A method for controlling the pollution of discharging into the river from a municipal drainage pumping station by using a storage pond

Abstract

The present invention discloses a method for controlling the pollution of discharging into the river by a municipal drainage pump station by using a storage tank. A storage tank with combined functions and effects is designed behind the rainwater pump group of the pump station. The storage tank is used to temporarily store combined sewage, misconnected sewage, initial rainwater, etc., and form unpowered quality improvement in the storage tank, increase the concentration of intercepted sewage in the pump station, and reduce the pollutants entering the river when the pump station discharges into the river. The method of the present invention can alleviate the impact of the pump station discharging into the river on the river water quality and solve the problem of river black odor. The present invention can be applied to drainage systems of various systems, with diverse effects, flexible operation, less engineering investment, low operation and maintenance costs, and at the same time can increase the engineering benefits of existing projects, and can effectively control the pollution of the pump station discharging into the river in a short period. It is not only applicable to the treatment of combined sewer overflow pollution, but also can be applied to the treatment of initial rain pollution in separate sewer systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of black and odorous river treatment, and is a facility for controlling the pollution of pumping stations discharging into the river. Specifically, it refers to a method for controlling the pollution of municipal drainage pumping stations discharging into the river by using a storage tank. Background Art

[0002] With the rapid development of cities and the continuous increase in population density, the water environment problems of rivers have become increasingly prominent. The problems of black and odorous rivers have a serious impact on the living quality of surrounding residents and the urban image. In addition to the destruction of the river ecosystem caused by urban construction, the main cause of river blackening and odoring is the external source pollution caused by direct pollutant discharge into the river, which is the main reason for the external source pollution of black and odorous rivers.

[0003] In the existing measures for controlling the pollution of discharging into the river, they mainly include the source control of initial rainwater, the renovation of rain and sewage mixed connections in pipelines, the dredging of drainage pipelines, the interception of pollutants at pumping stations, the off-site treatment of sewage, etc. However, due to the limitations of each technical means, it is difficult to solve the problem of river blackening and odoring in a short time.

[0004] The source control technology of initial rainwater refers to using source control technology to reduce the pollutants in the initial rainfall runoff, prevent pollutants from entering the municipal drainage pipeline, and finally enter the receiving river with the discharge of the pumping station. However, the pollution of the initial rainfall runoff belongs to non-point source pollution, which involves a large area. Traditional source control technology cannot cover most areas in a short time, resulting in the ineffective control of the pollution of the initial rainfall runoff.

[0005] The renovation of rain and sewage mixed connections in drainage pipelines refers to eliminating the mixed connection points in municipal pumping stations through engineering renovation to prevent sewage from entering the rainwater system and reduce the pollutants entering the river with the discharge of the pumping station. However, there are numerous mixed connection points in the municipal drainage system, and the workload of one-by-one investigation and renovation is huge, with a long cycle, and it is impossible to effectively control the pollutants entering the river due to pipeline mixing in the short term.

[0006] Drainage pipeline dredging is to regularly clean the sediments in the pipeline to prevent a large amount of rainwater from scouring the sediments at the bottom of the pipeline during rainfall and then the pollutants enter the river with the discharge of the pumping station. However, due to limited social resources, the dredging cycle of pipelines is relatively long, and the sediments in the main drainage system pipeline are large in quantity and difficult to clean, so the traditional drainage pipeline dredging technology has limited effect on controlling the pollution of pumping stations discharging into the river.

[0007] The technology of intercepting pollutants at pumping stations refers to setting up intercepting facilities in drainage pumping stations to intercept the sewage mixed in dry weather, the initial rainwater in rainy days, etc., to prevent pollutants from entering the river with the discharge of the pumping station. However, the scale of the intercepting pump is much smaller than that of the rain pump, and the scale of the intercepting pump in the rain pumping station is even one fortieth of that of the rain pump. When a rainfall event occurs, the intercepting pump cannot discharge a large amount of rainwater mixed with pollutants into the sewage system in rainy days, and the rain pump must be turned on to discharge into the river, resulting in pollutants entering the water body.

