A paddy field water-retreating spatio-temporal dynamic grading sewage interception system and method

Abstract

The application discloses a rice field water recession space-time dynamic grading sewage interception system and method, a control terminal is electrically connected with a real-time rainfall intensity monitoring device, a field water level gauge and a real-time water recession water quality monitoring device to acquire data, a pollution output risk index is calculated according to a last fertilization interval, a fertilization intensity, a real-time rainfall intensity and a conductivity value, and an intelligent three-way shunt valve, a backflow pump station and a mass flow controller are controlled; the intelligent three-way shunt valve shunts the water recession to a series connection type modular purification device or an ecological ditch or backflows to a rice field irrigation channel; the series connection type modular purification device comprises a first-stage adsorption box and a second-stage biochemical box which are distributed in a stepped manner, the first-stage adsorption box is provided with a water flow buffering device, an extractable adsorption filter element and a water drop reoxygenation disc along a water flow direction, and the second-stage biochemical box comprises an aerobic nitrification zone and an anoxic denitrification zone. The application realizes grading treatment of the water recession, replacement of the modular filter element and power-free reoxygenation, and reduces operation and maintenance cost and energy consumption.

Description

Technical Field

[0001] This invention relates to the fields of agricultural non-point source pollution control and agricultural water and soil engineering technology, and in particular to a spatiotemporal dynamic graded interception system and method for paddy field drainage, which aims to reduce and utilize nitrogen and phosphorus pollutants in the drainage of farmland (especially paddy fields) in irrigation areas throughout the entire process. Background Technology

[0002] Currently, agricultural non-point source pollution has become one of the main causes of water eutrophication, with paddy field runoff characterized by concentrated discharge time, large flow fluctuations, and drastic changes in pollutant concentrations ("pulse effect"). Existing technical solutions for the treatment of paddy field runoff typically employ an "end-of-pipe interception" approach, including: (1) Traditional ecological ditch technology: By modifying existing drainage ditches and planting emergent plants (such as canna lilies and calamus), nitrogen and phosphorus are removed by plant absorption and microbial degradation.

[0003] (2) Fixed adsorption interception dam: A permeable dam filled with adsorption materials such as zeolite, ceramsite, and biochar is set up in the ditch to physically adsorb the water flowing through it.

[0004] (3) End-of-pipe constructed wetlands: Surface flow or subsurface flow wetlands are constructed at the end of the drainage system for centralized treatment.

[0005] The aforementioned existing technologies typically employ a "passive, all-time interception" operation mode, meaning that regardless of the concentration of the influent, the water flows through the treatment facility along a fixed path, which presents the following significant drawbacks: (1) The adsorption material is wasted and the operation and maintenance cost is high: The concentration of paddy field drainage water is extremely high only for a short period of time after fertilization (about 7-10 days), and the concentration is low for most of the rest of the time. The existing technology adopts the "always-on mode", which causes the expensive adsorption packing to perform ineffective adsorption during the low concentration period, and even desorption occurs, which greatly shortens the life of the packing and increases the frequency of replacement and labor costs.

[0006] (2) Poor resistance to shock loads: In the early stage of rainstorm runoff, the flow rate is large and the pollutant concentration is high (initial flushing effect). Traditional ecological ditches or integrated equipment have a fixed hydraulic retention time (HRT). During the rainstorm period, the water flow penetrates rapidly, causing pollutants to overflow and be discharged directly without treatment, resulting in a sharp drop in treatment efficiency.

[0007] (3) Low resource utilization rate: Existing technologies lack the ability to identify "water and fertilizer". During the critical period of water demand for rice or when the nutrients in the receding water are suitable, water bodies containing valuable nitrogen and phosphorus nutrients are often directly treated as wastewater and discharged, failing to achieve the resource reuse of "fertilizer and water not flowing into the fields".

[0008] (4) Poor terrain adaptability: In the hilly and mountainous areas of southern China, the farmland is fragmented and has a large elevation difference, making it difficult to deploy large-scale, contiguous wetland treatment systems.

[0009] (5) The control algorithm is disconnected from the agricultural mechanism: Most existing intelligent control schemes use single hydrological parameters such as rainfall or water level as control inputs, and do not incorporate the agricultural law of pollutant concentration decay over time after fertilization into the algorithm model. This makes it impossible to distinguish between "high-risk runoff" and "low-risk runoff" at the algorithm level. The system either intercepts runoff at all times, resulting in waste, or it misses the high-concentration runoff in the early stage of fertilization by relying solely on rainfall threshold control. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention proposes a spatiotemporally dynamic graded pollution interception system and method for paddy field drainage.

[0011] The specific technical solution is as follows: A spatiotemporally dynamic graded pollution interception system for paddy field drainage includes: a real-time rainfall intensity monitoring device, a field surface water level gauge installed at the outlet of the paddy field, a real-time drainage water quality monitoring device, a control terminal, and an intelligent three-way diversion valve installed at the end of the main drainage pipe. The first diversion path of the intelligent three-way diversion valve is connected to a series modular purification device via a mass flow controller, the second diversion path is connected to an ecological ditch, and the third diversion path is connected to the irrigation canal of the paddy field via a return pump station. The control terminal is electrically connected to the real-time rainfall intensity monitoring device, the field surface water level gauge, and the real-time drainage water quality monitoring device to acquire data. It generates a control strategy through a built-in pollution output risk index calculation model, controlling the intelligent three-way diversion valve connected to it to guide the corresponding diversion path, the return pump station, and the mass flow controller. The monitoring data of the real-time drainage water quality monitoring device includes conductivity values. The pollution output risk index calculation model determines the pollution output risk index based on the last fertilization interval, real-time rainfall intensity, and conductivity values. The series-connected modular purification device includes a primary adsorption tank and a secondary biochemical tank arranged in a stepped manner. The primary adsorption tank is equipped with a water flow buffer device, multiple extractable adsorption filter cartridges, and a cascading reoxygenation disc along the water flow direction. The cascading reoxygenation disc is located at the vertical connection between the two tanks. The secondary biochemical tank includes an aerobic nitrification zone for nitrogen removal, and its discharge port is connected to the external environment.

