CN115931456A

CN115931456A - Water body micro-plastic fixed-depth acquisition and pretreatment integrated device and use method thereof

Info

Publication number: CN115931456A
Application number: CN202211406892.6A
Authority: CN
Inventors: 白雪; 李畅; 罗丹; 史怡
Original assignee: Hohai University HHU
Current assignee: Hohai University HHU
Priority date: 2022-11-10
Filing date: 2022-11-10
Publication date: 2023-04-07

Abstract

A water body micro-plastic fixed-depth collecting and preprocessing integrated device and a using method thereof comprise a water collecting unit, a precipitation unit, a flotation unit, a digestion unit, an enrichment unit, an air supply unit and an electric control unit, wherein the water collecting unit comprises a water collecting component, and a first flowmeter, a first water pump and a timed water valve which are arranged on the water collecting component; the sedimentation unit comprises a sedimentation tank and a sludge hopper arranged at the bottom of the sedimentation tank; the flotation unit comprises a flotation tank, an aeration disc set, a flotation liquid storage tank, a waste liquid recovery tank, a floating block assembly and a bendable hose; the digestion unit comprises a digestion solution storage tank and a reaction chamber; the enrichment unit includes filter vat, rotatory reposition of redundant personnel subassembly, multistage filter screen. The method can realize the integrated pretreatment of in-situ collection, in-situ separation, flotation, digestion and fractional enrichment of a large amount of micro-plastics at different depths of the water environment, reduce the interference of various environmental factors in the collection, separation, flotation, digestion and fractional enrichment processes, and improve the efficiency and reliability of the micro-plastic pretreatment process.

Description

Water body micro-plastic fixed-depth acquisition and pretreatment integrated device and use method thereof

Technical Field

The invention relates to the technical field of water environment pollutant detection, in particular to a water body micro-plastic fixed-depth acquisition and pretreatment integrated device and a using method thereof.

Background

Since the invention, the large-scale production is started in the 40 th century since the plastics have the excellent characteristics of durability, light weight, corrosion resistance, strong plasticity and the like, the annual yield of the world plastics is dramatically increased from 200 ten thousand tons in 1950 to 4.6 million tons in 2019, and the total global plastic yield is expected to reach 330 million tons in 2050. However, due to the problems of large usage amount of plastic products and poor management, a large amount of plastic in aquatic environment is accumulated and continuously flows into organisms, rivers, lakes, estuaries, coastlines and marine ecological units. Under the influence of various environmental factors such as ultraviolet irradiation, wind power, water flow and the like, the waste plastics are gradually degraded into plastic fragments with smaller sizes. Among them, the micro plastics (plastic fibers, chips, particles, etc. with particle size less than 5 mm) are a persistent organic pollutant that poses a serious threat to human health and ecological units because of their small particles, large amount, wide distribution, easy ingestion by aquatic organisms, stability in the environment and easy migration, and can cause immeasurable damage to water environment and aquatic organisms.

In order to clarify the occurrence level, migration mechanism and ecological environment influence of the micro plastic in the water body environment, scientific and reliable sample collection and pretreatment devices and use methods thereof still need to be further optimized and improved. Firstly, effective collection of water body samples is the basis for carrying out follow-up research work, but the existing sampling device usually only collects micro plastic samples on the surface layer of the water body, for example, the chinese patent application with publication number CN111076976A discloses a synchronous collection system for multi-particle-diameter micro plastics in a blockage-preventing water body, which can synchronously classify and collect the particle diameters of the micro plastics in a large sample water body, but cannot adjust the sampling depth as required, thereby reducing the practicability and the application range of the device. Secondly, the separation and extraction of the micro-plastic in the water environment generally transports the collected sample back to a laboratory for individual processing, so that the accuracy and reliability of the data can be influenced by potential environmental pollution sources in the processes of sample collection, storage, transportation and experiment. In addition, the existing devices for separating micro-plastics have the defects of incomplete separation, complex function operation, narrow application range and the like, for example, the chinese patent application with publication number CN112845522A proposes an integrated device for efficiently separating micro-plastics and desorbing adsorbed pollutant parts in sediments and a use method thereof, which can realize integration of micro-plastic crushing, stirring, digestion, desorption, separation and collection, but only one layer of micro-plastic filter screen is arranged at the separation and collection part, so that micro-plastic separation with different particle sizes cannot be realized according to requirements, and the micro-plastics can be further crushed by crushing and stirring, which is not beneficial to subsequent research, and the recovery rate of samples and the reliability of data can be effectively improved by the integrated operation of micro-plastic fixed-depth in-situ collection and separation and extraction. Therefore, in order to realize collection, in-situ separation, digestion and fractional enrichment of a large amount of micro-plastics in different water depths in different water body environments, the operation is simple and convenient, the reliability and accuracy of data are improved, and the interference of various environmental factors in the collection, in-situ separation, digestion and fractional enrichment processes is reduced, a water body micro-plastic depth-setting collection and pretreatment integrated device which is efficient, accurate, simple to operate, multifunctional and wide in application range is urgently needed.

Disclosure of Invention

The technical problem to be solved is as follows: aiming at the problems in the prior art, the invention provides a depth-fixed collection and pretreatment integrated device for water body micro-plastics and a using method thereof, which can realize in-situ collection and pretreatment of a large amount of micro-plastics at different depths in a water environment, complete a pretreatment integrated process of collection, in-situ separation flotation, digestion and fractional enrichment of water body micro-plastic samples, reduce the interference of various environmental factors in the collection, separation flotation, digestion and fractional enrichment processes, and improve the efficiency and reliability of the micro-plastic pretreatment process.

The technical scheme is as follows: a water body micro-plastic depth-setting acquisition and pretreatment integrated device comprises a water acquisition unit, a precipitation unit, a flotation unit, a digestion unit, an enrichment unit, an air supply unit and an electric control unit;

the water sampling unit comprises a water sampling assembly, a first flowmeter, a first water pump and a timing water passing valve, wherein the first flowmeter, the first water pump and the timing water passing valve are sequentially arranged at the water outlet end of the water sampling assembly;

the sedimentation unit comprises a sedimentation tank and a sludge hopper arranged at the bottom of the sedimentation tank, the sedimentation tank is a vertical sedimentation tank, the sedimentation tank comprises an aerator pipe and a first sludge electromagnetic control valve, the air outlet end of the aerator pipe is arranged in the sedimentation tank, the first sludge electromagnetic control valve is arranged at the bottom of the sedimentation tank, the sludge hopper comprises a first sludge discharge port, the first sludge discharge port is arranged on one side of the bottom of the sludge hopper, the water outlet of the water collection assembly is connected with the top of the sedimentation tank, and the sedimentation unit is used for settling large-scale silt particles in a water sample;

the flotation unit comprises a flotation tank group, an aeration disc group, a flotation liquid storage tank, a waste liquid recovery tank, a flotation block assembly and a bendable hose, the bottom of each flotation tank in the flotation tank group is wedge-shaped, the flotation tank group comprises a first flotation tank, a second flotation tank and a third flotation tank which are communicated side by side in sequence, a sludge electromagnetic control valve II is arranged at the bottom of the first flotation tank, a waste liquid valve I is arranged at the bottom of the second flotation tank, a waste liquid valve II is arranged at the bottom of the third flotation tank, the sludge electromagnetic control valve II, the waste liquid valve I and the waste liquid valve II are used for controlling the discharge of sludge and waste liquid in the flotation tanks, the aeration disc group comprises a first aeration disc group, a second aeration disc group and a third aeration disc group, one aeration disc group is correspondingly distributed on the left side wall of one flotation tank, the flotation liquid storage tank is arranged inside the flotation unit and at the top of the flotation tank, the flotation liquid storage tank comprises a water level sensor I and a plunger I, the first water level sensor is arranged on one side inside the flotation liquid storage tank and used for monitoring the residual amount of the flotation liquid, the first plunger piston is arranged at the top of the flotation liquid storage tank, the flotation liquid storage tank is communicated with the first flotation tank, the second flotation tank and the third flotation tank through pipelines respectively, a first flow control valve, a second flow control valve and a third flow control valve are arranged at the joints respectively and used for controlling the flow velocity and the on-off of the flotation liquid in the pipelines respectively, the waste liquid recovery tank is arranged at the bottom of the flotation tank group and comprises a first sludge discharge port, a first drain pipe and a first drain valve arranged on the first drain pipe, the second sludge discharge port is arranged on one side of the waste liquid recovery tank close to the bottom of the first flotation tank, the first drain pipe is arranged on one side of the waste liquid recovery tank close to the bottom of the third flotation tank, the floating block assembly and the bendable hose are arranged inside the third flotation tank, and the floating block assembly is connected with the liquid inlet end of the bendable hose, absorbing a non-precipitation layer water sample in the third flotation tank through a floating block assembly; the top of the sedimentation tank is communicated with the top of the first flotation tank through a first water pipe, a second water pump and a first water valve are arranged on the first water pipe, and the flotation unit is used for flotation of micro-plastics in a water sample;