[0008] An off-site sewage treatment device refers to a small sewage treatment system installed inside or around a municipal pumping station to treat the sewage in the forebay of the pumping station and the initial rainwater during rainy days online. However, the scale of the off-site treatment device is limited and it cannot handle a large amount of runoff generated during rainy days and pollutants flushed from the drainage system pipelines in a short time.

[0009] The current pumping station discharge control technology has limitations such as a long construction period, high investment, and no immediate effect in the short term. In addition, some drainage pumping stations are equipped with storage ponds inside the pumping station, which are connected in parallel with the forebay of the pumping station to collect initial rainwater and reduce the peak of rainwater runoff. However, at present, many drainage systems are operating in a high water level mode, the main pipe diameter of the system is large, the flow velocity of dry weather sewage in the pipeline is low, pollutants are easily deposited at the bottom of the pipe, and the sewage with a low concentration enters the forebay of the pumping station. When a rainfall event occurs and the water level in the forebay rises and the storage pond is opened, the pollutant concentration in the rainwater entering the storage pond is low, resulting in a low control efficiency of the storage pond for initial rainwater. Generally, a drain pump is required to empty the storage pond, with high energy consumption. The burial depth of the storage pond can reach more than 20m underground, with high project investment, high cleaning and maintenance costs, and poor engineering benefits.

[0010] Therefore, inventing a storage pond applied to a municipal pumping station can effectively control the pollution of the pumping station discharge, reduce the pollutants entering the river, and is a necessary means to achieve the long-term improvement of black and odorous rivers. Summary of the Invention

[0011] The purpose of the present invention is to provide a method for controlling the pollution of the discharge of a municipal drainage pumping station by using a storage pond, which can improve the concentration of the intercepted sewage in the pumping station by using the storage pond, control the pollutants entering the river, reduce the impact of the pumping station discharge on the black and odorous of the river, maintain the effect of the treatment of black and odorous rivers, and achieve long-term improvement.

[0012] To achieve the above purpose, the technical solution of the present invention is as follows: A method for controlling the pollution of the discharge of a municipal drainage pumping station by using a storage pond, the municipal drainage pumping station includes a forebay of the pumping station, a sewage interception pump group, and a rainwater pump group, and the rainwater pump group is connected to the pumping station outlet well; it is characterized in that a storage pond is arranged after the rainwater pump group, the storage pond is communicated with the pumping station outlet well, and at the same time a connecting pipe is arranged at the bottom of the storage pond to communicate with the forebay of the pumping station, and an emptying pipe is arranged in the storage pond for emptying the storage pond; a first control gate is arranged between the outlet well and the external drainage river, a second control gate is arranged between the storage pond and the pumping station outlet well, a third control gate is arranged at the connecting pipe between the bottom of the storage pond and the forebay of the pumping station, and a fourth emptying gate is arranged at the emptying pipe of the storage pond; the municipal drainage pumping station is provided with a pumping station control system, and liquid level and water quality monitoring devices are installed in the forebay of the pumping station and in the storage pond;

[0013] The method includes the following steps:

[0014] Step 1: Close the first control gate, the third control gate, and the fourth control gate on dry days, open the second control gate, and at the same time start the rainwater pump group to enter the storage tank water inlet mode. After the rainwater pump group lifts the water in the pump station forebay to the pump station outlet well, it flows into the storage tank by gravity;

[0015] Step 2: When the storage tank is full, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system to close the rainwater pump group and the second control gate. The pollutants in the stored water in the storage tank undergo natural sedimentation and accumulate at the bottom of the tank;

[0016] Step 3: After a period of sedimentation, the water quality of the uppermost layer in the storage tank is better. When the water quality of the upper layer is better than the permitted river discharge water quality, the water quality monitoring device in the storage tank transmits a signal to the pump station control system to open the first control gate and the second control gate, so that the uppermost layer of water in the storage tank enters the river through the pump station outlet well;

