A sponge type road side ditch infiltration-sewage separation system and method

Abstract

This invention discloses a sponge-type roadside ditch infiltration-clean water and sewage separation system and method, relating to the field of municipal road drainage technology. It includes a rainwater collection unit, a sedimentation tank unit, a water quality monitoring unit, an intelligent diversion control well, a graded treatment unit, an end-of-pipe treatment and graded discharge unit, and a data management and feedback unit. In this invention, based on real-time water quality and rainfall data, it can automatically intercept and transport initially highly polluted rainwater to the municipal sewage network, while guiding later-stage clean rainwater to subsequent treatment or direct discharge / infiltration. This graded treatment of rainwater prevents highly polluted runoff from directly entering the purification ditch, significantly reducing non-point source pollution load, achieving precise separation of clean and sewage, and effectively controlling non-point source pollution. Clean later-stage rainwater, after treatment, can replenish groundwater through infiltration or be directly discharged into rivers, while highly polluted rainwater is collected separately and enters the sewage network, effectively reducing the water environment pollutant load from road rainwater runoff.

Description

Technical Field

[0001] This invention relates to the field of municipal road drainage technology, specifically to a sponge-type roadside ditch infiltration-cleaning and sewage separation system and method. Background Technology

[0002] Sponge roads are ecological municipal roads that integrate permeable pavement, retention green space, rainwater collection pipe network, interception and diversion, and rainwater detection unit on the basis of meeting the functions of vehicle and pedestrian traffic. They realize six major functions of rainwater infiltration, retention, storage, purification, utilization and drainage, and locally absorb and purify rainwater on the road surface, reduce runoff pollution and reduce urban flooding.

[0003] For example, Chinese patent CN113248077B discloses a carbon neutralization system and method for a highway sponge-type composite side ditch, which includes three units connected horizontally in sequence: a sediment pre-sedimentation ditch, a filter oil absorption ditch, and an ecological purification ditch. The three units work together to complete low-impact development functions such as runoff collection, drainage, purification, and utilization.

[0004] The aforementioned patents do not include a targeted initial rainwater interception and sewage separation structure. The high-concentration runoff carrying pollutants such as mud, oil, and heavy metals in the initial stage of rainfall is not intercepted separately and transported to the municipal sewage network for treatment. Instead, it flows directly into the side ditch purification channel, resulting in incomplete control of non-point source pollution and significantly increasing the difficulty of subsequent treatment in the purification channel.

[0005] The existing system does not establish a graded treatment model of "highly polluted initial rainwater entering the plant and clean mid-to-late stage rainwater infiltrating into rivers." It always mixes the initial polluted rainwater with the mid-to-late stage clean rainwater for treatment. On the one hand, the highly polluted initial rainwater continuously impacts the filter layer, ecological matrix, and vegetation system in the purification ditch, which easily causes rapid blockage of the filler pores and decline in the activity of microbial communities. This significantly reduces the purification efficiency, permeability, and service life of the side ditches, and the water treatment effect deteriorates significantly after long-term operation. On the other hand, the mixed rainwater runoff can only replenish groundwater through infiltration or overflow directly into the surrounding rivers. The unintercepted highly polluted rainwater will directly cause secondary pollution of groundwater and non-point source pollution of river water bodies, and cannot effectively reduce the pollutant load brought by the road runoff.

[0006] Meanwhile, this integrated treatment model without diversion confuses the treatment paths of sewage and clean water, violates the construction concept of sponge city pollution control at the source, and is difficult to accurately adapt to the differentiated treatment needs of rainwater with different rainfall periods and different pollution levels. The overall water treatment is not targeted and effective, and the control of road surface pollution is not thorough, which greatly limits the application effect of sponge ditch system in water environment management in urban roads and municipal highways. Summary of the Invention

[0007] The purpose of this invention is to provide a sponge-type roadside ditch infiltration-clean water separation system and method to solve the problems of the integrated treatment mode without separation proposed in the background art, which confuses the treatment paths of sewage and clean water, violates the construction concept of sponge city source pollution control, is difficult to accurately adapt to the differentiated treatment needs of rainwater with different rainfall periods and different pollution levels, has poor overall water treatment targeting and effectiveness, and is not thorough in controlling road surface pollution, which greatly limits the application effect of sponge ditch system in water environment management in urban roads and municipal highways.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a sponge-type roadside ditch infiltration-sewage diversion system, comprising a rainwater collection unit, a sedimentation tank unit, a water quality monitoring unit, an intelligent diversion control well, a graded treatment unit, an end-of-pipe treatment and graded discharge unit, and a data management and feedback unit;

[0009] The rainwater collection unit is used to collect road surface runoff and perform preliminary filtration.

[0010] The rainwater harvesting unit includes a diversion and interception unit, which is used to separate the initial highly polluted rainwater and the middle and later clean rainwater collected by the rainwater harvesting unit.

[0011] The water quality monitoring unit detects the pollution concentration of rainwater runoff in real time through an online water quality monitoring device, obtains real-time rainfall intensity and cumulative rainfall through a rainfall sensor, and uploads the detection data to the data management and feedback unit in real time.

[0012] The intelligent diversion control well performs calculations and judgments based on the water quality data and rainfall data returned by the water quality monitoring unit, combined with the algorithm model built into the data management and feedback unit. Based on the judgment results, it generates and issues control commands to drive the equipment in the diversion and interception unit and the graded treatment unit to complete the switching of working conditions.

[0013] The graded treatment unit consists of three treatment tanks connected in series, which respectively perform triple purification of rainwater by interception and sedimentation of large particulate pollutants, filtration of fine particles and adsorption of oil, and biodegradation of dissolved pollutants and absorption by plants.

[0014] The end-of-pipe treatment and graded discharge unit guides the effluent to different discharge paths according to the real-time water quality of the purified effluent detected by the end-of-pipe water quality monitoring device.

[0015] The data management and feedback unit connects to various modules via the Internet of Things, and has functions such as data acquisition and storage, analysis and modeling, intelligent decision support and remote control, and is connected to the urban water affairs integrated management platform.