the digestion unit comprises a reaction chamber, a support, a flow control valve IV and a digestion solution storage tank arranged at the top of the reaction chamber, the digestion solution storage tank is fixed at the top of the reaction chamber through the support, the bottom end of the digestion solution storage tank is communicated with the top end of the reaction chamber through a pipeline, the flow control valve IV is arranged at a connecting pipeline and used for controlling the flow rate and the on-off state of digestion solution, a plunger II is arranged at the top of the digestion solution storage tank, a water level sensor II is arranged inside (at the bottom end), the reaction chamber comprises a water level sensor III, a motor, a rotating shaft, a stirring paddle, an electric heating rod and a water temperature sensor, the water level sensor III is arranged at the bottom of one side inside the reaction chamber and used for monitoring the water level and preventing dry burning, the motor is arranged outside the reaction chamber, the rotating shaft and the stirring paddle are arranged inside the reaction chamber and used for fully mixing water sample and digestion solution, the reaction efficiency is improved, the rotating shaft is horizontally arranged at the bottom of the water level sensor III, the electric heating rod is arranged inside the reaction chamber and at the bottom of the rotating shaft and used for heating the water sample and digestion solution in the reaction chamber, the motor is respectively electrically connected with the water sample collection unit through a water pump II and a water discharge hose, which are arranged inside the reaction chamber;

the enrichment unit comprises a filter barrel, a rotary distribution component and a multistage filter screen, the filter barrel is a cuboid, three layers of horizontal mounting grooves are formed in the inner wall of the filter barrel, a first mounting groove, a second mounting groove and a third mounting groove are formed in the inner wall of the filter barrel from top to bottom respectively, the multistage filter screen comprises a first-stage filter screen, a second-stage filter screen and a third-stage filter screen, the multistage filter screen is inserted into the filter barrel through the corresponding mounting grooves in an insertion sheet mode, the top center of the filter barrel is communicated with the bottom of the reaction chamber through a water pipe II, a water pump II and a water valve III are arranged on the water pipe II, the rotary distribution component is arranged inside the filter barrel and is connected with the water pipe II, a water discharge pipe II is arranged on one side of the bottom of the filter barrel, a water discharge valve II is arranged on the water discharge pipe II, and the enrichment unit is used for filtering a digested water sample and realizing the graded enrichment of micro-plastics;

the air supply unit is respectively connected with the aeration pipe and the aeration disc set, and a valve is arranged at the tail end of the air supply unit to control the opening and closing of the air flow;

the electronic control unit is electrically connected with the water depth sensor, the flowmeter I, the water pump I, the timing water-through water valve, the sludge electromagnetic control valve I, the water pump II, the water-through valve I, the water level sensor I, the flow control valve II, the flow control valve III, the sludge electromagnetic control valve II, the waste liquid valve I, the waste liquid valve II, the drain valve I, the water pump III, the water-through valve II, the water level sensor II, the flow control valve IV, the water level sensor III, the water temperature sensor, the water pump IV, the water-through valve III and the drain valve II.

Preferably, the water sampling assembly comprises a water sampling water pipe, a sinker, a grid, a clamping groove, a floater, a fishing line and a hook, the grid is connected to the outer side of a liquid inlet end at the bottom of the water sampling water pipe through the clamping groove, the aperture of the grid is not larger than 5mm, the sinker is connected with the lower end of the grid, a water depth sensor is fixedly connected with the outer side of the bottom end of the water sampling water pipe, and the floater is connected with the water sampling water pipe through the hook and the fishing line.

Preferably, the first flotation tank further comprises a guide plate, the guide plate is arranged near the liquid inlet of the first flotation tank and used for preventing a water sample from splashing, a water passing baffle is arranged at the joint of the first flotation tank, the second flotation tank and the third flotation tank, a water passing opening is formed in the water passing baffle and can enable the upper-layer water sample in the upper-layer flotation tank to flow into the lower-layer flotation tank, a first water passing baffle and a first water passing opening are arranged between the first flotation tank and the second flotation tank, and a second water passing baffle and a second water passing opening are arranged between the second flotation tank and the third flotation tank.

Preferably, the floating block assembly comprises a floating block, a magnet block and a plurality of gravity balls, the floating block is sleeved on the outer surface of the liquid inlet end of the bendable hose, the liquid inlet end of the bendable hose is positioned at the upper part of the middle part of the floating block, the magnet block is embedded in the top end of the middle part of the floating block, the gravity balls are movably connected to the two sides of the floating block, and the vertical position of the floating block in a water sample is controlled by adjusting the quantity of the gravity balls; and a strong current magnetic block is fixed on the side wall of the third flotation cell, the strong current magnetic block is in magnetic attraction fit with the magnet block, the strong current magnetic block is electrically connected with the electric control unit, before flotation work is carried out in the third flotation cell, the strong current magnetic block is electrified, the floating block is adsorbed on the strong current magnetic block through the iron block, so that the whole floating block assembly can be fixed on the right side wall of the third flotation cell, when the third flotation cell works to water sample layering, the power supply of the strong current magnetic block is turned off, the floating block falls into an upper non-sedimentation layer and continuously sinks until the floating block falls into a lower sedimentation layer surface, and the non-sedimentation layer is absorbed through a bendable hose to enter the digestion unit.

Preferably, the sedimentation tank further comprises a first pressure balance valve, and the first pressure balance valve is arranged at the top end of the sedimentation tank; the reaction chamber further comprises a second pressure balance valve, and the second pressure balance valve is arranged at the top end of the reaction chamber.

Preferably, the rotary distribution assembly comprises a connector, a water pipe, a rotary seat, a water retaining cover and a spray head, one end of the connector is connected with the water outlet end of the water pipe, the other end of the connector is communicated with the rotary seat through the water pipe which is vertically arranged, the spray head is communicated with the bottom end of the rotary seat, spray holes with the aperture of 2-3 mm are distributed in the water outlet of the spray head, the water retaining cover is arranged above the rotary seat and used for preventing a water sample sprayed by the spray head from splashing outwards, the water sample enters the spray head below through the water pipe and is pushed by the centrifugal action and the reaction force to drive the rotary seat and the spray head arranged on the rotary seat to rotate, so that a non-precipitated water sample layer can be uniformly dispersed to a large extent and enters the multistage filter screen below, and the separation efficiency is effectively improved.

Preferably, fixing frames and handles are arranged on the outer sides of the first-stage filter screen, the second-stage filter screen and the third-stage filter screen, the fixing frames are arranged on the outer edge of the filter screens, the handles are arranged on one sides of the fixing frames, the aperture of the first-stage filter screen is 500-1000 micrometers, the aperture of the second-stage filter screen is 100-200 micrometers, and the aperture of the third-stage filter screen is 10-20 micrometers.