[0017] Step 4: When the emptying of the upper layer of water is completed, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system to close the second control gate and open the fourth control gate to empty the middle layer of the storage tank. The discharged water is used to flush the drainage main pipe or directly transported to the sewage collection system;

[0018] Step 5: After the middle layer of water in the storage tank is emptied, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system to open the third control valve, so that the water with a higher concentration at the bottom of the storage tank enters the pump station forebay, and the sewage is pumped to the sewage collection system through the sewage interception pump group in the pump station forebay.

[0019] ]>Furthermore, the operating conditions of the storage tank can be divided into dry-day conditions and rainy-day conditions. On dry days, the mixed sewage enters the drainage system and finally enters the pump station forebay, causing the water level in the forebay to rise. By starting the rainwater pump group, the mixed sewage is lifted into the storage tank; after the rainwater pump starts, it will disturb the pump station forebay, causing the bottom sludge in the forebay to turn up, mixing the deposited pollutants in the forebay with the water in the forebay and entering the storage tank together; due to the opening of the rainwater pump, the flow velocity in the main pipe of the drainage system increases, scouring the bottom sludge in the main pipe of the system, and the pollutants are finally pumped into the storage tank, avoiding the direct discharge of pollutants into the river when rain flushes the bottom sediments of the main pipe of the system and the pump station forebay during rainfall events. On rainy days, the initial rainwater, the bottom sediments scoured by rain in the main pipe of the system, and the bottom sludge in the pump station forebay first enter the storage tank, and then are discharged into the river after the storage tank is full, minimizing the impact of the initial rainwater on the river water quality.

[0020] Furthermore, the storage tank is located behind the rainwater pump group. The storage tank can temporarily store the combined sewage and mixed sewage from the pump station forebay and the main pipe of the drainage system. The sewage quality can be improved without power in the storage tank, increasing the concentration of the intercepted sewage in the drainage pump station.

[0021] The storage tank can achieve power-free quality improvement, causing pollutants entering the storage tank to accumulate at the bottom of the tank, forming high-concentration sewage. The high-concentration sewage in the drainage system is transported to the sewage system through a sewage interception pump group, and the relatively clean water in the upper layer of the storage tank is discharged into the river. By starting the rainwater pump group multiple times on dry days and repeating the cycle, the pollutants deposited in the main pipe of the drainage system are gradually transported to the sewage system, achieving the separation of clean and dirty water at the source and reducing the total amount of pollutants entering the river during river discharge.

[0022] Furthermore, a flow channel is provided at the bottom of the storage tank to prevent sediment deposition. When the storage tank is emptied and flushed, the rainwater pump group can be used to pump the water in the front pool of the pump group to flush the storage tank, and the "dirty water" after flushing is returned to the front pool of the pump station through the bottom connecting pipe, and the "dirty water" is transported to the sewage system by the sewage interception pump group.

[0023] Further, the storage tank can adopt the construction forms of underground, semi-underground, and above-ground according to conditions such as the land use around the pump station and the lift of the rainwater pump. For pump stations with a relatively high lift of the rainwater pump, the storage tank can adopt the above-ground or semi-underground form; for pump stations with a relatively low lift of the rainwater pump, an underground storage tank can be used. By adjusting the lift of the rainwater pump, the burial depth of the storage tank can be achieved. Therefore, for pump stations with high requirements for the surrounding environmental landscape and limited land use, semi-underground or underground storage tanks can be adopted, and greening can be set on the top of the storage tank; for areas with good land use conditions and low landscape requirements, above-ground or semi-underground storage tanks can be used.

