A device and method for simulating sediment resuspension under hydrodynamic conditions

Abstract

This invention provides a device and method for simulating sediment resuspension under hydrodynamic action, relating to the field of sediment simulation. Addressing the problem that current wave-generating simulations of dynamic disturbances easily lead to the breakage of suspended particles, this invention simulates the action of water flow in a natural river by installing baffles within the water tank cavity to form multiple flow channels. The segmented circulation of water flow simulates the sediment resuspension process. When the grid blades agitate the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow. The originally concentrated impact force is dispersed to various parts of the grid, and when it is transmitted to the suspended particles, the magnitude and concentration of the force are significantly reduced, preventing the particles from breaking due to excessive external force.

Description

Technical Field

[0001] This invention relates to the field of sediment simulation, and more specifically to a device and method for simulating sediment resuspension under hydrodynamic conditions. Background Technology

[0002] Sediments are a crucial destination and reservoir for pollutants in rivers. However, due to hydrodynamic forces, sediments can be resuspended, forming suspended particulate matter (SPM) and re-releasing pollutants. SPM shares similar structure and composition with sediments, containing various particulate inorganic minerals and organic matter. Pollutants can also bind to SPM through a series of physical, chemical, and biological processes. More importantly, SPM has better exchange characteristics with the overlying water than sediments. Pollutants entering the water may first be adsorbed by SPM and undergo complex environmental behaviors influenced by hydrochemical conditions, thereby altering the distribution and final fate of pollutants in the aquatic environment. Therefore, studying the resuspension process of sediments under hydrodynamic influence is of great significance.

[0003] Currently, two main methods are commonly used to investigate sediment resuspension processes under hydrodynamic forces: in-situ field measurements and laboratory simulations. Field observations, due to the uncontrollable nature of water flow magnitude and the intensity and duration of biological disturbance, often result in highly random variations in the obtained results, limiting theoretical analysis and thus their application is relatively limited. In contrast, laboratory simulations are more frequently conducted, employing three types of devices: triangular flasks, straight tubes, and flumes. These devices include triangular flasks, cylindrical flumes, annular flumes, and other types of straight flumes. Triangular flask sediment resuspension devices can simulate the natural sediment resuspension process in the laboratory. By loading a certain amount of sediment and water sample into the triangular flask, disturbance is generated through stirring or agitation to simulate sediment erosion. Straight tube resuspension devices place the sediment at the bottom and use oscillating grids, pistons, propellers, etc., to create water disturbance, causing the sediment to resuspend and release pollutants. Annular or straight flumes use pumps, wavemakers, and blowers to generate directional flow of overlying water, causing bottom sediment resuspension. Among these three methods and devices, the triangular flask and straight pipe types have limited volume and their hydrodynamic disturbance mechanisms differ greatly from the actual situation, failing to reflect the flow field of real water bodies and the resuspension and release of bottom sediment pollutants. Therefore, they have considerable limitations and cannot study the quantitative relationship between hydrodynamics, sediment resuspension, and pollutant release. The flume type simulates natural water bodies and is closer to the actual situation. Chinese patent (publication number CN106840600B, publication date 20170613) discloses a ring flume device for simulating sediment resuspension under the influence of seabed seepage. It generates water flow at different velocities through a generator and rotating rollers. The water flow acts on the soil bed in the flume, causing the surface sediments to be resuspended. However, the current flume simulation method uses a wave-generating method to simulate dynamic disturbance, resulting in a complex overall structure. It requires the construction of a closed ring flume, and the impact of the flow-generating rollers can cause the water flow to impact the particles, leading to breakage, affecting particle aggregation, and changing the physical properties of suspended particles. This does not match the state of suspended particles under natural conditions, resulting in poor simulation accuracy. Summary of the Invention

[0004] The purpose of this invention is to address the deficiencies of existing technologies by providing a device and method for simulating sediment resuspension under hydrodynamic action. By installing baffles within the cavity of a water tank to form multiple flow channels, the device simulates the flow of water in a natural river. The segmented circulation of water flow simulates the sediment resuspension process. When the grid blades agitate the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow. The originally concentrated impact force is dispersed to various parts of the grid, and when it is transmitted to the suspended particles, the magnitude and concentration of the force are greatly reduced, preventing the particles from breaking due to excessive external force.