Based on the use method of the integrated device for collecting and pretreating micro-plastic in water body at fixed depth, the steps are as follows:

injecting the flotation solution and the digestion solution into a flotation solution storage tank and a digestion solution storage tank through a first plunger and a second plunger, and opening a first water level sensor and a second water level sensor through an electric control unit to monitor the residual amount of the storage solution; arranging a multi-stage filter screen in a three-stage mounting groove; putting the inlet end of the water sampling assembly into the collected water body, opening a water depth sensor through an electric control unit, and adjusting the length of a water sampling water pipe based on the reading of the water depth sensor to enable the water sampling water pipe to reach the expected depth; opening a first flowmeter, a first water pump and a timing water-through valve through an electric control unit, collecting a water sample, adjusting the flow of the first water pump through the first flowmeter according to a preset sampling amount to enable the flow to be stable at a certain flow, and setting the timing water-through valve to achieve the effect of timing opening and closing;

step two, a water sample firstly enters a precipitation unit, air is supplied to an aeration pipe through an air control unit, the water sample in the precipitation unit is aerated, after the water sample is layered through preliminary aeration and precipitation of the precipitation unit, large-particle impurities are deposited in a precipitation tank, an electric control unit opens a water pump II and a water through valve I, the obtained upper-layer solution enters a flotation unit, and when the impurities are precipitated to a certain amount, a sludge electromagnetic control valve I is opened, so that the deposited impurities enter a sludge hopper;

when a water sample enters the first flotation tank, opening a first flow control valve through an electric control unit to enable flotation liquid to enter the first flotation tank, opening a first aeration disc set through an air control unit, and carrying out aeration flotation on the water sample; when the upper non-precipitation layer solution in the first flotation tank is discharged into a second flotation tank, a second aeration disc set is opened through a pneumatic control unit, when a water sample overflows from the second flotation tank to a third flotation tank, a third aeration disc set is opened through the pneumatic control unit, all stages of aeration disc sets are closed after sufficient aeration flotation, and standing is carried out to enable the water sample to be fully layered; enabling the floating block assembly in the third flotation tank to fall into the upper non-settling layer and continuously sink until the floating block assembly falls onto the surface of the lower settling layer; opening a water pump III and a water valve II through an electric control unit to enable the obtained non-precipitation layer solution to enter a digestion unit through a floating block assembly; after the flotation is finished, opening a sludge electromagnetic control valve II, a waste liquid valve I and a waste liquid valve II through an electric control unit, and enabling waste liquid in the flotation tank group to enter a waste liquid recovery tank;

opening a flow control valve IV, a water level sensor III and a water temperature sensor II through an electric control unit, enabling the digestion solution to enter a reaction chamber, starting a motor to supply power to a stirring paddle and an electric heating rod when the mixed solution of the water sample and the digestion solution is not located in the water level sensor III, heating the mixed solution to a preset temperature, uniformly stirring, closing the motor, and standing for digestion; repeating the steps, and after the water sample is completely digested, opening a water pump IV and a water valve III through the electric control unit to enable the water sample to enter the enrichment unit;

step five, the water sample enters a grading enrichment unit, and after the water sample is divided by the rotary dividing component, the micro plastic with different particle sizes in the water sample is sequentially intercepted by a first-stage filter screen, a second-stage filter screen and a third-stage filter screen in the filter barrel and is continuously enriched; opening a second drain valve through the electric control unit to discharge the filtered water sample;

after a preset sampling amount is reached, closing a water depth sensor, a flow meter I, a water pump I, a timing water-through water valve, a sludge electromagnetic control valve I, a water pump II, a water-through valve I, a water pump III, a water-through valve II, a water level sensor I, a flow control valve II, a flow control valve III, a sludge electromagnetic control valve II, a waste liquid valve I, a waste liquid valve II, a water level sensor II, a flow control valve IV, a water level sensor III, a water temperature sensor II, a water pump IV, a water-through valve III and a drain valve II through an electronic control unit, disassembling a first-stage filter screen, a second-stage filter screen and a third-stage filter screen, and collecting micro-plastics on the filter screens; opening a sludge discharge port to discharge sludge in a sludge hopper; and opening the first drain valve through the electric control unit to drain the waste liquid in the waste liquid recovery tank, and opening the second sludge discharge port to discharge deposited impurities in the waste liquid recovery tank.

Preferably, the digestion solution stored in the digestion solution storage tank is hydrogen peroxide solution, enzyme (proteinase K) solution, acid solution or alkali solution.

Preferably, the flotation solution stored in the flotation solution storage tank is a saturated sodium chloride solution, a saturated zinc chloride solution or a saturated sodium iodide solution.

Has the beneficial effects that:

1) According to the integrated device for depth-fixed collection and pretreatment of the micro-plastic in the water body, the water sample is collected through the water collection unit, the micro-plastic in the water sample is separated through the precipitation unit and the flotation unit, the water sample is subjected to in-situ digestion through the digestion unit, and the micro-plastic is subjected to fractional enrichment through the enrichment unit, so that the integrated process of depth-fixed collection, separation, in-situ digestion and enrichment of the micro-plastic in the water body is completed, the influence of various environmental factors in the processes of sampling, storage, transportation and pretreatment in a laboratory is avoided, the experimental error is effectively reduced, the collection and pretreatment efficiency of a large number of samples is improved, and the integrated device has the advantages of high repeatability, high accuracy, wide application range and the like;

2) According to the integrated device for collecting and pretreating micro-plastics in the water body at the fixed depth, the depth of the water inlet end of the water collecting water pipe is adjusted through the water depth sensor, a large number of water samples in a certain water depth range in the water body can be collected, the occurrence level and the migration rule of the micro-plastics in the vertical direction of the water body can be conveniently researched, large-particle impurities in different water body environments can be preliminarily screened out by selecting a grid specification with the aperture not larger than 5mm, the integrated device is suitable for collecting samples of various water bodies, and the interference of environmental impurities is reduced;

3) According to the depth-fixed collection and pretreatment integrated device for the micro-plastics in the water body, provided by the invention, multiple times of aeration flotation is realized on a water sample through the three-stage flotation tank in the flotation unit, so that the micro-plastics in the water sample can be effectively separated, wherein the floating block assembly is positioned between the upper non-precipitation layer and the lower precipitation layer, so that the precipitation layer substances are prevented from being sucked into the hose, the extraction and separation efficiency of effective samples in supernatant can be improved, and the subsequent grading enrichment effect is improved.

Drawings

FIG. 1 is a schematic structural view of an integrated device for collecting and pretreating micro-plastics in a fixed depth in a water body, provided by the invention;

FIG. 2 is a schematic view of a grid structure;

FIG. 3 is a schematic view of a card slot structure;

FIG. 4 is a schematic view of a slider assembly;

FIG. 5 is a schematic view of a rotary manifold assembly;

FIG. 6 is a schematic view of a strainer insert of the present invention;

in the figure:

11 is a sinker; 12 is a grid; 13 is a card slot; 131 is a screw hole; 14 is a water depth sensor; 151 is a floater; 152 is a fishing line; 153 is a hook; 16 is a water collecting pipe; 17 is a first flowmeter; 18 is a first water pump; 19 is a timing water-through valve;

21 is a sedimentation tank; 22 is an aeration pipe; 23 is a sludge electromagnetic control valve I; 24 is a sludge hopper; 25 is a first pressure balance valve; 26 is a first sludge discharge port; 27 is a water pump II; 28 is a first water passing valve; 29 is a water pipe I;

31 is a guide plate; 32 is a flotation solution storage tank; 321 is a plunger I; 322 is a water level sensor I; 3231 is a first flow control valve; 3232 flow control valve II; 3233 flow control valve III; 3311 is water baffle I; 3312 and making a first water outlet; 3321 is a water passing baffle II; 3322 is water passing hole II; 3411 is a first aeration disc group; 3412 is a second aeration disc group; 3413 is a third aeration disc group; 3421 is the first flotation tank; 3422 is a second flotation tank; 3423 is the third flotation tank; 3431 is a second electromagnetic control valve for sludge; 3432 is waste liquid valve I; 3433 is waste liquid valve II; 35 is a waste liquid recovery tank; 361 is a sludge discharge outlet II; 3621 is a first drain pipe; 3622 is a first drain valve; 37 is a floating block component; 371 is strong electromagnetic block; 372 is a bendable hose; 373 is a floating block; 374, a magnet block; 375 is a gravity ball; 38 is a water pump III; 39 is a water valve II;

41 is a digestion liquid storage tank; 411 is a water level sensor II; 412 is plunger two; 413 is a flow control valve IV; 414 is a support; 42 is a reaction chamber; 421 is a water level sensor III; 4221 is a rotating shaft; 4222 stirring paddle; 4223 is an electric heating rod; 4224 is an electric motor; 423 is a water temperature sensor; 424 is a second pressure balance valve; 47 is a water pump IV; 48 is a water valve III; 49 is a water pipe II;

51 is a filter vat; 52 is a rotating flow-splitting assembly; 521 is a connecting head; 522 is a water delivery pipe; 523 is a rotary seat; 524 is a water retaining cover; 525 is a spray head; 526 is a jet hole; 53 is a primary filter screen; 531 is a first mounting groove; 532 is a fixed frame; 533 is a handle; 54 is a secondary filter screen; 541 is a second mounting groove; 55 is a three-level filter screen; 551 is a third mounting groove; 561 is a drain pipe II; 562 is a second drain valve.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific examples, but the embodiments of the present invention are not limited thereto, and for process parameters not specifically noted, reference may be made to conventional techniques.