[0012] Furthermore, the water flow buffer device is a pre-overflow buffer weir, which is located near the inlet of the primary adsorption tank, dividing the primary adsorption tank into an inlet buffer side and a filter cartridge treatment side. After the return water in the first diversion path enters the inlet buffer side through the inlet, when the liquid level on the inlet buffer side reaches the weir crest elevation of the pre-overflow buffer weir, the return water crosses the pre-overflow buffer weir and enters the filter cartridge treatment side, and flows through multiple extractable adsorption filter cartridges in sequence.

[0013] Furthermore, multiple removable adsorption filter cartridges are respectively installed on the side wall of the filter cartridge processing side by sliding rails, and the removable adsorption filter cartridges are filled with modified biochar bags; the secondary biochemical tank includes an upstream aerobic nitrification zone and a downstream anoxic denitrification zone, the aerobic nitrification zone is filled with porous suspended balls or volcanic rock packing, and the anoxic denitrification zone is filled with porous suspended balls or volcanic rock packing, as well as anaerobic microorganisms.

[0014] Furthermore, the surface of the cascading reoxygenation disc is evenly distributed with multiple sets of sieve holes; the real-time rainfall intensity monitoring device uses a rain gauge or soil moisture sensor, or adopts the API real-time data interface of the local meteorological station to obtain the real-time rainfall intensity.

[0015] Furthermore, if the pollution output risk index is greater than or equal to the high-risk threshold, the control terminal controls the intelligent three-way diversion valve to switch to the first diversion path; If the pollution output risk index is greater than the low risk threshold and less than the high risk threshold; or if the pollution output risk index is less than or equal to the low risk threshold and the field water level is greater than or equal to the relatively poor water level, then the control terminal controls the intelligent three-way diversion valve to be directed to the second diversion path. If the pollution output risk index is less than or equal to the low-risk threshold and the field water level is less than the relatively poor water level, the control terminal controls the intelligent three-way diversion valve to switch to the third diversion path.

[0016] Furthermore, the water flow buffer device is connected to the ecological ditch through a bypass channel, and a controllable valve body is installed in the bypass channel. Under normal operating conditions, the controllable valve body is closed by default. The allowable inflow rate of the series modular purification device is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. When the real-time flow rate entering the series modular purification device exceeds the allowable inflow rate, the controllable valve body opens.

[0017] A spatiotemporally dynamic graded pollution interception method for paddy field drainage, based on the aforementioned spatiotemporally dynamic graded pollution interception system for paddy field drainage, includes the following steps: Step 1: The control terminal acquires real-time rainfall intensity, conductivity value, fertilization intensity coefficient, and last fertilization interval t, and combines it with the pollution output risk index calculation model to calculate the current pollution output risk index in real time. Step 2: Determine the relationship between the current pollution output risk index and the preset risk threshold, and generate a dynamic operation strategy accordingly; the dynamic operation strategy includes: a high-efficiency purification strategy, an ecological absorption strategy, and a recycling strategy; If the current pollution output risk index is greater than or equal to the high-risk threshold, a powerful purification strategy will be generated. If the current pollution output risk index is greater than the low risk threshold but less than the high risk threshold; or if the current pollution output risk index is less than or equal to the low risk threshold and the field water level is greater than or equal to the relatively poor water level, then an ecological absorption strategy is generated. If the current pollution output risk index is less than or equal to the low-risk threshold and the field water level is less than the relatively poor water level, then a recycling strategy is generated. Step 3: The control terminal executes the dynamic operation strategy described above. If the strategy generated in step two is a powerful purification strategy, the control terminal controls the intelligent three-way diversion valve to tangent to the first diversion path and starts the mass flow controller to limit the flow rate. The allowable inflow rate is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. The effluent enters the series modular purification device and is purified using adsorption materials. If the strategy generated in step two is an ecological absorption strategy, then the control terminal controls the intelligent three-way diversion valve to switch to the second diversion path, and the water enters the ecological ditch, where plants are used to purify the water. If the strategy generated in step two is a recycling strategy, the control terminal controls the intelligent three-way diversion valve to switch to the third diversion path and starts the return pump station, so that the water flows back to the irrigation canal of the paddy field.

[0018] Furthermore, in step one, the pollution output risk index calculation model is as follows: the pollution output risk index is equal to the sum of the product of crop and landform coefficients, fertilization intensity coefficients, real-time rainfall intensity, and pollutant concentration decay over time, and the product of water quality feedback sensitivity coefficients and real-time conductivity values.

[0019] Furthermore, in step three, when the powerful purification strategy is implemented, after the effluent enters the series-connected modular purification device, the effluent is purified sequentially through the following operations: (1) The effluent enters the water flow buffer device through the inlet, and then passes through multiple extractable adsorption filter cartridges to achieve adsorption and interception of pollutants. (2) The water body falls from the primary adsorption tank to the secondary biochemical tank through the cascading reoxygenation plate, and the dissolved oxygen in the water body increases under the action of the cascading reoxygenation plate and gravitational potential energy; (3) The secondary biochemical tank includes an upstream aerobic nitrification zone and a downstream anoxic denitrification zone. The water body sequentially passes through the aerobic nitrification zone to convert ammonia nitrogen into nitrate nitrogen, and through the anoxic denitrification zone to reduce nitrate nitrogen into nitrogen gas to achieve total nitrogen removal, and is discharged to the external environment from the discharge outlet.

[0020] Furthermore, it also includes the following fault tolerance and safety control: when fertilization information is missing, real-time monitoring data exceeds the effective range, or the conductivity value reaches the abnormal threshold, the control terminal will output a powerful purification strategy by default. The water flow buffer device is connected to the ecological ditch through a bypass channel. A controllable valve is installed in the bypass channel. Under normal operating conditions, the controllable valve is closed by default. The allowable inflow rate of the series modular purification device is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. When the real-time flow rate entering the series modular purification device exceeds the allowable inflow rate, the controllable valve opens, and the excess water is discharged into the ecological ditch through the bypass channel.