[0005] The first objective of this invention is to provide a device for simulating sediment resuspension under hydrodynamic conditions, employing the following scheme:

[0006] include:

[0007] The water tank has an internal cavity, and baffles are installed inside the cavity, forming multiple flow channels that are divided by the baffles.

[0008] The impeller has at least one grid blade that can rotate with the impeller. The grid blade has through holes and extends into the cavity, disturbing the water in the flow channel when it is immersed in the water.

[0009] Furthermore, the impeller is provided with multiple grid blades, which are distributed sequentially upward around the impeller's rotation axis.

[0010] Furthermore, the impeller is connected to the drive element via a coupling, enabling relative rotation between the impeller and the water tank.

[0011] Furthermore, the horizontal cross-section of the cavity inside the water tank is an elongated hole, and the baffle includes an arc-shaped baffle and a flat baffle. The flat baffle is distributed perpendicular to the bottom surface of the cavity, and an arc-shaped baffle is arranged on both ends of the flat baffle. Flow channels are formed between the arc-shaped baffle and the flat baffle, between the flat baffle and the inner wall side of the cavity, and between the arc-shaped baffle and the inner wall side of the cavity.

[0012] Furthermore, the outer convex surface of the arc-shaped baffle is coaxially distributed with the inner concave surface of the adjacent elongated hole end.

[0013] Furthermore, a sampling nozzle is installed on the water tank, the sampling nozzle is connected to the cavity, and a control valve is installed on the sampling nozzle.

[0014] Furthermore, the top of the cavity is open, and the sampling nozzle is located below the water surface inside the flow channel.

[0015] Furthermore, the through holes are arrayed on the slatted blades.

[0016] A second objective of this invention is to provide a simulation method for a sediment resuspension simulation device under hydrodynamic action as described in the first objective, comprising:

[0017] Prepare sufficient overlying water and freeze-dried sediment, spread the sediment at the bottom of the cavity, and slowly pour the overlying water into the water tank;

[0018] The impeller rotation disturbs the water in the flow channel through the grid blades, simulating hydrodynamic action, and the addition of antibiotics causes the sediment to be resuspended;

[0019] After the test cycle, samples were taken from the cavity to analyze the suspended particulate matter.

[0020] Furthermore, when the blades with grids are stirring the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow.

[0021] Compared with the prior art, the advantages and positive effects of this invention are:

[0022] To address the issue that current wave-generating simulations of dynamic disturbances can easily lead to the breakage of suspended particles, a new method is proposed. This method involves installing baffles within the water tank to create multiple flow channels that simulate the flow of water in a natural river. The segmented circulation of water simulates the resuspension of sediments. When the grid blades agitate the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow. The originally concentrated impact force is dispersed to various parts of the grid, and when it is transmitted to the suspended particles, the magnitude and concentration of the force are greatly reduced, preventing the particles from breaking due to excessive external force.

[0023] In preventing particle agglomeration, the grid structure makes the water flow around the particles more uniform and stable. Ordinary blade agitation easily creates areas of large localized water flow velocity differences, causing particles to be quickly pushed together and agglomerate. The uniform water flow with grid blades reduces these velocity differences, resulting in more dispersed particle movement in the water and reduced chances of collision and agglomeration. This effectively avoids changes in the physical properties of suspended particles, such as particle size, surface properties, and agglomeration state, more accurately simulating the state of suspended particles in natural environments. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a schematic diagram of the sediment resuspension simulation device under hydrodynamic action after installation in Embodiments 1 and 2 of the present invention.

[0026] Figure 2 This is a schematic diagram of the sediment resuspension simulation device under hydrodynamic action in Embodiments 1 and 2 of the present invention.

