary aerobic tank O2, and the tertiary aerobic tank O3. All aeration pipes 2 are connected to an aeration heat and mass gas flow meter 24. The other end of the aeration heat and mass gas flow meter 24 is connected to an aeration electric regulating valve 25. The other end of the aeration electric regulating valve 25 is connected to an air duct, an electric regulating valve 23, and the aerobic blower 9. The connection is as follows: the other end of the air duct connecting the electric regulating valve 23 is connected to the upper end of the membrane tank blower 8 and the membrane module 3, respectively; the first-stage anoxic tank A1, the second-stage anoxic tank A2, and the third-stage anoxic tank A3 are respectively connected to the carbon source dosing electromagnetic flow meter 26 through pipelines; the other end of the carbon source dosing electromagnetic flow meter 26 is connected to the carbon source dosing electric regulating valve 27; the other ends of the three carbon source dosing electric regulating valves 27 are connected to the carbon source dosing device 10; the first-stage aerobic tank O1, the second-stage aerobic tank O2, and the third-stage aerobic tank O3 are respectively connected to the defoaming dosing device 11 through pipelines; the online dissolved oxygen meter 13 is connected to the first-stage aerobic tank O1, the second-stage aerobic tank O2, and the third-stage aerobic tank O3, respectively; and the online thermometer 14 is connected to the first-stage aerobic tank O1. The other end of the cooling system electric valve 32 is connected to the electric sludge discharge valve 28; the phosphorus removal dosing device 12 is connected to the tertiary aerobic tank O3; the permeate tank 7 is connected to the permeate pump 6; the other end of the permeate pump 6 is connected to the membrane module 3; the online sludge concentration meter 15 and the online level meter 16 are connected to the MBR membrane tank; the primary anoxic tank A1, the primary aerobic tank O1, the secondary anoxic tank A2, the secondary aerobic tank O2, the tertiary anoxic tank A3, the tertiary aerobic tank O3, and the MBR membrane tank are installed sequentially; the primary anoxic tank A1, the secondary anoxic tank A2, and the tertiary anoxic tank A3 each contain a submersible mixer 1 and a membrane grid 18; three inlet electromagnetic flow meters 19 are connected to their respective inlet electric regulating valves 20; and the three inlet... The other end of the electromagnetic flowmeter 19 is located at the upper end of the membrane grid 18 of the primary anoxic tank A1, the secondary anoxic tank A2, and the tertiary anoxic tank A3, respectively. The inlet pipe is connected to the other end of the inlet electric regulating valve 20. The cooling tower 29 is connected to the plate heat exchanger 30 and the circulating pump 31, respectively. The plate heat exchanger 30 is also connected to the cooling system electric valve 32 and the circulating pump 31, respectively. The other end of the three sludge return electric regulating valves 22 is connected to their respective sludge return electromagnetic flowmeters 21. The other end of one sludge return electromagnetic flowmeter 21 is connected to the primary aerobic tank O1. The other end of two sludge return electromagnetic flowmeters 21 is connected to the primary anoxic tank AI. The other end of the electric sludge discharge valve 28 is connected to the sludge discharge pipe.

[0013] Example 2: As shown in Figure 1, an improved integrated leachate treatment device for waste transfer stations includes a treatment area and an equipment room. The treatment area comprises, in sequence according to the treatment process, a primary anoxic tank A1, a primary aerobic tank O1, a secondary anoxic tank A2, a secondary aerobic tank O2, a tertiary anoxic tank A3, a tertiary aerobic tank O3, and an MBR membrane tank. The device integrates point-to-point water inlet, multi-stage AO and multi-stage reflux, an external mixed liquor cooling system, and an intelligent control system into the integrated leachate treatment device for waste transfer stations. This utility model can effectively improve the efficiency of biochemical treatment, achieve energy saving and consumption reduction in engineering, and can also be applied to the treatment of other high-concentration, recalcitrant, or low C / N organic wastewater, achieving significant treatment results.

[0014] An improved integrated leachate treatment system for waste transfer stations includes a treatment area and an equipment room. The treatment area comprises, in sequence according to the treatment process, a primary anoxic tank A1, a primary aerobic tank O1, a secondary anoxic tank A2, a secondary aerobic tank O2, a tertiary anoxic tank A3, a tertiary aerobic tank O3, and an MBR membrane tank. The primary anoxic tanks A1, A2, and A3 are equipped with agitators; the primary aerobic tanks O1, O2, and O3 are equipped with aerators; the MBR membrane tank is equipped with a membrane module; and the tertiary aerobic tanks O3 and O3 are equipped with sludge return pumps. The equipment room contains a permeate pump, a permeate tank, a blower, a dosing device, and an electrical control cabinet. The treatment area is equipped with an online dissolved oxygen meter, an online thermometer, an online sludge concentration meter, and an online level gauge. The electrical control cabinet is connected to a touch screen and various electrical devices.