[0021] The beneficial effects of this invention are: (1) This invention establishes a pollution output risk index calculation model, which deeply couples the pollution source attenuation law after fertilization with the rainwater runoff transport effect and online water quality feedback at the mathematical level, solving the problem that existing technologies cannot distinguish between "clean rainwater" and "dirty rainwater", and forming three complete control states: high-risk enhanced purification, medium-risk ecological absorption, and low-risk water shortage reuse, realizing accurate identification and classification of "high-risk runoff with fertilizer" and "low-risk runoff without fertilizer".

[0022] (2) The extractable adsorption filter design of the present invention solves the problem of difficult maintenance. The "drop water reoxygenation plate" cleverly utilizes the gravitational potential energy to achieve oxygenation without power, which significantly reduces the operation and maintenance cost and energy consumption.

[0023] (3) This invention introduces real-time data conductivity value and rainfall intensity into the pollution output risk index calculation model, forming a dual protection mechanism of "theoretical calculation + actual measurement correction". When the real-time conductivity value reaches the critical threshold, the system will forcibly trigger the high-risk strategy regardless of the fertilization time information and rainfall intensity, preventing the direct discharge of high-concentration runoff due to farmers' failure to report fertilization. Attached Figure Description

[0024] Figure 1 This is an overall architecture diagram of the spatiotemporal dynamic graded sewage interception system for paddy field drainage in an embodiment of the present invention.

[0025] Figure 2 This is a cross-sectional structural diagram of the series-connected modular purification device in an embodiment of the present invention.

[0026] Figure 3 This is a flowchart of the spatiotemporal dynamic graded interception method for paddy field drainage in an embodiment of the present invention.

[0027] In the diagram, the components are: paddy field 1, rain gauge 2, field surface water level gauge 3, conductivity sensor 4, control terminal 5, intelligent three-way diversion valve 6, series modular purification device 7, ecological ditch 8, return pump station 9, mass flow controller 10; inlet 701, overflow buffer weir 702, extractable adsorption filter 703, cascading reoxygenation disc 704, secondary biochemical packing area 705, and discharge outlet 706. Detailed Implementation

[0028] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The objectives and effects of the present invention will become clearer as a result. The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] like Figure 1 As shown, a spatiotemporal dynamic graded interception system for paddy field drainage is arranged at the drainage end of paddy field 1. The system includes: rain gauge 2, field surface water level gauge 3, conductivity (i.e., EC) sensor 4, control terminal 5, intelligent three-way diversion valve 6, series modular purification device 7, ecological ditch 8, return pump station 9, and mass flow controller 10.

[0030] The sensor group consists of a rain gauge 2, a field water level gauge 3, and a conductivity sensor 4. The rain gauge 2 is positioned in an open area of ​​the field to monitor rainfall intensity (R) in real time. The field water level gauge 3 is vertically installed at the outlet of paddy field 1 to monitor the water depth (H). The probe of the conductivity sensor 4 is placed inside the main drainage pipe of paddy field 1 to monitor the conductivity value (EC) in real time. obs Electrical conductivity values ​​are used to characterize salinity and reflect changes in soluble ions in retreatwater. These values, along with fertilization information and rainfall data, are used to correct for pollution export risks.

[0031] Control terminal 5 includes a fertilization information input module for users to input the time of the most recent fertilization (T). fert The system uses a sensor array (SSA) and a fertilization intensity (M). Control terminal 5, as the core of the system, connects to the aforementioned sensor array and actuators (including the intelligent three-way diversion valve 6, the return pump station 9, and the mass flow controller 10) via signal lines (shown as dashed lines in the diagram). It has a built-in "Pollution Output Risk Index (PRI) calculation model" that calculates the control strategy in real time based on multi-source data. Control terminal 5 calculates the Pollution Output Risk Index PRI in real time according to the following formula: In the formula, t is the interval (days) between the last fertilization. The term reflects the agricultural law of exponential decay of pollutant concentration over time, denoted as the pollutant concentration decay term over time (this decay term reflects the decreasing trend of risk after the migration of nutrients is absorbed by crops, fixed by soil, or transformed over time). β is the time decay coefficient (its value depends on soil texture: for clay soils with strong adsorption capacity, pollutant release is slow and decay is slow, so it can be taken as 0.5-0.8; for loam, it can be taken as 0.8-1.2; for sandy soils with poor fertilizer retention, pollutants are easily lost and decay is fast, so it can be taken as 1.2-1.5). R is the real-time rainfall intensity (mm / h), used to reflect the rainfall-induced runoff and pollutant migration dynamics; M is the fertilizer intensity coefficient (the default value is 1, and it can be set to 1.2 during the topdressing period to reflect the impact of fertilizer application); α is the crop and landform coefficient, used to correct for the runoff risk of different fields. For standard plain paddy fields, the value is 1.0, and for fields with a slope greater than 5° or low vegetation cover (high runoff risk), the value is 1.2-1.5. EC obs γ represents the conductivity value (μS / cm) monitored in real time. γ is the water quality feedback sensitivity coefficient, determined from historical water quality data or on-site calibration.

[0032] Control terminal 5 further compares the calculated PRI value with a preset high-risk threshold. and low risk threshold Compare and combine the field surface water level H with the preset relative water shortage water level H. target The size relationship is used to generate hierarchical control commands, which drive the diversion actuator and mass flow controller to perform corresponding actions.