The present invention may be understood by those skilled in the art by reference to the following detailed description taken in conjunction with the accompanying drawings, in which it is noted that, for the sake of clarity and conciseness of the drawings, certain elements in the drawings are not necessarily drawn to scale. In addition, the number and size of the elements in the drawings are merely illustrative and are not intended to limit the scope of the present invention.

Example 1

A water body micro-plastic depth-fixed collecting and preprocessing integrated device is shown in figure 1 and comprises a water collecting unit, a precipitation unit, a flotation unit, a digestion unit, an enrichment unit, an air supply unit and an electric control unit.

The water sampling unit comprises a water sampling assembly, a first flowmeter 17, a first water pump 18 and a timing water passing valve 19, wherein the first flowmeter 17, the first water pump 18 and the timing water passing valve 19 are sequentially arranged at a water outlet end of the water sampling assembly, the water sampling assembly comprises a water depth sensor 14, the water depth sensor 14 is arranged at a water sampling end of the water sampling assembly, and the water depth sensor 14 and the water depth sensor are electrically connected with the electric control unit.

The sedimentation unit includes sedimentation tank 21 and locates the sludge bucket 24 of sedimentation tank bottom, sedimentation tank 21 is vertical flow sedimentation tank, and sedimentation tank 21 includes aeration pipe 22 and a mud solenoid electric valve 23, and aeration pipe 22 gives vent to anger the end and locates the inside of sedimentation tank 21, and the bottom of sedimentation tank 21 is located to a mud solenoid electric valve 23, and sludge bucket 24 includes a mud discharge opening 26, a mud discharge opening 26 is located sludge bucket 24 bottom one side, and the water sampling subassembly delivery port is connected with sedimentation tank 21 top, the sedimentation unit is arranged in the large-scale silt granule in the sediment water sample.

The flotation unit comprises a flotation cell group, an aeration disc group, a flotation liquid storage tank 32, a waste liquid recovery pool 35, a flotation block assembly 37 and a bendable hose 372, the bottom of each flotation cell in the flotation cell group is wedge-shaped, the flotation cell group comprises a first flotation cell 3421, a second flotation cell 3422 and a third flotation cell 3423 which are communicated side by side in sequence, a sludge electromagnetic control valve II 3431 is arranged at the bottom of the first flotation cell 3421, a waste liquid valve I3432 is arranged at the bottom of the second flotation cell 3422, a waste liquid valve II 3433 is arranged at the bottom of the third flotation cell 3423, the sludge electromagnetic control valve II 3431, the waste liquid valve I3432 and the waste liquid valve II 3433 are used for controlling the discharge of sludge and waste liquid in the flotation cells, the aeration disc group comprises a first aeration disc group 3411, a second aeration disc group 3412 and a third aeration disc group 3413, one aeration disc group is correspondingly distributed on the left side wall of one flotation cell group, the flotation liquid storage tank 32 is arranged in the flotation cell group and at the top of the flotation cell group 3411, the flotation solution storage tank 32 comprises a first water level sensor 322 and a first plunger 321, the first water level sensor 322 is arranged on one side inside the flotation solution storage tank 32 and is used for monitoring the residual amount of the flotation solution, the first plunger 321 is arranged on the top of the flotation solution storage tank 32, the flotation solution storage tank 32 is respectively communicated with the first flotation cell 3421, the second flotation cell 3422 and the third flotation cell 3423 through pipelines, a first flow control valve 3231, a second flow control valve 3232 and a third flow control valve 3233 are respectively arranged at the joints and are used for controlling the flow rate and the on-off of the flotation solution in the pipelines respectively, the waste liquid recovery tank 35 is arranged at the bottom of the flotation cell, the waste liquid recovery tank 35 comprises a second sludge discharge port 361, a first drain pipe 3621 and a first drain valve 3622 arranged on the first drain pipe 3621, the second sludge discharge port 361 is arranged on one side of the waste liquid recovery tank 35 close to the bottom of the first flotation cell 3421, the first drain pipe 3621 is arranged on one side of the waste liquid recovery tank 35 close to the bottom of the third flotation cell 3423, the floating block assembly 37 and the bendable hose 372 are arranged inside the third flotation tank 3423, the floating block assembly 37 is connected with the liquid inlet end of the bendable hose 372, and a non-sediment layer water sample in the third flotation tank 3423 is absorbed through the floating block assembly 37; the top of the sedimentation tank 21 is communicated with the top of the first flotation tank 3421 through a first water pipe 29, a second water pump 27 and a first water valve 28 are arranged on the first water pipe 29, and the flotation unit is usedAnd (3) floating the micro-plastic in the water sample. Specifically, the flotation unit utilizes flotation liquid and micro plastic (the density is generally 0.8 to 1.4 g/cm) ³ ) The microplastic is floated using a saturated sodium chloride solution (1.2 g/cm) ³ ) Saturated zinc chloride solution (1.6 g/cm) ³ ) Saturated sodium iodide solution (1.57 g/cm) ³ ) And the salt solution is equal. The saturated sodium chloride salt solution is optimal in view of economy and safety.

The digestion unit comprises a reaction chamber 42, a support 414, a flow control valve four 413 and a digestion solution storage tank 41 arranged at the top of the reaction chamber 42, the digestion solution storage tank 41 is fixed at the top of the reaction chamber 42 through the support 414, the bottom end of the digestion solution storage tank 41 is communicated with the top end of the reaction chamber 42 through a pipeline, the flow control valve four 413 is arranged at a connecting pipeline and used for controlling the flow rate and the on-off of digestion solution, a plunger second 412 is arranged at the top of the digestion solution storage tank 41, a water level sensor second 411 is arranged inside (at the bottom end), the reaction chamber 42 comprises a water level sensor third 421, a motor 4224, a rotating shaft 4221, a stirring paddle 4222, an electric heating rod 4223 and a water temperature sensor 423, the water level sensor third 421 is arranged at the bottom of the inner side of the reaction chamber 42 and used for monitoring the water level and preventing the dry burning condition, the motor 4224 is arranged outside the reaction chamber 42, the rotating shaft 4221 and the stirring paddle 4222 are arranged inside the reaction chamber 42 and used for fully mixing a water sample and digestion solution, the stirring paddle 4221 is arranged at the bottom of the reaction chamber and electrically connected with a water sample discharge hose 4238, the water sample collection and the water pump 4221, the water sample discharge hose 4223 are arranged in the reaction chamber, and connected with the water discharge chamber 4221 and the water pump 4224 respectively, and the water sample discharge hose 4238, and the water sample discharge chamber, and the water collection hose 4221. The plunger is used for injecting digestion liquid, the water level sensor is used for monitoring the capacity of the digestion liquid, the digestion liquid directly flows into the reaction chamber through the liquid outlet pipe, in-situ digestion of the micro-plastic sample is realized, and organic matters carried on the surface of the micro-plastic are removed. The water level sensor is used for monitoring the capacity in the reaction chamber, and can avoid the phenomenon of dry burning. The heating rod is used for heating the water sample and the digestion solution in the reaction chamber, and the stirring paddle enables the water sample and the digestion solution to be fully mixed, so that the reaction efficiency is improved. The water temperature sensor is used for monitoring the temperature of a water sample in the reaction chamber and ensuring that the temperature of the water sample is kept in a proper range. The digestion solution is one of hydrogen peroxide solution, enzyme (proteinase K) solution, acid solution or alkali solution, preferably hydrogen peroxide solution with the mass fraction of 30%.

