Experimental device and experimental method for simulating nitrogen and phosphorus release of water sediment

Abstract

The invention belongs to the technical field of environmental engineering, and discloses an experimental device and an experimental method for simulating nitrogen and phosphorus release of water body sediments. The device comprises an experiment main body unit, an environment simulation unit, a water quality regulation and control unit, a mobile monitoring unit, an automatic sampling module and an intelligent regulation and control module. Wherein the experiment main body unit is provided with a water tank for accommodating sediments and a water body; the environment simulation unit is integrated with a water flow disturbance assembly, an aeration assembly, an illumination assembly and a heating assembly; the water quality regulation and control unit regulates water chemical parameters; the mobile monitoring unit performs spatial dynamic detection on the water body; the automatic sampling module automatically collects overlying water and interstitial water of the sediment according to a specified time interval; the intelligent regulation and control module coordinates operation of all the units, and multi-scene simulation and closed-loop regulation and control are achieved. Accurate simulation, real-time monitoring and intelligent regulation and control of the migration and release process of the sediment-water interface substance under different environmental conditions can be achieved, and the accuracy and comprehensiveness of experimental data are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering technology, specifically to an experimental apparatus and method for simulating nitrogen and phosphorus release from water sediments. Background Technology

[0002] With the increasing severity of water pollution, eutrophication of nitrogen and phosphorus in lakes, reservoirs, and rivers has become increasingly prominent. As an important reservoir of nutrients in water bodies, sediment releases nitrogen and phosphorus compounds under specific hydrodynamic, dissolved oxygen, temperature, and pH conditions, thus becoming a key endogenous factor influencing the evolution of water quality.

[0003] In research on water pollution mechanisms and remediation, the material exchange process at the sediment-overhead water interface is a crucial link influencing the migration and release of nutrients such as nitrogen and phosphorus. Researchers typically use simulation devices to reproduce the physical, chemical, and biological conditions of natural water bodies. By controlling parameters such as temperature, dissolved oxygen, water flow disturbance, and nutrient concentration, they analyze the contribution and response patterns of sediments to water quality. Existing devices for simulating water sediments include: a tank, an inlet / outlet system, an aeration device, a chemical dosing module, an online monitoring unit, and a sampling device. The tank holds sediments and overhead water and is the main area for material exchange and environmental regulation. The inlet / outlet system regulates water flow and renewal through circulation pumps and pipelines. The aeration device is located at the bottom of the tank to control dissolved oxygen levels. The chemical dosing module quantitatively adds acid, alkali, or nutrient solutions to adjust the physicochemical parameters of the water. The online monitoring unit deploys sensors to monitor indicators such as pH, dissolved oxygen, and redox potential in real time. The sampling device collects water samples. However, the sampling device can only collect water samples from the top of the water body. The test results only reflect the changes in the water body and cannot accurately reflect the material migration and transformation process inside the bottom sediment. The test data has a certain deviation, which affects the reliability of the test results. Summary of the Invention

[0004] This invention provides an experimental apparatus and method for simulating nitrogen and phosphorus release from sediments in water bodies, in order to solve the problem that the test results cannot accurately reflect the migration and transformation process of substances inside the sediment and that the test data are biased.

[0005] In a first aspect, the present invention provides an experimental apparatus for simulating the release of nitrogen and phosphorus from aquatic sediments, comprising: The main experimental unit is a water tank used to contain sediments and water. An environmental simulation unit is used to simulate various environmental conditions in the water tank. It includes: a water flow disturbance component, which is disposed on the side wall of the water tank and whose inlet and outlet ends extend into the water; an aeration component, which is mounted above the water tank and whose aeration end extends into the water; a lighting component, which is disposed on the side wall or top of the water tank; and a heating component, which is attached to the inner wall or bottom of the water tank. A water quality control unit is used to adjust the water quality in the water tank. It includes a dosing component, which is disposed on the outer wall of the water tank and its output end is in fluid communication with the inlet end of the water flow disturbance component. Mobile monitoring units are used for multi-point water quality monitoring. An automatic sampling module includes: a water sampling flow path, the inlet of which extends into the water body and the outlet of which is connected to a sampling terminal; a sediment interstitial water sampling flow path, the inlet of which extends into the sediment and a high-precision injection pump is provided at the inlet; the outlet of the sediment interstitial water sampling flow path is connected to a plurality of first sampling bottles, and the plurality of first sampling bottles are disposed on one side of the outer wall of the water tank. An intelligent control module is installed at the sampling terminal and is electrically connected to the environmental simulation unit, the water quality control unit, the automatic sampling module, and the mobile monitoring unit. The intelligent control module can collect real-time water quality data from the mobile monitoring unit and perform comprehensive analysis in conjunction with the offline analysis results from the automatic sampling module. Based on preset experimental scenarios and control strategies, it can precisely control the operating parameters of the environmental simulation unit and the water quality control unit.