[0015] The single inlet method of the leachate system was changed. Instead, inlet flange interfaces and membrane grids were set for the primary anoxic tank A1, the secondary anoxic tank A2, and the tertiary anoxic tank A3, thereby realizing point-to-point water intake; the total inlet flow rate was distributed in a ratio of 6:3:1.

[0016] The single-stage reflux method of the sludge mixed liquor was changed. Instead, the first-stage reflux is from the MBR membrane tank to the first-stage anoxic tank A1, with a sludge reflux ratio of 500% to 600%; the second-stage reflux is from the first-stage aerobic tank O1 to the first-stage anoxic tank A1, with a sludge reflux ratio of 600% to 1200%; and the standby stage reflux is from the MBR membrane tank to the first-stage aerobic tank O1, with the reflux pump shared with the sludge reflux pump from the MBR membrane tank to the first-stage anoxic tank A1.

[0017] An external mixed liquor cooling system is provided to cool the mixed liquor in each reaction tank during extremely high temperatures. The mixed liquor is circulated using a sludge return pump installed in the MBR membrane tank. The sludge return pump is equipped with an outlet bypass pipeline and an electric valve for connecting the plate heat exchanger and cooling tower.

[0018] It is equipped with various remote signal instruments and electric valves to achieve intelligent control. The proportion of water inlet at each point is controlled by the electromagnetic flowmeter and electric regulating valve installed in each anoxic tank; the proportion of sludge return is controlled by the online sludge concentration meter in the membrane tank, the electromagnetic flowmeter and electric regulating valve installed on the sludge return pipe; the start and stop of the cooling system is achieved by the online thermometer installed in the primary aerobic tank O1 to achieve temperature control linkage; the air volume of the blower is controlled by the online dissolver in each aerobic tank, the calorific gas flowmeter installed on the aeration duct and the electric regulating valve.

[0019] By improving traditional integrated leachate treatment equipment for waste transfer stations, incorporating point-to-point water inlet, multi-stage AO and multi-stage reflux, external mixed liquor cooling system, and intelligent control system into the integrated equipment, the amount of carbon source added and operating energy consumption can be significantly reduced. At the same time, it can efficiently remove total nitrogen, thereby improving the overall effluent quality. Moreover, it is convenient for operators to intelligently control, thus solving the shortcomings of most current containerized integrated treatment equipment in treating leachate from waste transfer stations, such as high operating energy consumption, poor effluent quality, and difficulty in operation and control.

[0020] Example 3: As shown in Figure 1, an improved integrated leachate treatment equipment for a waste transfer station includes a treatment area and an equipment room. The treatment area includes a primary anoxic tank A1, a primary aerobic tank O1, a secondary anoxic tank A2, a secondary aerobic tank O2, a tertiary anoxic tank A3, a tertiary aerobic tank O3, and an MBR membrane tank, arranged sequentially according to the treatment process. The primary anoxic tanks A1, A2, and A3 are equipped with agitators; the primary aerobic tanks O1, O2, and O3 are equipped with aerators; the MBR membrane tank is equipped with a membrane module; and the tertiary aerobic tanks O3 and O3 are equipped with sludge return pumps. The equipment room is equipped with a permeate pump, a permeate tank, a blower, a dosing device, and an electrical control cabinet. The treatment area is equipped with an online dissolved oxygen meter, an online thermometer, an online sludge concentration meter, and an online level gauge.

[0021] One preferred solution is to change the single water inlet method of the leachate system, and instead set water inlet flange interfaces and their own membrane grids for the primary anoxic tank A1, the secondary anoxic tank A2, and the tertiary anoxic tank A3, thereby realizing point-to-point water inlet; the total water inlet flow rate is distributed in a ratio of 6:3:1.

[0022] The second preferred option changes the single-stage reflux method of the sludge mixed liquor. Instead, the first-stage reflux is from the MBR membrane tank to the first-stage anoxic tank A1, with a sludge reflux ratio of 500% to 600%; the second-stage reflux is from O1 to the first-stage anoxic tank A1, with a sludge reflux ratio of 600% to 1200%; and the standby stage reflux is from the MBR membrane tank to O1, with the reflux pump shared with the sludge reflux pump from the MBR membrane tank to the first-stage anoxic tank A1.

[0023] The third preferred option is to have an external mixed liquor cooling system, which is used to cool the mixed liquor in each reaction tank during extremely high temperatures. The mixed liquor is circulated using a sludge return pump installed in the MBR membrane tank. The sludge return pump is equipped with an outlet bypass pipeline and an electric valve for connecting the plate heat exchanger and the cooling tower.

