CN115266621A - A kind of in-situ water body microplastic detection device and detection method thereof - Google Patents

Abstract

The invention relates to the technical field of environmental detection and pollutant purification, in particular to an in-situ water body micro-plastic detection device and a detection method thereof. The in-situ water body plastic detection device comprises a flow channel; a large-aperture filter screen is arranged at the inlet of the flow passage, and a small-aperture filter screen and a heating resistance screen are sequentially arranged at the outlet from inside to outside; and a water pump, a flowmeter, a biological cracking sprayer, an optical detection instrument, an ultrasonic generator and a fan are embedded in the middle section of the flow channel. The detection device and the detection method thereof can realize real-time detection of the micro-plastics in the water body in various complex environments.

Description

An in-situ water body microplastic detection device and detection method thereof

technical field

The invention relates to the technical field of environmental detection and purification of pollutants, in particular to an in-situ water body microplastic detection device and a detection method thereof.

Background technique

Since most microplastics degrade slowly and accumulate in the natural environment, the degree of pollution will be exacerbated. Therefore, microplastic pollution in water bodies has become a serious and extensive global environmental issue.

The existing microplastic research methods are mainly based on "water sampling-laboratory analysis", which is limited by the detection principle and cannot directly detect the quality of microplastics in situ. Microplastics will age and break during transportation, which will affect the accuracy of test results. Moreover, the sampling and detection methods are different, and many research results are expressed in completely different forms. There is no unified evaluation standard for the degree of microplastic pollution, and the detection of microplastics is difficult and dangerous. In addition to the above methods, TGA (thermogravimetric analysis) has been newly developed, which is a thermal analysis technique for measuring the relationship between material quality and temperature under program-controlled temperature. It can draw a quantitative standard curve for microplastics, so that the mass content of microplastics Quantitative analysis is available. This method requires high ambient temperature, and the uncertainty of in-situ detection is obvious. Moreover, it can only judge the mass content, but cannot judge the particle concentration, and cannot completely detect various indicators of microplastics.

Chinese patent CN 111175199 A discloses a rapid automatic multi-functional detection device and method for seawater microplastics, the purpose of which is to shorten the detection time and reduce the problem of poor consistency of detection results caused by time, but it does not have the in-situ, On-site or online detection functions, such as no adaptive detection range adjustment and energy-saving control strategy.

Therefore, the development of in-situ detection devices for microplastics in water bodies is the general trend for the precise detection of microplastics in the future.

Contents of the invention

The object of the present invention is to provide an in-situ water body microplastic detection device and a detection method thereof, which can realize real-time detection of water body microplastics in various complex environments.

To achieve the above object, the present invention adopts the following technical solutions:

An in-situ water body plastic detection device, comprising a flow channel; the inlet of the flow channel is provided with a filter screen, and the outlet is provided with a filter membrane and a heating resistance net sequentially from the inside to the outside; the middle section of the flow channel is equipped with a water pump and a flow meter , biological cracking sprayer, optical detection instrument, ultrasonic generator and fan.

A liquid level sensor is installed at the inlet of the flow channel, and an electronic valve is installed at the outlet.

The flow channel is used to detect the flow of water body. The water pump is used to draw a sufficient amount of water to be detected into the flow channel. A flow meter is arranged above the water pump, and the flow meter is used to control the liquid amount of the water body to be detected entering the flow channel, that is, the detection amount. The biological cracking sprinkler is used for spraying the biological cracking liquid into the flow channel to decompose the microorganisms in the water body to be detected flowing in the flow channel, so as to improve the detection accuracy. The ultrasonic generator is used for layering the cells to be detected for biological impurities in the water body. The blower is used to blow the cell layer treated by the ultrasonic generator to the outside of the flow channel and discharge it out of the detection device. The optical detection instrument includes a data acquisition unit and a data processing unit. The data acquisition unit is a camera. The data processing unit is equivalent to a controller and an actuator. When the pretreated testing water flows through the optical testing instrument, the optical testing instrument takes pictures of the passing testing water, collects microstructure images of the water to be tested, and sends the collected data to the data processor of the optical testing instrument for processing. The data processor is also used to control the flow of the detected water body in the entire flow channel through the liquid level sensor at the inlet of the flow channel and the electronic valve at the outlet of the flow channel. The optical detection instrument is installed at the rear end of the flow channel, and the optical detection instrument should be located in an environment with a better continuous light source for the camera and a position where the water flow velocity is uniform.