[0006] Beneficial effects The environmental simulation unit can simultaneously reproduce the combined effects of environmental factors such as disturbance, aeration, light, and temperature in a single water tank, creating an experimental environment that closely resembles real hydrodynamic and physicochemical conditions, thereby improving the realism and repeatability of the experiment. The chemical dosing output of the water quality control unit is connected to the water flow disturbance component, ensuring that the added chemicals are fully mixed and evenly diffused in the return water path, achieving precise control of the water's physicochemical conditions. Mobile monitoring units distributed along the inner wall of the tank can collect key parameters such as dissolved oxygen, pH, and redox potential in real time, transmitting the data to the intelligent control module. The intelligent control module automatically adjusts the disturbance intensity, aeration rate, and chemical dosing rate based on the monitoring data, forming an automatic closed-loop control system of monitoring-decision-execution, significantly reducing human intervention errors. The automatic sampling module has both overlying water sampling and sediment interstitial water sampling channels, enabling the collection of water samples from both overlying water and sediment interstitial water. This accurately reflects the dynamic changes in nitrogen and phosphorus migration and release between sediments and at the water interface, improving the representativeness and timeliness of experimental data.

[0007] In one optional embodiment, the sediment interstitial water sampling path includes: multiple sampling tubes, which are spaced apart on the inner wall of the water tank. The bottom end of each sampling tube extends into the sediment, and the top end of each sampling tube is connected to the first sampling bottle via a connecting tube. Each sampling tube has a set of sampling holes, and the depth of the sampling holes on each sampling tube is different. A dialysis membrane is provided on each sampling hole, and a high-precision injection pump is provided inside the sampling tube.

[0008] Beneficial effects High-precision syringe pumps enable continuous collection of interstitial water samples without disturbing the sediments, solving the problem of traditional sampling methods that easily damage the pore structure of sediments and cause overlying water to mix with the interstitial water samples. High-precision syringe pumps can achieve stable extraction of pore water from sediments at low flow rates, significantly improving the accuracy and repeatability of nutrient concentration measurements such as nitrogen and phosphorus.

[0009] In one optional embodiment, the sampling terminal is equipped with a peristaltic pump, and the water sampling flow path and the sediment interstitial water sampling flow path are connected to the peristaltic pump. The peristaltic pump is connected to multiple second sampling bottles through pipelines to quantitatively deliver the collected water samples to each second sampling bottle, thereby realizing automatic and continuous water sampling.

[0010] In one optional embodiment, the water flow disturbance component includes a pumping component, an inlet pipe, and an outlet pipe; the pumping component is fixed to a base on the side wall of the water tank, its inlet end extends into the water body through the inlet pipe, and its outlet end returns to the water body through the outlet pipe; both the inlet pipe and the outlet pipe are equipped with valve bodies for controlling the water flow path and flow rate.

[0011] In one optional embodiment, the dosing assembly includes a dosing tank and a dosing pipe; the dosing tank is located on the outer wall of the water tank and is connected to the outlet pipe through the dosing pipe; the dosing pipe is equipped with the valve body and a flow sensor for precisely controlling the dosage and dosing rate of the chemical solution.

[0012] In one optional embodiment, the aeration assembly includes: an air pump, air pipes, and aeration elements; the air pump is located on one side of the water tank, and multiple aeration elements are connected to the air pipes arranged along the length and / or width of the water tank; the aeration elements are connected to the air pipes via telescopic devices, and their depth in the water can be adjusted according to experimental requirements.

[0013] In one optional embodiment, the mobile monitoring unit includes: a slide rail mounted above the water tank; a water quality monitor movably connected to the slide rail via a sliding base; and a measuring probe connected to the water quality monitor and extending into the water body.

[0014] In one optional embodiment, the bottom of the water tank is provided with a sludge discharge hole and a drain hole, which are used to discharge sediment and overlying water, respectively; the inner wall of the water tank is coated with an anti-biofilm coating to inhibit the formation and adhesion of biofilm during the experiment.

[0015] Secondly, the present invention also provides an experimental method for simulating nitrogen and phosphorus release from aquatic sediments, applied to an experimental apparatus for nitrogen and phosphorus release from aquatic sediments, comprising the following steps: S1: Lay a certain depth of sediment at the bottom of the tank and inject overlying water; S2: Set the target experimental scenario through the intelligent control module, and automatically or manually start the water flow disturbance component, aeration component, lighting component and / or heating component of the environmental simulation unit based on the preset control strategy to simulate the required water environment conditions. S3: Activate the mobile monitoring unit to monitor the environmental parameters of the water body in real time by moving or fixing the water quality monitor and measuring probe, and transmit the monitoring data to the intelligent control module in real time. S4: Based on real-time data or preset programs from the mobile monitoring unit, the intelligent control module controls the dosing component of the water quality control unit to precisely add chemicals to the water body in order to regulate the water quality. S5: Start the automatic sampling module. The intelligent control module controls the water body sampling flow path and the sediment interstitial water sampling flow path to automatically sample according to the preset sampling strategy, and collect the overlying water sample and the sediment interstitial water sample at different depths respectively. S6: The intelligent control module integrates the real-time data from the mobile monitoring unit and the offline analysis results from the automatic sampling module, performs data fusion and comprehensive analysis, and can dynamically adjust the operating parameters of the environmental simulation unit and the water quality control unit. S7: After the experiment, the sediment and the overlying water were discharged through the mud discharge hole and the drain hole at the bottom of the tank, respectively.