[0016] Preferably, the diversion and interception unit includes the following steps when separating rainwater:

[0017] a. Real-time monitoring and judgment: The data collected by the water quality monitoring sensor and the rainfall sensor in the synchronous water quality monitoring unit are used to generate instructions for controlling the opening and closing of the electric gate and specifying the water flow path in the central control platform in the intelligent diversion control well;

[0018] b. Automatic execution and separation: Receives the instructions generated by a, executes the switching of the inlet / purification gate and the bypass / sewage gate, guides water flow, and changes the water flow path;

[0019] c. Path orientation and transport: Clean rainwater flows to the sedimentation tank unit, while polluted rainwater flows to the municipal sewage network.

[0020] Preferably, the sedimentation tank unit is used to specifically intercept and settle physical pollutants contained in the clean mid-to-late stage rainwater released by the diversion and interception unit.

[0021] Preferably, in the intelligent diversion control well, the judgment result is the final instruction generated by the data management and feedback unit after model calculation, including the initial rain interception, rainwater purification and emergency overflow instructions.

[0022] Preferably, when the intelligent diversion control well drives the diversion and interception unit and the graded processing unit to complete the operating condition switch, the five operating conditions are as follows:

[0023] 1) Treatment + Reuse Operation: Open the valve leading to the tertiary treatment tank and start the reclaimed water pump.

[0024] 2) Treatment + Discharge / Permeation Operation: Open the discharge valve or permeation pipe control valve.

[0025] 3) Recirculation mode: Open the recirculation pipeline valve, start the recirculation pump, and send part of the effluent back to the secondary / tertiary treatment tank.

[0026] 4) Overflow condition: Open the electric gate of the overflow channel.

[0027] 5) Direct discharge / permeation mode: Skip the staged treatment unit and directly open the discharge valve or permeation valve.

[0028] Preferably, in the graded treatment unit, the primary treatment tank is a sedimentation channel, the secondary treatment tank is a filter oil absorption channel, and the tertiary treatment tank is an ecological purification channel; the secondary treatment tank is equipped with a backwashing interface and has an oil-absorbing fiber layer, a first filter layer, and a second filter layer arranged from top to bottom, with a grid plate on top of the two filter layers; the tertiary treatment tank has carbon sink vegetation, a planting soil layer, a modified ceramsite layer, a gravel layer, and modified volcanic rock arranged from top to bottom, and the tank is filled with modified gravel.

[0029] Preferably, when the end-of-pipe treatment and graded discharge unit guides the effluent in grades, it sets a judgment threshold to determine whether the quality of the purified effluent meets the standards. If it meets the standards, it determines whether there is a need for reuse. If there is a need, it discharges the effluent into a greywater reuse tank for greening / sprinkling / landscape replenishment. If there is no need, it discharges directly or infiltrates into the water for replenishing rivers / rainwater pipe networks / groundwater. If the water quality does not meet the standards, it determines whether the liquid level exceeds the warning level. If it exceeds the warning level, it discharges the effluent into a safety overflow outlet and into the downstream rainwater pipe network. If it does not exceed the warning level, the water is discharged into a return pipeline and enters the secondary treatment tank and tertiary treatment tank for secondary deep purification until the effluent quality meets the standards.

[0030] Preferably, the algorithm model built into the data management and feedback unit adopts a three-layer architecture: the first layer is a rule comparison layer, the second layer is a dynamic threshold correction layer, and the third layer is a model optimization layer. During each rainfall event, the first layer is executed in real time, the second layer is continuously executed, and the third layer updates the model parameters in the background based on the actual effect data of the rainfall.

[0031] Preferably, the first layer compares the real-time sensor detection values ​​with a preset static threshold and outputs a logical judgment result; the second layer has a built-in dynamic parameter adjustment model based on the initial flushing effect, which establishes a mathematical mapping relationship between "rainfall intensity - runoff flow - pollutant concentration" and dynamically corrects the pollution judgment threshold according to the real-time rainfall conditions; the third layer learns from historical operating data through the PPO algorithm to continuously optimize control parameters and diversion strategies. The model is constantly retrained based on historical rainfall data to optimize the diversion threshold and infiltration strategy.

[0032] A sponge-type roadside ditch infiltration-sewage separation method includes the following steps:

[0033] S1. Rainfall Triggering and Real-time Monitoring: After rainfall begins, the rainwater collection unit quickly collects road runoff, and the water quality monitoring unit collects hydrological and water quality monitoring data such as COD, turbidity, SS, rainfall intensity, cumulative rainfall, and liquid level at a frequency of seconds, and uploads them to the data management and feedback unit.

[0034] S2. Preliminary Assessment and Precise Diversion: Determine the current stormwater runoff, match diversion paths based on the assessment results, and generate precise diversion instructions, which include the following:

[0035] 21. First-level rule comparison: Based on static thresholds, the following criteria are used: diversion standard (runoff thickness < 4 mm); initial rainfall stage (COD > 100 mg / L or cumulative rainfall < diversion standard); clean rainwater (COD < 50 mg / L) emergency overflow (liquid level > warning level).

[0036] 22. Second-layer dynamic threshold correction: Adjust the thresholds of COD, liquid level, etc., according to the real-time rainfall intensity to correct the preliminary judgment results.

[0037] 23. Final instruction generation: Output the instructions "Initial rain interception", "Rainwater purification" or "Emergency overflow".

[0038] S3. Diversion Execution and Path Guidance: The diversion and interception unit receives the instruction generated by S2, switches the gate, and discharges polluted rainwater into the municipal sewage network; clean rainwater is discharged into the sedimentation tank unit.

[0039] S4. Selection of initial operating conditions for staged treatment: Select the initial operating conditions based on the influent COD value.

[0040] COD > 100 mg / L → Treatment + Reuse (enters tertiary treatment tank → greywater reuse tank); 50 < COD ≤ 100 mg / L → Treatment + Discharge or Treatment + Infiltration; COD ≤ 50 mg / L → Direct Discharge or Infiltration (skips the tiered treatment unit).

[0041] S5. Dynamic Operating Condition Switching: During rainfall, the system dynamically switches operating conditions based on real-time feedback: when the treatment load is too high or the effluent does not meet the standards, backflow is added; when the liquid level exceeds the warning level or there is extreme rain, overflow is switched; when the reuse tank is full, it switches from reuse to discharge / infiltration; when the water quality becomes cleaner, it skips the graded treatment unit and directly discharges / infiltrates.