[0024] In the present invention, the storage tank is arranged behind the rainwater pump group, making the best use of the existing facilities of the municipal pump station. Through the rainwater pump, the mixed sewage on dry days, the initial rainwater on rainy days, and the scoured pipeline sediments are pumped into the storage tank, effectively reducing the pollutants entering the water body through river discharge at the pump station. The construction mode of the storage tank can be flexibly set according to the characteristics of the pump station. The storage tank can be emptied by gravity to save energy consumption, and the "sewage" is stratified by the storage tank to achieve the separation of clean and dirty water in the pump station, improving the collection efficiency of the sewage collection system. The storage tank can achieve intelligent control and flexible operation through liquid level and water quality monitoring. Compared with the traditional construction method of the storage tank, the present invention can increase the usage frequency of the storage tank, enhance the control effect of the storage tank on mixed sewage, initial rainwater, and pipeline sediment pollutants, while being more energy-saving, saving project investment, and greatly increasing the engineering benefits of the storage tank.

[0025] The method for controlling river discharge pollution at the pump station by constructing a storage tank provided by the present invention has the following advantages:

[0026] (1) The control effect of the storage tank on initial rainwater, mixed sewage, and pipeline sediment pollutants is enhanced;

[0027] (2) The construction method and location setting of the storage tank are flexible and variable, greatly reducing the burial depth and saving investment;

[0028] (3) The frequency of using the storage tank is increased, enhancing the project benefits;

[0029] (4) The gravity drainage method is adopted to empty the storage tank, saving energy consumption;

[0030] (5) It has flexible operation, convenient management, and relatively low operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic cross-sectional view of a storage tank of the present invention.

[0032] Figure 2 It is a schematic plan layout view of a storage tank of the present invention.

[0033] Figure 3 It is a process flow chart of a storage tank of the present invention.

[0034] The figure includes: municipal drainage pump station 1, forebay 11 of the pump station, sewage interception pump group 12, rainwater pump group 13, storage tank 14, pump station outlet well 15, first control gate 31, second control gate 32, third control gate 33, fourth control gate 34, connecting pipe 35, gravity drain pipe 36. DETAILED DESCRIPTION OF THE INVENTION

[0035] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings.

[0036] The storage tank of the present invention is set adjacent to the municipal drainage pump station, and the storage tank and the facilities in the existing municipal pump station form a pollutant discharge control system into the river. As Figure 1 shown, this system includes:

[0037] The forebay 11, sewage interception pump group 12, rainwater pump group 13, and storage tank 14 in the municipal drainage pump station 1. There is a pump station outlet well 15 behind the rainwater pump group 13. The pump station outlet well 15 is located above the storage tank 14. A first control gate 31 is set between the pump station outlet well 15 and the river, a second control gate 32 is set between the pump station outlet well 15 and the storage tank 14, a connecting pipe 35 and a third control gate 33 are set between the storage tank 14 and the forebay 11 of the pump station, and a fourth control gate 34 is set at the drain pipe of the storage tank. An intelligent control system is added to the control room of the municipal drainage pump station 1, and water level and water quality monitoring systems are installed in the forebay 11 and the storage tank 14.

[0038] The first control gate 31, the second control gate 32, the third control gate 33, and the fourth control gate 34 are used to switch the pumping station's river discharge mode, regulating pond opening mode, regulating pond emptying mode, regulating pond flushing mode, etc. When the first control gate 31 is opened and the second control gate 32 and the third control gate 33 are closed, the rainwater pumping station 13 is started simultaneously to enter the river discharge mode; when the first control gate 31, the third control gate 33, and the fourth control gate 34 are closed and the second control gate 32 is opened, the rainwater pump group 13 is started simultaneously to enter the regulating pond opening mode; when the rainwater pump group 13 is closed and the third control gate 33 and the fourth control gate 34 are opened, the regulating pond emptying mode is entered; when the first control gate 31 and the fourth control gate 34 are closed and the second control gate 32 and the third control gate 33 are opened, the rainwater pump group is started simultaneously to enter the regulating pond flushing mode.