[0016] Beneficial effects The mobile monitoring unit monitors key parameters such as dissolved oxygen, pH, and redox potential in the water in real time. The automatic sampling module collects water samples from the top layer of the water body and the interstitial water samples based on the monitoring parameters. The collected water samples can accurately reflect the nitrogen and phosphorus release patterns of the sediments, making the experimental data more accurate. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an experimental device for simulating nitrogen and phosphorus release from water sediments according to an embodiment of the present invention; Figure 2This is a front view of an experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to an embodiment of the present invention; Figure 3 This is a top view of an experimental apparatus for simulating nitrogen and phosphorus release from water sediments, according to an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 11. Water tank; 12. Sludge discharge hole; 13. Drainage hole; 21. Water flow disturbance component; 211. Pumping component; 212. Inlet pipe; 213. Outlet pipe; 214. Valve body; 22. Aeration component; 221. Air pump; 222. Air pipe; 223. Aeration component; 224. Telescopic device; 23. Lighting component; 24. Heating component. 31. Dosing assembly; 311. Dosing tank; 312. Dosing pipe; 41. Slide rail; 42. Water quality monitor; 43. Measuring probe; 51. Water sampling flow path; 52. Sediment interstitial water sampling flow path; 521. Sampling tube; 522. Sampling hole group; 53. Sampling terminal; 54. First sampling bottle. 6. Intelligent control module. Detailed Implementation

[0020] 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. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The following is combined Figures 1 to 3 The following describes embodiments of the present invention.

[0022] According to an embodiment of the present invention, an experimental apparatus for simulating nitrogen and phosphorus release from water sediments is provided, comprising: an experimental main unit, an environmental simulation unit, a water quality control unit, a mobile monitoring unit, an automatic sampling module, and an intelligent control module 6, for accommodating a water tank 11 containing sediments and water; for simulating various environmental conditions within the water tank 11, comprising: a water flow disturbance component 21 disposed on the side wall of the water tank 11, with its inlet and outlet extending into the water; an aeration component 22 mounted above the water tank 11, with its aeration end extending into the water; a lighting component 23 disposed on the side wall or top of the water tank 11; a heating component 24 attached to the inner wall or bottom of the water tank 11; and a chemical dosing component 31 for regulating the water quality within the water tank 11, the chemical dosing component 31 being disposed on the outer wall of the water tank 11, and its output end being fluidly connected to the inlet end of the water flow disturbance component 21. This system is used for multi-point water quality monitoring and includes: a water sampling flow path 51, with its inlet extending into the water body and its outlet connected to a sampling terminal 53; a sediment interstitial water sampling flow path 52, with its inlet extending into the sediment and equipped with a high-precision injection pump at the inlet; the outlet of the sediment interstitial water sampling flow path 52 is connected to multiple first sampling bottles 54, which are located on one side of the outer wall of the water tank 11; and an intelligent control module 6 located at the sampling terminal 53. The intelligent control module 6 is electrically connected to the environmental simulation unit, the water quality control unit, the automatic sampling module, and the mobile monitoring unit. The intelligent control module 6 can collect real-time water quality data from the mobile monitoring unit and can combine the offline analysis results from the automatic sampling module for comprehensive judgment. Based on preset experimental scenarios and control strategies, it can precisely control the operating parameters of the environmental simulation unit and the water quality control unit.

[0023] A base is provided at the bottom of the water tank 11. The water tank 11 has a rectangular structure and is made of transparent tempered glass, with dimensions of 2m long × 2m wide × 1.5m high. The glass thickness is ≥15mm, facilitating observation of the water body and sediment at the bottom. Sediment is laid at the bottom of the water tank 11, and water is added inside the water tank 11. The water flow disturbance component 21 is fixed to one side of the water tank 11, with its inlet / outlet extending from the top of the water tank 11 into the overlying water. It creates a controllable flow field and shear conditions without directly contacting the sediment at the bottom of the tank, simulating natural hydrodynamics caused by wind waves or inflow / outflow. The aeration component 22 is located above the water tank 11, with its aeration end extending into the water body. It is used to regulate the dissolved oxygen level in the water and, in conjunction with the water flow disturbance component 21, to create different mass transfer conditions. The lighting component 23 is also located above the water tank 11, with its luminous surface facing the water surface to simulate day / night light cycles and different light intensity environments. The heating element 24 is connected to the inner wall of the water tank 11 to maintain a constant water temperature.