[0027] The components include: 1. Water tank; 2. Sampling nozzle; 3. Cavity; 4. Arc-shaped baffle; 5. Flat baffle; 6. Grille blade; 7. Drive element; 8. Controller; 9. Switch; 10. Adjustment knob; 11. Coupling. Detailed Implementation

[0028] Example 1

[0029] In a typical embodiment of the present invention, such as Figures 1-2 As shown, a simulation device for sediment resuspension under hydrodynamic action is presented.

[0030] In studies of sediment resuspension under hydrodynamic conditions, while flume-type simulations closely approximate reality, wave-generating simulations of dynamic disturbances are complex and prone to affecting the physical properties of suspended particles. Therefore, this embodiment provides a sediment resuspension simulation device under hydrodynamic conditions. Baffles are installed in the cavity 3 of the water tank 1 to form multiple flow channels, and an impeller with grid blades 6 is arranged to simulate water disturbance, achieving a sediment resuspension simulation that more closely resembles a natural river environment, while simultaneously preventing suspended particles from breaking due to excessive external forces.

[0031] like Figure 1 As shown, the sediment resuspension simulation device under hydrodynamic action mainly includes a water tank 1 and an impeller. A cavity 3 is formed inside the water tank 1, and baffles are installed inside the cavity 3 to divide it into multiple flow channels. This simulates the flow conditions in a natural river. The flow of a natural river is influenced by various factors such as riverbed topography and bank shape, resulting in complex flow patterns. By setting baffles in the water tank 1 to form multiple flow channels, the water flow can experience changes in direction and velocity as it flows through different channels, creating a complex flow environment similar to that of a natural river. This provides more realistic hydrodynamic conditions for sediment resuspension, thus more accurately simulating the resuspension process of sediments in a natural river.

[0032] The impeller is equipped with at least one perforated grid blade 6, which extends into the cavity 3 and is immersed in the water. As the impeller rotates, it agitates the water within the flow channel. During this agitation, the grid structure of the blade 6 divides the water flow into multiple smaller streams. When the water flows through the grid, the originally concentrated impact force is dispersed across the grid. Compared to ordinary blades directly stirring the water, the grid blade 6 disperses the force of the water flow, reducing the impact on suspended particles and preventing them from breaking due to excessive external force, thus protecting the physical properties of the suspended particles. The perforations on the blades further increase the dispersion and fluidity of the water flow, making the flow more uniform.

[0033] The multi-segment flow channels formed by the baffles inside tank 1 effectively simulate the complex water flow in natural rivers. Compared with methods such as oscillating, piston, propeller, and annular flumes, this approach more closely approximates the resuspension and release mechanism of sediment pollutants under the action of water flow in natural rivers. It provides a more realistic hydrodynamic environment for sediment resuspension research, making the research results more practically valuable and facilitating in-depth research on the relationship between hydrodynamics, sediment resuspension, and pollutant release. The design with gridded blades 6 successfully prevents suspended particles from breaking due to excessive external forces, maintaining the physical properties of the suspended particles. It accurately simulates the behavior of suspended particles under natural conditions, improving the accuracy and reliability of experimental data. This is of great significance for studying the interaction between pollutants and suspended particles, and also provides a structural basis for conducting high-quality sediment resuspension research at a low cost.

[0034] like Figure 1 As shown, multiple grid blades 6 are arranged circumferentially around the impeller's axis of rotation, enabling more uniform and thorough disturbance of the water. The simultaneous operation of multiple blades increases the contact area and disturbance range with the water, allowing more water to flow per unit time and producing a stronger stirring effect. Compared to a single blade, the circumferential distribution of multiple blades ensures that the water flow experiences a more balanced force in all directions, reducing dead zones and optimizing the flow field distribution. This helps to create a more complex water flow distribution within tank 1, enhancing the simulation of sediment resuspension, improving the accuracy and reliability of the experiment, and making the experimental results more representative of the real-world sediment resuspension situation in natural rivers.