Further, the large-aperture filter screen includes a filter screen main body and a plurality of filter holes 1 provided on the filter screen main body, and the aperture value range of the filter hole 1 is 1 mm to 1 cm; the large-aperture filter screen is made of stainless steel strainer.

Further, the small-pore filter membrane includes a filter membrane main body and a plurality of filter holes 2 set on the filter membrane main body, and the pore diameter of the filter hole 2 ranges from 1 nm to 10 μm; microporous membrane. Compared with the traditional mesh filter membrane, the biggest feature of the ion microporous membrane is that it has a real geometric pore size, the pore size can be strictly controlled in a wide range (0.01-15μm), and the pore size is uniform. The ion microporous membrane has high separation selectivity, absolutely intercepts any particles larger than the pore size, and the separation efficiency can reach 100%. The ion microporous filter membrane is made of polyester membrane, which does not absorb the substances in the filtrate, and can prevent the effective components in the filtrate from being absorbed and lost. There will not be any migratable substances into the filtrate, so the filtrate will not be polluted.

Further, the biological cracking sprayer is modified according to the chemical spraying structure of forestry biological hazard prevention. Spraying devices are placed on the upper and lower sides of the pipeline to crack the flowing fluid, and the cracked fluid passes through the outlet of the flow channel. Outflow to optical detection instrument. The biological cracking sprinkler is embedded and installed on the pipeline, and the sealing of the pipeline must be ensured during installation.

Further, the optical detection instrument adopts any one of a visible light detector, an infrared spectrometer or a Raman spectrometer.

Further, the ultrasonic generator uses the circuit board control signal to transmit the ultrasonic transmitter to generate ultrasonic waves of corresponding frequency to vibrate the microplastics to the surface of the fluid at high speed, and then discharge the fluid pipes to reduce the pollution of microplastics.

The present invention also relates to a detection method of the above-mentioned in-situ water body plastic detection device, the method comprising the following steps:

S1, sample injection

The detection device of the present invention is placed in places where detection of microplastics is required, such as water inlets of household water pipes, detection valves of reservoirs, deep-sea detection areas, etc. Turn on the water pump to draw a set volume of water to be tested. The water to be tested enters the flow channel from the inlet of the flow channel. When the water to be tested passes through the large-aperture filter, some impurities in the water to be tested are filtered out by the large-aperture filter. The volume of the water body to be tested for each sample injection is collected by using a flow meter arranged on the water pump.

S2, pre-processing

The water body to be tested after being filtered by the large-aperture filter continues to flow forward along the flow channel. Part of the microorganisms in the water to be detected are killed, and when the liquid in the cracking device flows out, part of the microorganisms are killed, thus reducing the interference of microplastic detection. When the water body to be detected flows through the ultrasonic generator, the ultrasonic waves emitted by the ultrasonic generator are used to vibrate and pulverize the microorganisms, plankton or microbial corpses in the water body to be detected, so as to improve the accuracy of microplastic detection.

S3, enrichment

After pretreatment, the water body to be detected reaches the small-pore filter membrane, and the microplastics in the water body to be detected are enriched on the small-pore filter membrane, and the remaining substances flow out from the outlet of the flow channel after the water body to be tested passes through the small-pore filter membrane. A fan is used to air-dry the microplastics enriched on the small-aperture filter membrane, and a heating resistor net is used to heat and dry the microplastics enriched on the small-aperture filter membrane.

S4. Optical detection

Optical detection instruments are used to detect the microplastics enriched on the small-pore filter membrane to obtain the type and concentration of microplastics. The purpose of optical detection is to detect the types of microplastics and their corresponding concentrations. On the small-pore filter membrane, the microscopic camera is used to estimate the amount of microplastics in the form of imaging, and then Raman and infrared spectroscopy are used to make an estimate. The physical properties of microplastics are different to determine the type of microplastics.