[0033] The intelligent three-way diversion valve 6 is installed at the end of the main drainage pipe and is controlled and driven by the control terminal 5 to distribute the water flow to three different paths: (1) First diversion path (enhanced purification channel): connected to the series modular purification device 7. A mass flow controller 10 is installed on the inlet pipe of the series modular purification device 7. The mass flow controller 10 is electrically connected to the control terminal 5 and is used to precisely adjust the water volume entering the series modular purification device 7 to ensure that the actual hydraulic residence time is not lower than the preset value, and to prevent the adsorption failure caused by excessively fast flow rate during rainstorms. Specifically, the control terminal 5 adjusts the flow rate according to the effective capacity V of the series modular purification device 7. eff and preset hydraulic residence time T HRT According to Q set ≤V eff / T HRT Determine the preset processing flow rate Q set For a single paddy field or independent control and drainage unit, the maximum outflow rate at its outlet under the maximum water level difference (i.e., the maximum flow rate entering the first diversion path) is Q. out,max Q must be satisfied out,max ≤Q setand the preset processing flow Q set This serves as the setpoint for the mass flow controller 10; in cases of excessively rapid short-term flow rate increases, the second diversion path is simultaneously activated to reduce the flow rate exceeding the preset processing flow rate Q. set Part of the receding water flows into ecological ditch 8.

[0034] (2) Second diversion path (ecological absorption channel): connected to ecological ditch 8, which is planted with emergent plants to treat low-concentration wastewater.

[0035] (3) Third diversion path (circulation reuse channel): connected to the return pump station 9, the outlet pipe of the return pump station 9 is connected back to the irrigation canal of paddy field 1 to realize closed-loop circulation of fertilizer and water.

[0036] To address the issues of easy clogging, difficult maintenance, and oxygen deficiency, this invention features a unique structural design for the "series-connected modular purification device 7" in the first diversion path, such as... Figure 2 As shown, the main body of the series-connected modular purification device 7 is arranged in a stepped manner, including an upstream primary adsorption tank and a downstream secondary biochemical tank, with a vertical height difference of 20-30cm between the two, and the water flows from high to low.

[0037] The primary adsorption box (adsorption interception zone) includes: an inlet 701, an overflow buffer weir 702, a removable adsorption filter element 703, and a cascading reoxygenation disc 704. The inlet 701 is used to guide the drainage ditch water (i.e., the backflow) in the first diversion path into the series-connected modular purification device 7.

[0038] An overflow buffer weir 702 is positioned near the inlet 701 within the primary adsorption tank (hereinafter referred to as the primary tank), dividing the primary tank into an inlet buffer side and a filter cartridge treatment side. The height of the overflow buffer weir 702 is lower than that of the primary tank, and the specific height is determined according to actual needs. In high-efficiency purification mode, the effluent first enters the inlet buffer side through the inlet 701. When the liquid level reaches the weir crest elevation, the effluent crosses the upstream overflow buffer weir 702 and enters the filter cartridge treatment side, flowing sequentially through multiple extractable adsorption filter cartridges 703. The overflow buffer weir 702 is used to reduce the kinetic energy of the incoming water, homogenize the water flow and water quality, and reduce the direct impact on the primary filter cartridges through weir-crossing water distribution.

[0039] Furthermore, the inlet buffer side is connected to the ecological ditch 8 via a bypass channel. A controllable valve is installed in the bypass channel, which is closed by default under normal operating conditions. The allowable inflow rate of the series-connected modular purification device 7 is determined based on its effective volume and preset hydraulic retention time. When the real-time flow rate entering the series-connected modular purification device 7 exceeds the allowable inflow rate, the controllable valve opens. The allowable inflow rate setting is used to prevent rapid water penetration during heavy rain, which could lead to adsorption failure. At the same time, the bypass channel is used to guide the excess water into the ecological ditch 8, protecting the adsorption filter element and preventing uncontrolled discharge.

[0040] Multiple removable adsorption filter cartridges 703 are arranged along the water flow direction and are installed on the treatment side of the filter cartridge by being pulled out individually via vertical stainless steel slide rails. Each removable adsorption filter cartridge 703 is a standardized drawer structure filled with modified biochar packets, with a handle on the top. When a removable adsorption filter cartridge 703 is saturated, maintenance personnel can simply pull out the saturated removable adsorption filter cartridge 703 vertically upwards and replace it without digging or emptying the primary housing, just like pulling out a drawer.

[0041] The cascading reoxygenation disc 704 is located at the connection between the effluent weir of the primary adsorption tank and the inlet of the secondary biological treatment tank. The effluent weir of the primary adsorption tank is located downstream of the extractable adsorption filter cartridge 703. Multiple sets of sieve holes are evenly distributed on the surface of the cascading reoxygenation disc 704. Water flows out from the higher primary adsorption tank, is broken into fine droplets by the cascading reoxygenation disc 704, and falls, utilizing gravitational potential energy to increase the gas-liquid contact area, thereby increasing the dissolved oxygen in the water entering the aerobic nitrification zone of the secondary biological treatment tank. This achieves a dissolved oxygen (DO) level of 3-5 mg / L, eliminating the need for electric aeration equipment and realizing powerless oxygenation.

[0042] The secondary biological treatment tank (deep treatment zone) includes a secondary biological treatment packing zone 705 and an outlet 706. The secondary biological treatment packing zone 705, located within the secondary biological treatment tank, includes an aerobic nitrification zone filled with porous suspended balls or volcanic rock packing to oxidize ammonia nitrogen into nitrate nitrogen. The outlet 706 is located at the very end of the unit, through which the treated effluent, meeting standards, is discharged into the external environment.

[0043] Preferably, the secondary biological packing zone 705 also includes an anoxic denitrification zone. The aerobic nitrification zone is located upstream (i.e., the upper layer) of the secondary biological packing zone 705, and the anoxic denitrification zone is located downstream (i.e., the lower layer). The anoxic denitrification zone is filled with porous suspended balls or volcanic rock packing, as well as anaerobic microorganisms (denitrifying bacteria are selected in this embodiment). Through the natural gradient consumption of dissolved oxygen in the water flow direction and the anoxic microenvironment inside the packing layer, the attached denitrifying bacteria can use the residual organic carbon source in the water to reduce nitrate nitrogen to nitrogen gas (N2) and remove it from the water.

