A combined sewer overflow pollution control system and method of treatment thereof

Abstract

The application discloses a combined system of overflow pollution control and a treatment method thereof, which comprises a duckbill valve arranged at an overflow port of a intercepting well, a first water quality on-line monitor and a three-way valve arranged at a rear sewage pipeline of the duckbill valve, two pipelines of the three-way valve, a water inlet pipe of a hydraulic rotary screen and a bypass pipeline, and a water outlet end of the bypass pipeline connected to a river channel; a water inlet end of the hydraulic screen is connected to the three-way valve, and a water outlet end is connected to a sand and sedimentation chamber through a sewage pipe; an inner ring of the sand and sedimentation chamber is a sand pool, and an outer ring is a sedimentation tank, a bottom hole of a retaining wall for sewage circulation is arranged between the sand pool and the sedimentation tank; and a biological rotating disc is connected to the sand and sedimentation chamber through a biological rotating disc water inlet pipe. The system is simple, convenient to operate, fast in starting time, accurate in control, low in operation cost, high in treatment efficiency, capable of reducing pollution of river water caused by combined overflow, and capable of achieving a side treatment effect on the river water.

Description

Technical Field

[0001] This invention relates to the field of water environment management technology, and in particular to a combined sewer overflow pollution control system and its treatment method. Background Technology

[0002] Urban drainage systems are divided into combined sewer systems and separate sewer systems. Intercepting combined sewer systems use a single pipeline to transport a mixture of rainwater and sewage, with a separate interceptor pipe transporting a portion of the mixture to a wastewater treatment plant. This method effectively mitigates water pollution caused by combined sewer systems. However, with increased rainfall, when the actual collected rainwater flow exceeds the pipeline's designed interception capacity, combined sewer overflows can occur and enter rivers. Currently, the problem of pipe sedimentation due to prolonged low-flow-rate operation of sewage collection pipes during the dry season is prominent in my country. Combined sewer overflows carrying large amounts of pipe sediment after rainfall are a significant source of black and odorous water in many urban rivers after rain. Because combined sewer overflows mix dry season sewage, rainwater runoff, and sediment flushed from the pipes, they have higher levels of particulate matter and suspended solids, as well as a certain concentration of organic matter. This results in greater fluctuations in water quality and quantity, exhibiting intermittent and explosive characteristics, and a stronger short-term impact on river water quality.

[0003] The primary technical approach for river water environment restoration is source control and interception of pollution, focusing on endogenous treatment. To address the negative impact of combined sewer overflows on river water quality, a combined sewer overflow pollution control system needs to be developed. This system should rapidly intercept and purify the overflow mixture in the early stages of rainfall, reducing the total amount of pollutants directly entering the river. It should also mitigate the impact of low-concentration, high-volume overflow mixtures on treatment units during the later stages of rainfall. Furthermore, to avoid the pollution control system becoming idle due to lack of water during the dry season, the dry season treatment capacity of the treatment units, especially biological treatment units, should be considered. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology. To achieve the above objective, a combined overflow pollution control system and its treatment method are adopted to solve the problems mentioned in the background technology.

[0005] A combined sewer overflow pollution control system and treatment method thereof, comprising an intercepting well, a hydraulic screen, a sedimentation chamber, a biological rotating disc, a control system, an bypass pipeline, and a river water pipeline;

[0006] The overflow outlet of the intercepting well is equipped with a duckbill valve, and the sewage pipeline after the duckbill valve is equipped with a first online water quality monitoring instrument and a three-way valve. The three-way valve is equipped with two pipelines, namely a hydraulic rotating screen inlet pipe and an bypass pipe, and the outlet end of the bypass pipe is connected to the river.

[0007] The inlet end of the hydraulic screen is connected to a three-way valve, and the outlet end is connected to the sedimentation chamber via a sewage pipe.

[0008] The inner ring of the sedimentation chamber is a sedimentation tank, and the outer ring is a settling tank. A bottom hole of a retaining wall is provided between the sedimentation tank and the settling tank to facilitate the flow of sewage.

[0009] The biological rotating disc is connected to the sedimentation chamber via a biological rotating disc inlet pipe. The outlet end of the biological rotating disc is equipped with a disinfection device and a second online water quality monitoring instrument. The bottom of the biological rotating disc is equipped with a biological rotating disc sludge collection pipe, and an external biological rotating disc sludge discharge pipe is also connected. The inlet end of the biological rotating disc is simultaneously connected to a river water inlet pump and a river water pipeline.