[0024] The fourth preferred option is to achieve intelligent control by incorporating various remote signal instruments and electric valves. The proportion of water inlet at each point is controlled by electromagnetic flow meters and electric regulating valves installed in each anoxic tank; the sludge return ratio is controlled by online sludge concentration meters in the membrane tank, electromagnetic flow meters on the sludge return pipes, and electric regulating valves; the start and stop of the cooling system is achieved through temperature control linkage via online thermometers installed in the primary aerobic tank O1; and the air volume of the blowers is controlled by online dissolving instruments in each aerobic tank, calorific gas flow meters on the aeration ducts, and electric regulating valves.

[0025] The operation method and functions of each part of the improved integrated leachate treatment equipment for waste transfer stations are described in detail below:

[0026] The integrated equipment consists of a container made of corrosion-resistant carbon steel. The container is placed on a civil engineering foundation and can be moved as needed. The equipment door is located on one side of the equipment room. The equipment room and the various stages of anoxic, aerobic, and membrane treatment areas are separated.

[0027] During operation, leachate is fed into the primary anoxic tank A1, secondary anoxic tank A2, and tertiary anoxic tank A3 through the inlet flange. The effluent from the primary anoxic tank A1 enters the primary aerobic tank O1. The outlet of the primary aerobic tank O1 is connected to the inlet of the secondary anoxic tank A2. The outlet of the secondary anoxic tank A2 is connected to the inlet of the secondary aerobic tank O2. The outlet of the secondary aerobic tank O2 is connected to the inlet of the tertiary anoxic tank A3. The outlet of the tertiary anoxic tank A3 is connected to the inlet of the tertiary aerobic tank O3. The outlet of the tertiary aerobic tank O3 is connected to the inlet of the MBR membrane tank. The effluent from the MBR membrane tank is self-primed into the permeate tank by a permeate pump. The permeate tank effluent meets discharge standards.

[0028] The integrated equipment is divided into zones based on the theoretically calculated HRT ratios of each reaction tank. The volume of each aerobic tank is designed to accommodate the actual layout requirements of the aeration pipes, while the anoxic tanks are designed with a stirring intensity of 10–15 W / m³. 3 Each aerobic tank is equipped with an online dissolved oxygen meter, maintaining a dissolved oxygen level of 2 mg / L or below. The operation of the agitator is linked to the liquid level in the reaction tank.

[0029] The membrane module in the MBR membrane tank uses reinforced polyvinylidene fluoride (PVDF) hollow fiber membranes with a pore size of 0.1 μm, a membrane flux of approximately 5 LMH, and a membrane module purge intensity of 130–160 Nm. 3 / h. The MBR membrane tank is equipped with an online level gauge, and the feed water lift pump is linked to the membrane tank level and the feed water tank level.

[0030] The permeate pump in the equipment room also serves as the online membrane cleaning pump, and the permeate tank also serves as the membrane backwash water tank. Acid and alkali membrane cleaning agents are prepared on-site for immediate use. The permeate pump is linked to the MBR membrane tank level and the permeate tank level, as well as the membrane tank blower and the membrane tank sludge return pump.

[0031] The equipment room is equipped with two blowers: a variable frequency aerobic aeration blower and a fixed frequency membrane tank blower. The outlet ducts of both blowers are connected by pipes and electrically operated regulating valves for easy operation and control, thereby saving total aeration air volume and reducing energy consumption. The blowers operate normally 24 hours a day and are controlled by a PLC.

[0032] The equipment room is equipped with a carbon source dosing system, with dosing points at the inlet of the primary anoxic tank A1, the secondary anoxic tank A2, and the tertiary anoxic tank A3; it is also equipped with a phosphorus removal dosing system, with dosing point at the tertiary anoxic tank A3. The start and stop of each dosing pump are linked to the product water pump.

[0033] The sludge discharge pump is shared with the sludge return pump installed in the MBR membrane tank. Sludge is discharged to the sludge tank via an electric sludge discharge valve installed on the sludge return pipe. The sludge discharge pump is linked to the sludge tank level.

[0034] The sludge return pump inside the MBR membrane tank also serves as a hydraulic defoaming pump, with the defoaming point being the same as the return point. Duckbill jets are installed at the outlets of the defoaming / return pipes of the primary anoxic tank A1 and the primary aerobic tank O1 to enhance the hydraulic defoaming effect. A defoaming agent dosing system is installed in the equipment room, with the dosing point at the inlet of the primary aerobic tank O1, the secondary aerobic tank O2, and the tertiary aerobic tank O3. The start and stop of the defoaming pump are linked to the aerobic blower.

