Rainwater collecting and circulating method based on municipal pipe network

Abstract

The invention provides a rainwater collection and circulation method based on a municipal pipe network, and belongs to the technical field of rainwater drainage treatment.The rainwater collection and circulation method comprises the steps that foundation pit accumulated water and outdoor scattered drainage water are collected in a classified mode through a water collection network, and differential sedimentation treatment is executed according to a turbidity normalization coefficient; a five-stage water storage saturation grading system is established, the opening degree of a flow guide groove flashboard is automatically adjusted through a floating plate linkage device, weather forecast data is introduced to calculate the volume ratio of a reserved regulation and storage space, emptying operation is executed in advance, a rainstorm judgment function is called to comprehensively evaluate the rainfall working condition, and an emergency overflow channel is automatically opened under the rainstorm condition. The target operation frequency of the variable-frequency water pump is dynamically calculated through the pump frequency adjustment function, a multi-stage compensation mechanism is started according to the flow deviation, and the technical problem that a rainwater collection system on a construction site cannot achieve cooperative control over dynamic adjustment of the water storage capacity and emergency discharge under the rainstorm working condition is solved.

Description

Technical Field

[0001] This invention belongs to the field of rainwater drainage treatment technology, and more specifically, relates to a rainwater collection and recycling method based on municipal pipe networks. Background Technology

[0002] In the field of rainwater resource utilization at construction sites, traditional technologies mainly employ fixed-capacity storage tanks combined with simple sedimentation treatment devices to collect rainwater, triggering discharge operations by setting fixed water level thresholds. These systems can meet basic rainwater collection needs under normal rainfall conditions and are widely used in construction sites, municipal engineering projects, and other construction scenarios. However, traditional technologies have significant drawbacks. Their water storage capacity management relies on static settings, making it impossible to predict the extent to which future rainfall will occupy the storage tank capacity based on weather forecasts, resulting in the inability to reserve storage space in advance before heavy rain. Simultaneously, the discharge control of traditional systems depends on manual judgment or triggering by a single water level threshold, lacking a comprehensive assessment mechanism for rainfall intensity and water saturation, leading to delayed emergency response during sudden heavy rainstorms. In other words, existing technologies suffer from the technical problem of failing to achieve coordinated control of dynamic water storage capacity adjustment and emergency discharge in rainstorm conditions at construction sites. Summary of the Invention

[0003] In view of this, the present invention provides a rainwater collection and circulation method based on municipal pipe networks, which can solve the technical problem in the prior art that the rainwater collection system at the construction site cannot achieve dynamic adjustment of water storage capacity and coordinated control of emergency discharge under heavy rain conditions.

[0004] This invention is implemented as follows: It provides a rainwater collection and recycling method based on a municipal pipe network. Rainwater from the construction site is divided into two categories: pit accumulator water and outdoor drainage, and transported separately to corresponding primary sedimentation tanks. Turbidity is detected in the primary sedimentation tanks, and a turbidity normalization coefficient is calculated. When the turbidity normalization coefficient of the pit accumulator water exceeds the pit turbidity threshold, a three-stage sedimentation process is initiated. When the turbidity normalization coefficient of the outdoor drainage is lower than the drainage turbidity threshold, it is directly transported to a buffer storage tank. The water saturation of the buffer storage tank is monitored in real time, and a five-level water saturation classification system is established. The opening of the guide channel gate is automatically adjusted according to different saturation levels via a float linkage device. Rainfall intensity is collected using a rain gauge, and a rainstorm condition coefficient is calculated using a rainstorm determination function. When the rainstorm condition coefficient is greater than the rainstorm initiation threshold and the water saturation is within the specified range, a rainstorm condition is determined. Upon reaching the first-level saturation state, the emergency overflow channel is immediately activated, and the system operation mode is switched to the rainstorm protection state. Real-time water level data of the buffer storage tank is collected through radar water level gauges, and combined with future rainfall forecast data obtained from the meteorological forecast system, the reserved storage space calculation function is called to obtain the reserved storage space volume ratio. When the reserved storage space volume ratio exceeds the emptying trigger threshold, the emptying operation is performed in advance. The inflow flow monitoring value is collected, and the pump frequency adjustment function is called to calculate the target operating frequency of the variable frequency pump. When the flow deviation normalization value between the inflow flow monitoring value and the standard design flow exceeds the first-level adjustment threshold, the pump frequency adjustment is performed. When the flow deviation normalization value exceeds the second-level adjustment threshold, the second-level flow compensation mechanism is activated simultaneously, and the rainwater that has undergone sedimentation treatment and meets the water quality standards is transported to the construction water pipeline network. Clean rainwater exceeding the storage tank capacity is discharged to the municipal drainage ditch through the diversion channel.

[0005] Specifically, the turbidity normalization coefficient is calculated by performing a ratio calculation between the measured turbidity value and the designed maximum turbidity threshold to obtain a dimensionless parameter.

[0006] Wherein, the turbidity determination threshold of the foundation pit is ∈ [0.60, 0.70], with a preferred value of 0.65, and the turbidity determination threshold of the scattered discharge is ∈ [0.30, 0.40], with a preferred value of 0.35.

[0007] The three-stage precipitation process includes a coarse precipitation unit, a medium precipitation unit, and a fine precipitation unit connected in sequence.

[0008] In the five-level water saturation classification system, the first level of saturation corresponds to water saturation ∈ [0.80, 1.00], the second level of saturation corresponds to water saturation ∈ [0.60, 0.80), the third level of saturation corresponds to water saturation ∈ [0.40, 0.60), the fourth level of saturation corresponds to water saturation ∈ [0.20, 0.40), and the fifth level of saturation corresponds to water saturation ∈ [0, 0.20].

[0009] The floating plate linkage device includes a floating plate assembly installed on the water surface of the buffer reservoir and a guide channel gate plate mechanically connected to the floating plate assembly. When the water saturation is below the third level of saturation, the floating plate position drops, driving the guide channel gate plate to close completely.

[0010] The input of the rainstorm determination function includes the rainfall intensity monitoring value and the water storage saturation, and the output is the rainstorm condition coefficient. The rainstorm condition coefficient is calculated by multiplying the ratio of the rainfall intensity monitoring value to the design intensity benchmark value by the water storage saturation weighting coefficient.

[0011] The design strength benchmark value is 18 mm / h, and the rainstorm initiation threshold is ∈ [0.85, 0.95], with a preferred value of 0.90.

[0012] The emergency overflow channel is a bypass pipeline system independent of the conventional drainage path, and the design flow rate of the emergency overflow channel is 1.8 to 2.5 times the conventional drainage capacity.

[0013] The inputs to the reserved space calculation function include the predicted total future rainfall, the current water storage capacity of the buffer reservoir, and the total volume of the buffer reservoir. The output is the reserved storage space volume ratio, which is calculated by dividing the sum of the predicted total future rainfall and the current water storage capacity of the buffer reservoir by the total volume of the buffer reservoir.

[0014] The predicted total future rainfall is calculated using the rainfall forecast data for the next 6 hours obtained from the meteorological forecast system. The air venting trigger threshold is ∈ [0.80, 0.90], with a preferred value of 0.85.

[0015] The input of the pump frequency adjustment function includes the monitored influent flow rate and the standard design flow rate, and the output is the target operating frequency. The target operating frequency is calculated by adding the frequency adjustment coefficient to the reference operating frequency and multiplying it by the normalized flow deviation value.

[0016] The normalized value of the flow deviation is calculated by subtracting the standard design flow from the influent flow monitoring value and dividing the result by the standard design flow.

[0017] Wherein, the reference operating frequency is 37.5Hz, the frequency adjustment coefficient is 15Hz, the first-level adjustment threshold is ∈ [0.20, 0.30], with a preferred value of 0.25, and the second-level adjustment threshold is ∈ [0.35, 0.45], with a preferred value of 0.40.

[0018] The second-level flow compensation mechanism is automatically activated when the pump frequency adjustment cannot control the flow deviation normalization value within 0.15, and provides additional flow regulation capability by turning on the standby water pump or adjusting the opening of the guide channel gate.