[0035] The coupling 11 connects the impeller and the drive element 7, enabling power transmission between them and allowing the impeller to rotate under the drive element 7. Simultaneously, the coupling 11 has the ability to compensate for misalignment between the two shafts. Due to manufacturing errors, installation errors, or thermal expansion of the shafts, the shafts of the drive element 7 and the impeller may not be perfectly aligned. The coupling 11 can compensate for axial, radial, and angular misalignments, ensuring smooth power transmission. Furthermore, the coupling 11 can absorb vibration and shock, reducing vibration and noise in the transmission system, protecting the drive element 7 and the impeller, and extending the service life of the equipment.

[0036] In this embodiment, the driving element 7 can be an electric motor, which is connected to a controller. The controller is equipped with a switch 9 and an adjustment knob 10. The switch 9 controls the start and stop of the electric motor, and the adjustment knob 10 can adjust the output speed of the electric motor, thereby adjusting the speed of the impeller-driven grid blades 6. At the same time, the controller can also adjust the direction of the impeller, which can ensure that the impeller can operate stably and reliably, providing a continuous and stable hydrodynamic source for sediment resuspension simulation, ensuring the stability of the experimental process, and avoiding deviations in experimental results due to transmission problems.

[0037] like Figure 1 and Figure 2As shown, the horizontal cross-section of the cavity 3 inside the water tank 1 is an elongated oval opening, fitted with an arc-shaped baffle 4 and a flat baffle 5. The water tank 1 is manufactured using acrylic, which is low-cost, corrosion-resistant, and allows for easy observation of water flow characteristics and sediment suspension. It can be connected to various testing instruments and sampling devices. The flat baffle 5 is perpendicular to the bottom surface of the cavity 3, dividing the cavity 3 vertically. The arc-shaped baffle 4, the flat baffle 5, and the inner wall of the cavity 3 form specially shaped flow channels. As the water flows through these channels, its direction and speed constantly change due to the changing channel shape. The convex surface of the arc-shaped baffle 4 is coaxially distributed with the concave surface at the end of its adjacent elongated opening. This design makes the water flow smoother in the arc-shaped area, reducing energy loss and turbulence, ensuring the water flows along a predetermined path, and further simulating the complex and variable water flow conditions in natural rivers. The unique multi-segment flow channel simulates a complex water flow environment more similar to that of a natural river, improving the realism of the simulation of sediment resuspension process and providing more realistic experimental conditions for research.

[0038] A sampling nozzle 2 is installed on water tank 1 and connected to the cavity 3. The sampling nozzle 2 is positioned below the water surface within the flow channel, facilitating water sample collection during device operation. A control valve on the sampling nozzle 2 allows for control of the timing and flow rate of water sample collection, ensuring representative samples are obtained. Sampling below the water surface yields a mixed sample of overlying water and suspended particulate matter, which is used for subsequent analysis of various components (such as pollutant concentrations) to study changes in related substances during sediment resuspension. This enables real-time and convenient water sample collection during experimental operation, providing necessary sample support for research on the migration and transformation of substances during sediment resuspension, facilitating in-depth analysis of experimental data and leading to accurate research conclusions.

[0039] The through-holes are arrayed on the grid blades 6, enhancing their dispersing effect on the water flow. When water flows through the arrayed through-holes, it is broken into more fine water streams, allowing the water to diffuse more evenly into the surrounding water after passing through the blades. This uniform water flow distribution not only reduces the impact force of the water flow on suspended particles but also allows suspended particles in the water to be distributed more evenly, reducing local particle aggregation.

[0040] Specifically, when the grid blades 6 agitate the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow. When the water flows through the grid, the originally concentrated impact force is dispersed to various parts of the grid, and when it is transmitted to the suspended particles, the magnitude and concentration of the force are greatly reduced. When the water flow encounters the horizontal and vertical bars of the grid blades 6, it will be diverted along the perimeter of the bars, preventing a single powerful stream from directly impacting the particles. This dispersion effectively reduces the impact force of the water flow on the suspended particles, preventing the particles from breaking due to excessive external force. In terms of preventing particle agglomeration, the grid structure makes the water flow around the particles relatively more uniform and stable. When ordinary blades agitate, it is easy to create areas with large differences in local water flow velocity, and the particles will be quickly pushed together under the action of velocity difference, resulting in agglomeration. However, the uniform water flow with grid blades 6 reduces this velocity difference, and the particles move more dispersedly in the water, reducing the chance of collision and agglomeration. This effectively avoids changes in the physical properties of suspended particles, such as particle size, surface properties, and agglomeration state, and more accurately simulates the state of suspended particles in the natural environment.