[0039] During dry weather, the mixed sewage in the plot and the branch pipes flows into the main drainage system pipe 2 and is transported to the pumping station forebay 11 of the municipal drainage pumping station 1. Pollutants in the water accumulate in the pipeline during transportation to form pipeline sediments, and the pollutant concentration of the sewage reaching the pumping station forebay 11 is relatively low. When the regulating pond inlet mode is opened, the flow velocity in the main drainage system pipe 2 increases, scouring the sediments at the bottom of the pipe, and the pollutant concentration in the pipeline rapidly increases. The pollutants flow through the pumping station forebay 11 with the water flow. At the same time, due to the opening of the rainwater pump 13, the bottom mud in the forebay is turned up, and the pollutants enter the regulating pond 14 together. After the regulating pond 14 is full, the rainwater pump 13 is closed to stop the water inlet, and the pollutants in the water naturally settle in the regulating pond 14 and accumulate at the bottom of the pond. After a period of time, the regulating pond emptying mode is opened, the upper layer of water with a relatively low concentration is discharged into the river, the middle layer of sewage with a general water quality is emptied into the sewage system or used to flush the main drainage system pipe 2, and the lower layer of sewage with a relatively high concentration is sent to the pumping station forebay through the connecting pipe and finally transported to the sewage system through the intercepting sewage pump.

[0040] The method for controlling the river discharge pollution of the pumping station by using the regulating pond of the present invention includes the following steps:

[0041] Step 1, during dry weather, the first control gate 31, the third control gate 33, and the fourth control gate 34 are closed, the second control gate 32 is opened, and the rainwater pump group 13 is started simultaneously to enter the regulating pond inlet mode. After the rainwater pump group 13 lifts the water in the pumping station forebay 11 to the outlet well 15, it flows into the regulating pond 14 by gravity.

[0042] Step 2, when the regulating pond 14 is full, the liquid level monitoring system in the regulating pond 14 transmits a signal to the pumping station control system to close the rainwater pump group 13 and the second control gate 32, and the pollutants in the stored water in the regulating pond 14 naturally settle and accumulate at the bottom of the pond.

[0043] Step 3, after sedimentation for a period of time, the water quality of the uppermost layer in the storage tank 14 is relatively good. When the water quality of the upper layer is better than the permitted water quality for discharging into the river, open the first control gate 31 and the second control gate 32 to allow the water in the uppermost layer of the storage tank 14 to enter the river through the pumping station outlet well 15.

[0044] Step 4, after the emptying of the upper layer of water is completed, close the second control gate 32 and open the fourth control gate 34 to empty the middle layer of the storage tank 14. The water quality of the middle layer is average, and the discharged water is used to flush the drainage main pipe 2 or directly transported to the sewage collection system.

[0045] Step 5, after the middle layer of water in the storage tank 14 is emptied, open the fourth control valve 34 to allow the water with a higher concentration at the bottom layer of the storage tank 14 to enter the forebay of the pumping station, and pump the sewage to the sewage collection system through the sewage pumping unit 12 in the forebay.

[0046] In the present invention, the forebay 11, the sewage pumping unit 12, the rainwater pumping unit 13, and the pumping station outlet well 15 in the municipal pumping station 1 are all basic facilities of a general municipal pumping station. Only by setting a storage tank 14 behind the rainwater pumping unit 13 can the effective control of the pollution discharged from the pumping station be achieved.

[0047] The rainwater pumps are an important part of the municipal pumping station and are only used on rainy days, resulting in a low equipment utilization rate. Conventional storage tanks are generally connected in parallel with the forebay of the pumping station, have a relatively deep burial depth, and require a large investment. Moreover, they are generally used on rainy days with a low usage frequency. By setting a storage tank behind the rainwater pumping unit and simultaneously setting connecting control gates in the present invention, the operation modes of the storage tank are increased, and the utilization efficiency of the rainwater pumping unit and the storage tank is improved, thereby enhancing the engineering benefits.