[0019] The inflow rate monitoring value is collected in real time by an electromagnetic flowmeter installed on the inlet pipe of the buffer reservoir, and the typical range of the standard design flow rate is 20. / h to 80 / h.

[0020] This invention proposes a method for incorporating meteorological forecast data into water storage capacity management. By using a reserved space calculation function to assess the capacity occupancy of the water storage tank due to future rainfall, and by performing an emptying operation in advance when the reserved storage space volume ratio exceeds the emptying trigger threshold, sufficient storage space is reserved before heavy rain arrives. This method solves the problem of insufficient heavy rain response capacity caused by static water storage capacity management in traditional technologies, realizing proactive capacity regulation based on meteorological forecasts. Simultaneously, this invention establishes a heavy rain judgment function that comprehensively assesses rainfall intensity and water saturation. When the heavy rain condition coefficient exceeds the heavy rain initiation threshold and the water saturation reaches the first level of saturation, the emergency overflow channel is immediately opened and the system switches to heavy rain protection mode, achieving rapid emergency response under heavy rain conditions. In summary, this invention solves the technical problem mentioned in the background art where construction site rainwater harvesting systems cannot achieve coordinated control of dynamic water storage capacity adjustment and emergency discharge under heavy rain conditions. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention.

[0022] Figure 2 A schematic diagram of the overall layout of the rainwater harvesting and recycling system. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0024] like Figure 1 The diagram shows a flowchart of a rainwater harvesting and recycling method based on a municipal pipe network provided by the present invention. This method includes the following steps:

[0025] S01. Rainwater at the construction site is divided into two categories, pit water and outdoor drainage, through a water collection network and transported to the corresponding primary sedimentation tanks respectively.

[0026] S02. Turbidity of rainwater in primary sedimentation tank is detected and turbidity normalization coefficient is calculated. When the turbidity normalization coefficient of the water in the foundation pit exceeds the foundation pit turbidity judgment threshold, the three-stage sedimentation treatment process is started. When the turbidity normalization coefficient of outdoor drainage is lower than the drainage turbidity judgment threshold, it is directly transported to the buffer storage tank.

[0027] S03. Real-time monitoring of the water saturation of the buffer reservoir and establishment of a five-level water saturation classification system; automatic adjustment of the opening of the guide channel gate according to different saturation levels through the float linkage device.

[0028] S04. Collect rainfall intensity monitoring values ​​through rain gauges and call the rainstorm judgment function to calculate the rainstorm condition coefficient. When the rainstorm condition coefficient is greater than the rainstorm initiation threshold and the water storage saturation is in the first level of saturation, immediately open the emergency overflow channel and switch the system operation mode to rainstorm protection mode.

[0029] S05. Collect real-time water level data of the buffer reservoir through radar water level gauge and combine it with future rainfall forecast data obtained from meteorological forecast system. Call the reserved space calculation function to obtain the reserved storage space volume ratio. When the reserved storage space volume ratio exceeds the emptying trigger threshold, execute the emptying operation in advance.

[0030] S06. Collect the influent flow monitoring value and call the pump frequency adjustment function to calculate the target operating frequency of the variable frequency pump. When the normalized value of the flow deviation between the influent flow monitoring value and the standard design flow exceeds the first-level adjustment threshold, pump frequency adjustment is performed. When the normalized value of the flow deviation exceeds the second-level adjustment threshold, the second-level flow compensation mechanism is started at the same time.

[0031] S07. Rainwater that has undergone sedimentation treatment and meets water quality standards will be transported to the construction water pipeline network. Clean rainwater exceeding the capacity of the storage tank will be discharged into the municipal drainage ditch through the diversion channel.

[0032] The turbidity normalization coefficient is a dimensionless parameter obtained by comparing the measured turbidity value with the designed maximum turbidity threshold. The calculation formula is as follows: the turbidity normalization coefficient is equal to the measured turbidity value in NTU divided by the designed maximum turbidity threshold of 800 NTU. The turbidity normalization coefficient is used to quantify the relative content of suspended particulate matter in rainwater and serves as the basis for determining the sedimentation treatment level.

[0033] The turbidity threshold for the foundation pit is the critical value for determining whether the water in the foundation pit needs to undergo three-stage sedimentation treatment. The turbidity threshold for the foundation pit is determined by regression analysis of the turbidity normalization coefficient and sedimentation treatment effect of 50 sets of foundation pit water samples under different working conditions. The empirical value range of the turbidity threshold for the foundation pit is 0.60 to 0.70, with a preferred value of 0.65.

[0034] The turbidity threshold for outdoor drainage is a critical value for determining whether outdoor drainage is directly transported to the buffer reservoir. The turbidity threshold for outdoor drainage is determined by correlation analysis of the turbidity normalization coefficient and water quality compliance rate of 30 outdoor drainage samples. The empirical value range of the turbidity threshold for outdoor drainage is 0.30 to 0.40, with a preferred value of 0.35.

[0035] The three-stage sedimentation process includes a coarse sedimentation unit, a medium sedimentation unit, and a fine sedimentation unit connected in sequence. The coarse sedimentation unit is used to remove sand and gravel particles with a particle size greater than 0.5 mm, the medium sedimentation unit is used to remove mud and sand particles with a particle size between 0.1 mm and 0.5 mm, and the fine sedimentation unit is used to remove suspended solids with a particle size less than 0.1 mm and to accelerate the sedimentation process by adding flocculants.

[0036] The five-level water saturation classification system divides the volume utilization rate of the buffer reservoir into five levels: the first level of saturation corresponds to a water saturation of [0.80, 1.00], the second level of saturation corresponds to a water saturation of [0.60, 0.80], the third level of saturation corresponds to a water saturation of [0.40, 0.60], the fourth level of saturation corresponds to a water saturation of [0.20, 0.40], and the fifth level of saturation corresponds to a water saturation of [0, 0.20]. The water saturation is calculated by the ratio of the real-time water level value measured by the radar water level gauge to the effective depth of the reservoir.

[0037] The formula for calculating the water saturation is as follows: the water saturation is equal to the real-time water level value in meters divided by the effective depth of the reservoir in meters. The water saturation is a dimensionless parameter and is used to determine the current volume utilization status of the buffer reservoir.

[0038] The floating plate linkage device includes a floating plate assembly installed on the water surface of the buffer reservoir and a guide channel gate mechanically connected to the floating plate assembly. When the water saturation is below the third level of saturation, the floating plate position drops, driving the guide channel gate to close completely. When the water saturation rises to the second level of saturation, the opening of the guide channel gate is set to 30% to 50%. When the water saturation reaches the first level of saturation, the opening of the guide channel gate is set to 80% or more to achieve rapid discharge of rainwater.

[0039] The rainstorm determination function is used to comprehensively assess whether the current rainfall conditions have reached the rainstorm level. The inputs include the rainfall intensity monitoring value in mm / h and the water saturation. The output is the rainstorm condition coefficient. The calculation formula of the rainstorm determination function is as follows: the rainstorm condition coefficient is equal to the rainfall intensity monitoring value in mm / h divided by the design intensity benchmark value of 18 mm / h and then multiplied by the water saturation weight coefficient. The water saturation weight coefficient is equal to 0.4 plus 0.6 multiplied by the water saturation.

[0040] The design strength benchmark value is 18 mm / h, which is determined based on the statistical value of a 50-year return period rainstorm intensity from the historical meteorological data of the construction site area. The empirical value range of the design strength benchmark value is 15 mm / h to 22 mm / h.

[0041] The rainstorm activation threshold is a critical value for determining whether to activate the emergency overflow channel. The rainstorm activation threshold is determined by optimizing the relationship between system response data and overflow loss in 20 historical rainstorm events. The empirical value range of the rainstorm activation threshold is 0.85 to 0.95, with a preferred value of 0.90.

[0042] The emergency overflow channel is a bypass pipeline system independent of the conventional drainage path. The design flow rate of the emergency overflow channel is 1.8 to 2.5 times the conventional drainage capacity. When the system operation mode is switched to the rainstorm protection state, the electric valve of the emergency overflow channel will be fully opened within 15 seconds.