[0044] Based on the aforementioned spatiotemporal dynamic graded pollution interception system for paddy field drainage, this embodiment also proposes a spatiotemporal dynamic graded pollution interception method for paddy field drainage. This method adopts a dual closed-loop control of "model-driven + feedback correction" and includes the following steps: S1: Control terminal 5 acquires real-time data from the sensor array (real-time rainfall intensity R, conductivity value EC). obs The user-inputted fertilization information (interval t from the last fertilization and fertilization intensity coefficient M) is input into the pollution output risk index calculation model, which calculates the current pollution output risk index PRI (dimensionless) in real time. The formula is as follows: Water quality feedback sensitivity coefficient γ and conductivity critical value EC crit Should meet , making when At that time, water quality feedback item It can trigger the powerful purification strategy mentioned later on on its own, thereby enabling the forced interception of unreported fertilization or abnormal drainage.

[0045] S2: Based on the real-time PRI value, the control terminal 5 generates a dynamic operation strategy (including a high-efficiency purification strategy, an ecological absorption strategy, and a recycling strategy), and controls the system to automatically switch between the following three modes: Mode 1: High-efficiency purification mode.

[0046] The trigger condition for this mode is: The control terminal 5 generates a powerful purification strategy.

[0047] This model corresponds to the following scenario: heavy rainfall shortly after fertilization, or EC obs The value is abnormally high (due to unauthorized discharge or underreporting).

[0048] The corresponding system actions in this mode are as follows: Control terminal 5 controls intelligent three-way diversion valve 6 to tangent to the first diversion path, and controls mass flow controller 10 to ensure that the flow rate of the effluent entering the first diversion path does not exceed Q. set The water flows through the first-stage adsorption tank of the series-connected modular purification device 7 to remove high concentrations of phosphorus. After being reoxygenated by a cascade, it enters the second-stage biochemical tank to remove ammonia nitrogen.

[0049] Mode 2: Ecological absorption mode.

[0050] The trigger condition for this mode is: ,or and The control terminal 5 generates an ecological absorption strategy.

[0051] The scenario corresponding to this mode is: rainfall in the later stage of fertilization, or light rain outside the fertilization period.

[0052] The corresponding system action for this mode is as follows: Control terminal 5 controls intelligent three-way diversion valve 6 to switch to the second diversion path. Water flows into ecological ditch 8, where it is biologically absorbed by plants and bottom sediment microorganisms, saving on adsorption material consumption.

[0053] Mode 3: Recycled mode.

[0054] The trigger condition for this mode is: And the water level of the field ,in, For relatively low water levels, control terminal 5 generates a recycling strategy.

[0055] The scenario for this mode is: the water quality is relatively clean and the fields need water.

[0056] The corresponding system action for this mode is as follows: control terminal 5 controls intelligent three-way diversion valve 6 to switch to the third diversion path, and starts return pump station 9 to pump low-risk drainage back to the irrigation canal of paddy field 1.

[0057] The present invention has the following alternative: 1. Replacement of perception and control algorithms.

[0058] Rainfall sensing alternatives: Real-time monitoring by the rain gauge 2 can be replaced by a "real-time data interface of the local meteorological station's API" or a "soil moisture sensor." Soil moisture saturation is a precursor to runoff. When soil moisture reaches a set threshold or its rate of change is abnormal, it can be used to determine runoff generation conditions and correct the risk index. When using a soil moisture sensor, the rate of change in soil moisture is converted into equivalent rainfall intensity, which serves as the input value for R in the pollution output risk index calculation model.

[0059] Water quality feedback alternatives: The conductivity sensor 4 is inexpensive and can be replaced by a "turbidity sensor" (characterizing particulate phosphorus loss) or an "online ammonia nitrogen electrode" (directly measuring nitrogen), although the cost is higher, the principle is the same.

[0060] Formal replacement of the PRI mathematical model: This invention adopts an exponential decay model. This part can be replaced by a "logarithmic decay model", a "piecewise linear function", or a "neural network black box model" based on big data, as long as the core logic is "the risk decreases over time after fertilization", it falls within the scope of protection of this patent.

[0061] Alternatives to decision-making logic: Continuous PRI index calculation can be replaced by "fuzzy logic control" or discrete "multi-level lookup table method". For example, a lookup table containing multiple combinations such as "heavy rain + just applied fertilizer" and "weak rain + just applied fertilizer" can be established to determine the action of the intelligent three-way diversion valve 6.

[0062] 2. Hardware structure replacement.

[0063] The intelligent three-way diversion valve 6 can be replaced by a combination of three independent one-way solenoid valves; or in open channel systems, diversion can be achieved by changing the cross-section of the water flow using an electric gate or a hydraulic flap dam.

[0064] Alternatives for backflow pumping: For terraced areas with elevation differences, the backflow pumping station 9 can be replaced by a "siphon pipe + vacuum breaker valve" structure, which utilizes the gravity siphon principle to achieve water reuse.

[0065] Drawer-type structure alternative: The side-extractable removable adsorption filter element 703 can be replaced by a "top-mounted (basket structure)" or "rotary chuck type" structure. For example, the filter element can be made into a cylindrical shape, and a rotating mechanism can be used to quickly switch to a spare filter element.

[0066] Alternatives to reoxygenation methods: The 704 cascading reoxygenation disc utilizes gravitational potential energy, which can be replaced by a "Venturi jet" that uses the negative pressure generated by the contraction of water flow to draw in air; or an "solar micro-power aeration pump" can be used for active oxygenation.

[0067] Overflow protection alternative: The overflow buffer weir 702 at the inlet end can be replaced by a "side bar" combined with a "bypass pipe". When the water level in front of the bar is too high, the bypass is triggered to open.