[0024] The dosing assembly 31 and the water flow disturbance assembly 21 are located on the same side of the water tank 11 and connected to the outer wall of the water tank 11. The outlet of the dosing assembly 31 is connected to the outlet of the water flow disturbance assembly 21, allowing the added chemicals to diffuse rapidly and mix evenly in the water. The dosage is set and recorded by the intelligent control module 6. This embodiment does not limit the specific form of the dosing mechanism or the type of chemical, in order to adapt to different experimental schemes.

[0025] The mobile monitoring unit is used to measure parameters such as dissolved oxygen, pH, temperature, and redox potential in water bodies online. The measurement frequency and data storage of the mobile monitoring unit are managed uniformly by the intelligent control module 6.

[0026] The water sampling flow path 51 extends from the top of the water tank 11 to a predetermined depth of the overlying water to collect the overlying water sample and transport the sample to the sampling terminal 53; the sediment interstitial water sampling flow path 52 extends into the sediment and obtains the pore (interstitial) water sample in the sediment through a high-precision injection pump; the sediment interstitial water sampling flow path 52 is connected to the first sampling bottle 54.

[0027] The intelligent control module 6 is used for setting dosing parameters, displaying water status, and recording experimental data. During the operation of the experimental device, the intelligent control module 6 coordinates the disturbance intensity of the water body, the duration of illumination, the aeration rate, and the heating temperature according to the preset operating condition curve, and archives the monitoring data and sampling control commands.

[0028] In one embodiment, the bottom of the water tank 11 is provided with a mud discharge hole 12 and a drain hole 13, which are used to discharge sediment and overlying water, respectively; the inner wall of the water tank 11 is coated with an anti-biofilm coating to inhibit the formation and adhesion of biofilm during the experiment.

[0029] Specifically, the sludge discharge hole 12 is located at the lowest point of the bottom of the water tank 11 to ensure smooth discharge of sediment; the drain hole 13 is located above the sludge discharge hole 12 to facilitate rapid water discharge. Corrosion-resistant valve assemblies are installed on both holes. The valves can be PTFE ball valves or PVC gate valves, and their opening and closing are controlled by an external knob, ensuring the sealing and safety of the drainage and sludge discharge process. To prevent accidental leakage of sediment or water samples during the experiment, silicone gaskets are used to seal between the valves and the sludge discharge hole 12 and the drain hole 13, facilitating valve disassembly and cleaning while maintaining good airtightness and watertightness.

[0030] To reduce the impact of microbial attachment and algae growth in the water body on the water tank 11, a layer of anti-biofilm coating is uniformly applied to the inner wall and bottom surface of the water tank 11. The coating can be made of siloxane-based or fluorinated polymer-based materials, which have low surface energy and high smoothness, and can effectively inhibit the adhesion and growth of algae, bacteria and biofilm.

[0031] In one embodiment, the water flow disturbance component 21 includes a pumping component 211, an inlet pipe 212, and an outlet pipe 213. The pumping component 211 is fixed to a base on the side wall of the water tank 11, with its inlet end extending into the water body through the inlet pipe 212 and its outlet end returning to the water body through the outlet pipe 213. Both the inlet pipe 212 and the outlet pipe 213 are equipped with valve bodies 214 for controlling the water flow path and flow rate.

[0032] Specifically, a rectangular base is connected to one outer wall of the water tank 11, and a vibration-damping rubber pad is laid on the upper surface of the base to support and fix the water pump 211. The water pump 211 is preferably a small brushless DC water pump, whose inlet end is connected to the inlet pipe 212. The inlet pipe 212 is made of water-resistant PVC or silicone tubing and extends vertically into the overlying water from the top of the water tank 11 to ensure that the water intake is always below the water surface and does not come into contact with sediment.

[0033] The drain end of the pumping unit 211 is connected to the outlet pipe 213. The outlet pipe 213 also extends into the water body from the top of the water tank 11 and is arranged tangentially along the water tank 11 below the water surface via a 45° elbow or flat nozzle, so that the water jet forms a directional circulation below the water surface, creating a controllable flow rate in the water body without touching the bottom sediment. A ball valve is connected in series on the outlet pipe 213 to regulate the start and stop of the water flow and the water flow rate. The valve body 214 is connected to the outlet pipe 213 via a quick-connect coupling or clamp for easy disassembly and cleaning. To avoid suspending sediment, the outlet maintains an appropriate vertical distance from the sediment surface. When a weak water flow disturbance is needed in the water body, the outlet height can be increased or the valve opening can be decreased. When a stronger disturbance is needed, the outlet height can be appropriately lowered or the pump speed and valve opening can be increased.