[0043] The reserved space calculation function is used to predictively assess the impact of future rainfall on the reservoir's capacity. The input includes the predicted total future rainfall value provided by the meteorological forecast system, in units of... The unit for the current water storage capacity of the buffer reservoir is... The unit for the total volume of the buffer reservoir is... The output is the reserved storage space volume ratio. The calculation formula for the reserved space calculation function is as follows: The reserved storage space volume ratio is equal to the predicted total future rainfall, and the unit is... Including the current water storage capacity of the buffer reservoir, the unit is: The sum of the two parts divided by the total volume of the buffer reservoir is the unit. .

[0044] The predicted total future rainfall is calculated using rainfall forecast data for the next 6 hours obtained from a meteorological forecasting system. The calculation formula is as follows: The unit of the predicted total future rainfall is... This equals the predicted cumulative rainfall in mm multiplied by the catchment area of ​​the construction site in mm. Then divide by 1000.

[0045] The current water storage capacity of the buffer reservoir is calculated based on the real-time water level measured by a radar level gauge. The calculation formula is as follows: The unit of the current water storage capacity of the buffer reservoir is... The unit of the real-time water level value is meters (m), multiplied by the unit of the bottom area of ​​the buffer reservoir. .

[0046] The venting trigger threshold is a critical value for determining whether to perform a venting operation in advance. The venting trigger threshold is determined by statistical analysis of the effect evaluation data of 15 pre-venting operations. The empirical value range of the venting trigger threshold is 0.80 to 0.90, with a preferred value of 0.85.

[0047] The pump frequency adjustment function is used to dynamically calculate the optimal operating frequency of the variable frequency pump based on the inlet flow deviation. The input includes the unit of the inlet flow monitoring value. The units for / h and standard design flow rate are: / h, the output is the target operating frequency in Hz, and the calculation formula of the pump frequency adjustment function is as follows: the target operating frequency in Hz is equal to the reference operating frequency of 37.5Hz plus the frequency adjustment coefficient of 15Hz multiplied by the flow deviation normalization value.

[0048] The formula for calculating the normalized flow deviation value is as follows: the normalized flow deviation value is equal to the influent flow rate monitoring value, and the unit is... / h minus the standard design flow rate is the unit. The difference after / h, divided by the standard design flow rate unit, is / h.

[0049] The reference operating frequency is 37.5Hz. The reference operating frequency corresponds to the operating state of the variable frequency pump under the standard design flow rate. The reference operating frequency is calculated and determined based on the rated parameters of the variable frequency pump and the pipeline resistance characteristic curve.

[0050] The frequency adjustment coefficient is 15Hz. The frequency adjustment coefficient is determined by testing the flow response characteristics of the variable frequency water pump at different frequencies. The empirical value range of the frequency adjustment coefficient is 12Hz to 18Hz.

[0051] The first-level adjustment threshold is the critical value for determining whether to perform pump frequency adjustment. The first-level adjustment threshold is determined by balancing the adjustment accuracy requirements of the variable frequency water pump and the stability of the system. The empirical value range of the first-level adjustment threshold is 0.20 to 0.30, with a preferred value of 0.25.

[0052] The secondary adjustment threshold is the critical value for determining whether to activate the second-level flow compensation mechanism. The secondary adjustment threshold is determined by a comprehensive evaluation of the upper limit of the single pump adjustment capacity and the system safety margin. The empirical value range of the secondary adjustment threshold is 0.35 to 0.45, with a preferred value of 0.40.

[0053] The second-level flow compensation mechanism is automatically activated when the pump frequency adjustment cannot control the flow deviation to within 0.15. It provides additional flow regulation capability by turning on the backup water pump or adjusting the opening of the guide channel gate. The response time of the second-level flow compensation mechanism is no more than 45 seconds.

[0054] The inflow rate monitoring value is collected in real time by an electromagnetic flow meter installed in the inlet pipe of the buffer reservoir. The electromagnetic flow meter has a measurement accuracy of ±1% and a data acquisition frequency of once every 3 seconds.

[0055] The standard design flow rate is determined based on the water demand and rainwater harvesting capacity of the construction site, and the typical range of the standard design flow rate is 20. / h to 80 / h.

[0056] The rainfall intensity monitoring value is collected in real time by a rain gauge installed at the construction site and recorded in mm / h. The rain gauge has a measurement accuracy of ±2% and the data collection frequency is once every minute.

[0057] The radar level gauge uses a non-contact measurement method and is installed at the center of the top of the buffer reservoir. The measurement accuracy reaches ±2mm, and the data acquisition frequency is once every 5 seconds. The radar level gauge transmits the collected water level data to the central control system through a wireless transmission module.

[0058] The weather forecasting system obtains rainfall forecast information for the next 6 to 24 hours by accessing the real-time data interface of regional meteorological stations. The forecast information includes the start time of rainfall, duration, predicted cumulative rainfall, and peak rainfall intensity. The data update frequency of the weather forecasting system is once every 30 minutes.

[0059] The variable frequency water pump operates within a frequency range of 25Hz to 50Hz, corresponding to a flow rate adjustment range of 50% to 100% of the standard design flow rate. When the inflow flow rate monitoring value is within the range of 75% to 100% of the standard design flow rate, the variable frequency water pump maintains the current frequency setting.

[0060] The diversion channel is an open channel set between the primary sedimentation tank and the municipal drainage ditch. The bottom slope of the diversion channel is 2% to 3% to ensure the gravity flow of rainwater. The width of the diversion channel is calculated and determined based on the maximum design drainage flow rate and flow velocity of 0.8m / s to 1.2m / s.

[0061] The opening degree of the guide channel gate is the ratio of the actual opening height of the guide channel gate to the maximum opening height of the guide channel gate. The opening degree of the guide channel gate is automatically adjusted according to the water saturation through the mechanical transmission mechanism of the float linkage device.

[0062] The water quality compliance determination is based on three indicators: turbidity, suspended solids concentration, and pH. Turbidity must be below 20 NTU, suspended solids concentration must be below 50 mg / L, and pH must be within the range of 6.5 to 8.5. These three indicators are detected in real time by online water quality monitoring instruments and the data is transmitted to the central control system.

[0063] As one embodiment of the present invention, it also includes a rainwater collection and circulation system based on a municipal pipe network. The system is automated through a computer control unit. The computer control unit is equipped with a storage medium that stores program instructions. When the program instructions are run in the computer control unit, they execute the steps in the above method and realize centralized control of the water collection network, sedimentation treatment unit, buffer storage tank, variable frequency water pump and guide channel gate.

[0064] The specific implementation methods of the above steps are described in detail below.

[0065] The specific implementation of step S01 is to achieve source diversion and collection of rainwater by setting up a classified water collection network at the construction site. This step first sets up drainage ditches at the bottom and around the foundation pit and configures submersible pumps to pump the accumulated water to the primary sedimentation tank of the foundation pit. At the same time, rainwater grates and collection pipes are set up on the hardened outdoor ground to guide the surface runoff to the primary sedimentation tank of the outdoor drainage. This classified collection method is based on the principle of the difference in the degree of pollution of rainwater from different sources. Since the accumulated water in the foundation pit usually contains a large amount of silt and construction waste, while the outdoor drainage is relatively clean, source classification can avoid clean rainwater from being polluted by high turbidity accumulated water, thereby improving the efficiency of subsequent treatment and reducing the overall treatment cost.

[0066] The specific implementation of step S02 involves real-time water quality assessment of rainwater in two types of primary sedimentation tanks using an online turbidity detection system. This step uses a turbidity sensor to measure the intensity of light scattering by suspended particulate matter in the rainwater and normalizes the measured value with the designed maximum turbidity threshold of 800 NTU to obtain a turbidity normalization coefficient. Based on the principle of regression analysis, the turbidity judgment threshold for the foundation pit is determined to be 0.65. When the turbidity normalization coefficient of the foundation pit water exceeds this threshold, the system determines that a three-stage sedimentation treatment process including a coarse sedimentation unit, a medium sedimentation unit, and a fine sedimentation unit needs to be initiated to remove suspended solids of different particle sizes. For outdoor drainage, the turbidity judgment threshold is set to 0.35. When its turbidity normalization coefficient is lower than this value, correlation analysis confirms that the water quality basically meets the standards and can be directly transported to the buffer storage tank. This intelligent graded treatment strategy achieves optimized allocation of treatment resources.