[0041] In this embodiment, when the sediment is released, the biological activity of the sediment is preserved by freeze-drying the sediment, and the original shape of the sediment is also preserved. In addition, the freeze-dried product has a large specific surface area and can be quickly rehydrated.

[0042] Example 2

[0043] In another typical embodiment of the present invention, such as Figure 1 Figure 2 As shown, a simulation method for a sediment resuspension simulation device under hydrodynamic action is presented, which utilizes the sediment resuspension simulation device under hydrodynamic action as described in Example 1.

[0044] A simulation method for a sediment resuspension simulation device under hydrodynamic conditions includes:

[0045] Prepare sufficient overlying water and freeze-dried sediment, lay the sediment at the bottom of cavity 3, and slowly pour the overlying water into water tank 1;

[0046] The impeller rotation disturbs the water in the flow channel through the grid blades 6, simulating hydrodynamic action, and adds chemicals to suspend the sediment;

[0047] After the test cycle, samples were taken from cavity 3 to analyze the suspended particulate matter.

[0048] When the blades with grids 6 are stirring the water, the grid structure divides the water flow into multiple small streams, thus dispersing the force of the water flow.

[0049] Implementation method 1:

[0050] The simulation method is illustrated by taking the effect of different salinity conditions on the adsorption of antibiotics by suspended particulate matter as an example.

[0051] Connect the impeller and drive element 7 using coupling 11, connect drive element 7 and controller via wire, close all valves, turn off switch 9, and set adjustment knob 10 to 0 mark.

[0052] Prepare sufficient amounts of overlying water with different salinities and freeze-dried sediment. Lay the sediment at the bottom of the chamber 3 and slowly pour the overlying water into the tank. The height ratio of sediment to overlying water is 1:10, and the height of the overlying water should not exceed 2 / 3 of the depth of the chamber 3.

[0053] When simulating hydrodynamic action, turn on switch 9, turn on adjustment knob 10 to slowly reach the maximum speed, and after it stabilizes, adjust the antibiotic concentration to 2 mg / L.

[0054] The experiment was conducted in 4-hour cycles. After 4 hours, a water sample containing a mixture of water and particulate matter was taken from sampling nozzle 2. After processing, the concentration of antibiotics in the water sample was detected by high performance liquid chromatography-tandem mass spectrometry to study the effect of suspended particulate matter on antibiotic adsorption under different salinity conditions.

[0055] Implementation Method 2:

[0056] The effects of sediments on antibiotic adsorption under different hydrodynamic conditions were simulated using simulation methods.

[0057] Prepare sufficient top dressing water, using a pre-prepared 2mg / L antibiotic solution.

[0058] The freeze-dried sediment was mixed with the overlying water at a height ratio of 3:10, and the height of the sediment did not exceed the lowest point of the blade rotation.

[0059] After running for 8 hours, the reaction was stopped, and the sediment was removed.

[0060] Adjust the knob to 30 rpm, 60 rpm, and 90 rpm in sequence, and repeat the above steps.

[0061] The concentration of antibiotics in water samples before and after the reaction was determined by solid-phase extraction-liquid chromatography-tandem mass spectrometry to study the adsorption behavior of sediments on antibiotics under different hydrodynamic conditions.

[0062] Implementation Method 3

[0063] The adsorption mechanism of norfloxacin in river sediments was investigated using a simulation method.

[0064] Prepare sufficient overlay water, which is a 0.01 mol / L CaCl2 solution, and norfloxacin concentration is 5 mg / L.

[0065] Take an appropriate amount of freeze-dried sediment and place it at the bottom, add top water, and adjust the rotation speed to make the sediment concentration reach 10g / L.