[0042] S6. End-of-pipe tiered discharge: The end-of-pipe water quality monitoring device detects the purified effluent. The standard for compliance is that data from multiple consecutive sampling cycles must meet the standards. If the effluent meets the standards and there is a need for reuse, it is discharged into the greywater reuse tank. If the effluent meets the standards but there is no need for reuse, it is directly discharged or infiltrated. If the effluent does not meet the standards and the water level does not exceed the warning level, it is returned to the secondary and / or tertiary treatment tanks in the tiered treatment unit for further purification. If the effluent does not meet the standards and the water level exceeds the warning level, it is discharged into the downstream stormwater network through the safety overflow outlet.

[0043] S7. Rainfall End and System Reset: The data management and feedback unit issues a reset command, the diversion and interception unit closes the rainwater channel and restores the sunny day sewage interception mode; the graded treatment unit stops treatment, empties the internal water body, enters standby state, and waits for the next rainfall.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] 1. In this invention, by setting up a rainwater collection unit, a water quality monitoring unit, an intelligent diversion control well, and a diversion interception unit, it can automatically intercept and transport the initial high-pollution rainwater to the municipal sewage network based on real-time water quality and rainfall data, and guide the clean rainwater in the middle and later stages to subsequent treatment or direct discharge / infiltration. This achieves a graded treatment mode of "high-pollution initial rainwater entering the plant and clean middle and later stages rainwater infiltrating into the river," which avoids high-pollution runoff from directly entering the purification channel from the source, significantly reduces the non-point source pollution load, achieves precise separation of clean and polluted water, and effectively controls non-point source pollution. The clean middle and later stages rainwater, after treatment, can be infiltrated to replenish groundwater or directly discharged into the river, while the high-pollution rainwater is collected separately and enters the sewage network, eliminating secondary pollution of groundwater and non-point source pollution of river water caused by mixed runoff infiltration or overflow, and effectively reducing the water environment pollutant load brought by road rainwater runoff.

[0046] 2. In this invention, since the initial rainwater with high pollution is effectively intercepted and discharged from the system, it avoids its continuous impact on the filter layer, ecological matrix and vegetation system in the graded treatment unit, reduces the risk of clogging of the filler pores, ensures the purification efficiency and permeability of the ditch, and significantly extends the overall service life of the system. The long-term water treatment effect is stable and reliable. With the help of the three-layer algorithm model in the water quality monitoring unit, data management and feedback unit, the system can dynamically correct the diversion threshold and switch the treatment mode according to the changes in real-time rainfall intensity, runoff flow and pollutant concentration. It can realize the rapid switching of multiple modes such as infiltration, discharge, return and overflow, so that the entire system can accurately adapt to the rainwater treatment needs of different rainfall periods and different pollution levels, improve the system's targeting and effectiveness for water treatment, and is suitable for urban roads and municipal highways. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the principle of a sponge-type roadside ditch infiltration-sewage separation system of the present invention;

[0048] Figure 2 This is a flowchart of a sponge-type roadside ditch infiltration-sewage separation method according to the present invention;

[0049] Figure 3 This is a schematic cross-sectional view of the primary treatment tank of a sponge-type roadside ditch infiltration-sewage separation system according to the present invention;

[0050] Figure 4 This is a schematic cross-sectional view of the secondary treatment tank of a sponge-type roadside ditch infiltration-sewage separation system according to the present invention;

[0051] Figure 5 This is a schematic cross-sectional view of the three-stage treatment tank of a sponge-type roadside ditch infiltration-cleaning and sewage separation system according to the present invention.

[0052] Legend: 1. Rainwater harvesting unit; 11. Diversion and interception unit; 2. Sedimentation tank unit; 3. Water quality monitoring unit; 4. Intelligent diversion control well; 5. Graded treatment unit; 6. End-of-pipe treatment and graded discharge unit; 7. Data management and feedback unit. Detailed Implementation

[0053] 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.

[0054] Example 1: Refer to Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown: A sponge-type roadside ditch infiltration-sewage diversion system includes a rainwater collection unit 1, a sedimentation tank unit 2, a water quality monitoring unit 3, an intelligent diversion control well 4, a graded treatment unit 5, an end-of-pipe treatment and graded discharge unit 6, and a data management and feedback unit 7.

[0055] Rainwater harvesting unit 1 is used to collect road surface runoff and perform preliminary filtration;

[0056] The rainwater harvesting unit 1 consists of an inlet ditch, a road surface inlet, a bar screen and a primary interception net, and a diversion and regulation channel. After rainfall begins, the inlet ditch and inlet quickly collect road surface runoff and promptly guide the road surface polluted rainwater into the system for treatment, preventing untreated polluted runoff from directly flowing into downstream rivers or infiltrating to replenish groundwater. At the same time, the inlet bar screen installed at the connection between the inlet ditch and the diversion and interception unit 11 intercepts large floating objects, and the diversion and regulation channel installed at the end of the inlet ditch temporarily stores short-term high-intensity runoff peaks.

[0057] Rainwater harvesting unit 1 includes a diversion and interception unit 11, which is used to separate the initial highly polluted rainwater and the middle and later clean rainwater collected by rainwater harvesting unit 1.

[0058] When separating rainwater, the diversion and interception unit 11 includes the following steps:

[0059] a. Real-time monitoring and judgment: The data collected by the water quality monitoring sensor and the rainfall sensor in the synchronous water quality monitoring unit 3 are used to generate instructions for controlling the electric gate and specifying the water flow path in the central control platform in the intelligent diversion control well 4.

[0060] b. Automatic execution and separation: Receives the instructions generated by a, executes the switching of the inlet / purification gate and the bypass / sewage gate, guides water flow, and changes the water flow path;

[0061] c. Path orientation and transport: Clean rainwater flows to sedimentation tank unit 2, while polluted rainwater flows to the municipal sewage network.

[0062] The inlet / purification gate is installed on the pipe between the outlet of rainwater collection unit 1 and the inlet of sedimentation tank unit 2; the bypass / sewage gate is installed on the bypass pipe, the end of which is connected to the municipal sewage network. The switching sequence is as follows: In the sunny interception mode, the inlet / purification gate is closed and the bypass / sewage gate is open, and the initial combined sewage directly enters the sewage network; In the early stage of rainfall, the two gates remain in the above state, and the polluted rainwater is discharged into the sewage network through the bypass pipe; In the later stage of clean rainwater, the bypass / sewage gate is closed first, and the inlet / purification gate is opened after a 2-second delay, and the water flows into sedimentation tank unit 2; In the emergency overflow command, both gates are opened at the same time, and the overflow electric gate is opened additionally; After the rainfall ends and reset, the inlet / purification gate is closed first, and the bypass / sewage gate is opened after a 2-second delay, and the interception mode is restored.