[0068] 3. This invention also has the following fault tolerance and security control mechanisms: (1) Fertilizer information missing fault tolerance: When the user fails to input the most recent fertilization time and fertilization intensity through the fertilization information input module, or the input data is obviously unreasonable (such as the fertilization time being in the future), the control terminal 5 marks the status as "fertilization information missing" and outputs a strong purification strategy by default (i.e., switching to the first diversion path) until the user supplements valid fertilization information or EC. obs continuously below EC crit It will automatically deactivate after the preset duration is reached.

[0069] (2) Sensor data anomaly tolerance: When the conductivity value EC obs Real-time data for rainfall intensity R or field water level H are outside their respective effective measurement ranges (e.g., EC). obs When a negative value is generated (or the instrument's measurement range exceeds its upper limit), or when data updates are interrupted for more than the preset timeout period, the control terminal 5 will also output a powerful purification strategy by default, reflecting the "safe failure" design principle.

[0070] (3) Overflow safety bypass: In the event of a short-term excessive flow rate increase, a second diversion path will be activated simultaneously to ensure that the flow rate exceeds the preset processing flow rate Q. set Part of the receding water flows into ecological ditch 8; if the real-time flow rate entering the first diversion path still exceeds the allowable flow rate Q... set(For example, in cases where the outflow of water during a rainstorm is much greater than the treatment capacity of the purification device), exceeding Q. set Part of the wastewater is guided by the overflow buffer weir 702 into the bypass channel, and then discharged into the ecological ditch 8 for ecological absorption, without passing through the extractable adsorption filter 703. This mechanism ensures that under extreme rainfall conditions, the hydraulic retention time in the primary adsorption tank is not less than the preset value, and that excess wastewater is treated by the ecological ditch 8 before being discharged, preventing uncontrolled direct discharge.

[0071] (4) No water receding state: When the water level H on the field surface is lower than the elevation of the outlet and there is no rainfall, the system is in standby state and all actuators remain closed.

[0072] The present invention will be specifically described below through examples.

[0073] Example 1 This embodiment selects a typical plain paddy irrigation area in the Taihu Lake Basin for verification. The geomorphological characteristics are: plain area, clay soil type, with strong water and fertilizer retention capacity. Model parameters are set as follows: crop and geomorphological coefficient α = 1.0 (standard plain paddy field), attenuation coefficient β = 0.6 (relatively slow pollutant release in clay soil), fertilization intensity coefficient during the basal fertilizer period M = 1.0, and feedback sensitivity coefficient γ = 0.025. The threshold is set as: PRI high-risk threshold. Low risk threshold Relative water level H target =5cm. Critical conductivity value EC crit =800μS / cm, verifying the EC forced interception constraint: ,satisfy Requirements.

[0074] To verify the response capability of the present invention under different agricultural meteorological conditions, three typical time points (scenario A, B, and C) were selected for data review.

[0075] Scenario A: Heavy rainfall following fertilization (verification of high-efficiency purification mode).

[0076] Operating conditions: On the second day after fertilization (t=2), a sudden rainstorm occurred, with a real-time rainfall intensity of R=35mm / h, and the electrical conductivity EC was monitored. obs =650μS / cm.

[0077] The pollution output risk index is calculated as follows: .

[0078] Judgment result: The area was deemed high-risk, and a high-efficiency purification mode was activated.

[0079] System Actions: Control terminal 5 controls intelligent three-way diversion valve 6 to switch to the first diversion path, and activates mass flow controller 10 to limit flow rate. The water flows into the series-connected modular purification device 7.

[0080] Scenario B: Moderate rain during the later stages of fertilization (verification of ecological absorption model).

[0081] Operating conditions: 15 days after fertilization (t=15), moderate rain, real-time rainfall intensity R=12mm / h, electrical conductivity EC was monitored. obs =300μS / cm.

[0082] The pollution output risk index is calculated as follows: .

[0083] Judgment result: The risk level was determined to be medium, and the ecological absorption mode was activated.

[0084] System Action: Control terminal 5 controls intelligent three-way diversion valve 6 to switch to the second diversion path, and water flows into ecological ditch 8, where it is naturally purified by plants without the adsorption material being consumed.

[0085] Scenario C: Water shortage during non-fertilization period (verification of recycling mode).

[0086] Operating conditions: 25 days after fertilization (t=25), no rain or light rain, real-time rainfall intensity R=2mm / h, electrical conductivity EC was monitored. obs =150μS / cm, water level on the field surface H=3cm.

[0087] The pollution output risk index is calculated as follows: .

[0088] Judgment result: It was determined to be low risk, and Once the water shortage conditions are met, the recycling mode will be activated.

[0089] System Action: Control terminal 5 controls intelligent three-way diversion valve 6 to switch to the third diversion path, starts return pump station 9, and pumps the returned water back to the field for irrigation, achieving zero discharge.

[0090] Example 2 Three experimental fields were set up for comparative testing, with a duration of one rice growing season (approximately 120 days).

[0091] Example 2 group: The conditions are the same as in Example 1, but multi-source fusion control is used to record various data of the paddy field during a rice growing season.

[0092] Comparative Example 1 (Traditional Ecological Ditch): Only ecological ditches are set up, and all drainage passes through the ecological ditches without diversion control.

[0093] Comparative Example 2 (Rainfall-controlled sewage interception): interception is based solely on rainfall control (when R>10mm / h), without considering the fertilization time t.

[0094] Table 1: Comparison of operational performance data within a growing season Data conclusions: (1) Compared with Comparative Example 1, Example 2 improved the total nitrogen removal rate by 33.2 percentage points, solving the problem of poor impact resistance of traditional ditches.

[0095] (2) In Example 2, the service life of the adsorption packing was extended by 3 times compared with Comparative Example 2, because the system intelligently avoided the ineffective consumption of the packing by "fertilizer-free rainfall".

[0096] (3) Example 2 provides an additional 1250m 3 / hm 2 The reuse of water significantly reduces irrigation water costs.