Compared with prior art, the advantages of the present invention are:

(1) The present invention adopts a flow channel design, so that a closed space can be established in a complex environment in situ during the flow of the liquid to be detected in the flow channel, and the types of microplastics in the liquid to be detected in the in situ environment and concentration to improve the accuracy and efficiency of the test results. Based on the obvious difference in morphology of different types of microplastics, the present invention uses a distinguishing algorithm to statistically output the types of microplastics, thereby realizing the real-time online output of particle concentration and particle types of microplastics. The controller of the execution environment of the algorithm used in the present invention adopts an embedded system, which has fast calculation speed and small size, reduces the complexity of the mutual cooperation of each unit, and can greatly reduce the volume of the instrument. At the same time, combined with closed-loop control, it has reached The purpose of reducing the minimum detection concentration lower bound and saving energy.

(2) Since the present invention can eliminate the influence of microorganisms in the fluid on the detection results, the structure of microplastics is relatively symmetrical, and the cells of microorganisms will not be symmetrical due to cell differentiation, and the cell structure of microorganisms has mature judging criteria. For example, cell nuclei, etc., which are very different from microplastics. Therefore, by photographing the microstructure of microplastics and microorganisms in the liquid to be detected, the present invention can distinguish microplastics and microorganisms by using the recognition model in machine learning training in the prior art, and improve the quality of in-situ water quality. Detection accuracy of microplastic detection.

(3) The present invention adopts the joint detection of visible light detection and dual spectrum in the particle detection of fluid, because the refractive index of different substances under different light is all different, this makes the photosensitizer refracted into the lens after the light source passes through the particles The optical signals of the components are also different, which greatly increases the particle shapes and types captured by the camera. Using the spectrum to analyze the particle types, the combination of the two improves the detection accuracy and detection range and improves the detection accuracy.

Description of drawings

Fig. 1 is the structural representation of detection device among the present invention;

Fig. 2 is the functional block diagram of detection method among the present invention;

Fig. 3 is the method flowchart of detection method among the present invention;

Fig. 4 is the functional block diagram of optical detection instrument among the present invention;

in:

1. Large aperture filter, 2. Electronic valve, 3. Water pump, 4. Flow meter, 5. Flow channel, 6. Biological cracking sprinkler, 7. Optical detection instrument, 8. Ultrasonic generator, 9. Fan, 10 , Small pore diameter filter membrane, 11, heating resistance network.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

A kind of in-situ water body plastic detection device as shown in Figure 1, comprises flow channel 5; The entrance of described flow channel 5 is provided with large-aperture filter screen 1, and the outlet is provided with small-aperture filter membrane 10 and heating successively from inside to outside. Resistance network 11; the middle section of the flow channel 5 is embedded with a water pump 3, a flow meter 4, a biolysis sprinkler 6, an optical detection instrument 7, an ultrasonic generator 8 and a fan 9. A liquid level sensor is installed at the inlet of the flow channel 5, and an electronic valve is installed at the outlet.

The flow channel 5 is used to detect the circulation of water body. The water pump 3 is used to draw a sufficient amount of water to be tested into the flow channel. A flow meter 4 is arranged above the water pump 3, and the flow meter 4 is used to control the liquid amount of the water body to be detected entering the flow channel, that is, the detection amount. The biolysis sprayer 6 is used to spray the biolysis liquid into the flow channel 5 to decompose the microorganisms in the water body to be detected flowing in the flow channel 5 and improve the detection accuracy of microplastics. The ultrasonic generator 8 is used for layering the cells to be detected for biological impurities in the water body. The blower 9 is used to blow the cell layer treated by the ultrasonic generator 8 to the outside of the flow channel 5 and out of the detection device. The optical detection instrument 7 includes a data acquisition unit and a data processing unit. The data acquisition unit is a camera. The data processing unit includes a controller and an actuator. When the pretreated water body for detection flows through the optical detection instrument 7, the optical detection instrument 7 takes pictures of the passing water body to be detected, collects microstructure images of the water body to be detected, and sends the collected data to the data processor of the optical detection instrument 7 to process. The data processor is also used to control the flow of the detected water body in the entire flow channel through the liquid level sensor at the inlet of the flow channel 5 and the electronic valve at the outlet of the flow channel. The optical detection instrument 7 is installed at the rear end of the flow channel 5 (i.e. close to the outlet end of the flow channel), and the optical detection instrument 7 should be located in an environment with a better continuous light source for the camera and a uniform water flow velocity.