[0034] When the water flow disturbance component 21 is running, the pumping unit 211 is first activated, allowing water to be drawn in through the inlet pipe 212 and ejected through the outlet pipe 213, forming a closed loop of water being drawn from and flowing back into the water body. The flow rate is adjusted by the ball valve on the outlet pipe 213, and the orientation and height of the outlet are also adjusted to provide continuous and adjustable disturbance to the water body, thus reproducing the hydrodynamic conditions caused by wind waves or other factors while maintaining the stability of the sediment surface structure.

[0035] In one embodiment, the dosing assembly 31 includes a dosing tank 311 and a dosing pipe 312; the dosing tank 311 is located on the outer wall of the water tank 11 and is connected to the outlet pipe 213 through the dosing pipe 312; the dosing pipe 312 is equipped with a valve body 214 and a flow sensor for precisely controlling the amount and rate of drug dosing.

[0036] Specifically, the dosing tank 311 is fixed to the base and is located on the same side as the pump 211. The top of the dosing tank 311 is equipped with a sealing cap and a vent. The dosing pipe 312 is a corrosion-resistant flexible hose. One end passes through the sealing cap from the top of the dosing tank 311 and extends downwards into the chemical solution, maintaining a certain distance from the bottom of the dosing tank 311 to avoid drawing in bottom sediments. The other end is connected to the outlet pipe 213 of the water flow disturbance component 21, allowing the chemical solution to be injected into the water while the water flow disturbance component 21 is operating. The valve body 214 is used for fine-tuning and controlling the dosing flow rate; a corrosion-resistant regulating valve is preferred. A flow sensor monitors the dosing flow rate of the dosing pipe 312.

[0037] In one embodiment, the aeration assembly 22 includes: an air pump 221, an air pipe 222, and an aeration element 223; the air pump 221 is located on one side of the water tank 11 and is connected to multiple aeration elements 223 through multiple air pipes 222 arranged along the length and / or width of the water tank 11; the aeration element 223 is connected to the air pipe 222 through a telescopic device 224, and its depth in the water can be adjusted according to experimental requirements.

[0038] Specifically, the air pump 221 is located on one side of the water tank 11, and multiple air pipes 222 at the top of the water tank 11 are interconnected. The output end of the air pump 221 is connected to one of the air pipes 222. The air pipes 222 are preferably made of aging-resistant silicone or polyurethane flexible tubing. To ensure stable installation, a pressure block and a clip are installed at the top of the air pipe 222 to prevent displacement. Multiple aeration elements 223 are fixedly connected to the bottom of each air pipe 222 along its length. The aeration elements 223 are either aeration stones or aeration heads, which extend into the water to a depth of 20-30 cm to allow air bubbles to diffuse evenly within the water. A certain distance is maintained between the bottom surface of the aeration element 223 and the surface of the sediment to prevent the air bubbles generated by the aeration element 223 from affecting the sediment.

[0039] The fixed end of the telescopic device 224 is connected to the bottom end of the air pipe 222, and the telescopic end is connected to the aeration element 223. The telescopic device 224 has a through hole along its length, and a flexible air hose is installed in the through hole. One end of the flexible air hose is connected to the air pipe 222, and the other end is connected to the aeration element 223, ensuring that the gas in the air pipe 222 can be transmitted to the aeration element 223. The telescopic device 224 can be an electric telescopic rod or a pneumatic guide rod.

[0040] In one embodiment, the mobile monitoring unit includes: a slide rail 41 mounted above the water tank 11; a water quality monitor 42 movably connected to the slide rail 41 via a sliding base; and a measuring probe 43 connected to the water quality monitor 42 and extending into the water body.

[0041] Specifically, multiple movable water quality monitors 42 are evenly arranged on the top of the water tank 11. The sensitive ends of the measuring probes 43 face the water body and are led out through watertight cables. The cables are waterproof and connected to the intelligent control module 6, which is electrically connected to the intelligent control module 6. For ease of maintenance, detachable measuring probes 43 can be selected, which can be removed independently for cleaning. This embodiment does not limit the type, quantity, or cable model of the probes, as long as it satisfies the function of evenly arranging the measuring probes 43 and electrically connecting them to the intelligent control module 6.

[0042] In one embodiment, the sediment interstitial water sampling flow path 52 includes: a plurality of sampling tubes 521, which are spaced apart on the inner wall of the water tank 11. The bottom end of the sampling tube 521 extends into the sediment, and the top end of the sampling tube 521 is connected to the first sampling bottle 54 through a connecting tube. Each sampling tube 521 has a set of sampling holes 522, and the sampling holes 522 on each sampling tube 521 have a different depth. A dialysis membrane is provided on the sampling holes, and a high-precision injection pump is provided inside the sampling tube 521.