[0063] The sedimentation tank unit 2 reduces the water flow velocity through the gradually expanding cross-section and the baffle plate. Combined with the inclined bottom plate and the sunken sedimentation tank, it uses gravity to cause solid pollutants in the clean mid-to-late stage rainwater released by the diversion and interception unit 11 to settle and collect. At the same time, it relies on the debris interception structure to intercept floating debris, thereby achieving graded interception and sedimentation of physical pollutants in the rainwater.

[0064] Water quality monitoring unit 3 detects the pollution concentration of rainwater runoff in real time through an online water quality monitoring device, obtains real-time rainfall intensity and cumulative rainfall through a rain gauge, and uploads the detection data to data management and feedback unit 7 in real time.

[0065] The online water quality monitoring device is a flow-through pool-type sensor array, installed at the outlet of rainwater collection unit 1 or upstream of diversion and interception unit 11. It automatically extracts water samples and performs steady-flow pretreatment through a water pump, flow-through pool, and filter. The core sensor array consists of optical sensors and electrochemical sensors. Among them, the optical sensors use ultraviolet absorption to detect COD and light scattering to detect turbidity and SS, while the electrochemical sensors use ion-selective electrode method to detect ammonia nitrogen and pH.

[0066] The intelligent diversion control well 4 receives water quality and rainfall monitoring data collected by the water quality monitoring unit 3, and performs calculations and judgments using the three-layer algorithm model of the data management and feedback unit 7; based on the judgment results, it generates and issues control commands to drive the electric valves and water pumps in the diversion and interception unit 11 and the graded treatment unit 5 to complete the corresponding working condition switching.

[0067] The judgment result is the final instruction generated by the data management and feedback unit 7 after model calculation, including the instructions for initial rain interception, rainwater purification, and emergency overflow. After the judgment result is generated, the data management and feedback unit 7 sends it to the PLC in the intelligent diversion control well 4 through the communication interface. After receiving the instruction, the intelligent diversion control well 4 controls the opening and closing of the control inlet / purification gate and bypass / sewage gate in the diversion interception unit 11, opens the electric valve and water pump in the graded treatment unit 5, performs five-condition switching, and after the equipment completes the action, it feeds back the status to the data management and feedback unit 7 through the sensor, forming a closed-loop control.

[0068] The five operating conditions are as follows:

[0069] 1) Treatment + Reuse Operation: Open the valve leading to the tertiary treatment tank and start the reclaimed water pump.

[0070] 2) Treatment + Discharge / Permeation Operation: Open the discharge valve or permeation pipe control valve.

[0071] 3) Recirculation mode: Open the recirculation pipeline valve, start the recirculation pump, and send part of the effluent back to the secondary / tertiary treatment tank.

[0072] 4) Overflow condition: Open the electric gate of the overflow channel.

[0073] 5) Direct discharge / permeation mode: Skip the staged treatment unit 5 and directly open the discharge valve or permeation valve.

[0074] The graded treatment unit 5 consists of three treatment tanks connected in series, which respectively carry out triple purification of rainwater by intercepting and settling large particulate pollutants, filtering fine particles and adsorbing oil, and biodegrading dissolved pollutants and absorbing them by plants. Among them, the first treatment tank is a sedimentation channel, the second treatment tank is a filter and oil absorption channel, and the third treatment tank is an ecological purification channel.

[0075] The bottom of the primary treatment tank on the inlet side is equipped with a sand collection hopper, and the bottom plate slopes from the outlet side to the inlet side to form a sludge collection slope; a baffle is installed in the middle of the sludge collection slope, and a sludge collection trough is formed at the intersection of the baffle and the sludge collection slope to collect the settled sludge and suspended solids.

[0076] The secondary treatment tank is equipped with a backwashing interface and consists of an oil-absorbing fiber layer, a first filter layer, and a second filter layer from top to bottom. A grid plate is installed on the top of the two filter layers.

[0077] The tertiary treatment tank consists of carbon sink vegetation, a planting soil layer, a modified ceramsite layer, a gravel layer, and modified volcanic rock, arranged from top to bottom. The tank is filled with modified gravel.

[0078] The end-of-pipe treatment and graded discharge unit 6 guides the effluent to different discharge paths according to the real-time water quality of the purified effluent detected by the end-of-pipe water quality monitoring device.

[0079] The system employs a "stable compliance judgment" logic—only when the test data for three consecutive sampling cycles (each sampling cycle is 5 minutes) are within the acceptable range is the water quality officially judged as "compliant." The test data includes COD, ammonia nitrogen, total phosphorus, suspended solids, turbidity, and pH. The end-point water quality testing device consists of a water pump, pipelines, a filter, a flow chamber, a multi-parameter sensor array, and an online total phosphorus analyzer. The multi-parameter sensor array is integrated inside the flow chamber. COD, turbidity, and SS are measured using optical sensing principles, while ammonia nitrogen and pH are measured using electrochemical sensing principles. This allows for the simultaneous detection of the above five water quality indicators. Total phosphorus is analyzed using an independent online automatic analyzer, and quantitative detection is performed using the ammonium molybdate spectrophotometric method. Only when all test data are within the acceptable range is the water quality officially deemed "compliant". Based on the Class IV water standard in the "Surface Water Environmental Quality Standard" GB3838-2002 and the "Water Quality Standard for Urban Reclaimed Wastewater for Miscellaneous Uses" GB / T18920-2020, the following water quality compliance thresholds are set: COD ≤ 30 mg / L, ammonia nitrogen ≤ 1.5 mg / L, total phosphorus ≤ 0.3 mg / L, suspended solids (SS) ≤ 10 mg / L, turbidity ≤ 10 NTU, and pH 6-9.

[0080] Based on preset judgment thresholds, the system determines whether the quality of the purified water at the end of the process meets the standards. If it does, it determines whether there is a need for reuse. If there is a need, the water is discharged into a greywater reuse tank for use as water for greening / sprinkling / landscape replenishment. If there is no need, the water is discharged directly or infiltrated into the river / rainwater network / groundwater replenishment. If the water quality does not meet the standards, it determines whether the water level exceeds the warning level. If it does, the water is discharged into a safety overflow outlet and discharged into the downstream rainwater network. If it does not exceed the warning level, the water is discharged into a return pipeline and enters the secondary and tertiary treatment tanks for secondary deep purification until the effluent quality meets the standards.