The enrichment unit comprises a filter vat 51, a rotary diversion assembly 52 and a multistage filter screen, the filter vat 51 is a cuboid, the inner wall is provided with three layers of horizontal installation grooves, from top to bottom are a first installation groove 531, a second installation groove 541 and a third installation groove 551 respectively, the multistage filter screen comprises a one-stage filter screen 53, a second-stage filter screen 54 and a third-stage filter screen 55, the multistage filter screen is inserted into the filter vat through corresponding installation grooves in an insertion sheet mode, the top center of the filter vat 51 is communicated with the bottom of the reaction chamber 42 through a water pipe II 49, a water pump IV 47 and a water valve III 48 are arranged on the water pipe II 49, the rotary diversion assembly is arranged inside the filter vat 51 and is connected with the water pipe II 49, a water drain pipe II 561 is arranged on one side of the bottom of the filter vat 51, a water drain valve II 562 is arranged on the water drain pipe II 561, the enrichment unit is used for filtering a digested water sample, and realizing the hierarchical enrichment of micro-plastics.

The air supply unit is respectively connected with the aeration pipe 22 and the aeration disc set, and a valve is arranged at the tail end of the air supply unit to control the opening and closing of the air flow.

The electric control unit is electrically connected with the water depth sensor 14, the flowmeter I17, the water pump I18, the timing water passing water valve 19, the sludge electromagnetic control valve I23, the water pump II 27, the water passing valve I28, the water level sensor I322, the flow control valve I3231, the flow control valve II 3232, the flow control valve III 3233, the sludge electromagnetic control valve II 3431, the waste liquid valve I3432, the waste liquid valve II 3433, the drain valve I3622, the water pump III 38, the water passing valve II 39, the water level sensor II 411, the flow control valve IV 413, the water level sensor III 421, the water temperature sensor 423, the water pump IV 47, the water passing valve III 48 and the drain valve II 562.

step one, injecting the flotation solution and the digestion solution into the flotation solution storage tank 32 and the digestion solution storage tank 41 through a first plunger 321 and a second plunger 412, and opening a first water level sensor 322 and a second water level sensor 411 through an electric control unit to monitor the residual amount of the storage solution; arranging a multi-stage filter screen in a three-stage mounting groove; placing the inlet end of the water collecting assembly into the collected water body, opening the water depth sensor 14 through the electric control unit, placing the inlet end of the water collecting unit into the collected water body, and adjusting the length of a water collecting water pipe based on the reading of the water depth sensor 14 to enable the water collecting water pipe to reach the expected depth; opening a first flowmeter 17, a first water pump 18 and a timing water-through valve 19 through an electric control unit, and collecting a water sample;

step two, a water sample firstly enters a precipitation unit, air is supplied to an aeration pipe 22 through an air control unit, the water sample in the precipitation unit is aerated, after the water sample is layered through preliminary aeration and precipitation of the precipitation unit, large-particle impurities are deposited in a precipitation tank, an electric control unit opens a water pump II 27 and a water valve I28, the obtained upper-layer solution enters a flotation unit, and when the impurities are precipitated to a certain amount, a sludge electromagnetic control valve I23 is opened, so that the deposited impurities enter a sludge hopper 24;

step three, when a water sample enters the first flotation tank 3421, opening a first flow control valve 3231 through an electric control unit to enable flotation liquid to enter the first flotation tank 3421, and opening a first aeration disc set 3411 through an air control unit to perform aeration flotation on the water sample; when the upper non-precipitation layer solution in the first flotation tank 3421 is discharged into the second flotation tank 3422, the second aeration disc set 3412 is opened through the air control unit, when a water sample overflows from the second flotation tank 3422 to the third flotation tank 3423, the third aeration disc set 3413 is opened through the air control unit, and after sufficient aeration flotation, the aeration disc sets of all stages are closed and are kept stand to enable the water sample to be fully layered; the floating block assembly in the third flotation tank 3423 falls into the upper non-settling layer and continues to sink until the floating block assembly falls onto the surface of the lower settling layer; opening a third water pump 38 and a second water valve 39 through an electric control unit to enable the obtained non-precipitation layer solution to enter the digestion unit through the floating block assembly; after finishing the flotation, opening a second sludge electromagnetic control valve 3431, a first waste liquid valve 3432 and a second waste liquid valve 3433 through an electric control unit to enable waste liquid in the flotation tank group to enter a waste liquid recovery tank 35;

step four, opening a flow control valve IV 413, a water level sensor III 421 and a water temperature sensor II 423 through an electric control unit, enabling the digestion solution to enter the reaction chamber 42, starting a motor 4224 to supply power to a stirring paddle 4222 and an electric heating rod 4223 when the mixed solution of the water sample and the digestion solution is beyond the water level sensor III 421, heating the mixed solution to a preset temperature and uniformly stirring, closing the motor 4224, standing and digesting; repeating the steps, and after the water sample is digested, opening a water pump IV 47 and a water valve III 48 through the electric control unit to enable the water sample to enter the enrichment unit;

step five, the water sample enters a grading enrichment unit, and after being divided by the rotary dividing component 52, the micro-plastics with different particle sizes in the water sample are sequentially intercepted and continuously enriched by a first-stage filter screen 53, a second-stage filter screen 54 and a third-stage filter screen 55 in the filter barrel; opening a second drain valve 562 through the electric control unit to discharge the filtered water sample;

step six, after the preset sampling amount is reached, closing the water depth sensor 14, the flowmeter I17, the water pump I18, the timing water-passing water valve 19, the sludge electromagnetic control valve I23, the water pump II 27, the water-passing valve I28, the water pump III 38, the water-passing valve II 39, the water level sensor I322, the flow control valve I3231, the flow control valve II 3232, the flow control valve III 3233, the sludge electromagnetic control valve II 3431, the waste liquid valve I3432, the waste liquid valve II 3433, the water level sensor II 411, the flow control valve IV 413, the water level sensor III 421, the water temperature sensor II 423, the water pump IV 47, the water-passing valve III 48 and the drain valve II 562 through the electric control unit, disassembling the primary filter screen 53, the secondary filter screen 54 and the tertiary filter screen 55, and collecting micro-plastics on the filter screen; opening a first sludge discharge port 26 to discharge sludge in the sludge hopper 24; and opening a first drain valve 3622 through an electric control unit, draining the waste liquid in the waste liquid recovery tank 35, and opening a second sludge discharge port 361 to discharge deposited impurities in the waste liquid.

Example 2

The difference from embodiment 1 is that the water sampling assembly comprises a water sampling pipe 16, a sinker 11, a grating 12 (see fig. 2), a clamping groove 13 (see fig. 3, a screw hole 131 is arranged on the clamping groove 13), a floater 151, a fishing line 152 and a hook 153, wherein the grating 12 is connected to the outer side of the liquid inlet end at the bottom of the water sampling pipe 16 through the clamping groove 13, the aperture of the grating 12 is not more than 5mm, the sinker 11 is connected with the lower end of the grating 12, a water depth sensor 14 is fixedly connected with the outer side of the bottom end of the water sampling pipe 16, and the floater 151 is connected with the water sampling pipe 16 through the hook 153 and the fishing line 152. During the use, adopt among the water unit the sinker can connect in the lower extreme of grid through vertical connecting rope to can change the sinker of different quality according to different sampling depth and water environment, so that the sinker reaches the effect of stabilizing the water unit of adopting. The depth of the water inlet end of the water sampling water pipe is adjusted through the reading of the water depth sensor. Can change grid quantity and aperture according to the water environment of difference to reach the great size impurity in the prefilter sampling water, and block it and alleviate the effect of follow-up processing pressure in whole device outside. The sampling unit provided by the invention can change the sampling depth and is suitable for different sampling water bodies by changing the specification of the grating.

The first flotation tank 3421 further comprises a guide plate 31, the guide plate 31 is arranged near the liquid inlet of the first flotation tank 3421 and used for preventing water samples from splashing, a water passing baffle is arranged at the joint of the first flotation tank 3421, the second flotation tank 3422 and the third flotation tank 3423, a water passing hole is formed in the water passing baffle and can enable the upper-layer water sample in the upper-stage flotation tank to flow into the lower-stage flotation tank, a first water passing baffle 3311 and a first water passing hole 3312 are arranged between the first flotation tank 3421 and the second flotation tank 3422, and a second water passing baffle 3321 and a second water passing hole 3322 are arranged between the second flotation tank 3422 and the third flotation tank 3423.