[0035] Overflow pipes are installed in the first-stage anoxic tank A1, the first-stage aerobic tank O1, the second-stage aerobic tank O2, and the third-stage aerobic tank O3.

[0036] An external mixed liquor cooling system is provided, with appropriate cooling equipment selected based on the actual influent water quality and local temperature conditions. The cooling system's start and stop are linked to the online thermometer installed in the primary aerobic tank (O1), maintaining the temperature at 30℃ or below.

[0037] The odorous gases generated by each reaction tank are collected through pipelines and then sent by induced draft fans to the deodorization system of the waste transfer station for unified treatment.

[0038] The equipment room is equipped with a touch screen, which can display, set and control all equipment and instruments in the system, making it convenient for operators to achieve intelligent control and operate in a convenient and efficient manner.

[0039] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An improved integrated equipment for leachate treatment at a waste transfer station, characterized in that, The facility includes a treatment area and an equipment room. The treatment area consists of a primary anoxic tank, a primary aerobic tank, a secondary anoxic tank, a secondary aerobic tank, a tertiary anoxic tank, a tertiary aerobic tank, and an MBR membrane tank, all connected in sequence. The primary, secondary, and tertiary anoxic tanks are equipped with agitators, the primary, secondary, and tertiary aerobic tanks are equipped with aerators, the MBR membrane tank is equipped with membrane modules, and the tertiary aerobic tank and MBR membrane tank are equipped with sludge return pumps. The equipment room contains a permeate pump, a permeate tank, a blower, a dosing device, and an electrical control cabinet. The treatment area is equipped with an online dissolved oxygen meter, an online thermometer, an online sludge concentration meter, and an online level gauge.

2. The improved integrated leachate treatment facility for a waste transfer station according to claim 1, characterized in that, The primary anoxic tank, secondary anoxic tank, and tertiary anoxic tank are each equipped with an inlet flange interface and their own membrane grid, and are equipped with an external mixed liquor cooling system. The sludge return pump is equipped with an outlet bypass pipeline and an electric valve.

3. The improved integrated leachate treatment facility for a waste transfer station according to claim 1, characterized in that, The primary anoxic tank, primary aerobic tank, secondary anoxic tank, secondary aerobic tank, tertiary anoxic tank, tertiary aerobic tank, and MBR membrane tank are installed in sequence.

4. The improved integrated leachate treatment facility for a waste transfer station according to claim 1, characterized in that, The MBR membrane tank contains membrane modules and a first sludge return pump. Aeration pipes are located in the primary, secondary, and tertiary aerobic tanks. All aeration pipes are connected to aeration heat and mass gas flow meters. The other end of each flow meter is connected to an electric aeration regulating valve. The other end of each valve is connected to an air duct connecting to an electric regulating valve and an aerobic blower. The other end of the air duct connecting to the electric regulating valve is connected to the membrane tank blower and the upper end of the membrane module. The primary anoxic tank, secondary anoxic tank, and... The three-stage anoxic tanks are each connected to a carbon source dosing electromagnetic flow meter via pipelines. The other end of each electromagnetic flow meter is connected to a carbon source dosing electric regulating valve. The other ends of the three electric regulating valves are connected to the carbon source dosing device. The primary, secondary, and tertiary aerobic tanks are each connected to an antifoaming dosing device via pipelines. An online dissolved oxygen meter is connected to each of the primary, secondary, and tertiary aerobic tanks. An online thermometer is connected to the primary aerobic tank. The other end of the cooling system's electric valve is connected to an electric... The sludge discharge valve is connected; the phosphorus removal dosing device is connected to the tertiary aerobic tank; the permeate tank is connected to the permeate pump; and the other end of the permeate pump is connected to the membrane module. Online sludge concentration meters and online level gauges are connected to the MBR membrane tank. Submersible mixers and membrane screens are installed in the primary, secondary, and tertiary anoxic tanks, respectively. Three influent electromagnetic flow meters are connected to their respective influent electric regulating valves. The other ends of the three influent electromagnetic flow meters are located at the membrane screens in the primary, secondary, and tertiary anoxic tanks, respectively. At the top, the inlet pipe is connected to the other end of the inlet electric regulating valve. The cooling tower is connected to the plate heat exchanger and the circulating pump respectively. The plate heat exchanger is also connected to the cooling system electric valve and the circulating pump respectively. The other end of the three sludge return electric regulating valves is connected to their respective sludge return electromagnetic flow meters. The other end of one sludge return electromagnetic flow meter is connected to the first-stage aerobic tank. The other end of two sludge return electromagnetic flow meters is connected to the first-stage anoxic tank. The other end of the electric sludge discharge valve is connected to the sludge discharge pipe.

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