[0097] This invention proposes the following key technical points: (1) A pollution output risk index calculation model based on the coupling of multi-source data of "agriculture-gas-water".

[0098] Constructed Mathematical Model. For the first time, agricultural fertilization patterns (time decay term) are deeply coupled with hydrological and meteorological data (real-time rainfall intensity) at the algorithmic level, and EC is introduced. obs As a safety correction, when The water quality feedback item can independently trigger high-risk strategies. Compared with existing technologies, it can accurately eliminate ineffective treatment conditions such as "fertilizer-free rainfall" and significantly extend the life of adsorption materials.

[0099] (2) The structure of the purification device integrating "drawer-type quick exchange" and "falling water reoxygenation".

[0100] The primary adsorption tank adopts a side-sliding drawer-type filter cartridge structure, solving the engineering pain point of difficulty in replacing saturated adsorption packing. A porous cascading reoxygenation disc 704 is installed at the connection between the primary adsorption tank and the secondary biological treatment tank, utilizing gravitational potential energy to achieve non-powered aeration, solving the problem of insufficient dissolved oxygen for biological denitrification in flooded environments. Within the secondary biological treatment tank, an aerobic nitrification zone and anoxic denitrification zone are sequentially formed along the water flow direction, utilizing the concentration gradient formed by the natural consumption of dissolved oxygen along the flow path to achieve denitrification within the same tank. Furthermore, the primary adsorption tank is equipped with a bypass channel, allowing drainage water exceeding the allowable flow rate to bypass the adsorption filter cartridges and directly enter the ecological ditch 8, protecting the filter cartridges while ensuring drainage safety under extreme rainfall.

[0101] (3) "Model-driven + feedback correction" dual closed-loop control logic.

[0102] PRI is calculated at the input via a dependency model, and at the output via EC. obs Real-time monitoring values ​​are used for weight correction. This retains the low-cost advantage of model prediction (no need for expensive online nitrogen and phosphorus analyzers) while preventing the risk of direct discharge due to farmers' failure to report fertilizer application through the "one-vote veto" mechanism of conductivity sensor 4.

[0103] (4) A three-level dynamic diversion strategy based on PRI threshold: interception-elimination-use.

[0104] Set PRI dual threshold ( The governance model is divided into three modes: high-efficiency purification, ecological absorption, and recycling. This realizes the transformation from simply "meeting emission standards" to "resource utilization," maximizing the conservation of irrigation water resources while ensuring environmental safety.

[0105] In summary, this invention constructs a dynamic management and control system driven by agricultural biochemical mechanisms. Unlike existing technologies that rely solely on passive management based on physical parameters (rainfall or water level), this invention innovatively couples the pollution source attenuation law after agricultural fertilization (pollutants decay exponentially over time), the effects of rainfall runoff transport, and online water quality feedback. It establishes a multi-source data fusion-based pollution output risk index calculation model and sets up an EC anomaly forced interception mechanism to ensure a safety net in case of missing fertilization information. This enables accurate identification and classification of "high-risk runoff with fertilization" and "low-risk runoff without fertilization," achieving efficient purification of high-pollution output risk, ecological absorption of medium-risk runoff, and reuse of low-risk fertile water. Based on this, combined with the original integrated hardware device of "drawer-type adsorption + cascading reoxygenation", the engineering pain points of traditional facilities in agricultural field environments, such as easy clogging, difficult maintenance and failure due to lack of oxygen, have been solved. Finally, a set of intelligent management and control solutions has been formed that integrates "quantitative identification of source risks, three-level dynamic diversion in the process and closed-loop reuse of fertilizer and water at the end", which significantly improves the non-point source pollution reduction rate while greatly reducing operation and maintenance costs and resource waste.

[0106] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A spatiotemporally dynamic graded pollution interception system for paddy field drainage, characterized in that, include: The system includes a real-time rainfall intensity monitoring device, a field surface water level gauge installed at the outlet of the paddy field, a real-time drainage water quality monitoring device, a control terminal, and an intelligent three-way diversion valve installed at the end of the main drainage pipe. The intelligent three-way diversion valve's first diversion path is connected to a series-connected modular purification device via a mass flow controller, its second diversion path is connected to an ecological ditch, and its third diversion path is connected to the irrigation canal of the paddy field via a return pump station. The control terminal is electrically connected to the real-time rainfall intensity monitoring device, the field surface water level gauge, and the real-time drainage water quality monitoring device to acquire data. It generates a control strategy based on a built-in pollution output risk index calculation model, controlling the intelligent three-way diversion valve connected to it to guide the corresponding diversion path, the return pump station, and the mass flow controller. The monitoring data from the real-time drainage water quality monitoring device includes conductivity values. The pollution output risk index calculation model determines the pollution output risk index based on the last fertilization interval, real-time rainfall intensity, and conductivity values. The series-connected modular purification device includes a primary adsorption tank and a secondary biochemical tank arranged in a stepped manner. The primary adsorption tank is equipped with a water flow buffer device, multiple extractable adsorption filter cartridges, and a cascading reoxygenation disc along the water flow direction. The cascading reoxygenation disc is located at the vertical connection between the two tanks. The secondary biochemical tank includes an aerobic nitrification zone for nitrogen removal, and its discharge port is connected to the external environment.

2. The spatiotemporal dynamic graded sewage interception system for paddy field drainage according to claim 1, characterized in that, The water flow buffer device uses a pre-overflow buffer weir, which is located near the inlet of the primary adsorption tank, dividing the primary adsorption tank into an inlet buffer side and a filter cartridge treatment side. After the return water in the first diversion path enters the inlet buffer side through the inlet, when the liquid level on the inlet buffer side reaches the weir crest elevation of the pre-overflow buffer weir, the return water crosses the pre-overflow buffer weir and enters the filter cartridge treatment side, and flows through multiple extractable adsorption filter cartridges in sequence.