[0081] The built-in algorithm model of the data management and feedback unit 7 connects various modules through the Internet of Things, and has the functions of data acquisition and storage, analysis and modeling, intelligent decision support and remote control. It is configured with a standardized communication interface and can realize data interaction and command communication with the urban water affairs integrated management platform in accordance with the general communication protocol.

[0082] The built-in algorithm model of the data management and feedback unit 7 adopts a three-layer architecture. The first layer is the rule comparison layer, the second layer is the dynamic threshold correction layer, and the third layer is the model optimization layer. During each rainfall event, the first layer is executed in real time, the second layer is continuously executed during the rainfall, and the third layer runs in the background, updating the model parameters based on the actual effect data of the rainfall, and providing a better strategy basis for the next rainfall.

[0083] The first layer compares the real-time sensor readings with preset static thresholds and outputs a logical judgment result. Inputs include COD, turbidity, and SS values ​​from the water quality monitoring unit 3, as well as real-time rainfall intensity and cumulative rainfall from the rainfall sensor. It also includes the well level from the diversion and interception unit 11 and the graded treatment unit 5, and initial rainfall interception commands / rainwater purification commands / emergency overflow commands. The judgment threshold is:

[0084] COD: 100mg / L, judged as highly polluted; <50mg / L, judged as clean rainwater;

[0085] Rainfall: If the cumulative rainfall is less than the runoff diversion standard, it is determined to be the initial rainfall stage;

[0086] Liquid level: Above the warning level, deemed an emergency overflow;

[0087] The runoff rejection standard is runoff thickness <4mm, where runoff thickness refers to the depth of surface runoff generated by the road surface, and its relationship with cumulative rainfall, catchment area, and runoff coefficient is as follows:

[0088]

[0089] In the formula, To accumulate rainfall, The road's catchment area, This is the runoff coefficient;

[0090] Under a typical road cross-section, and They are approximately equal, therefore ,Pick =0.9, then =4mm corresponding =4 / 0.9≈4.4mm, based on which the system converts the runoff diversion standard to: when the cumulative rainfall... When the rainfall is less than 4.4 mm, it is considered to be in the initial rainfall stage, and flow diversion is implemented.

[0091] The second layer incorporates a dynamic parameter adjustment model based on the initial scouring effect. By establishing a mathematical mapping relationship between rainfall intensity, runoff flow, and pollutant concentration, it dynamically corrects the pollution judgment threshold according to real-time rainfall conditions, thus solving the problem that static thresholds cannot cover complex rainfall scenarios.

[0092] Among them, the dynamic parameter adjustment model based on the initial flushing effect uses the exponential decay formula to characterize the change law of pollutant concentration under the initial flushing, calculates the runoff flow rate in combination with rainfall intensity, and dynamically corrects the pollution judgment threshold based on real-time rainfall intensity, establishing a mathematical mapping relationship between rainfall intensity, runoff flow rate and pollutant concentration, the specific expression of which is as follows:

[0093] ;

[0094] ;

[0095] ;

[0096] In the formula, for Constant pollutant concentration This represents the initial peak concentration. The scour attenuation coefficient is determined based on the type of underlying surface in the catchment area and the number of preceding dry days. For asphalt pavements, the value of k ranges from 0.05 to 0.15 min. -1 For drought periods of ≥5 days, the larger value is taken; for drought periods of <2 days, the smaller value is taken. For cement pavement, k ranges from 0.08 to 0.20 min. -1 ;

[0097] for Rainfall intensity at any time This refers to the duration of rainfall. The dynamic pollution threshold This is a static threshold. This represents the regional average rainfall intensity. This is a correction factor (0-1, used to control the adjustment range of rainfall intensity fluctuations on the pollution threshold). For runoff flow, This is the runoff coefficient (0.8-0.95 for roads). The catchment area.

[0098] The third layer learns from historical operational data through machine learning algorithms to continuously optimize control parameters and diversion strategies. The model is constantly retrained based on historical rainfall data to optimize diversion thresholds and infiltration strategies.

[0099] Based on historical diversion effect feedback, the diversion threshold is optimized using PPO. The COD diversion threshold and turbidity diversion threshold are dynamically adjusted according to rainfall intensity, cumulative rainfall, influent COD, turbidity and liquid level. The optimization goal is to reduce the misdischarge of clean water and system energy consumption while ensuring the compliance rate of effluent. After every 10 rainfalls, the system automatically retrains and updates the threshold using historical data to achieve the optimal balance between "interception accuracy" and "clean water utilization rate".

[0100] When LSTM predicts filter media lifespan, it calculates the remaining service days of each filter media layer based on the cumulative treated water volume, influent suspended solids concentration, backwashing frequency, and effluent turbidity trends. A replacement warning is issued when the predicted lifespan is less than 30 days. When FP-Growth optimizes operational strategies, it stores the characteristics of each rainfall event (rainfall type, number of preceding drought days, diversion strategy adopted, operating condition sequence, and final compliance rate) in a database. Through association rule mining, strongly associated rules are extracted to form a knowledge base. When a new rainfall event begins, the system prioritizes matching strategies from similar scenarios in the knowledge base as initial control references, forming a callable strategy knowledge base.

[0101] Precise triage mechanism

[0102] After rainfall is triggered, the water quality monitoring unit 3 collects COD, turbidity, SS, rainfall intensity, cumulative rainfall and liquid level data in real time at a frequency of seconds, and uploads them to the data management and feedback unit 7. The first layer of rule comparison layer makes judgments based on static thresholds and outputs basic decision tendency.

[0103] During the continuous rainfall, the second-layer dynamic threshold correction layer of the data management and feedback unit 7 dynamically adjusts thresholds such as COD and liquid level according to the real-time rainfall intensity, and sends them back to the first layer to generate the final instruction—initial rain interception instruction, rainwater purification instruction, or emergency overflow instruction; after receiving the final instruction, the diversion and interception unit 11 opens the corresponding interception, purification, or overflow channel within milliseconds to seconds; the graded treatment unit 5 simultaneously performs the corresponding level of treatment on the incoming rainwater (such as interception and storage, purification and discharge, or safe overflow), and feeds back its own operating status.