[0066] The temperature was room temperature, the rotation speed was 90 r / min, and the sampling times were set to 1h, 2h, 4h, 6h, 8h, 12h, 24h, 36h and 48h respectively.

[0067] The concentration of norfloxacin in water samples was determined by solid-phase extraction-liquid chromatography-tandem mass spectrometry.

[0068] Fitting equations: Experimental data were fitted using pseudo-first-order, pseudo-second-order kinetic, and intraparticle diffusion models to obtain adsorption kinetic parameters. These kinetic parameters were then used to explain the adsorption mechanism. The adsorption kinetic model is as follows:

[0069] Pesudo-first-order kinetics model:

[0070] ln(q e -q t 0 = lnq e -k1t

[0071] Taking the logarithm of both sides, we get:

[0072]

[0073] q t (mg / g) and q e (mg / g) represents the solid phase concentration of the solute at time t and adsorption equilibrium, respectively; k1(h-1) is the rate constant of pseudo-first-order adsorption.

[0074] Pesudo-second-order kinetics model:

[0075]

[0076] t / q t As y, t as x yields:

[0077]

[0078] k2 (mg / (kg·h)) is the rate constant for pseudo-secondary adsorption.

[0079] Intra-particle diffusion model:

[0080] q t =k p t 1 / 2 +C

[0081] k p (mg / (kg·h1 / 2)) is the diffusion rate constant within the particle.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for simulating sediment resuspension under hydrodynamic conditions, characterized in that, include: The water tank has an internal cavity with an open top. The sampling nozzle is connected to the cavity and positioned below the water surface in the flow channel. Baffles are installed inside the cavity, forming multiple flow channels that are divided by the baffles. The horizontal cross-section of the cavity inside the water tank is an elongated oval hole. The baffles include arc-shaped baffles and flat baffles. The outer convex surface of the arc-shaped baffles is coaxially distributed with the inner concave surface of the adjacent elongated oval hole end. The flat baffles are distributed perpendicular to the bottom surface of the cavity. Arc-shaped baffles are arranged at both ends of the flat baffles. Flow channels are formed between the arc-shaped baffles and the flat baffles, between the flat baffles and the inner wall of the cavity, and between the arc-shaped baffles and the inner wall of the cavity. The impeller has at least one grid blade that can rotate with the impeller. The grid blade has through holes and extends into the cavity, disturbing the water in the flow channel when it is immersed in the water.

2. The sediment resuspension simulation device under hydrodynamic action as described in claim 1, characterized in that, The impeller is provided with multiple grid blades, which are arranged in a ring upward around the impeller's rotation axis.

3. The sediment resuspension simulation device under hydrodynamic action as described in claim 1 or 2, characterized in that, The impeller is connected to the drive element via a coupling, enabling relative rotation between the impeller and the water tank.

4. The sediment resuspension simulation device under hydrodynamic action as described in claim 1, characterized in that, The water tank is equipped with a sampling nozzle, which is connected to the cavity, and a control valve is installed on the sampling nozzle.

5. The sediment resuspension simulation device under hydrodynamic action as described in claim 1, characterized in that, The through holes are arrayed on the grid blades.

6. A simulation method for a sediment resuspension simulation device under hydrodynamic action, utilizing the sediment resuspension simulation device under hydrodynamic action as described in any one of claims 1-5, characterized in that, include: Prepare sufficient overlying water and freeze-dried sediment. Place the sediment at the bottom of the cavity and slowly pour the overlying water into the water tank. The impeller rotation disturbs the water in the flow channel through the grid blades, simulating hydrodynamic action, and the addition of antibiotics causes the sediment to be resuspended; After the test cycle, samples were taken from the cavity to analyze the suspended particulate matter.

7. The simulation method of the sediment resuspension simulation device under hydrodynamic action as described in claim 6, characterized in that, When the blades with grids are stirring the water, the grid structure divides the water flow into multiple smaller streams, thus dispersing the force of the water flow.

Images