3. The spatiotemporal dynamic graded sewage interception system for paddy field drainage according to claim 2, characterized in that, Multiple removable adsorption filter cartridges are installed on the side wall of the filter cartridge processing side by sliding rails. The removable adsorption filter cartridges are filled with modified biochar bags. The secondary biochemical tank includes an upstream aerobic nitrification zone and a downstream anoxic denitrification zone. The aerobic nitrification zone is filled with porous suspended balls or volcanic rock packing, and the anoxic denitrification zone is filled with porous suspended balls or volcanic rock packing, as well as anaerobic microorganisms.

4. The spatiotemporal dynamic graded pollution interception system for paddy field drainage according to claim 1, characterized in that, The surface of the cascading reoxygenation plate is evenly distributed with multiple sets of sieve holes; the real-time rainfall intensity monitoring device uses a rain gauge or soil moisture sensor, or adopts the API real-time data interface of the local meteorological station to obtain the real-time rainfall intensity.

5. The spatiotemporal dynamic graded sewage interception system for paddy field drainage according to claim 1, characterized in that, If the pollution output risk index is greater than or equal to the high-risk threshold, the control terminal controls the intelligent three-way diversion valve to switch to the first diversion path; If the pollution output risk index is greater than the low risk threshold and less than the high risk threshold; If the pollution output risk index is less than or equal to the low risk threshold and the field water level is greater than or equal to the relatively poor water level, then the control terminal controls the intelligent three-way diversion valve to switch to the second diversion path. If the pollution output risk index is less than or equal to the low-risk threshold and the field water level is less than the relatively poor water level, the control terminal controls the intelligent three-way diversion valve to switch to the third diversion path.

6. The spatiotemporal dynamic graded pollution interception system for paddy field drainage according to claim 1, characterized in that, The water flow buffer device is connected to the ecological ditch through a bypass channel. A controllable valve body is installed in the bypass channel. Under normal operating conditions, the controllable valve body is closed by default. The allowable inflow rate of the series modular purification device is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. When the real-time flow rate entering the series modular purification device exceeds the allowable inflow rate, the controllable valve body opens.

7. A method for spatiotemporal dynamic graded pollution interception of paddy field drainage, implemented based on the spatiotemporal dynamic graded pollution interception system for paddy field drainage as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: The control terminal acquires real-time rainfall intensity, conductivity value, fertilization intensity coefficient, and last fertilization interval t, and combines it with the pollution output risk index calculation model to calculate the current pollution output risk index in real time. Step 2: Determine the relationship between the current pollution output risk index and the preset risk threshold, and generate a dynamic operation strategy accordingly; The dynamic operation strategy includes: a high-efficiency purification strategy, an ecological absorption strategy, and a recycling strategy. If the current pollution output risk index is greater than or equal to the high-risk threshold, a powerful purification strategy will be generated. If the current pollution output risk index is greater than the low risk threshold but less than the high risk threshold; or if the current pollution output risk index is less than or equal to the low risk threshold and the field water level is greater than or equal to the relatively poor water level, then an ecological absorption strategy is generated. If the current pollution output risk index is less than or equal to the low-risk threshold and the field water level is less than the relatively poor water level, then a recycling strategy is generated. Step 3: The control terminal executes the dynamic operation strategy described above. If the strategy generated in step two is a powerful purification strategy, the control terminal controls the intelligent three-way diversion valve to tangent to the first diversion path and starts the mass flow controller to limit the flow rate. The allowable inflow rate is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. The effluent enters the series modular purification device and is purified using adsorption materials. If the strategy generated in step two is an ecological absorption strategy, then the control terminal controls the intelligent three-way diversion valve to switch to the second diversion path, and the water enters the ecological ditch, where plants are used to purify the water. If the strategy generated in step two is a recycling strategy, the control terminal controls the intelligent three-way diversion valve to switch to the third diversion path and starts the return pump station, so that the water flows back to the irrigation canal of the paddy field.

8. The spatiotemporal dynamic graded pollution interception method for paddy field drainage according to claim 7, characterized in that, In step one, the pollution output risk index calculation model is as follows: the pollution output risk index is equal to the product of crop and landform coefficient, fertilization intensity coefficient, real-time rainfall intensity, and pollutant concentration decay over time, plus the product of water quality feedback sensitivity coefficient and real-time conductivity value.

9. The spatiotemporal dynamic graded interception method for paddy field drainage according to claim 7, characterized in that, In step three, when the powerful purification strategy is implemented, after the effluent enters the series modular purification device, the effluent is purified through the following operations in sequence: (1) The effluent enters the water flow buffer device through the inlet, and then passes through multiple extractable adsorption filter cartridges to achieve adsorption and interception of pollutants. (2) The water body falls from the primary adsorption tank to the secondary biochemical tank through the cascading reoxygenation plate, and the dissolved oxygen in the water body increases under the action of the cascading reoxygenation plate and gravitational potential energy; (3) The secondary biochemical tank includes an upstream aerobic nitrification zone and a downstream anoxic denitrification zone. The water body sequentially passes through the aerobic nitrification zone to convert ammonia nitrogen into nitrate nitrogen, and through the anoxic denitrification zone to reduce nitrate nitrogen into nitrogen gas to achieve total nitrogen removal, and is discharged to the external environment from the discharge outlet.

10. The spatiotemporal dynamic graded pollution interception method for paddy field drainage according to claim 7, characterized in that, It also includes the following fault tolerance and safety control: when fertilization information is missing, real-time monitoring data exceeds the effective range, or the conductivity value reaches the abnormal threshold, the control terminal will output a powerful purification strategy by default. The water flow buffer device is connected to the ecological ditch through a bypass channel. A controllable valve is installed in the bypass channel. Under normal operating conditions, the controllable valve is closed by default. The allowable inflow rate of the series modular purification device is determined according to the effective volume of the series modular purification device and the preset hydraulic residence time. When the real-time flow rate entering the series modular purification device exceeds the allowable inflow rate, the controllable valve opens, and the excess water is discharged into the ecological ditch through the bypass channel.

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