[0010] As a further embodiment of the present invention: the bottom of the sedimentation chamber is an inverted triangular structure, the bottom of the sedimentation tank is connected to a sand discharge pipe, a perforated sludge collection pipe is provided at the apex of the triangle at the bottom of the sedimentation tank, which is connected to the sedimentation sludge discharge pipe, and a liquid level controller is provided at the water outlet of the sedimentation chamber.

[0011] As a further embodiment of the present invention: an inlet pipe is provided in the upper part of the sedimentation tank, a coagulant dosing pipe is provided in the upper part of the sedimentation tank, and a perforated overflow collection trough is provided around the top of the sedimentation tank.

[0012] As a further embodiment of the present invention: the duckbill valve, the first online water quality monitor, the three-way valve, the sedimentation outlet pump, the river water inlet pump, the liquid level controller, and the second online water quality monitor are all connected to the control system.

[0013] As a further embodiment of the present invention: the sedimentation sludge discharge pipe and the biological rotating disc sludge discharge pipe are respectively connected to the sedimentation sludge discharge pump and the biological rotating disc sludge discharge pump, and are connected to the interception well outlet through the sludge pipeline.

[0014] Another technical solution: A treatment method including a combined overflow pollution control system as described in any of the above claims, comprising the following steps:

[0015] Step S1: When rainfall occurs and the intercepting well overflows, the duckbill valve automatically opens, water flows through the pipeline, the control system is powered on, the three-way valve opens in the direction connected to the hydraulic screen, the overflow mixture enters the hydraulic screen through the sewage pipeline, pushing the hydraulic screen to rotate and intercept and remove plastic, large stones and other screenings, and collects them through the slag collection tank; the water from the hydraulic screen flows by gravity through the inlet pipe of the sedimentation chamber into the vertical flow sedimentation tank to remove larger impurities such as sand and gravel, and then flows into the sedimentation tank through the gap at the bottom of the retaining wall. The coagulant dosing pipe is opened to add coagulant and mix it with the sewage. The bottom sediment is collected by the sand discharge pipe and transported off-site. The settled sludge is collected by the perforated sludge discharge pipe and then transferred to the sludge pipeline through the sedimentation sludge discharge pipe and sedimentation sludge pump. The supernatant of the sedimentation tank is collected by the upper perforated overflow collection tank and then enters the biological rotating disc for biological treatment through the sedimentation effluent pump. After disinfection, it is discharged into the river.

[0016] Step S2: When it is in the middle and late stage of rainfall, and the water quality concentration is shown by the first online water quality monitoring instrument to be similar to the dry season concentration of the river water, close the hydraulic screen directional valve, open the bypass pipeline valve, and the overflow mixture is directly discharged into the river through the bypass pipeline.

[0017] Step S3: When the rainfall ends and the level controller shows that the water level at the outlet of the sedimentation chamber is lower than the set value, turn off the sedimentation outlet pump and turn on the river water inlet pump to pump river water into the biological rotating disc for biological treatment and keep the biological rotating disc continuously covered with biofilm. When the next rainfall occurs, turn off the river water inlet pump and repeat the steps during rainfall.

[0018] Step S4: The sludge from the biological rotating disc is transferred to the sludge pipeline via the biological rotating disc sludge discharge pipe and the biological rotating disc sludge discharge pump. Together with the settled sludge, it is transported to the intercepting well interception port and then transferred to the sewage treatment plant for treatment along with the intercepted sewage.

[0019] Compared with the prior art, the present invention has the following technical advantages:

[0020] By employing the above-mentioned technical solution and designing a bypass pipeline, the low-concentration, high-velocity, and high-volume overflow mixture from the middle and later stages of rainfall can be directly discharged into the river. At this time, the overflow mixture has minimal impact on the river channel, reducing wastewater treatment costs and minimizing the impact on treatment units. During the dry season, the designed river water pipeline pumps river water to a biological rotating disc for biological treatment, removing COD and NH4. + Substances such as -N that affect the nutrient status of water can be used for side treatment of river channels and continuous biofilm formation on biological rotating discs.