Referring to fig. 4, the floating block assembly comprises a floating block 373, a magnet block 374 and a plurality of gravity balls 375, the floating block 373 is sleeved on the outer surface of the liquid inlet end of the bendable hose 372, the liquid inlet end of the bendable hose 372 is positioned at the upper part of the middle part of the floating block 373, the magnet block 374 is embedded in the top end of the middle part of the floating block 373, the gravity balls 375 are movably connected to the two sides of the floating block, and the vertical position of the floating block 373 in a water sample is controlled by adjusting the number of the gravity balls 375; and a strong current magnetic block 371 is fixed on the side wall of the third flotation tank 3423, the strong current magnetic block 371 is matched with a magnet block 374 in a magnetic attraction manner, the strong current magnetic block 371 is electrically connected with an electric control unit, before flotation work is carried out in the third flotation tank, the strong current magnetic block is electrified, a floating block is adsorbed on the strong current magnetic block through an iron block, so that the whole floating block assembly can be fixed on the right side wall of the third flotation tank, when the third flotation tank works until water samples are layered, the power supply of the strong current magnetic block is turned off, the floating block falls into an upper non-sediment layer and continuously sinks until the floating block falls onto the surface of a lower sediment layer, and the non-sediment layer is absorbed through a bendable hose and enters the unit.

The sedimentation tank 21 further comprises a first pressure balance valve 25, and the first pressure balance valve 25 is arranged at the top end of the sedimentation tank 21; the reaction chamber 42 further comprises a second pressure balance valve 424, and the second pressure balance valve 424 is disposed at the top end of the reaction chamber 42. The first pressure balance valve and the second pressure balance valve are respectively used for ensuring the safety of the sedimentation tank and the reaction chamber.

Referring to fig. 5, the rotary distribution component 52 includes a connector 521, a water pipe 522, a rotary seat 523, a water retaining cover 524, and a spray head 525, one end of the connector 521 is connected to a water outlet end of a second water pipe 49, the other end is communicated with the rotary seat 523 through the vertically placed water pipe 522, the spray head 525 is communicated with a bottom end of the rotary seat 523, a spray hole 526 with a hole diameter of 2 to 3mm is arranged at a water outlet of the spray head 525, the water retaining cover 524 is arranged above the rotary seat 523, and is used for preventing a water sample sprayed out from the spray head from splashing, the water sample enters the spray head below through the water pipe, and under the pushing of a centrifugal action and a reaction force, the inflowing water sample drives the rotary seat and the spray head arranged thereon to rotate, so that the non-precipitation layer water sample can enter a multistage filter screen below in a uniformly dispersed manner to a large extent, and the separation efficiency is effectively improved.

Referring to fig. 6, fixing frames 532 and handles 533 are arranged outside the first-stage filter screen 53, the second-stage filter screen 54 and the third-stage filter screen 55, the fixing frames 532 are arranged on the outer edge of the filter screens, the handles 533 are arranged on one sides of the fixing frames 532, the aperture of the first-stage filter screen 53 is 500 to 1000 μm, the aperture of the second-stage filter screen 54 is 100 to 200 μm, and the aperture of the third-stage filter screen 55 is 10 to 20 μm.

Based on the use method of the integrated device for collecting and pretreating micro-plastics in the water body at fixed depth, the method comprises the following steps:

injecting the flotation solution and the digestion solution into a flotation solution storage tank and a digestion solution storage tank through a first plunger and a second plunger, and opening a first water level sensor and a second water level sensor through an electric control unit to monitor the residual amount of the storage solution; electrifying the strong electromagnetic block through the electric control unit to enable the floating block assembly to hover on the inner wall of the flotation cell III; the multistage filter screen is hermetically arranged in the three-stage mounting groove from large to small according to the preset aperture;

opening a water depth sensor through an electric control unit, putting an inlet end of a water sampling unit into the collected water body, and adjusting the length of a water sampling water pipe based on the reading of the water depth sensor to enable the water sampling water pipe to reach a preset depth; opening a first flowmeter, a first water pump and a timing water-through valve through an electric control unit, and collecting a water sample; the flow of the first water pump can be regulated to be stable at a certain flow through the first flowmeter according to a preset sampling amount, and the timing water-passing valve is arranged to achieve the effect of timing opening and closing;

the water sample firstly enters the precipitation unit, air is supplied to the aeration pipe through the air control unit, and the water sample in the precipitation unit is aerated; after the water sample is layered through preliminary aeration and sedimentation of the sedimentation unit, large-particle impurities are deposited in a sedimentation tank, an electric control unit opens a water pump II and a water valve I to enable the obtained upper-layer sample to enter a flotation unit, and when the impurities are precipitated to a certain amount, a sludge electromagnetic control valve I is opened to enable the deposited impurities to enter a sludge hopper;

when a water sample enters the first flotation tank, the first flow control valve is opened through the electric control unit to enable flotation liquid to enter the first flotation tank, and the first aeration disc set is opened through the air control unit to conduct aeration flotation on the water sample; when the water sample is full to the water outlet, the upper water sample in the first flotation tank is discharged into the second flotation tank due to the fact that the water level of the water sample continuously enters the water outlet to rise, the second aeration disc set is opened through the pneumatic control unit, when the water sample overflows from the second flotation tank to the third flotation tank through the water outlet, the third aeration disc set is opened through the pneumatic control unit, all stages of aeration disc sets are closed after full aeration flotation, and standing is carried out, so that the water sample is fully layered; the electric control unit is used for turning off the power supply of the strong electromagnetic block, and the floating block assembly in the third flotation tank falls into the upper non-settling layer and continuously sinks until the floating block assembly falls onto the surface of the lower settling layer; opening a third water pump and a second water valve through an electric control unit to enable the obtained non-precipitation layer solution to enter the digestion unit through the floating block assembly; after the flotation is finished, opening a sludge electromagnetic control valve II, a waste liquid valve I and a waste liquid valve II through an electric control unit, and enabling waste liquid in the flotation tank group to enter a waste liquid recovery tank;

opening a flow control valve IV, a water level sensor III and a water temperature sensor II through an electric control unit, enabling digestion liquid to enter a reaction chamber, starting a motor to supply power to a stirring paddle and an electric heating rod when the mixed liquid of the water sample and the digestion liquid reaches the water level sensor III, heating the mixed liquid to a preset temperature (70-80 ℃ is the preferred temperature), uniformly stirring, closing the motor, and standing for digestion; repeating the steps, after the water sample is digested, opening a water pump IV and a water valve III through the electric control unit, and enabling the water sample to enter an enrichment unit;

the water sample enters a grading enrichment unit, and after being divided by a rotary dividing component, micro plastic with different grain diameters in the water sample is sequentially intercepted by a first-stage filter screen, a second-stage filter screen and a third-stage filter screen in a filter barrel and is continuously enriched; opening a second drain valve through the electric control unit to discharge the filtered water sample;

after a preset sampling amount is reached, the electric control unit is used for closing the water depth sensor, the flowmeter I, the water pump I, the timing water-through water valve, the sludge electromagnetic control valve I, the water pump II, the water-through valve I, the water pump III, the water-through valve II, the water level sensor I, the flow control valve II, the flow control valve III, the sludge electromagnetic control valve II, the waste liquid valve I, the waste liquid valve II, the water level sensor II, the flow control valve IV, the water level sensor III, the water temperature sensor II, the water pump IV, the water-through valve III and the drain valve II.

Disassembling the first-stage filter screen, the second-stage filter screen and the third-stage filter screen, and collecting the micro plastic on the filter screens; opening a sludge discharge port to discharge sludge in a sludge hopper; and opening the first drain valve through the electric control unit, discharging the waste liquid in the waste liquid recovery tank, and opening the second sludge discharge port to discharge deposited impurities in the waste liquid recovery tank.

In an optional embodiment of the invention, the integrated use method for the fixed-depth collection and pretreatment of the micro-plastic in the water body further comprises the steps of performing tightness inspection and deionized water cleaning on the integrated device for the fixed-depth collection and pretreatment of the micro-plastic in the water body before sampling is started.

In an optional embodiment of the invention, the method for integrally using the depth-fixed collection and pretreatment of the micro-plastic in the water body further comprises the step of filling medicines into the flotation solution storage tank and the digestion solution storage tank before sampling is started.