Further, the large-aperture filter screen 1 includes a filter screen main body and a plurality of filter holes 1 provided on the filter screen main body, and the aperture of the filter hole 1 ranges from 1 mm to 1 cm; the large-aperture filter screen adopts Stainless steel strainer.

Further, the small-pore filter membrane 10 includes a filter membrane main body and several filter holes 2 provided on the filter membrane main body, the pore diameter of the filter hole 2 ranges from 1 nm to 10 μm; the small-pore filter membrane 10 Using ionic microporous membrane. Compared with the traditional mesh filter membrane, the biggest feature of the ion microporous membrane is that it has a real geometric pore size, the pore size can be strictly controlled in a wide range (0.01-15μm), and the pore size is uniform. The ion microporous membrane has high separation selectivity, absolutely intercepts any particles larger than the pore size, and the separation efficiency can reach 100%. The ion microporous filter membrane is made of polyester membrane, which does not absorb the substances in the filtrate, and can prevent the effective components in the filtrate from being absorbed and lost. There will not be any migratable substances into the filtrate, so the filtrate will not be polluted.

Further, the biological cracking sprinkler 6 is modified according to the spraying structure of the forestry biological hazard prevention. Spraying devices are placed on the upper and lower sides of the flow channel 5 to crack the fluid flowing through. The cracked fluid flows through the The outlet of the channel flows out to the optical detection instrument 7. The biological cracking sprinkler 6 is embedded and installed on the flow channel 5, and the sealing of the flow channel should be ensured during installation.

Further, the optical detection instrument 7 adopts any one of a visible light detector, an infrared spectrometer or a Raman spectrometer. The acquisition end of the optical detection instrument 7 uses a gigabit-level color high-speed camera to perform data differential analysis on the collected images, color image comparison and other algorithm processing to measure the microplastic content of the fluid, and the photosensitive sensor on the side to measure the microplastic content of different microplastics. The refractive index is used to assist in resolution and to verify camera detection results.

Further, the ultrasonic generator 8 uses the circuit board control signal to transmit the ultrasonic transmitter to generate ultrasonic waves of corresponding frequencies to vibrate the microplastics to the surface of the fluid at high speed, and then discharge the flow channel 5 to reduce the pollution of microplastics.

The present invention also relates to a detection method of the above-mentioned in-situ water body plastic detection device, the method comprising the following steps:

S1, sample injection

The detection device of the present invention is placed in places where microplastics in water bodies need to be detected, such as water inlets of household water pipes, reservoir detection valves, deep-sea detection areas, etc. Turn on the water pump 3 to extract a set volume of water to be tested. The water to be tested enters the flow channel 5 from the inlet of the flow channel 5. When the water to be tested passes through the large-aperture filter 1, some impurities in the water to be tested are filtered by the large-aperture filter. The filter screen 1 filters out, and the volume of the water body to be detected is collected by the flow meter 4 arranged on the water pump 3 for each sample injection.

S2, pre-processing

The water body to be detected after being filtered by the large-aperture filter continues to flow forward along the flow channel 5. When the water body to be detected flows through the biolysis sprinkler 6, the biolysis sprinkler 6 sprays biolysis to the water body to be detected in the flow channel 5. The biological lysate kills some microorganisms in the water body to be tested, which reduces the interference of microorganisms in the water body on the detection results of microplastics. When the water body to be detected flows through the ultrasonic generator 8, the water body microorganisms, plankton or microbial corpses in the water body to be detected are removed by the ultrasonic waves sent by the ultrasonic generator 8 (the microbial corpses refer to some microorganisms killed by the biological lysate in the front) dead bodies) to be vibrated and crushed to further improve the accuracy of microplastic detection in water bodies. The biological lysate can only kill a part of the cells, and the ultrasonic wave is equivalent to a supplementary method, which will more thoroughly remove the interference of the cells. The ultrasonic waves emitted by the ultrasonic generator will shatter all the cells, and the fragments obtained by the shattering will be filtered out through the small-pore filter membrane, but the ultrasonic waves have no effect on microplastics.

Microorganisms cannot be filtered only with a filter, because it is understood that in addition to using a filter to deal with larger volumes of impurities in seawater, only microorganisms are similar in size to microplastics and have the most disturbing factors. In addition, microorganisms also adhere to a certain amount Therefore, killing microorganisms and removing the microplastics is also a key step in the in situ detection of microplastics in water bodies. The invention adopts biological cracking and ultrasonic vibration to process microorganisms.