[0043] Multiple sampling tubes 521 are spaced apart along the inner wall of the water tank 11, with their lower ends passing through the bottom of the water tank 11 and extending into the sediment. The sampling tubes 521 are preferably made of corrosion-resistant material, and their outer walls are connected to the inner wall of the water tank 11 to ensure the stability of the sampling tubes 521 during the experiment, preventing displacement due to water disturbance or sediment changes. Each sampling tube 521 has at least one set of sampling holes along its height on its sidewall, located at the corresponding sediment depth. A dialysis membrane is installed on the outside of the sampling holes. Combined with the extraction by a high-precision syringe pump, the dialysis membrane allows dissolved nitrogen, phosphorus, and other substances in the interstitial water to permeate, while simultaneously blocking sediment particles from entering the sampling tube 521, thereby reducing damage to the original sediment structure. The upper end of the sampling tube 521 is connected to the first sampling bottle 54 via a connecting tube, which is a flexible, corrosion-resistant hose. During the sampling process, a stable micro-negative pressure is formed in the sampling tube 521 by a high-precision injection pump, which allows the pore water of the sediment to enter the interior of the sampling tube 521 through the dialysis membrane and be transported to the first sampling bottle 54 along the sampling flow path, so as to realize continuous or timed collection of pore water at different depths of the sediment.

[0044] A high-precision injection pump is used to collect interstitial water from sediments at preset sampling frequencies (0.5-24 hours / time), with interstitial water collection and overlying water collection occurring at staggered times. When the mobile monitoring unit detects that various data points in the water body reach preset thresholds, the intelligent control module 6 sends a sampling command to trigger interstitial water sampling, collecting the interstitial water and storing it in the first light-protected sampling bottle 54.

[0045] In one embodiment, a peristaltic pump is provided in the sampling terminal 53, and the water sampling flow path 51 is connected to the peristaltic pump. The peristaltic pump is connected to multiple second sampling bottles through pipelines to quantitatively deliver the collected water samples to each second sampling bottle, thereby realizing automatic and continuous sampling of the water.

[0046] Specifically, the sampling terminal 53 is a closed enclosure containing a multi-channel peristaltic pump. The channels of the peristaltic pump are connected to the corresponding water sampling flow path 51. A sampling bottle holder is installed below the peristaltic pump, with multiple second sampling bottles arranged according to channel zones. Each second sampling bottle has a quick-release cap and an independent inlet tube. The inlet tube on each second sampling bottle connects to a single channel within the peristaltic pump, ensuring that water samples enter their respective channel's second sampling bottle without mixing.

[0047] To ensure sampling stability, the peristaltic pump uses a flexible hose that matches the pump head, and the tubing is kept as short and straight as possible to reduce stagnation. The peristaltic pump's inherent unidirectional compression characteristic prevents backflow and ensures quantitative delivery. The intelligent control module 6 controls the start / stop and sampling sequence of the sampling terminal 53. After each sampling, the control module records the bottle position number and the collected volume, and switches to the next empty bottle, enabling multi-bottle dispensing and time-segmented sampling. To reduce air contamination, each channel is filled with liquid and vented before the first run. After sampling, the second sampling bottle is sealed and stored by replacing the cap or affixing a sealing film.

[0048] The intelligent control module 6 sets the timed sampling program and sends it to the sampling control module. The peristaltic pump automatically performs the sampling operation according to the preset time sequence, collects the overlying water sample at the corresponding time point and stores it in the corresponding sampling bottle. The specified time points include all or part of 0.5h, 1h, 1.5h, 2h, 3h, 4h, 5h, 6h, 8h, 10h, 12h, 24h, 36h, 48h, 60h, and 72h. After collection, the second sampling bottle is stored in the sampling terminal 53. According to an embodiment of the present invention, another aspect provides an experimental method for simulating nitrogen and phosphorus release from aquatic sediments, applied to an experimental apparatus for nitrogen and phosphorus release from aquatic sediments, comprising the following steps: S1: Lay a certain depth of sediment at the bottom of the water tank 11 and inject the overlying water; S2: Set the target experimental scenario through the intelligent control module 6, and automatically or manually start the water flow disturbance component 21, aeration component 22, lighting component 23 and / or heating component 24 of the environmental simulation unit based on the preset control strategy to simulate the required water environment conditions. S3: Activate the mobile monitoring unit to monitor the environmental parameters of the water body in real time via the water quality monitor 42 and the measuring probe 43, and transmit the monitoring data to the intelligent control module 6 in real time. S4: Based on real-time data or preset programs from the mobile monitoring unit, the intelligent control module 6 controls the dosing component 31 of the water quality control unit to precisely add chemicals to the water body in order to regulate the water quality. S5: Start the automatic sampling module. The intelligent control module 6 controls the water body sampling flow path 51 and the sediment interstitial water sampling flow path 52 to automatically sample according to the preset sampling strategy, and collect the overlying water sample and the sediment interstitial water sample at different depths respectively. S6: The intelligent control module 6 integrates the real-time data of the mobile monitoring unit and the offline analysis results of the automatic sampling module, performs data fusion and comprehensive analysis, and can dynamically adjust the operating parameters of the environmental simulation unit and the water quality control unit. S7: After the experiment, the sediment and the overlying water are discharged through the mud discharge hole 12 and the drainage hole 13 at the bottom of the water tank 11, respectively.