In actual use, the grid with the appropriate specification can be selected according to the water environment of sampling, and the quality of the sinker and the length of the water sampling pipe from the grid to the hook are controlled through the reading in the water depth sensor so as to achieve the purpose of sampling water samples at the fixed depth.

The embodiments described above are presented to facilitate one of ordinary skill in the art to understand and practice the present invention. The scope of the present invention is not limited to the description of the above embodiments and examples, and it should be noted that those skilled in the art to which the present invention pertains may make several equivalent substitutions or obvious modifications without departing from the spirit of the present invention, and all of the properties or uses are the same and should be considered as falling within the scope of the present invention.

Claims

1. A water body micro-plastic depth-setting acquisition and pretreatment integrated device is characterized by comprising a water acquisition unit, a precipitation unit, a flotation unit, a digestion unit, an enrichment unit, an air supply unit and an electric control unit;

the water sampling unit comprises a water sampling assembly, a first flowmeter (17), a first water pump (18) and a timed water passing valve (19), wherein the first flowmeter (17), the first water pump (18) and the timed water passing valve (19) are sequentially arranged at the water outlet end of the water sampling assembly, the water sampling assembly comprises a water depth sensor (14), the water depth sensor (14) is arranged at the water sampling end of the water sampling assembly, and the water depth sensor (14) is electrically connected with the electric control unit;

the sedimentation unit comprises a sedimentation tank (21) and a sludge hopper (24) arranged at the bottom of the sedimentation tank, the sedimentation tank (21) is a vertical sedimentation tank, the sedimentation tank (21) comprises an aeration pipe (22) and a sludge electromagnetic control valve I (23), the air outlet end of the aeration pipe (22) is arranged in the sedimentation tank (21), the sludge electromagnetic control valve I (23) is arranged at the bottom end of the sedimentation tank (21), the sludge hopper (24) comprises a sludge discharge opening I (26), the sludge discharge opening I (26) is arranged on one side of the bottom of the sludge hopper (24), and the water outlet of the water collection assembly is connected with the top of the sedimentation tank (21);

the flotation unit comprises a flotation cell group, an aeration disc group, a flotation liquid storage tank (32), a waste liquid recovery pool (35), a floating block assembly (37) and a bendable hose (372), the bottom of each flotation cell in the flotation cell group is wedge-shaped, the flotation cell group comprises a first flotation cell (3421), a second flotation cell (3422) and a third flotation cell (3423) which are communicated in parallel and in sequence, a sludge electromagnetic control valve II (3431) is arranged at the bottom of the first flotation cell (3421), a waste liquid valve I (3432) is arranged at the bottom of the second flotation cell (3422), a waste liquid valve II (3433) is arranged at the bottom of the third flotation cell (3423), the aeration disc group comprises a first aeration disc group (3411), a second aeration disc group (3412) and a third aeration disc group (3413), one aeration disc group is correspondingly distributed on the left side wall of one flotation cell, the flotation liquid storage tank (32) is arranged inside the flotation cell and at the top of the flotation cell, the flotation liquid storage tank (32) comprises a water level sensor I (322) and a plunger (321), one plunger (3432) which is respectively communicated with the first flotation cell (3432) and the second flotation cell (3423), one flotation cell (3432), and a flexible hose (3432) which are arranged at the top of the flotation cell (3431), the waste liquid recovery tank (35) is arranged at the bottom of the flotation tank group, the waste liquid recovery tank (35) comprises a sludge discharge port II (361), a drain pipe I (3621) and a drain valve I (3622) arranged on the drain pipe I (3621), the sludge discharge port II (361) is arranged on one side, close to the bottom of the first flotation tank (3421), of the waste liquid recovery tank (35), the drain pipe I (3621) is arranged on one side, close to the bottom of the third flotation tank (3423), of the waste liquid recovery tank (35), a floating block assembly (37) and a bendable hose (372) are arranged inside the third flotation tank (3423), the floating block assembly (37) is connected with the liquid inlet end of the bendable hose (372), and a non-precipitation layer water sample in the third flotation tank (3423) is sucked through the floating block assembly (37); the top of the sedimentation tank (21) is communicated with the top of the first flotation tank (3421) through a first water pipe (29), and a second water pump (27) and a first water valve (28) are arranged on the first water pipe (29);

the digestion unit comprises a reaction chamber (42), a support (414), a flow control valve four (413) and a digestion solution storage tank (41) arranged at the top of the reaction chamber (42), the digestion solution storage tank (41) is fixed at the top of the reaction chamber (42) through the support (414), the bottom end of the digestion solution storage tank (41) is communicated with the top end of the reaction chamber (42) through a pipeline, the flow control valve four (413) is arranged at a connecting pipeline, a plunger II (412) is arranged at the top of the digestion solution storage tank (41), a water level sensor II (411) is arranged inside the digestion solution storage tank, the reaction chamber (42) comprises a water level sensor III (421), a motor (4224), a rotating shaft (4221) and a stirring paddle (4222) are arranged inside the reaction chamber (42), the rotating shaft (4221) is horizontally arranged at the bottom of the water level sensor III (421), the reaction chamber (42) is electrically connected with the rotating shaft (4221) and the electric heating paddle (4221), the rotating shaft (4221) is electrically connected with the electric heating pump (4221) and the electric heating pump (4221) respectively, and the electric heating pump (4221) are arranged inside the reaction chamber (42), the top of the reaction chamber (42) is communicated with the water outlet end of the bendable hose (372) through a pipeline at one side opposite to the electric heating rod (4223), and a third water pump (38) and a second water valve (39) are arranged on a connecting pipeline;

the enrichment unit comprises a filter barrel (51), a rotary diversion assembly (52) and a multi-stage filter screen, the filter barrel (51) is a cuboid, three layers of horizontal installation grooves are formed in the inner wall of the filter barrel, a first installation groove (531), a second installation groove (541) and a third installation groove (551) are formed in the filter barrel from top to bottom respectively, the multi-stage filter screen comprises a first-stage filter screen (53), a second-stage filter screen (54) and a third-stage filter screen (55), the multi-stage filter screen is inserted into the filter barrel in an inserting mode through corresponding installation grooves, the center of the top of the filter barrel (51) is communicated with the bottom of the reaction chamber (42) through a second water pipe (49), a fourth water pump (47) and a third water valve (48) are arranged on the second water pipe (49), the rotary diversion assembly is arranged inside the filter barrel (51) and connected with the second water pipe (49), a second drain pipe (561) is arranged on one side of the bottom of the filter barrel (51), and a second drain valve (562) is arranged on the drain pipe (561);

the air supply unit is respectively connected with the aeration pipe (22) and the aeration disc group, and a valve is arranged at the tail end of the air supply unit to control the opening and closing of the air flow;

the electric control unit is electrically connected with the water depth sensor (14), the first flowmeter (17), the first water pump (18), the timing water passing water valve (19), the first sludge electromagnetic control valve (23), the second water pump (27), the first water passing valve (28), the first water level sensor (322), the first flow control valve (3231), the second flow control valve (3232), the third flow control valve (3233), the second sludge electromagnetic control valve (3431), the first waste liquid valve (3432), the second waste liquid valve (3433), the first drain valve (3622), the third water pump (38), the second water passing valve (39), the second water level sensor (411), the fourth flow control valve (413), the third water level sensor (421), the water temperature sensor (423), the fourth water pump (47), the third water passing valve (48) and the second drain valve (562).

2. The integrated device for collecting and pretreating micro-plastic in water body at fixed depth according to claim 1, wherein the water collection assembly comprises a water collection pipe (16), a sinker (11), a grating (12), a clamping groove (13), a floater (151), a fishing line (152) and a hook (153), the grating (12) is connected to the outer side of a liquid inlet end at the bottom of the water collection pipe (16) through the clamping groove (13), the aperture of the grating (12) is not more than 5mm, the sinker (11) is connected with the lower end of the grating (12), a water depth sensor (14) is fixedly connected with the outer side of the bottom end of the water collection pipe (16), and the floater (151) is connected with the water collection pipe (16) through the hook (153) and the fishing line (152).