S3, enrichment

After pretreatment, the water body to be tested reaches the small-pore filter membrane 10, and the microplastics in the water body to be tested are enriched on the small-pore filter membrane 10, and the remaining substances pass through the small-pore filter membrane 10 along with the water body to be tested. Outflow. The fan 9 is used to air-dry the microplastics enriched on the small-aperture filter membrane 10 , and the heating resistor net 11 is used to heat and dry the microplastics enriched on the small-aperture filter membrane 10 .

S4. Optical detection

Optical detection instruments are used to detect the microplastics enriched on the small-pore filter membrane to obtain the type and concentration of microplastics. The purpose of optical detection is to detect the types of microplastics and their corresponding concentrations. On the last plane, the microscopic camera is used to estimate the amount of microplastics in the form of imaging, and then Raman and infrared spectroscopy are used to use different microplastics. The different physical properties of plastics determine the types of microplastics.

Since the dual spectrum can only detect the microplastic information of one point, if the point scanning method is used, not only the design is complicated, but also the scanning time will be very long. After the camera of the optical detection instrument has finished shooting and detecting, several locations where there are more microplastics are selected as the distribution coordinates of microplastics. The optical detection instrument uses a camera to take pictures of the microplastics enriched on the small-pore filter membrane. From the photos, it can be seen which areas have more microplastics and which areas have less microplastics. Select a few more microplastics to distribute more The location of , as the distribution coordinates of microplastics. Dual-spectrum detection only needs to detect the corresponding points according to the distribution coordinates of microplastics, which greatly reduces the detection time. Dual-spectrum detection refers to the detection of microplastics using infrared spectroscopy and Raman spectroscopy, which are existing technologies for detecting microplastics with these two spectra. The present invention determines the detection position of dual-spectrum detection through the distribution coordinates of microplastics, instead of scanning the whole area, which will greatly reduce the working time of dual-spectrum and obtain relatively accurate results.

Since the microorganisms in the water were not completely removed during the pretreatment process, in order to improve the robustness of the system, when using optical detection instruments for detection, image processing methods were used to distinguish and screen microplastics and microorganisms. Recognize different objects based on pictures, similar to AI face recognition, and identify microplastics and microorganisms from images. Since the shape of microorganisms is relatively symmetrical and neat, such as a circle, an ellipse, or symmetrical antennae. The shape of microplastics has no obvious rules, and the symmetry is not strong. Therefore, starting from these characteristic points, microorganisms and microplastics can be well distinguished. How to distinguish the symmetry or asymmetry of the shape of the detected object is realized by using the existing AI technology.

The optical detection in the present invention adopts the joint detection of visible light detection and dual spectrum and the detection instrument's algorithm for distinguishing microplastics and microorganisms. The principle block diagram of the optical detection instrument adopted in the present invention is shown in FIG. 4 . The invention switches the light source at the light source opposite to the camera of the optical detection instrument. Since the refractive index of different substances is different under different light, this makes the light signal of the photosensitive element refracted into the lens after the light source passes through the particles is also different, so that the shape and type of particles captured by the camera are greatly increased. The joint detection of visible light detection and dual spectrum not only improves the detection accuracy, but also improves the detection ability and expands the detection range.

Because microscopic structures can be photographed, microplastics and microorganisms can be distinguished through recognition algorithms. The reason is that the structure of microplastics is relatively symmetrical, and the morphology of microbial cells will not be symmetrical due to cell differentiation, and the cell structure of microorganisms has already Mature judgment criteria, such as cell nuclei, are quite different from microplastics; so as long as the microstructure can be photographed and a mature machine learning-trained recognition model can be used to distinguish the two, this can improve detection accuracy. And it lays the foundation for the subsequent detection of mass concentration.

The specific process of the detection method of the in-situ water body microplastic detection device described in the present invention is shown in Figure 3:

(1) Before the detection is carried out, judge whether the last detection is completed, mainly by judging whether the temperature of the heating resistor network 11 has been reduced to the temperature value A when not working, and judging whether the work of the optical detection instrument 7 is over. The unit returns the signal.

(2) Open the electronic inlet valve 2 after confirming that the last detection is completed. After the fluid passes through the large-aperture filter screen 1, the flow meter 4 detects the total water body volume. When the total water body volume reaches the set threshold N, close the water inlet valve (i.e. Electronic valve 2).