[0104] Throughout the rainfall event, the water quality monitoring unit 3 continuously updates the data, the dynamic threshold correction layer continuously optimizes the threshold, and the diversion and interception unit 11 and the graded treatment unit 5 dynamically adjust the gate opening and treatment mode according to the latest instructions to achieve full-cycle adaptive diversion of rainfall runoff. After the rainfall ends, the data management and feedback unit 7 issues a reset command, the diversion and interception unit 11 closes the rainwater channel and returns to the sunny day sewage interception mode, and the graded treatment unit 5 stops rainwater treatment and enters standby mode, with the system waiting for the next rainfall.

[0105] Graded treatment with five operating conditions: seepage, drainage, reuse, overflow, and return.

[0106] After rainfall is triggered, the graded treatment unit 5 selects the initial operating condition based on the influent water quality (COD) and the preliminary judgment results of the data management and feedback unit 7:

[0107] 1) COD > 100 mg / L → Treatment + Reuse;

[0108] 2) 50 < COD ≤ 100 mg / L → Treatment + Discharge or Treatment + Infiltration;

[0109] 3) COD≤50mg / L→direct discharge or osmosis (skip graded treatment unit 5).

[0110] The triggering conditions for switching between five operating conditions are as follows:

[0111] If the treatment load is too high (flow rate > 120% of design value or liquid level rise rate > 5cm / min) or the effluent does not meet the standards, a superimposed reflux condition will occur.

[0112] When the liquid level in the graded treatment unit 5 exceeds the warning level (>1.3m) or there is extreme rainstorm (rainfall intensity>15mm / h), it will switch to overflow mode.

[0113] The reuse tank is full (liquid level > 95% of effective volume) → switch from "reuse" to "discharge" or "infiltration";

[0114] Water quality becomes cleaner (COD drops to ≤50mg / L) → skip stage 5 treatment and directly "discharge" or "infiltrate";

[0115] According to the "Outdoor Drainage Design Standard" GB 50014, the safety factor for the regulating tank can be taken as 1.1 to 1.5. This scheme takes 1.2, which is 120%. The liquid level rise rate of 5cm / min is calibrated by the measured data during the system commissioning stage. According to GB 50014, the effective water depth of the sedimentation tank should not be greater than 1.5m, and the warning water level is set at 1.3m.

[0116] During rainfall, the data management and feedback unit 7 dynamically switches operating conditions based on real-time feedback from the graded processing unit 5, including processing load, internal liquid level, reuse tank water level, and infiltration rate.

[0117] If the treatment load is too high or the effluent does not meet the standards, a superimposed recirculation mode will be used (the end-of-pipe treatment and graded discharge unit 6 will send part of the effluent back to the graded treatment unit 5 for further treatment).

[0118] When the liquid level in the graded treatment unit 5 exceeds the warning level or there is an extreme rainstorm, the system switches to overflow mode (the overflow channel of the end-of-pipe treatment and graded discharge unit 6 is opened).

[0119] The reuse tank is full → switch from "reuse" to "discharge" or "infiltration";

[0120] The water quality becomes cleaner → skipping the graded treatment unit 5, the intelligent diversion control well 4 directly performs "discharge" or "infiltration";

[0121] After the rainfall stops, the system resets: the graded treatment unit 5 is emptied, the intelligent diversion control well 4 closes all channels, the end treatment and graded discharge unit 6 closes the backflow and overflow, and returns to standby.

[0122] Example 2: Refer to Figure 2 As shown: A sponge-type roadside ditch infiltration-sewage separation method includes the following steps:

[0123] Step 1, Rainfall Triggering and Real-time Monitoring: After rainfall begins, rainwater collection unit 1 quickly collects road runoff, and water quality monitoring unit 3 collects data such as COD, turbidity, SS, rainfall intensity, cumulative rainfall, and liquid level at a frequency of seconds, and uploads them to data management and feedback unit 7.

[0124] Step 2, Preliminary Assessment and Precise Diversion: Determine the current stormwater runoff, match diversion paths based on the assessment results, and generate precise diversion instructions, which specifically include the following:

[0125] 21. First-level rule comparison: Based on the static threshold, the judgment is as follows:

[0126] Discarding criteria (runoff thickness < 4 mm);

[0127] Initial rainfall stage (COD > 100 mg / L or cumulative rainfall < diversion standard);

[0128] Clean rainwater (COD < 50 mg / L);

[0129] Emergency overflow (liquid level > warning level);

[0130] 22. Second-layer dynamic threshold correction: Adjust the thresholds of COD, liquid level, etc., according to the real-time rainfall intensity to correct the preliminary judgment results.

[0131] 23. Final instruction generation: Output the instructions "Initial rain interception", "Rainwater purification" or "Emergency overflow".

[0132] Step 3, Diversion Execution and Path Guidance: The diversion and interception unit 11 receives the instruction generated in Step 2, switches the gate, discharges polluted rainwater into the municipal sewage network, and discharges clean rainwater into the sedimentation tank unit 2.

[0133] Step 4: Selection of Initial Operating Conditions for Staged Treatment: Select the initial operating conditions based on the influent COD value.

[0134] COD > 100 mg / L → Treatment + Reuse (enters tertiary treatment tank → greywater reuse tank);

[0135] 50 < COD ≤ 100 mg / L → Treatment + Discharge or Treatment + Osmosis;

[0136] COD≤50mg / L→direct discharge or osmosis (skip graded treatment unit 5).

[0137] Step 5, Dynamic Operating Condition Switching: During rainfall, the operating conditions are dynamically switched based on real-time feedback. If the treatment load is too high or the effluent does not meet the standards, the recirculation condition is superimposed; if the liquid level exceeds the warning level or there is extreme rain, the overflow condition is switched; if the reuse tank is full, the "reuse" is switched to "discharge" or "infiltration"; if the water quality becomes cleaner, the staged treatment unit 5 is skipped, and the water is directly discharged or infiltrated.

[0138] Step Six: End-of-pipe tiered discharge: The end-of-pipe water quality monitoring device tests the purified effluent (COD, ammonia nitrogen, total phosphorus, SS, turbidity, pH value). The standard for compliance is set as the data meeting the standards for multiple consecutive sampling cycles. If the standard is met and there is a need for reuse, it is discharged into the reclaimed water reuse tank. If there is no need for reuse, it is directly discharged or infiltrated. If the standard is not met, and the liquid level does not exceed the warning level, it is returned to the secondary / tertiary treatment tank for deep purification. If the liquid level exceeds the warning level, it is discharged into the downstream rainwater pipe network through the safety overflow outlet.