[0048] The rainwater pumps configured in the municipal pumping station generally select a suitable pump head according to the water level in the forebay of the pumping station and the water level of the pumping station outlet. According to the pump head of the configured rainwater pumps, storage tanks with different construction forms can be selected. For municipal pumping stations with a relatively high pump head, the storage tank can adopt a semi-underground or above-ground form; for municipal pumping stations with a relatively low pump head, the storage tank can adopt an underground or semi-underground form. Compared with traditional storage tanks, the burial depth of the storage tank is greatly reduced, saving engineering investment.

[0049] The intelligent control system includes water level and water quality monitoring devices in the forebay of the pumping station and the storage tank. The intelligent control system can automatically switch the operation mode according to the water level and water quality in the pumping station storage tank.

[0050] Turning on the storage tank inlet mode on dry days means collecting and "concentrating" the pipe sediments and misconnected sewage in the drainage system using the idle rainwater pumping unit and storage tank on non-rainy days. The rainwater pumps configured in the rainwater pumping unit can pump water from the forebay of the pumping station and enter the storage tank through the pipe of the pumping station outlet well. The pollutants settle and stratify in the storage tank, and the storage tank is emptied layer by layer to achieve the separation of clean and dirty water in the pumping station.

[0051] When the storage tank inlet mode is turned on in rainy days, the storage tank is used to collect the initial rainwater in rainy days and the pollutants generated by the scouring of the pipeline sediments brought by heavy rain.

[0052] The storage tank has a shallow burial depth and can adopt the form of gravity emptying to empty the sewage temporarily stored in the storage tank into the sewage collection system or for flushing the main pipe of the drainage system, saving energy consumption.

[0053] After the storage tank is used up, it does not need to be manually cleaned. The water in the front pool of the pumping station can be pumped by the rainwater pump group to flush the storage tank, saving resources and reducing operation and maintenance costs; a chute 37 is arranged at the bottom of the storage tank to prevent siltation. As Figure 2 shown, the chute is distributed in a serpentine shape along the length direction of the storage tank, including a straight channel arranged along the width direction of the storage tank and a curved channel connecting two adjacent straight channels. The straight channel is provided with a slope, and the slope is between 0.5% and 1%. At the turning point of the chute, the slope of the curved channel is 1% to 2%. The bottom of the chute is arc-shaped, and the bottom radius of the chute is between 0.8 m and 1.2 m. By arranging the chute, the flow velocity at the bottom of the storage tank is increased, the siltation at the bottom of the tank is reduced, and the flushing efficiency of the storage tank is improved. It should be noted that Figure 1 This is only a schematic diagram of the sectional view of the present invention, so the slope of the chute is not shown in the figure. In fact, in this embodiment, the chute 37 is arranged at the bottom of the storage tank with a slope, and the setting direction of the slope is as Figure 2 shown.

[0054] The inlet mode of the storage tank can be switched according to the liquid level conditions in the front pool of the pumping station and the storage tank, saving energy consumption to the greatest extent: when the water level in the front pool of the pumping station is higher than the liquid level in the storage tank, the control gate at the bottom connection can be opened, and the gravity inlet mode can be adopted; when the liquid level in the storage tank is higher than the water level in the front pool of the pumping station, the control gate at the bottom connection needs to be closed, and the pump lifting mode is adopted for inlet.

[0055] The storage tank of the present invention can control the pollutants entering the river by collecting the combined sewage, initial rainwater, etc. in the drainage system in dry seasons and rainy seasons. At the same time, the non-powered quality improvement method is adopted to increase the concentration of the intercepted sewage in the municipal pumping station. The intercepted flow is small, effectively reducing the burden on the sewage treatment plant. After the storage tank is used, it does not need to be manually cleaned, has no bottom mud, is highly energy-efficient, saves land and engineering investment. The storage tank makes the greatest possible use of the existing municipal facilities, improves the utilization rate of municipal facilities, increases the engineering benefits, and effectively controls the pollution of the pumping station discharging into the river in the short term.