[0067] The specific implementation of step S03 involves establishing a five-level water saturation classification system based on real-time water level monitoring and automatically adjusting the guide channel gate using a float linkage device. This step calculates the water saturation parameter by comparing the real-time water level measured by the radar level gauge with the effective depth of the reservoir. Based on this parameter, the reservoir's volume utilization status is divided into five levels: Level 1 (0.80 to 1.00) indicates near full capacity; Level 2 (0.60 to 0.80) indicates a higher water level; Level 3 (0.40 to 0.60) indicates a medium water level; Level 4... Level 1 corresponds to 0.20 to 0.40, indicating a lower water level, while Level 5 corresponds to 0 to 0.20, indicating an extremely low water level. The float assembly moves up and down on the water surface as the water level rises and falls, and drives the guide channel gate to change its opening degree through a lever transmission mechanism. When the water level is below Level 3, the gate is completely closed to maximize water storage. When the water level rises to Level 2, the gate opening degree is set to 30% to 50% for moderate drainage. When the water level reaches Level 1, the gate opening degree is set to more than 80% for rapid discharge to avoid overflow. This mechanical linkage control method is based on the principle of hydrostatics and can achieve automatic adjustment without external energy.

[0068] The specific implementation of step S04 involves establishing a rainstorm condition judgment mechanism that integrates rainfall intensity and water storage status, and configuring an emergency overflow channel. This step involves collecting the current rainfall intensity using a rain gauge and normalizing it with the design intensity benchmark value of 18 mm / h. Simultaneously, a water storage saturation weighting coefficient is introduced to correct the degree of rainfall impact. This weighting coefficient is calculated using a linear weighting method, consisting of 0.4 plus 0.6 multiplied by the water storage saturation, thus obtaining a rainstorm condition coefficient that comprehensively reflects the current level of danger. When this coefficient exceeds the rainstorm initiation threshold of 0.90 and the water storage saturation is simultaneously at the first level of saturation, the system determines that there is an overflow risk and immediately opens the emergency overflow channel. This channel is an independent bypass pipeline system with a design flow rate of 1.8 to 2.5 times the conventional drainage capacity. The electric valve completes the full opening operation within 15 seconds. This dual judgment mechanism, based on the optimized analysis results of historical rainstorm events, can effectively prevent system overload.

[0069] The specific implementation of step S05 involves establishing a calculation model for reserved storage space based on meteorological forecast data and implementing a forward-looking drainage strategy. This step obtains rainfall forecast information for the next 6 hours, including the predicted cumulative rainfall, by accessing the data interface of regional meteorological stations. This rainfall is multiplied by the catchment area of ​​the construction site and divided by 1000 to convert it into the predicted total rainfall. At the same time, the current water storage volume is calculated by multiplying the real-time water level value measured by the radar water level gauge by the bottom area of ​​the reservoir. The sum of the two is divided by the total volume of the reservoir to obtain the reserved storage space volume ratio. When this ratio exceeds the drainage trigger threshold of 0.85, the system determines that future rainfall may cause the reservoir to overflow and performs drainage operation in advance. This predictive control strategy determines the optimal threshold based on the principle of probability statistics through 15 historical pre-drainage effect evaluations. Compared with the passive response method, it can free up storage space in advance to cope with the upcoming rainfall.

[0070] The specific implementation of step S06 is to establish a dynamic adjustment mechanism for the variable frequency pump based on flow deviation feedback. This step involves real-time monitoring of the inflow rate of the buffer reservoir inlet pipe using an electromagnetic flowmeter and comparing it with the standard design flow rate to calculate the flow deviation normalization value. This normalization value reflects the relative deviation between the actual flow rate and the design flow rate. Based on this deviation value, the system uses a linear adjustment algorithm to calculate the target operating frequency of the variable frequency pump. Specifically, it adds a frequency adjustment coefficient of 15Hz and the flow deviation normalization value to the base operating frequency of 37.5Hz. When the flow deviation normalization value exceeds the first-level adjustment threshold of 0.25, pump frequency adjustment is performed to correct the flow deviation. When it exceeds the second-level adjustment threshold of 0.40, the single pump adjustment capacity is insufficient, and the second-level flow compensation mechanism needs to be activated simultaneously. This mechanism provides additional adjustment capacity by turning on the standby pump or adjusting the opening of the guide channel gate, with a response time of no more than 45 seconds. This graded adjustment strategy takes into account both adjustment accuracy and system stability based on the test data of the variable frequency pump flow response characteristics.

[0071] The specific implementation of step S07 involves transporting rainwater that has undergone sufficient sedimentation treatment and meets water quality standards to the construction water network for recycling. This step involves online monitoring of the rainwater's turbidity, suspended solids concentration, and pH. The requirements are that the turbidity be below 20 NTU, the suspended solids concentration be below 50 mg / L, and the pH be within the range of 6.5 to 8.5. Rainwater meeting these standards is pressurized by a variable frequency pump and then transported to various water points on the construction site for purposes such as concrete curing, vehicle washing, and dust suppression. Clean rainwater that meets water quality standards after sedimentation treatment but exceeds the storage capacity of the buffer reservoir is discharged into the municipal drainage ditch through a diversion channel. The diversion channel is an open channel with a bottom slope of 2% to 3% to achieve gravity-driven discharge. Its width is calculated and determined based on the maximum design drainage flow rate and flow velocity of 0.8 m / s to 1.2 m / s. This rainwater resource utilization method reduces both municipal water supply consumption and the load on the drainage network.

[0072] It should be noted that the key technical ideas of this invention include the following aspects. Firstly, a graded sedimentation treatment system based on turbidity normalization is established. By normalizing the measured turbidity values ​​of rainwater from different sources and setting differentiated judgment thresholds, precise allocation of sedimentation treatment resources is achieved, avoiding the resource waste caused by applying a uniform treatment process to all rainwater in traditional methods. Simultaneously, the cascaded design of three-stage sedimentation units enables efficient removal of suspended solids of different particle sizes. Secondly, a calculation model for reserved storage space integrating meteorological forecast data is constructed. This model overcomes the limitations of traditional rainwater management systems that rely solely on real-time monitoring for passive response. By introducing future rainfall forecast information, it achieves a shift from passive response to proactive prevention, enabling the system to free up storage space before heavy rain arrives, thus significantly improving the system's ability to cope with extreme weather. Thirdly, a graded adjustment mechanism based on flow deviation feedback is designed. This mechanism calculates the normalized value of flow deviation in real time and sets two-level adjustment thresholds, achieving progressive control from single pump frequency adjustment to multi-means collaborative compensation. Compared with the traditional fixed-frequency operation mode, it can better adapt to the dynamic changes in inflow and maintain stable system operation. The synergistic effect of the three technical approaches mentioned above is to construct an intelligent rainwater management system that integrates source classification, predictive control, and dynamic adjustment. This system ensures targeted water treatment through turbidity classification, enhances the system's foresight through meteorological forecasting, and guarantees operational stability through flow feedback. The three work together to form a closed-loop control system covering the entire process of collection, treatment, storage, and utilization. Compared with traditional rainwater management methods that rely on manual judgment and experience, this significantly improves the system's automation level and resource utilization efficiency.