[0021] During the dry season, the biological rotating disc continuously forms a biofilm in the river water, and during the rainy season, it can promptly treat COD and NH4 in overflow wastewater. + The system, including hydraulic screens and grit chambers, effectively removes larger particles, while the sedimentation tank further removes smaller particles (SS and TP), reducing the total amount of pollutants entering the river and regulating overflow to minimize the water volume impact on the biological rotating disc. During the dry season, sludge produced by the sedimentation tank and biological rotating disc is transferred to an intercepting well via sludge pumps and pipes, and then transported to the wastewater treatment plant for treatment, increasing the influent concentration and improving the plant's efficiency. The biological rotating disc is suitable for wastewater with a BOD5 concentration <10 mg / L, with a retention time of 0.5 to 2 hours, providing rapid purification and making it suitable for combined sewer overflow treatment. Online monitoring of water quality and quantity controls the retention time of the biological rotating disc to ensure that the effluent is similar to the river water quality, thus improving river water quality. This system does not require aeration or sludge return; the system connection is simple, control is precise, and operation and management are easy. Attached Figure Description

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of a pollution control system according to an embodiment of this application.

[0024] In the diagram: 1. Interception well; 2. Hydraulic screen; 3. Sedimentation chamber; 4. Biological rotating disc; 5. Control system; 6. Duckbill valve; 7. First online water quality monitor; 8. Three-way valve; 9. Level controller; 10. Sedimentation effluent pump; 11. River water inlet pump; 12. Check valve; 13. Second online water quality monitor; 14. Disinfection equipment; 15. Overpass pipeline; 16. River water inlet pipeline; 17. Sludge pipeline; 201. Hydraulic rotating screen inlet pipe; 202. Collection... 301. Slag tank; 302. Sedimentation tank; 303. Sedimentation inlet pipe; 304. Retaining wall; 305. Coagulant dosing device; 306. Perforated overflow collection trough; 307. Perforated sludge collection pipe; 308. Sand discharge pipe; 309. Sedimentation sludge discharge pipe; 310. Sedimentation sludge discharge pump; 311. Sand discharge valve; 401. Biological rotating disc inlet pipe; 402. Outlet pipe; 403. Biological rotating disc sludge collection pipe; 404. Biological rotating disc sludge discharge pipe; 405. Biological rotating disc sludge discharge pump. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please refer to Figure 1 In this embodiment of the invention, a combined overflow pollution control system includes an intercepting well 1, a hydraulic screen 2, a sedimentation chamber 3, a biological rotating disc 4, a control system 5, an bypass pipeline 15, and a river water inlet pipeline 16.

[0027] The overflow outlet of the intercepting well 1 is equipped with a duckbill valve 6, and the sewage pipeline after the duckbill valve 6 is equipped with a first online water quality monitor 7 and a three-way valve 8. The three-way valve 8 is equipped with two pipelines, namely the hydraulic rotating screen inlet pipe 201 and the bypass pipe 15, and the outlet end of the bypass pipe 15 is connected to the river.

[0028] The inlet end of the hydraulic screen 2 is connected to the three-way valve 8, and the outlet end is connected to the sedimentation chamber 3 through the sewage pipe, so that the screenings are collected through the slag collection tank 202.

[0029] The inner ring of the grit settling chamber 3 is a grit settling tank 301, and the outer ring is a vertical flow sedimentation tank 302. A baffle wall 304 with bottom holes for sewage flow is provided between the grit settling tank 301 and the sedimentation tank 302. A grit inlet pipe 303 is installed in the upper part of the grit settling tank 301. A coagulant dosing device 305 is introduced into the upper part of the sedimentation tank 302. The top perimeter is a perforated overflow collection trough 306.

[0030] In this embodiment, the bottom of the sedimentation chamber 3 is an inverted triangular structure, the bottom of the sedimentation tank is connected to the external sand discharge pipe 308, the apex of the triangle bottom of the sedimentation tank is provided with a perforated sludge collection pipe 307, which is connected to the external sedimentation sludge discharge pipe 309, and the outlet end of the sedimentation chamber 3 is provided with a liquid level controller 9.

[0031] In this embodiment, a sedimentation tank 301 is provided with a sedimentation inlet pipe 303 in the upper part, a coagulant dosing pipe 305 is provided in the upper part of the sedimentation tank 302, and a perforated overflow collection trough 306 is provided around the top of the sedimentation tank 302.