3. The integrated device for depth-fixed collection and pretreatment of micro-plastics in water bodies according to claim 1, wherein the first flotation tank (3421) further comprises a guide plate (31), the guide plate (31) is arranged near a liquid inlet of the first flotation tank (3421) and used for preventing a water sample from splashing, a water passing baffle is arranged at the joint of the first flotation tank (3421), the second flotation tank (3422) and the third flotation tank (3423), a water passing opening is formed in the water passing baffle and used for enabling an upper-layer water sample in an upper-layer flotation tank to flow into a lower-layer flotation tank, a first water passing baffle (3311) and a first water passing opening (3312) are arranged between the first flotation tank (3421) and the second flotation tank (3422), and a second water passing baffle (3321) and a second water passing opening (3322) are arranged between the second flotation tank (3422) and the third flotation tank (3423).

4. The integrated device for collecting and pretreating micro-plastic fixed depth water body of claim 1, wherein the floating block assembly comprises a floating block (373), a magnet block (374) and a plurality of gravity balls (375), the floating block (373) is sleeved on the outer surface of the liquid inlet end of the bendable hose (372), the liquid inlet end of the bendable hose (372) is positioned at the upper middle part of the floating block (373), the magnet block (374) is embedded at the top middle part of the floating block (373), the gravity balls (375) are movably connected to two sides of the floating block, and the vertical position of the floating block (373) in the water sample is controlled by adjusting the number of the gravity balls (375); and a strong electromagnetic block (371) is fixed on the side wall of the third flotation cell (3423), the strong electromagnetic block (371) is matched with a magnet block (374) in a magnetic attraction manner, and the strong electromagnetic block (371) is electrically connected with the electric control unit.

5. The integrated device for collecting and pretreating micro-plastics in a water body at a fixed depth according to claim 1, wherein the sedimentation tank (21) further comprises a first pressure balance valve (25), and the first pressure balance valve (25) is arranged at the top end of the sedimentation tank (21); the reaction chamber (42) further comprises a second pressure balance valve (424), and the second pressure balance valve (424) is arranged at the top end of the reaction chamber (42).

6. The water body micro-plastic depth-setting collection and pretreatment integrated device according to claim 1, wherein the rotary flow dividing assembly (52) comprises a connector (521), a water pipe (522), a rotary seat (523), a water retaining cover (524) and a spray head (525), one end of the connector (521) is connected with the water outlet end of a second water pipe (49), the other end of the connector is communicated with the rotary seat (523) through the vertically-arranged water pipe (522), the spray head (525) is communicated with the bottom end of the rotary seat (523), spray holes (526) with the aperture of 2-3 mm are distributed in the water outlet of the spray head (525), and the water retaining cover (524) is arranged above the rotary seat (523).

7. The device integrating the depth-fixed collection and the pretreatment of the micro-plastic in the water body as claimed in claim 1, wherein fixing frames (532) and handles (533) are arranged on the outer sides of the primary filter screen (53), the secondary filter screen (54) and the tertiary filter screen (55), the fixing frames (532) are arranged on the outer edge of the filter screens, the handles (533) are arranged on one sides of the fixing frames (532), the aperture of the primary filter screen (53) is 500 to 1000 μm, the aperture of the secondary filter screen (54) is 100 to 200 μm, and the aperture of the tertiary filter screen (55) is 10 to 20 μm.

8. The use method of the integrated device for collecting and pretreating micro-plastic in water body at fixed depth according to claim 1 is characterized by comprising the following steps:

injecting the flotation solution and the digestion solution into a flotation solution storage tank (32) and a digestion solution storage tank (41) through a plunger I (321) and a plunger II (412), and opening a water level sensor I (322) and a water level sensor II (411) through an electric control unit to monitor the residual amount of the storage solution; (ii) a Arranging a multi-stage filter screen in a three-stage mounting groove; putting the inlet end of the water sampling assembly into the collected water body, opening a water depth sensor (14) through an electric control unit, and adjusting the length of a water sampling water pipe based on the reading of the water depth sensor to enable the water sampling water pipe to reach the expected depth; opening a first flowmeter (17), a first water pump (18) and a timing water through valve (19) through an electric control unit, and collecting a water sample;

step two, a water sample firstly enters a precipitation unit, air is supplied to an aeration pipe (22) through an air control unit, the water sample in the precipitation unit is aerated, after the water sample is layered through preliminary aeration and precipitation of the precipitation unit, large-particle impurities are deposited in a precipitation tank, an electric control unit opens a water pump II (27) and a water valve I (28), the obtained upper-layer solution enters a flotation unit, and when the impurities are precipitated to a certain amount, a sludge electromagnetic control valve I (23) is opened, so that the deposited impurities enter a sludge hopper (24);

step three, when a water sample enters the first flotation tank (3421), opening a first flow control valve (3231) through an electric control unit to enable flotation liquid to enter the first flotation tank (3421), and opening a first aeration disc set (3411) through an air control unit to perform aeration flotation on the water sample; when the upper non-precipitation layer solution in the first flotation tank (3421) is discharged into a second flotation tank (3422), a second aeration disc set (3412) is opened through an air control unit, when a water sample overflows from the second flotation tank (3422) to a third flotation tank (3423), a third aeration disc set (3413) is opened through the air control unit, and after full aeration flotation, aeration disc sets of all stages are closed and are kept stand to enable the water sample to be fully layered; the floating block assembly in the third flotation tank (3423) falls into the upper non-sedimentation layer and continuously sinks until the floating block assembly falls onto the surface of the lower sedimentation layer; opening a third water pump (38) and a second water valve (39) through an electric control unit to enable the obtained non-precipitation layer solution to enter the digestion unit through the floating block assembly; after finishing the flotation, opening a second sludge electromagnetic control valve (3431), a first waste liquid valve (3432) and a second waste liquid valve (3433) through an electric control unit, so that the waste liquid in the flotation tank group enters a waste liquid recovery tank (35);

opening a flow control valve IV (413), a water level sensor III (421) and a water temperature sensor II (423) through an electric control unit, enabling digestion liquid to enter a reaction chamber (42), starting a motor (4224) to supply power to a stirring paddle (4222) and an electric heating rod (4223) when mixed liquid of the water sample and the digestion liquid is beyond the water level sensor III (421), heating the mixed liquid to a preset temperature and uniformly stirring, closing the motor (4224), standing and digesting; repeating the steps, after the water sample is digested, opening a water pump IV (47) and a water valve III (48) through the electric control unit, and enabling the water sample to enter the enrichment unit;

step five, the water sample enters a grading enrichment unit, and after being divided by a rotary dividing component (52), the micro plastics with different particle sizes in the water sample are sequentially intercepted and continuously enriched by a first-stage filter screen (53), a second-stage filter screen (54) and a third-stage filter screen (55) in a filter barrel; opening a second drain valve (562) through the electric control unit to discharge the filtered water sample;

step six, after a preset sampling amount is reached, closing a water depth sensor (14), a flowmeter I (17), a water pump I (18), a timing water passing water valve (19), a sludge electromagnetic control valve I (23), a water pump II (27), a water passing valve I (28), a water pump III (38), a water passing valve II (39), a water level sensor I (322), a flow control valve I (3231), a flow control valve II (3232), a flow control valve III (3233), a sludge electromagnetic control valve II (3431), a waste liquid valve I (3432), a waste liquid valve II (3433), a water level sensor II (411), a flow control valve IV (413), a water level sensor III (421), a water temperature sensor II (423), a water pump IV (47), a water passing valve III (48) and a water discharging valve II (562) through an electric control unit by an electric control unit, disassembling a first-stage filter screen (53), a second-stage filter screen (54) and a third-stage filter screen (55), and collecting micro plastic on the filter screen; opening a first sludge discharge port (26) to discharge sludge in a sludge hopper (24); and opening a first drain valve (3622) through an electric control unit, discharging the waste liquid in the waste liquid recovery tank (35), and opening a second sludge discharge port (361) to discharge deposited impurities in the waste liquid.

9. The use method of the integrated device for collecting and pretreating micro-plastics in water at fixed depth according to claim 8, wherein the digestion solution stored in the digestion solution storage tank (41) is hydrogen peroxide solution, enzyme (proteinase K) solution, acid solution or alkali solution.

10. The use method of the integrated device for collecting and pretreating micro-plastics in a fixed depth in water body according to claim 8, wherein the flotation solution stored in the flotation solution storage tank (32) is a saturated sodium chloride solution, a saturated zinc chloride solution or a saturated sodium iodide solution.