[0073] It should be noted that this invention also solves the following technical problem: the waste of sedimentation treatment resources due to turbidity differences in rainwater from different sources at construction sites. Traditional rainwater harvesting systems use a uniform sedimentation treatment process for rainwater from all sources, failing to consider the significant differences in sediment content between pit water and outdoor drainage. This results in the relatively good quality drainage undergoing unnecessary multi-stage sedimentation treatment, increasing treatment time and reagent consumption. This invention quantifies and evaluates rainwater from different sources by calculating a turbidity normalization coefficient. When the turbidity normalization coefficient of pit water exceeds the pit turbidity threshold, a three-stage sedimentation treatment process is initiated. Conversely, when the turbidity normalization coefficient of outdoor drainage is below the drainage turbidity threshold, it is directly transported to a buffer storage tank, realizing a differentiated treatment strategy based on turbidity characteristics. This classification treatment mechanism avoids over-treatment of low-turbidity rainwater, improves the treatment efficiency of the sedimentation system, and ensures the rational allocation of sedimentation treatment resources.

[0074] It should be noted that this invention also solves the following technical problem: the low operating efficiency of variable frequency pumps caused by fluctuations in the inflow rate of rainwater harvesting systems. In traditional systems, variable frequency pumps typically operate at a fixed frequency or with simple two-point regulation. When the inflow rate fluctuates due to changes in rainfall intensity, the pump's operating state cannot match the actual flow demand, leading to increased energy consumption or insufficient delivery capacity. This invention uses an electromagnetic flowmeter to collect inflow rate monitoring values ​​in real time, calls a pump frequency regulation function to calculate the normalized flow deviation value, and dynamically adjusts the target operating frequency of the variable frequency pump based on the deviation magnitude. When the normalized flow deviation value exceeds the first-level regulation threshold, pump frequency adjustment is executed; when it exceeds the second-level regulation threshold, a second-level flow compensation mechanism is simultaneously activated, providing additional flow regulation capacity by starting a backup pump or adjusting the opening of the guide channel gate. This multi-level flow response mechanism ensures that the variable frequency pump always operates within a frequency range that matches the inflow rate, avoiding frequent start-stops or inefficient operation caused by flow fluctuations.

[0075] Specifically, the principle of this invention is as follows: The fundamental reason why this invention can solve the above-mentioned technical problems lies in the construction of a two-layer control logic that combines predictive capacity management and real-time operating condition response. At the prediction level, by accessing the meteorological forecast system to obtain future rainfall data, a reserved space calculation function is used to quantify the degree to which future rainfall will occupy the reservoir capacity, transforming passive overflow discharge into proactive pre-emptive drainage, ensuring the system has sufficient storage capacity before heavy rain arrives. At the response level, the established heavy rain judgment function weights rainfall intensity monitoring values ​​and water saturation to form a comprehensive evaluation index—the heavy rain condition coefficient—avoiding the one-sidedness of single-parameter judgment. When the heavy rain condition coefficient exceeds the activation threshold, the system automatically switches to heavy rain protection mode and opens the emergency overflow channel, achieving rapid emergency response under multi-parameter collaborative judgment. This collaborative mechanism of predictive regulation and real-time response enables the system to both reserve storage capacity and rapidly discharge excess rainwater under heavy rain conditions, conforming to the engineering logic of heavy rain protection.

[0076] The following provides a specific embodiment 1 of the present invention, and the specific implementation of each step in this embodiment 1 is described in detail below.

[0077] In this embodiment, the specific implementation of step S01 is the same as described above, and will not be repeated in detail here.

[0078] The specific implementation of step S02 involves using an online turbidity detection system to perform real-time water quality assessment of rainwater in the two types of primary sedimentation tanks and determining the treatment path based on the turbidity normalization coefficient. This step first uses a turbidity sensor to measure the intensity of light scattering by suspended particulate matter in the rainwater to obtain the measured turbidity value, and then calculates the turbidity normalization coefficient. The calculation formula is expressed as follows:

[0079] ;

[0080] In the formula, is the turbidity normalization coefficient, which is dimensionless; The measured turbidity value is in NTU. To design the maximum turbidity threshold, a value of 800 NTU was selected.

[0081] For water accumulation in the foundation pit, when The three-stage precipitation process is initiated at that time, in which The threshold for determining turbidity in the foundation pit is empirically set at 0.65; for outdoor drainage, when The water is then directly transported to the buffer storage tank, where The threshold for determining turbidity in diffuse emissions is 0.35, based on empirical values.

[0082] The specific implementation of step S03 involves establishing a five-level water saturation classification system based on real-time water level monitoring and automatically adjusting the diversion channel gate using a float linkage device. This step first involves measuring the real-time water level using a radar level gauge, and then calculating the water saturation. The calculation formula is as follows:

[0083] ;

[0084] In the formula, The water saturation level is dimensionless. This is the real-time water level value, in meters (m). This refers to the effective depth of the reservoir, expressed in meters (m).

[0085] according to The value divides the utilization status of the reservoir volume into five levels, with the first level being saturation. The second-level saturation state corresponds to The third-level saturation state corresponds to The fourth level of saturation corresponds to The fifth level of saturation corresponds to The float assembly moves up and down on the water surface as the water level rises and falls, and drives the guide channel gate to change its opening degree through a lever transmission mechanism. When the gate is at level three or below, it is completely closed. When raised to the second level, the gate opening is set to 30% to 50%. When the first level is reached, the gate opening is set to 80% or more.

[0086] The specific implementation of step S04 involves establishing a rainstorm condition judgment mechanism that integrates rainfall intensity and water storage status, and configuring an emergency overflow channel. This step involves collecting the current rainfall intensity using a rain gauge and calculating the rainstorm condition coefficient in conjunction with the water storage saturation. The calculation formula is as follows:

[0087] ;

[0088] In the formula, The coefficient for heavy rain conditions is dimensionless. The rainfall intensity is measured in mm / h. The design strength benchmark value is set at 18 mm / h. This is the weighting coefficient for water saturation, which is dimensionless.

[0089] The formula for calculating the water saturation weighting coefficient is as follows:

[0090] ;

[0091] In the formula, This is a dimensionless weighting coefficient for water saturation. The value represents water saturation, which is dimensionless.

[0092] when and The system immediately activated the emergency overflow channel and switched the system operation mode to rainstorm protection mode, among which The threshold for triggering a rainstorm is 0.90, based on experience.

[0093] The specific implementation of step S05 involves establishing a calculation model for reserved storage space based on meteorological forecast data and implementing a forward-looking drainage strategy. This step first obtains future rainfall forecast data through the meteorological forecast system and calculates the predicted total future rainfall. The calculation formula is as follows:

[0094] ;

[0095] In the formula, This is a forecast of the total future rainfall, in units of... ; The cumulative rainfall is predicted, and the unit is mm. The water catchment area at the construction site is expressed in units of... .

[0096] The formula for calculating the current water storage capacity of the buffer reservoir is as follows:

[0097] ;

[0098] In the formula, The current water storage capacity of the buffer reservoir is expressed in units of... ; This is the real-time water level value, in meters (m). The bottom area of ​​the buffer reservoir is expressed in units of... .

[0099] The formula for calculating the volume ratio of reserved storage space is as follows:

[0100] ;

[0101] In the formula, The volume ratio for reserving storage space is dimensionless. This is a forecast of the total future rainfall, in units of... ; The current water storage capacity of the buffer reservoir is expressed in units of... ; The total volume of the buffer reservoir is expressed in units of... .

[0102] when The system performs a pre-emptive venting operation, in which The threshold for triggering the emptying process is empirically set at 0.85.

[0103] The specific implementation of step S06 is to establish a dynamic adjustment mechanism for the variable frequency water pump based on flow deviation feedback. This step first monitors the influent flow rate in real time using an electromagnetic flowmeter and calculates the normalized value of the flow deviation. The calculation formula is as follows:

[0104] ;

[0105] In the formula, This is the normalized value for the flow deviation, which is dimensionless. This is the inflow rate monitoring value, in units of... / h; Standard design flow rate, unit: / h.

[0106] The formula for calculating the target operating frequency of a variable frequency water pump is as follows:

[0107] ;

[0108] In the formula, The target operating frequency, in Hz; The reference operating frequency is 37.5Hz; This is the frequency adjustment factor, with a value of 15Hz; This is the normalized value for the flow deviation, which is dimensionless.