[0032] The biological rotating disc 4 is connected to the sedimentation chamber 3 via a biological rotating disc inlet pipe 401. A disinfection device 14 and a second online water quality monitoring instrument 13 are installed at the outlet end of the biological rotating disc 4. An outlet pipe 402 is installed on the side of the biological rotating disc 4, and a biological rotating disc sludge collection pipe 403 is installed at the bottom of the biological rotating disc 4, with an external biological rotating disc sludge discharge pipe 404 connected to it. The inlet end of the biological rotating disc 4 is simultaneously connected to a river water inlet pump 11 and a river water inlet pipeline 16. To prevent the effluent from the sedimentation tank 302 from directly entering the river, a check valve 12 is installed on the river water inlet pipeline 16.

[0033] In this embodiment, the duckbill valve 6, the first online water quality monitor 7, the three-way valve 8, the sedimentation effluent pump 10, the river water inlet pump 11, the level controller 9, and the second online water quality monitor 13 are all connected to and controlled by the control system 5. The monitored water quality indicators must be consistent, and can be COD and NH4. + -N and other water quality indicators.

[0034] In this embodiment, the sedimentation sludge discharge pipe 309 and the biological rotating disc sludge discharge pipe 404 are respectively connected to the sedimentation sludge discharge pump 310 and the biological rotating disc sludge discharge pump 405, and are connected to the interception port of the interception well 1 through the sludge pipeline 17.

[0035] Another technical solution: A treatment method for a combined overflow pollution control system 5, including any of the above, comprising the following steps:

[0036] Step S1: When rainfall occurs and the intercepting well 1 overflows, the duckbill valve 6 automatically opens, water flows through the pipeline, the control system 5 is energized, and the three-way valve 8 opens in the direction connected to the hydraulic screen 2. The overflow mixture enters the hydraulic screen 2 through the sewage pipeline, pushing the hydraulic screen 2 to rotate and intercept and remove plastic, large stones, and other screenings, which are then collected through the slag collection tank 202. The water effluent from the hydraulic screen 2 flows by gravity through the inlet pipe of the sedimentation chamber 3 into the vertical flow sedimentation tank 301 to remove larger impurities such as sand and gravel, and then passes through the retaining wall 3. 04 The bottom void flows into the sedimentation tank 302. The coagulant dosing pipe 305 is opened to add coagulant and mix it with the sewage. The bottom sand is collected by the sand discharge pipe 308 and the sand discharge valve 311 and then transported away. The settled sludge is collected by the perforated sludge discharge pipe and then transferred to the sludge pipeline 17 through the sedimentation sludge discharge pipe 309 and the sedimentation sludge discharge pump 310. The supernatant of the sedimentation tank 302 is collected by the upper perforated overflow collection tank 306 and then enters the biological rotating disc 4 through the sedimentation effluent pump 10 for biological treatment. After disinfection, it is discharged into the river.

[0037] Step S2: When it is in the middle and late stage of rainfall, and the water quality concentration is shown by the first online water quality monitor 7 to be similar to the dry season concentration of the river water, close the directional valve of the hydraulic screen 2, open the valve of the three-way valve 8 guiding the bypass pipeline 15, and the overflow mixture is directly discharged into the river through the bypass pipeline 15.

[0038] Step S3: When the rainfall ends, if the level controller 9 shows that the water level at the outlet of the sedimentation chamber 3 is lower than the set value, turn off the sedimentation outlet pump 10 and turn on the river water inlet pump 11 to pump river water into the biological rotating disc 4 for biological treatment and keep the biological rotating disc 4 continuously covered with biofilm. When the next rainfall occurs, turn off the river water inlet pump 11 and repeat the steps during rainfall.

[0039] Step S4: The sludge from the biological rotating disc 4 is transferred to the sludge pipeline 17 via the biological rotating disc sludge discharge pipe 404 and the biological rotating disc sludge discharge pump 405. Together with the settled sludge, it is transported to the interception well 1 interception port and transferred to the sewage treatment plant for treatment along with the intercepted sewage.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents, all of which should be included within the scope of protection of the invention.