[0139] Step 7, Rainfall End and System Reset: Data Management and Feedback Unit 7 issues a reset command, Diversion and Interception Unit 11 closes the rainwater channel and restores the sunny day sewage interception mode; Graded Treatment Unit 5 stops treatment, drains the internal water, and enters standby mode to wait for the next rainfall.

[0140] Example 3: The sponge-type roadside ditch infiltration-cleaning and sewage diversion method provided in this experiment is roughly the same as that in Example 2. The main difference is that the real-time judgment and dynamic threshold correction of the water quality monitoring unit 3 are not performed. Instead, the traditional fixed volume method is used for diversion.

[0141] Example 4: The sponge-type roadside ditch infiltration-cleaning and sewage diversion method provided in this experiment is roughly the same as that in Example 2. The main difference is that during the graded treatment, only the "treatment + discharge" single working condition is run, and the working condition is not switched.

[0142] Example 5: The sponge-type roadside ditch infiltration-cleaning and sewage separation method provided in this experiment is roughly the same as that in Example 2. The main difference is that in step six, the secondary treatment tank is not equipped with a backwashing interface, the filter layer is a single layer of quartz sand, the gravel layer in the tertiary treatment tank is replaced with a sawdust layer, and the modified gravel is replaced with microbial quick-dissolving balls.

[0143] Test Experiment

[0144] Example 2 was designated as the example group, and Examples 3-5 were designated as experimental groups 1-3. The influent water quality (road surface source) was as follows: COD 180-220 mg / L, ammonia nitrogen 4.5-5.2 mg / L, total phosphorus 0.8-1.1 mg / L, SS 250-320 mg / L, and turbidity 120-150 NTU.

[0145] Judgment criteria: COD≤30, ammonia nitrogen≤1.5, total phosphorus≤0.3, SS≤10, turbidity≤10NTU; Experiments were conducted on effluent COD, ammonia nitrogen, total phosphorus, effluent SS, turbidity, compliance rate, non-point source pollution rate and clogging cycle, and the relevant data were recorded in Table 1.

[0146] Table 1: Experimental Data Recording Table

[0147] Group COD (mg / L) Ammonia nitrogen (mg / L) Total phosphorus (mg / L) SS in effluent (mg / L) Turbidity (NTU) Compliance rate (%) Non-point source pollution rate (%) Congestion cycle (d) control group 22.8 0.85 0.21 6.2 7.5 98.6 92.3 95 Experimental group 1 48.5 2.15 0.41 18.6 19.2 62.1 75.6 42 Experimental group 2 35.2 1.67 0.35 12.5 13.7 78.2 83.6 68 Experimental group 3 29.4 1.41 0.26 9.8 9.5 89.3 88.5 30

[0148] In Table 1, the effluent COD, ammonia nitrogen, SS, and turbidity of Experimental Group 1 increased significantly, while the compliance rate and pollution reduction rate decreased significantly, and the filter media clogging cycle shortened. This indicates that precise diversion is the core of controlling the initial high pollution impact and ensuring stable compliance. In Experimental Group 2, the water quality indicators deteriorated significantly, the compliance rate and pollution reduction rate decreased, and the filter media lifespan shortened. This indicates that dynamic operating condition switching can adapt to different rainfall intensities and water quality fluctuations. In Experimental Group 3, the effluent indicators were close to the compliance threshold, the compliance rate decreased, and the filter media clogging cycle shortened. This proves that the combination of secondary pool backwashing and tertiary pool special filter media is the key to ensuring long-term stable purification and delaying clogging.

[0149] Example 2 employs a combination of precise diversion, five-condition graded treatment, and optimized filter media structure, resulting in optimal water treatment performance, non-point source pollution reduction capability, and system durability. Precise diversion effectively isolates highly polluted initial rainwater, preventing filter media impact. The five-condition switching enables full-cycle adaptive control, improving purification efficiency. Optimized filter media and backwashing design ensure long-term stable operation.

[0150] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sponge-type roadside ditch infiltration-sewage separation system, characterized in that: It includes a rainwater collection unit (1), a sedimentation tank unit (2), a water quality monitoring unit (3), an intelligent diversion control well (4), a graded treatment unit (5), an end-of-pipe treatment and graded discharge unit (6), and a data management and feedback unit (7). The rainwater collection unit (1) is used to collect road surface runoff and perform preliminary filtration; The rainwater collection unit (1) includes a diversion and interception unit (11), which is used to separate the initial highly polluted rainwater and the middle and later clean rainwater collected by the rainwater collection unit (1). The water quality monitoring unit (3) detects the pollution concentration of rainwater runoff in real time through an online water quality monitoring device, obtains real-time rainfall intensity and cumulative rainfall through a rain sensor, and uploads the detection data to the data management and feedback unit (7) in real time. The intelligent diversion control well (4) performs calculations and judgments based on the water quality data and rainfall data returned by the water quality monitoring unit (3) and the algorithm model built into the data management and feedback unit (7). Based on the judgment results, it generates and issues control commands to drive the equipment in the diversion interception unit (11) and the graded processing unit (5) to complete the switching of working conditions. The graded treatment unit (5) consists of three treatment tanks connected in series, which respectively carry out triple purification of rainwater by interception and sedimentation of large particulate pollutants, filtration of fine particles and adsorption of oil, biodegradation of dissolved pollutants and absorption by plants. The end-of-pipe treatment and graded discharge unit (6) guides the effluent to different discharge paths according to the real-time water quality of the purified effluent detected by the end-of-pipe water quality monitoring device. The data management and feedback unit (7) has a built-in algorithm model that connects to each module through the Internet of Things. It has functions of data collection and storage, analysis and modeling, intelligent decision support and remote control, and is connected to the urban water affairs integrated management platform.

2. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: The diversion and interception unit (11) includes the following steps when separating rainwater: a. Receive water quality and rainfall data monitored in real time by the water quality monitoring unit (3), and generate gate control instructions by the intelligent diversion control well (4); b. Receive the instructions generated by a and automatically switch between the inlet / purification gate and the bypass / sewage gate; c. Guide clean rainwater to sedimentation tank unit (2), and polluted rainwater flows to municipal sewage pipe network.

3. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: The sedimentation tank unit (2) is used to specifically intercept and settle the physical pollutants contained in the clean mid-to-late stage rainwater released by the diversion and interception unit (11).

4. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: In the intelligent diversion control well (4), the judgment result is the final instruction generated by the data management and feedback unit (7) after model calculation, including the initial rain interception, rainwater purification and emergency overflow instructions.

5. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: When the intelligent diversion control well (4) drives the equipment in the diversion and interception unit (11) and the graded processing unit (5) to complete the working condition switch, the five working conditions are as follows: 1) Treatment + Reuse Operation: Open the valve leading to the tertiary treatment tank and start the reclaimed water pump; 2) Treatment + Discharge / Permeation Operation: Open the discharge valve or permeation pipe control valve; 3) Recirculation mode: Open the recirculation pipeline valve, start the recirculation pump, and send part of the effluent back to the secondary / tertiary treatment tank; 4) Overflow condition: Open the electric gate of the overflow channel; 5) Direct discharge / permeation mode: Skip the staged treatment unit (5) and directly open the discharge valve or permeation valve.

6. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: In the graded treatment unit (5), the primary treatment tank is a sedimentation channel, the secondary treatment tank is a filter oil absorption channel, and the tertiary treatment tank is an ecological purification channel. The secondary treatment tank is equipped with a backwashing interface and is provided with an oil-absorbing fiber layer, a first filter layer, and a second filter layer from top to bottom. A grid plate is provided on the top of the two filter layers. The tertiary treatment tank is provided with carbon sink vegetation, a planting soil layer, a modified ceramsite layer, a gravel layer, and modified volcanic rock from top to bottom. The tank is filled with modified gravel.

7. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: When the end-of-pipe treatment and graded discharge unit (6) guides the effluent in grades, it sets a water quality judgment threshold and judges whether the purified effluent meets the standard according to the threshold. If it meets the standard, it selects to discharge into the reclaimed water pool or directly discharge / infiltrate according to the reuse requirements. If it does not meet the standard, it judges according to the liquid level: if the liquid level does not exceed the warning level, it flows back to the secondary treatment pool or the tertiary treatment pool for further purification. If the liquid level exceeds the warning level, it is discharged into the downstream rainwater pipe network through the safety overflow port.

8. The sponge-type roadside ditch infiltration-sewage separation system according to claim 1, characterized in that: The algorithm model built into the data management and feedback unit (7) adopts a three-layer architecture. The first layer is the rule comparison layer, the second layer is the dynamic threshold correction layer, and the third layer is the model optimization layer. During each rainfall event, the first layer is executed immediately, the second layer is continuously executed, and the third layer updates the model parameters in the background based on the actual effect data of the rainfall.

9. The sponge-type roadside ditch infiltration-sewage separation system according to claim 8, characterized in that: The first layer compares the detected value with the preset static threshold and outputs the logical judgment result; the second layer establishes a mapping model of rainfall intensity-runoff flow-pollutant concentration based on the initial flushing effect and dynamically corrects the pollution threshold; the third layer optimizes the diversion threshold and infiltration strategy through the PPO algorithm. The diversion threshold includes the COD threshold and the turbidity threshold.

10. A sponge-type roadside ditch infiltration-sewage separation method, applied to the sponge-type roadside ditch infiltration-sewage separation system according to any one of claims 1-9, characterized in that: Includes the following steps: S1. Rainfall triggering and real-time monitoring: After the rainfall begins, the rainwater collection unit (1) quickly collects road runoff, and the water quality monitoring unit (3) collects hydrological and water quality monitoring data and uploads it to the data management and feedback unit (7). S2. Preliminary judgment and precise diversion: Determine the current rainwater runoff, match the diversion path based on the judgment result calculated by the data management and feedback unit (7), and generate diversion instructions, which specifically include the following:

21. First-level rule comparison: Based on static threshold judgment: runoff thickness < 4mm is considered diversion; COD > 100mg / L or cumulative rainfall < diversion standard is considered initial rainfall stage; COD < 50mg / L is considered clean rainwater; liquid level > warning level is considered emergency overflow.

22. Second-level dynamic threshold correction: The threshold of hydrological and water quality monitoring data is dynamically adjusted according to real-time rainfall intensity to correct the preliminary judgment results; 23. Final instruction generation: Output instructions for initial rainwater interception, rainwater purification, or emergency overflow; S3, Diversion Execution and Path Guidance: The diversion interception unit (11) receives the instruction generated by S2, switches the gate, discharges polluted rainwater into the municipal sewage network, and discharges clean rainwater into the sedimentation tank unit (2). S4. Selection of initial operating conditions for graded treatment: The graded treatment unit (5) selects the initial operating conditions according to the COD value of the influent: When COD > 100 mg / L, it enters treatment + reuse; when 50 < COD ≤ 100 mg / L, it enters treatment + discharge / infiltration; when COD ≤ 50 mg / L, it skips graded treatment and directly discharges / infiltrates. S5. Dynamic operating condition switching: During rainfall, the system dynamically switches operating conditions based on real-time feedback: when the treatment load is too high or the effluent does not meet the standards, backflow is superimposed; when the liquid level exceeds the warning level or there is extreme rain, overflow is switched; when the reuse tank is full, it is switched from reuse to discharge / infiltration; when the water quality becomes cleaner, it skips the graded treatment unit (5) and directly discharges / infiltrates. S6. End-of-pipe graded discharge: The end-of-pipe water quality detection device detects the purified effluent. The standard for compliance is that the data of multiple consecutive sampling cycles meet the standard. If the standard is met and there is a need for reuse, the effluent is discharged to the reclaimed water reuse tank. If the standard is met but there is no need for reuse, the effluent is directly discharged or seeped into the water. If the standard is not met and the water level does not exceed the warning level, the effluent is returned to the secondary or tertiary treatment tank in the graded treatment unit (5) for further purification. If the standard is not met and the water level exceeds the warning level, the effluent is discharged into the downstream rainwater pipe network through the safety overflow outlet. S7. Rainfall ends and system reset: The data management and feedback unit (7) issues a reset command, the diversion and interception unit (11) closes the rainwater channel and restores the sunny day sewage interception mode; the graded treatment unit (5) stops treatment, drains the internal water body, enters standby state, and waits for the next rainfall.

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