[0109] when Pump frequency adjustment is performed at the appropriate time. At the same time, the second-level traffic compensation mechanism is activated, in which The first-level adjustment threshold has an empirical value of 0.25. The threshold for secondary regulation is 0.40, based on empirical values.

[0110] The specific implementation method of step S07 is the same as described above, and will not be repeated in detail here.

[0111] The design principle of the turbidity normalization coefficient calculation formula is to convert the absolute turbidity values ​​under different operating conditions into relative dimensionless parameters for unified judgment. The formula adopts the following form:

[0112] ;

[0113] This formula uses measured turbidity values. Compared with the preset design maximum turbidity threshold Normalization eliminated the influence of dimensions and made the judgment criteria portable. Based on regression and correlation analysis of 50 sets of pit water samples and 30 sets of outdoor drainage samples, two judgment thresholds of 0.65 and 0.35 were determined, respectively. This graded judgment strategy allows high-turbidity pit water to enter the three-stage sedimentation process, while low-turbidity outdoor drainage directly enters the water storage tank, thereby optimizing the allocation of treatment resources and reducing the overall treatment cost.

[0114] The formula for calculating water saturation directly reflects the current volume utilization status by using the ratio of real-time water level to the effective depth of the reservoir. The formula takes the following form:

[0115] ;

[0116] The dimensionless parameter, combined with the five-level classification system, provides a precise mechanical control basis for the floating plate linkage device, enabling the opening of the guide channel gate to be automatically adjusted with changes in water level and to discharge quickly when close to full load to avoid the risk of overflow.

[0117] The formula for calculating the rainstorm condition coefficient comprehensively considers two key factors: rainfall intensity and water storage status. The formula takes the following form:

[0118] ;

[0119] This formula uses rainfall intensity Normalization and introduction of water saturation weighting coefficient Dynamic assessment of the hazard level of the current working condition is achieved. The weighting coefficients are designed and represented using a linear weighting method as follows:

[0120] ;

[0121] The weighting coefficient formula enhances the system's sensitivity to rainfall intensity when the water saturation is high, thereby triggering the emergency overflow mechanism in advance. The 0.90 activation threshold determined based on the optimization analysis of 20 historical rainstorm events achieves a balance between preventing system overload and reducing unnecessary emissions.

[0122] The formula for calculating the volume ratio of reserved water storage space achieves forward-looking capacity management by integrating meteorological forecast data and current water storage status. The formula takes the following form:

[0123] ;

[0124] This formula uses the predicted total future rainfall value Compared with the current water storage Add them together and give the total volume The expected space occupancy values ​​are obtained through comparison, where the predicted total future rainfall is calculated using the following formula:

[0125] ;

[0126] When the reserved storage space volume ratio exceeds the threshold of 0.85, the system performs an early emptying operation to reserve storage space for upcoming rainfall. Compared with the passive response method, this predictive control strategy significantly reduces the overflow risk during rainstorms and improves the rainwater collection rate.

[0127] The normalized flow deviation value and the target operating frequency calculation formula constitute the closed-loop control system of the variable frequency water pump. The normalized flow deviation value formula adopts the following form:

[0128] ;

[0129] This formula is based on actual flow rate measurements. Compared with standard design flow The relative difference quantifies the system flow status, and the target operating frequency formula is expressed using a linear adjustment algorithm as follows:

[0130] ;

[0131] The formula is at the reference frequency. Based on the flow deviation Dynamic correction is performed. This graded adjustment strategy achieves automatic switching between single-pump frequency regulation and multi-unit coordination by setting two thresholds of 0.25 and 0.40. This enables the system to maintain stable operation under different flow conditions and control the flow deviation within a reasonable range, thereby ensuring the efficiency of rainwater collection and transportation.

[0132] To better understand and implement this invention, the following is a specific application scenario of this invention, Example 2:

[0133] The technical team applied a rainwater harvesting and recycling method based on the municipal pipe network at a large infrastructure construction site. The construction site covers an area of ​​approximately 45,000 square meters. The project included a 12m deep excavation pit and a large outdoor work area. During construction, the team faced the challenge of managing waterlogging caused by frequent rainfall during the rainy season, while also dealing with a large demand for construction water. Traditional methods both wasted water resources and burdened the drainage system. The technical team addressed this challenge by deploying an intelligent rainwater harvesting and recycling system, achieving efficient collection, treatment, and reuse of rainwater.

[0134] like Figure 2 As shown, the system consists of four parts: water collection, water delivery, water storage, and water use. The water collection is divided into two parts: one for water collected in the foundation pit with more silt, which must pass through a sedimentation tank before being discharged into the drainage ditch or used for water purposes; and the other for outdoor drainage with less silt, which can be directly discharged into the drainage ditch or used for construction water after passing through a sedimentation tank. During periods of heavy rainfall, the outdoor drainage can be directly discharged into the drainage ditch via a diversion channel; the impact of this drainage on the local water quality is negligible. To reduce the workload of cleaning the sedimentation tank, an automatic adjustment device is installed, which automatically opens and closes the drainage channel via a float and mechanical linkage. The technical team laid a 1850m long water collection network on site, separating the foundation pit water collection pipeline and the outdoor drainage collection pipeline into two independent systems. Six water collection wells were set up in the foundation pit area, and 12 rainwater collection inlets were set up in the outdoor work area.

[0135] The system is configured with two units, each with a volume of 180. and 120 The primary sedimentation tanks are designed to treat both the accumulated water in the foundation pit and the outdoor drainage. The buffer storage tank has a total designed volume of 500 cubic meters. The effective depth is 4.2m, and the bottom area is 119m. In a typical rainfall event in July 2024, the system's operational data fully demonstrated the practical effectiveness of this method. At the start of the rainfall, a large amount of sediment had accumulated in the foundation pit area due to construction disturbance; the water collection network transported the accumulated water from the pit to a depth of 180 meters. The primary sedimentation tank has a volume of [volume missing]. The online turbidity meter measured the actual turbidity value of the water in the foundation pit to be 548 NTU. The system automatically calculated the turbidity normalization coefficient to be 0.685, which exceeded the foundation pit turbidity judgment threshold of 0.65. The central control system immediately initiated the three-stage sedimentation treatment process.

[0136] The three-stage sedimentation system comprises a coarse sedimentation unit, a medium sedimentation unit, and a fine sedimentation unit arranged in series. The stagnant water from the foundation pit first enters the coarse sedimentation unit, which utilizes gravity settling with a residence time of 45 minutes. This effectively removes sand and gravel particles larger than 0.5 mm, reducing the effluent turbidity to 312 NTU. The water then flows into the medium sedimentation unit, which is equipped with an inclined plate sedimentation device with a residence time of 30 minutes. This further settles silt and sand particles between 0.1 mm and 0.5 mm in diameter, reducing the effluent turbidity to 156 NTU. Finally, in the fine sedimentation unit, the system automatically adds polyaluminum chloride flocculant at a dosage of 8 g per cubic meter of water. After a flocculation reaction time of 20 minutes, final sedimentation occurs, ultimately reducing the effluent turbidity to 15 NTU, meeting the water quality requirements for construction water.

[0137] Meanwhile, outdoor drainage is transported to 120 via a separate pipe network. A primary sedimentation tank with a volume of [volume missing]. Due to the hardened surface and low sediment content in the outdoor area, the turbidity measured by the turbidity meter was 245 NTU, and the calculated turbidity normalization coefficient was 0.306, lower than the turbidity threshold of 0.35 for scattered discharge. The system determined that this portion of rainwater did not require tertiary sedimentation treatment and directly entered the buffer storage tank through the delivery pipeline. At this time, the radar level gauge in the buffer storage tank showed a real-time water level of 1.68m, and the water saturation was 0.40, indicating a third-level saturation state. The float linkage device automatically adjusts the guide channel gate according to water level changes. When the water saturation is at the third-level saturation state, the float position is relatively low, and the guide channel gate is completely closed through a mechanical transmission mechanism, ensuring that clean rainwater is preferentially stored in the storage tank for construction use.