[0049] Specifically, sediment was evenly spread at the bottom of tank 11, and deionized water was added to tank 11. After standing for 1 hour to remove air bubbles, the environmental simulation unit was activated: water flow disturbance was used to establish a flow velocity of approximately 0.05 m / s in the water body, aeration was performed at a low intensity to gradually increase dissolved oxygen to (6.0±0.5) mg / L, and light was applied in a 12-hour light / 12-hour dark cycle. Heating was used to stabilize the water temperature at (25±1)℃. Subsequently, the mobile monitoring unit was activated to collect parameters such as dissolved oxygen, pH, temperature, and redox potential in real time, and threshold conditions (ORP≥50 mV or pH change ≥8.5) were set in the intelligent control module 6. At the same time, the sampling plan and sampling bottle number table were imported into the intelligent control module 6. The water quality control unit added acid and alkali reagents to the water body according to the preset program of the intelligent control module 6. The water quality control unit was not linked with the threshold trigger logic to ensure the authenticity of the experimental data. The water flow disturbance component 21 and the aeration component 22 will stop working 30 minutes before sampling, and then the sampling work will be carried out. Under the instructions of the intelligent control template, the automatic sampling module will collect water samples of the water body overlying on the water body and water samples of the sediment gaps at regular intervals, and save the water samples to the sampling terminal 53.

[0050] The intelligent control module 6 reads the water monitoring data transmitted from the mobile monitoring unit at a cycle of 1–5 seconds to determine whether to trigger priority sampling. When any monitoring parameter meets the threshold conditions set by the intelligent control module 6, the system automatically issues a priority sampling command and prioritizes the collection of interstitial water in sediments. The automatic sampling module sequentially opens the interstitial water sampling flow path 52, and a high-precision injection pump continuously draws interstitial water samples at a pressure of -10 kPa for 5 minutes, recording the channel number, timestamp, and bottle position number. After the interstitial water collection is completed and reset, the water sampling flow path 51 is restarted to collect overlying water samples. The entire process is a step-by-step, asynchronous collection to avoid mutual interference. If the water monitoring parameters continuously meet the priority sampling threshold, the intelligent control module 6 can repeat the priority collection process of interstitial water at a preset minimum interval (e.g., ≥10 min) to capture the material migration and transformation processes inside the sediment. During sampling, the intelligent control module 6 automatically associates and archives monitoring data with each sampling event for a storage period of ≥3 years. It employs timestamp encryption chain technology to ensure data integrity and is equipped with a timeline backtracking tool, supporting rapid location of key nodes by event tags (equipment failure, sudden water quality changes, human intervention). Simultaneously, the intelligent control module 6 establishes a one-to-one correspondence between "parameter trajectory and sampling bottle" and uploads monitoring data and various parameters to a cloud platform in real time for analysis.

[0051] Once the predetermined experimental duration (e.g., 24 h or 48 h) is reached, the environmental simulation unit, water quality control unit, and mobile monitoring unit are stopped sequentially. The sampling flow path is rinsed with clean water, the sampling bottles are sealed, and the data is exported. Subsequently, the overlying water and sediment are discharged through the drain hole 13 and the sludge discharge hole 12, respectively, completing one experimental cycle.

[0052] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An experimental apparatus for simulating nitrogen and phosphorus release from water sediments, characterized in that, include: The main experimental unit is a water tank (11) used to contain sediments and water. An environmental simulation unit is used to simulate various environmental conditions in the water tank (11), and includes: a water flow disturbance component (21) disposed on the side wall of the water tank (11), with its inlet and outlet extending into the water body; an aeration component (22) mounted above the water tank (11), with its aeration end extending into the water body; a lighting component (23) disposed on the side wall or top of the water tank (11); and a heating component (24) attached to the inner wall or bottom of the water tank (11). A water quality control unit is used to adjust the water quality in the water tank (11). It includes a dosing component (31), which is disposed on the outer wall of the water tank (11) and its output end is in fluid communication with the inlet end of the water flow disturbance component (21). Mobile monitoring units are used for automatic monitoring of water quality at multiple locations and for multiple indicators. The automatic sampling module includes: a water sampling flow path (51), whose inlet end extends into the water body and whose outlet end is connected to a sampling terminal (53); a sediment interstitial water sampling flow path (52), whose inlet end extends into the sediment and is equipped with a high-precision injection pump at the inlet end; the outlet end of the sediment interstitial water sampling flow path (52) is connected to a plurality of first sampling bottles (54), and the plurality of first sampling bottles (54) are disposed on one side of the outer wall of the water tank (11); The intelligent control module (6) is located in the sampling terminal (53). The intelligent control module (6) is electrically connected to the environmental simulation unit, the water quality control unit, the automatic sampling module, and the mobile monitoring unit. The intelligent control module (6) can collect real-time water quality data from the mobile monitoring unit and can make a comprehensive judgment by combining the offline analysis results of the automatic sampling module. Based on the preset experimental scenario and control strategy, the intelligent control module (6) can accurately control the operating parameters of the environmental simulation unit and the water quality control unit.

2. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The sediment interstitial water sampling flow path (52) includes: multiple sampling tubes (521), which are spaced apart on the inner wall of the water tank (11). The bottom end of each sampling tube (521) extends into the sediment, and the top end of each sampling tube (521) is connected to the first sampling bottle (54) through a connecting tube. Each sampling tube (521) has a set of sampling holes (522) with different depths. A dialysis membrane is provided on each sampling hole, and a high-precision injection pump is provided inside each sampling tube (521).

3. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The sampling terminal (53) is equipped with a peristaltic pump. The water sampling flow path (51) is connected to the peristaltic pump. The peristaltic pump is connected to multiple second sampling bottles through pipelines to quantitatively transport the collected water samples to each of the second sampling bottles, thereby realizing automatic and continuous sampling of the water.

4. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The water flow disturbance component (21) includes a pump (211), an inlet pipe (212), and an outlet pipe (213). The pump (211) is fixed on the base of the side wall of the water tank (11). Its inlet end extends into the water body through the inlet pipe (212), and its outlet end returns to the water body through the outlet pipe (213). Both the inlet pipe (212) and the outlet pipe (213) are equipped with valve bodies (214) for controlling the water flow path and flow rate.

5. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 4, characterized in that, The dosing assembly (31) includes a dosing tank (311) and a dosing pipe (312); the dosing tank (311) is located on the outer wall of the water tank (11) and is connected to the outlet pipe (213) through the dosing pipe (312); the dosing pipe (312) is equipped with the valve body (214) and a flow sensor for precisely controlling the amount and rate of drug addition.

6. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The aeration assembly (22) includes: an air pump (221), an air pipe (222), and an aeration element (223); the air pump (221) is located on one side of the water tank (11), and multiple aeration elements (223) are connected by multiple air pipes (222) arranged along the length and / or width of the water tank (11); the aeration element (223) is connected to the air pipe (222) through a telescopic device (224), and its depth in the water can be adjusted according to experimental requirements.

7. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The mobile monitoring unit includes: a slide rail (41) mounted above the water tank (11); a water quality monitor (42) movably connected to the slide rail (41) via a sliding base; and a measuring probe (43) connected to the water quality monitor (42) and extending into the water body.

8. The experimental apparatus for simulating nitrogen and phosphorus release from water sediments according to claim 1, characterized in that, The bottom of the water tank (11) is provided with a mud discharge hole (12) and a drain hole (13), which are used to discharge sediment and overlying water, respectively; the inner wall of the water tank (11) is coated with an anti-biofilm coating to inhibit the formation and adhesion of biofilm during the experiment.

9. An experimental method for simulating nitrogen and phosphorus release from aquatic sediments, applied to the experimental apparatus for simulating nitrogen and phosphorus release from aquatic sediments as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Lay a certain depth of sediment at the bottom of the water tank (11) and inject the overlying water; S2: Set the target experimental scenario through the intelligent control module (6), and automatically or manually start the water flow disturbance component (21), aeration component (22), light component (23) and / or heating component (24) of the environmental simulation unit based on the preset control strategy to simulate the required water environment conditions; S3: Start the mobile monitoring unit, and use the water quality monitor (42) and measuring probe (43) to monitor the environmental parameters of the water body in real time by moving or fixing the point, and transmit the monitoring data to the intelligent control module (6) in real time. S4: Based on the real-time data or preset program of the mobile monitoring unit, the intelligent control module (6) controls the dosing component (31) of the water quality control unit to accurately add chemicals to the water body to regulate the water quality; S5: Start the automatic sampling module. The intelligent control module (6) controls the water body sampling flow path (51) and the sediment interstitial water sampling flow path (52) to automatically sample according to the preset sampling strategy, and collect the overlying water sample and the sediment interstitial water sample at different depths respectively. S6: Intelligent control module (6) integrates the real-time data of the mobile monitoring unit and the offline analysis results of the automatic sampling module to perform data fusion and comprehensive analysis, and can dynamically adjust the operating parameters of the environmental simulation unit and the water quality control unit; S7: After the experiment, the sediment and the overlying water were discharged through the mud discharge hole (12) and the drainage hole (13) at the bottom of the water tank (11).

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