[0056] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be construed as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A method for controlling the pollution of discharging into the river in a municipal drainage pumping station by using a storage pool. The municipal drainage pumping station includes a forebay of the pumping station, a sewage interception pump group, and a rainwater pump group. The rainwater pump group is connected to the outlet well of the pumping station. It is characterized in that A storage tank is arranged behind the rainwater pump group. The storage tank is communicated with the outlet well of the pump station. Meanwhile, a connecting pipe is arranged at the bottom of the storage tank and communicated with the forebay of the pump station. A drain pipe is arranged in the storage tank for emptying the storage tank. A first control gate is arranged between the outlet well and the external drainage river. A second control gate is arranged between the storage tank and the outlet well of the pump station. A third control gate is arranged at the connecting pipe between the bottom of the storage tank and the forebay of the pump station. A fourth control gate is arranged at the drain pipe of the storage tank. The municipal drainage pump station is provided with a pump station control system. Liquid level and water quality monitoring devices are installed in the forebay of the pump station and in the storage tank. The method includes the following steps: Step 1, on dry days, close the first control gate, the third control gate, and the fourth control gate, open the second control gate, and at the same time start the rainwater pump group to enter the storage tank water inlet mode. After the rainwater pump group lifts the water in the forebay of the pump station to the outlet well of the pump station, it flows into the storage tank by gravity. Step 2, when the storage tank is full, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system, close the rainwater pump group and the second control gate, and the pollutants in the stored water in the storage tank will settle naturally and accumulate at the bottom of the tank. Step 3, after a period of sedimentation, the water quality of the uppermost layer in the storage tank is better. When the water quality of the upper layer is better than the permitted river discharge water quality, the water quality monitoring device in the storage tank transmits a signal to the pump station control system, open the first control gate and the second control gate, so that the uppermost layer of water in the storage tank enters the river through the outlet well of the pump station. Step 4, when the emptying of the upper layer of water is completed, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system, close the second control gate, and open the fourth control gate to empty the middle layer of the storage tank. The discharged water is used to flush the drainage main pipe or directly transported to the sewage collection system. Step 5, after the middle layer of water in the storage tank is emptied, the liquid level monitoring device in the storage tank transmits a signal to the pump station control system, open the third control gate, so that the water with a higher concentration at the bottom of the storage tank enters the forebay of the pump station, and the sewage is pumped to the sewage collection system through the sewage interception pump group in the forebay of the pump station. The operating conditions of the storage tank can be divided into dry-day conditions and rainy-day conditions. On dry days, the mixed sewage enters the drainage system and finally enters the forebay of the pump station, causing the water level in the forebay to rise. By starting the rainwater pump group, the mixed sewage is lifted into the storage tank. After the rainwater pump starts, it will disturb the forebay of the pump station, causing the bottom mud in the forebay to turn up, mixing the pollutants deposited in the forebay with the water in the forebay and entering the storage tank together. Due to the opening of the rainwater pump, the flow velocity in the main pipe of the drainage system increases, scouring the bottom mud in the main pipe of the system, and the pollutants are finally pumped into the storage tank, avoiding the situation that when a rain event occurs, the rain washes the sediment at the bottom of the main pipe of the system and the bottom mud in the forebay of the pump station, and the pollutants are directly discharged into the river. On rainy days, the initial rainwater, the sediment scoured from the bottom of the main pipe of the system by the rain, and the bottom mud in the forebay of the pump station first enter the storage tank, and then are discharged after the storage tank is full, reducing the impact of the initial rainwater on the river water quality to the greatest extent.

2. The method according to claim 1, wherein A chute is arranged at the bottom of the storage tank to prevent sludge accumulation.

3. The method according to claim 1, wherein The storage pond adopts an underground, semi-underground or above-ground construction form. For pumping stations with a relatively high head of rainwater pumps, the storage pond adopts an above-ground or semi-underground form; for pumping stations with a relatively low head of rainwater pumps, an underground storage pond is adopted.

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