[0138] During the continuous rainfall, the on-site rain gauge collected rainfall intensity data every minute. At the peak of the rainfall, the rain gauge recorded a rainfall intensity of 26.4 mm / h. The system called the rainstorm judgment function for calculation, at which point the water saturation level had risen to 0.88, belonging to the first level of saturation. The calculated water saturation weighting coefficient was 0.928, and the rainstorm condition coefficient was 1.36, exceeding the rainstorm initiation threshold of 0.90. The central control system immediately switched the operating mode to rainstorm protection mode, and the electric valve of the emergency overflow channel completed its full opening operation within 12 seconds. The emergency overflow channel is designed to have a flow rate 2.2 times the conventional drainage capacity, effectively avoiding the risk of overflow from the buffer storage tank. Excess rainwater was quickly discharged into the municipal drainage ditch through the bypass pipeline system.

[0139] The technical team connected to the real-time data interface of regional meteorological stations, enabling the system to obtain rainfall forecast information for the next 6 hours. Three hours before this rainfall event, the meteorological forecast system showed a predicted cumulative rainfall of 42 mm for the next 6 hours. The system then adjusted the forecast based on the construction site's catchment area of ​​45,000 square meters. The calculated total predicted rainfall is 1890. At this time, the radar level gauge measured a real-time water level of 3.15m, and the current water storage capacity of the buffer reservoir was 374.85m. The calculation results of the reserved space calculation function show that the reserved storage space volume ratio is 0.453. Although this value does not exceed the discharge trigger threshold of 0.85, the system continues to maintain normal operation mode, but continuously monitors water level changes and weather forecast updates.

[0140] During the period of reduced rainfall, the inflow rate into the buffer reservoir gradually decreased. An electromagnetic flowmeter installed on the inlet pipe collected data every 3 seconds, displaying the inflow rate monitoring value from its peak of 68... / h decreased to 42 / h. The standard design flow rate for this construction site is set at 55. / h, the flow deviation normalization value is -0.236. Since the absolute value of the flow deviation normalization value does not exceed the first-level regulation threshold of 0.25, the system will not perform pump frequency adjustment for the time being, and the variable frequency pump will continue to operate at the reference operating frequency of 37.5Hz. As the rainfall further weakens, the inflow flow rate monitoring value drops to 38 / h, the flow deviation normalization value becomes -0.309, and the absolute value exceeds the first-level adjustment threshold of 0.25. The pump frequency adjustment function calculates the target operating frequency as 32.865Hz, and the system automatically adjusts the frequency of the variable frequency water pump from 37.5Hz to 32.9Hz to ensure the dynamic balance between the outflow and inflow of water.

[0141] When the rainfall intensity increased again, the inflow rate monitoring value quickly rose to 82. The flow deviation normalization value reached 0.491 / h, exceeding the secondary regulation threshold of 0.40. Simply relying on pump frequency adjustment could no longer meet the flow control requirements, so the system automatically activated the secondary flow compensation mechanism. The standby pump started and reached the set frequency within 35 seconds, while the float linkage device automatically adjusted the opening of the diversion channel gate according to the rise in water saturation. At this point, the water saturation had risen to 0.72, reaching the secondary saturation state, and the diversion channel gate opening was set to 40%. Some rainwater was discharged into the municipal drainage ditch through the diversion channel, effectively preventing overload of the water storage tank.

[0142] The entire rainfall event lasted 8 hours, with a total collected rainfall volume of 3240 mm. Of which 2150 Rainwater, after sedimentation treatment, meets water quality standards and is supplied to the on-site concrete mixing plant, road spraying, and vehicle washing through the construction water pipeline network. (Remaining 1090) Excess rainwater is discharged into the municipal drainage ditch through a diversion channel and an emergency overflow channel. Online water quality monitoring instruments monitored the discharged rainwater in real time. Turbidity remained stable between 16 and 19 NTU, suspended solids concentration was between 32 and 46 mg / L, and pH was maintained within the range of 7.2 to 7.6. All three indicators met the discharge standards. System operation data are shown in Table 1.

[0143] Table 1 Key Parameters for System Operation During Typical Rainfall Events

[0144] Time period Rainfall intensity (mm / h) Water saturation Rainstorm Condition Coefficient Inflow rate ( / h) Variable frequency water pump frequency (Hz) Guide channel gate opening (%) 0 to 1 hour 8.2 0.40 0.40 28 37.5 0 1 to 2 hours 15.6 0.58 0.77 52 37.5 0 2 to 3 hours 26.4 0.88 1.36 82 44.2 40 3 to 4 hours 22.8 0.85 1.25 68 41.5 35 4 to 5 hours 12.4 0.72 0.72 42 37.5 40 5 to 6 hours 6.8 0.58 0.36 32 35.8 0 6 to 7 hours 3.2 0.45 0.16 18 32.9 0 7 to 8 hours 1.5 0.38 0.07 12 32.9 0

[0145] During the following month of continuous operation, the system collected and processed a total of 18,600 cubic meters of rainwater. 13,200 It is used to meet various water needs at the construction site, replacing the tap water that originally had to be drawn from the municipal water supply network. The changes in water quality parameters of different treatment units are shown in Table 2.

[0146] Table 2 Comparison of water quality parameters for each unit in the tertiary sedimentation treatment process.

[0147] Processing unit Influent turbidity (NTU) Effluent turbidity (NTU) Suspended solids removal rate (%) Duration of stay (minutes) Coarse precipitation unit 548 312 43.1 45 Medium precipitation unit 312 156 50.0 30 Fine precipitation unit 156 15 90.4 20

[0148] The technical team continuously monitored the system's automated control performance. The floating plate linkage device automatically adjusts the opening of the diversion channel gate based on real-time changes in water saturation, with a response time consistently between 8 and 12 seconds. When the water saturation rises from level three to level two, the opening of the diversion channel gate automatically adjusts from 0% to the range of 30% to 50%, achieving a dynamic balance between rainwater storage and discharge. When the water saturation reaches the first level of saturation, the opening of the diversion channel gate automatically increases to over 80%, rapidly discharging excess rainwater. The entire adjustment process requires no manual intervention, and the mechanical transmission mechanism operates smoothly and reliably.

[0149] The frequency regulation function of the variable frequency pump played a crucial role in ensuring stable system operation. During the monitoring period, the variable frequency pump adjusted its frequency 168 times within the range of 25Hz to 50Hz based on fluctuations in the influent flow rate, with an average adjustment increment of 2.8Hz. When the absolute value of the normalized flow deviation was between 0.25 and 0.40, single-pump frequency regulation was sufficient. When the absolute value of the normalized flow deviation exceeded 0.40, the second-stage flow compensation mechanism was activated 23 times, and the intervention of the standby pump effectively prevented system overload. Pump group coordinated operation data are shown in Table 3.

[0150] Table 3 Statistical Table of Variable Frequency Water Pump Regulation Response

[0151] Flow deviation normalization range Number of adjustments Main pump frequency adjustment range (Hz) Number of times the standby pump is started Traffic recovery time (seconds) 0.15 to 0.25 52 1.5 to 3.5 0 18 to 25 0.25 to 0.40 93 3.5 to 6.0 0 25 to 38 0.40 to 0.60 23 6.0 to 8.5 23 35 to 45

[0152] The radar level gauge collects water level data every 5 seconds with a measurement accuracy of ±2mm. The data is transmitted to the central control system in real time via a wireless transmission module. During a one-month operation period, the radar level gauge collected 518,400 sets of water level data, with a data transmission success rate of 99.7%. The weather forecast system updates rainfall forecast information every 30 minutes. Based on the forecast data, the system performed 15 pre-emptive drainage operations, effectively reserving storage capacity. Six hours before a heavy rainfall event, the reserved storage capacity calculation function determined the volume ratio to be 0.87, exceeding the drainage trigger threshold of 0.85. The system then lowered the buffer reservoir level from 3.8m to 2.1m in advance, successfully handling the subsequent 78mm of heavy rainfall.