Claims

1. A combined sewer overflow pollution control system, characterized by, It comprises intercepting well, hydraulic screen, sand and sedimentation chamber, biological rotating disc, control system, bypass pipeline and river pipeline; The overflow port of the intercepting well is provided with a duckbill valve, and the back sewage pipeline of the duckbill valve is provided with a first water quality on-line monitor and a three-way valve, the three-way valve is provided with two pipelines, which are a hydraulic rotating screen water inlet pipe and a bypass pipeline respectively, and the water outlet end of the bypass pipeline is connected to a river channel; The water inlet end of the hydraulic screen is connected to the three-way valve, and the water outlet end is connected to the sand and sedimentation chamber through a sewage pipe; The inner ring of the sand and sedimentation chamber is a sand pool, and the outer ring is a sedimentation pool, and a bottom hole gap of a retaining wall is arranged between the sand pool and the sedimentation pool for sewage flow; The bottom of the sand and sedimentation chamber is a reverse triangular structure, the bottom of the sand pool is connected to a sand discharge pipe, the bottom of the sedimentation pool is provided with a perforated mud collecting pipe at the top of the triangle, and the sedimentation pool is connected to a sediment discharge pipe, and the water outlet end of the sand and sedimentation chamber is provided with a liquid level controller; The sediment discharge pipe and the biological rotating disc mud discharge pipe are respectively connected with a sediment discharge pump and a biological rotating disc mud discharge pump, and are connected with the intercepting well intercepting port through a sludge pipeline; The biological rotating disc is connected with the sand and sedimentation chamber through a biological rotating disc water inlet pipe, the water outlet end of the biological rotating disc is provided with a disinfection device and a second water quality on-line monitor, the bottom of the biological rotating disc is provided with a biological rotating disc mud collecting pipe, and the biological rotating disc mud discharge pipe is connected outside, and the biological rotating disc water inlet end is simultaneously connected with a river water inlet pump and a river pipeline; The duckbill valve, the first water quality on-line monitor, the three-way valve, the sediment discharge pump, the river water inlet pump, the liquid level controller, and the second water quality on-line monitor are connected with the control system.

2. The combined sewer overflow pollution control system of claim 1, wherein, The upper part of the sand pool is provided with a water inlet pipe, the upper part of the sedimentation pool is provided with a coagulant dosing pipe, and the top periphery of the sedimentation pool is a perforated overflow water collecting tank.

3. A process comprising a combined sewer overflow pollution control system according to any one of claims 1 to 2, characterized in that, It comprises the following steps: Step S1, when it rains, when the intercepting well overflows, the duckbill valve automatically opens, the pipeline is watered, the control system is powered on, the three-way valve is connected to the water inlet pipe of the sand and sedimentation chamber, and the water inlet pipe is connected to the sand and sedimentation chamber through a sewage pipeline. The overflow mixed liquid enters the hydraulic screen, pushes the hydraulic screen to rotate to intercept and remove plastic and large stones, and collects them through a slag collecting tank; the water outlet of the hydraulic screen flows into the vertical flow type sand pool through the sand and sedimentation chamber water inlet pipe to remove larger impurities, then flows into the sedimentation pool through the bottom gap of the retaining wall, opens the coagulant dosing pipe to add coagulant and mix with sewage, collects the bottom sand through the sand discharge pipe and transports it outside, collects the sediment sludge through the perforated sludge discharge pipe, and then transfers it to the sludge pipeline through the sediment sludge pump and the sediment sludge pump, collects the supernatant of the sedimentation pool through the upper perforated overflow water collecting tank, and then enters the biological rotating disc for biological treatment through the sediment discharge pump, and then is discharged into the river channel after disinfection; Step S2, when the water quality concentration displayed by the first water quality on-line monitor is equivalent to the river water concentration in the dry season in the later period of rainfall, the water inlet pipe of the sand and sedimentation chamber is closed, and the bypass pipeline valve is opened, and the overflow mixed liquid is directly discharged into the river channel through the bypass pipeline. Step S3, when the rainfall ends, the liquid level controller shows that the water outlet end liquid level of the sand and sediment chamber is lower than the set value, the sediment water outlet pump is closed, the river water inlet pump is opened, the river water is pumped into the biological rotating disc for biological treatment, and the biological rotating disc is kept for biofilm formation. At the next rainfall, the river water inlet pump is closed, and the steps during rainfall are repeated; Step S4, the biological rotating disc sludge is transferred to the sludge pipeline by the biological rotating disc sludge discharge pipe and the biological rotating disc sludge discharge pump, and is transported to the intercepting well intercepting port together with the sediment sludge, and is transferred to the sewage treatment plant for treatment together with the intercepted sewage.

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