[0153] This invention represents a significant technological advancement over traditional construction site rainwater treatment methods. Traditional methods typically employ simple open ditch drainage or single-stage sedimentation tanks, lacking a mechanism for classifying rainwater from different sources. This results in high-turbidity pit water directly impacting treatment facilities, reducing overall treatment efficiency and increasing the frequency of sedimentation tank cleaning. This invention establishes a water collection network to classify and transport pit water and outdoor drainage to corresponding primary sedimentation tanks, automatically determining the treatment level based on the turbidity normalization coefficient, achieving precise graded treatment of rainwater. The three-stage sedimentation process incorporates removal units for suspended particles of different sizes, improving sediment removal efficiency and reducing the load on subsequent treatment compared to traditional single-stage sedimentation. Traditional methods often rely on manual judgment and valve operation for rainwater storage and discharge, leading to delayed response and potential problems such as overflow or untimely emptying of storage tanks. This invention establishes a five-stage water saturation classification system in conjunction with a floating plate linkage device, achieving automated adjustment of the guide channel gate opening and adaptively controlling the rainwater storage and discharge ratio based on the real-time water level of the storage tank. The rainstorm judgment function comprehensively considers two key factors: rainfall intensity and water saturation. It can accurately identify rainstorm conditions and promptly activate emergency overflow channels, avoiding the system overload risk caused by the lag in judgment in traditional methods. The reserved space calculation function obtains future rainfall forecast data by connecting to the meteorological forecast system, realizing prediction-based proactive storage space management, reserving sufficient capacity in advance compared to the traditional passive response mode. The variable frequency pump's pump frequency adjustment function dynamically optimizes the operating frequency according to the real-time fluctuation of the influent flow, avoiding the energy waste or insufficient processing capacity problems caused by the flow mismatch of traditional fixed frequency pumps. The second-level flow compensation mechanism automatically activates backup equipment or adjusts the discharge channel when the single pump's adjustment capacity is insufficient, establishing a multi-level flow control system. The entire system achieves integrated management of water collection, sedimentation, storage, and transportation through a central control unit, integrating the dispersed processing units into a collaborative organic whole, improving the overall efficiency and reliability of rainwater collection and circulation.

[0154] It should be noted that the variables involved in this invention are explained in detail in Table 4.

[0155] Table 4. Variable Explanation Table

[0156] Turbidity normalization coefficient Measured turbidity value Design maximum turbidity threshold : Turbidity determination threshold for foundation pit Threshold for determining turbidity in scattered emissions Water saturation Real-time water level value Effective depth of the reservoir Rainstorm Condition Coefficient Rainfall intensity monitoring value Design strength benchmark value Water saturation weighting coefficient Rainstorm activation threshold Forecast of total future rainfall Forecast cumulative rainfall Water catchment area at the construction site Current water storage capacity of the buffer reservoir : Bottom area of ​​the buffer reservoir Reserved storage space volume ratio Total volume of the buffer reservoir Emptying trigger threshold : Normalized value of flow deviation Inflow rate monitoring value Standard design flow rate Target operating frequency Reference operating frequency Frequency adjustment coefficient Level 1 adjustment threshold Secondary regulation threshold

[0157] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A rainwater harvesting and recycling method based on municipal pipe networks, characterized in that, Rainwater from the construction site is divided into two categories—excavation pit water and outdoor drainage—through a water collection network and transported to corresponding primary sedimentation tanks. Turbidity of the rainwater in the primary sedimentation tanks is measured, and the turbidity normalization coefficient is calculated. When the turbidity normalization coefficient of the excavation pit water exceeds the turbidity threshold, a three-stage sedimentation treatment process is initiated. When the turbidity normalization coefficient of the outdoor drainage is below the turbidity threshold, it is directly transported to a buffer storage tank. The water saturation of the buffer storage tank is monitored in real time, and a five-level water saturation classification system is established. Based on different saturation levels, the opening of the diversion channel gate is automatically adjusted via a float linkage device. Rainfall intensity is collected using a rain gauge, and a rainstorm condition coefficient is calculated using a rainstorm determination function. When the rainstorm condition coefficient is greater than the rainstorm initiation threshold and the water saturation is at the first level of saturation, an emergency overflow is immediately activated. The system switches its operation mode to rainstorm protection mode, collects real-time water level data of the buffer reservoir through radar water level gauges, and combines it with future rainfall forecast data obtained from the meteorological forecast system to call the reserved space calculation function to obtain the reserved storage space volume ratio. When the reserved storage space volume ratio exceeds the emptying trigger threshold, the emptying operation is performed in advance. The system collects the inflow flow monitoring value and calls the pump frequency adjustment function to calculate the target operating frequency of the variable frequency pump. When the flow deviation normalization value between the inflow flow monitoring value and the standard design flow exceeds the first-level adjustment threshold, the pump frequency adjustment is performed. When the flow deviation normalization value exceeds the second-level adjustment threshold, the second-level flow compensation mechanism is activated simultaneously. The rainwater that has undergone sedimentation treatment and meets the water quality standards is transported to the construction water pipeline network. Clean rainwater exceeding the reservoir capacity is discharged to the municipal drainage ditch through the diversion channel.

2. The rainwater harvesting and recycling method based on municipal pipe network according to claim 1, characterized in that, The turbidity normalization coefficient is calculated by dividing the measured turbidity value by the design maximum turbidity threshold to obtain a dimensionless parameter.

3. The rainwater harvesting and recycling method based on municipal pipe networks according to claim 2, characterized in that, The turbidity determination threshold for the foundation pit is ∈ [0.60, 0.70], with a preferred value of 0.65, and the turbidity determination threshold for the scattered discharge is ∈ [0.30, 0.40], with a preferred value of 0.

35.

4. The rainwater harvesting and recycling method based on municipal pipe network according to claim 3, characterized in that, The three-stage precipitation process includes a coarse precipitation unit, a medium precipitation unit, and a fine precipitation unit connected in sequence.

5. The rainwater harvesting and recycling method based on municipal pipe network according to claim 4, characterized in that, In the five-level water saturation classification system, the first level of saturation corresponds to water saturation ∈ [0.80, 1.00], the second level of saturation corresponds to water saturation ∈ [0.60, 0.80), the third level of saturation corresponds to water saturation ∈ [0.40, 0.60), the fourth level of saturation corresponds to water saturation ∈ [0.20, 0.40), and the fifth level of saturation corresponds to water saturation ∈ [0, 0.20].

6. The rainwater harvesting and recycling method based on municipal pipe network according to claim 5, characterized in that, The floating plate linkage device includes a floating plate assembly installed on the water surface of the buffer reservoir and a guide channel gate plate mechanically connected to the floating plate assembly. When the water saturation is below the third level of saturation, the floating plate position drops, driving the guide channel gate plate to close completely.

7. The rainwater harvesting and recycling method based on municipal pipe network according to claim 6, characterized in that, The input to the rainstorm determination function includes the rainfall intensity monitoring value and the water storage saturation, and the output is the rainstorm condition coefficient, which is calculated by multiplying the ratio of the rainfall intensity monitoring value to the design intensity benchmark value by the water storage saturation weighting coefficient.

8. The rainwater harvesting and recycling method based on municipal pipe network according to claim 7, characterized in that, The design strength benchmark value is 18 mm / h, and the rainstorm initiation threshold is ∈ [0.85, 0.95], with a preferred value of 0.

90.

9. The rainwater harvesting and recycling method based on municipal pipe network according to claim 8, characterized in that, The emergency overflow channel is a bypass pipeline system independent of the conventional drainage path, and the design flow rate of the emergency overflow channel is 1.8 to 2.5 times the conventional drainage capacity.

10. The rainwater harvesting and recycling method based on municipal pipe networks according to claim 9, characterized in that, The inputs to the reserved space calculation function include the predicted total future rainfall, the current water storage capacity of the buffer reservoir, and the total volume of the buffer reservoir. The output is the reserved storage space volume ratio, which is calculated by dividing the sum of the predicted total future rainfall and the current water storage capacity of the buffer reservoir by the total volume of the buffer reservoir.

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