(3) Due to the different microbial content in different waters, it needs to be judged. If the microbial content exceeds the threshold C, then select the biological cracking sprinkler 6 to spray the biological cracking liquid and turn on the ultrasonic generator 8 to send out ultrasonic waves. Lysis and sonication. The spraying of the biological lysate is a relatively closed tank, and both the sampling valve and the sampling valve have spraying devices. When the fluid volume in the tank reaches the set value, it starts to spray the lysate and then flows out after staying for a corresponding period of time.

(4) After biolysis and ultrasonic removal of biological impurities, the fluid passes through the small-pore filter membrane 10, and the small-pore filter membrane 10 is used for second filtration. The microplastics in the water body to be detected are enriched on the filter membrane 10 with a small pore size, and the remaining substances flow out from the outlet of the flow channel 5 through the filter membrane 10 with a small pore size along with the water body to be detected. The fan 9 is used to air-dry the microplastics enriched on the small-aperture filter membrane 10 to reduce the moisture content, and the heating resistor net 11 is used to heat and dry the microplastics enriched on the small-aperture filter membrane 10 .

(5) Optical detection is carried out on the microplastics enriched on the small-aperture filter membrane 10. The light sources at the optical detection instrument 7 are respectively visible light, Raman spectrum, and infrared spectrum, which emit different light rays respectively. The camera detects the microplastics under visible light Particles collect data, and the photosensitive sensor in the optical detection instrument 7 collects light refracted by microplastics when other spectra are irradiated to determine the type of particles.

(6) Count according to the comprehensive detection of the optical detection instrument, and detect the concentrations of various microplastics X ₁ , X ₂ . . . If X ₁ , X ₂ ... are too small, or equal to 0, it means that the total volume of water drawn is not enough. You can continue to open the valve and add water to reach the minimum detectable concentration; do another test, if the repeated test results remain unchanged, it means insufficient In order to obtain the detection minimum concentration range. If the minimum value is reached, the fluid is repeatedly detected and the detection result is output as the concentration of each microplastic is X _i /N.

(7) Finally, the flow channel 1, the large-aperture filter screen 1 and the small-aperture filter membrane 10 are cleaned, and the reset device is ready for the next detection.

In summary, the present invention integrates sampling, pretreatment, enrichment and optical detection technologies, and can detect the abundance and types of microplastics in water in real time in situ.

The above-mentioned embodiments are only descriptions of preferred implementations of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (8)

1. The utility model provides an normal position water plastics detection device which characterized in that: comprises a flow passage; a filter screen is arranged at the inlet of the flow channel, and a filter membrane and a heating resistance net are sequentially arranged at the outlet from inside to outside; and the middle section of the flow channel is provided with a water pump, a biological cracking sprayer, an optical detection instrument, an ultrasonic generator and a fan.

2. The in-situ water body plastic detection device according to claim 1, wherein: and a liquid level sensor is installed at the inlet of the flow channel, and an electronic valve is installed at the outlet of the flow channel.

3. The in-situ water body plastic detection device according to claim 1, wherein: the flow channel is used for detecting the circulation of the water body; the water pump is used for pumping sufficient water to be detected into the flow channel; a flow meter is arranged above the water pump and used for controlling the liquid amount of the water body to be detected entering the flow channel, namely the detected amount; the biological cracking sprayer is used for spraying biological cracking liquid into the flow channel and decomposing microorganisms in the water body to be detected flowing in the flow channel; the ultrasonic generator is used for carrying out layering treatment on cells of biological impurities in the water body to be detected; and the fan is used for blowing the cell layer processed by the ultrasonic generator to the outer side of the flow channel and discharging the cell layer out of the detection device.

4. The in-situ water body plastic detection device according to claim 1, wherein: the optical detection instrument comprises a data acquisition unit and a data processing unit; the data acquisition unit is a camera; the data processing unit comprises a controller and an actuator; the optical detection instrument is used for photographing the flowing water body to be detected, acquiring the microstructure image of the water body to be detected, and sending the acquired image data to the data processor of the optical detection instrument for processing; the data processor is also used for controlling the flow of the water body to be detected in the whole flow channel through the liquid level sensor at the inlet of the flow channel and the electronic valve at the outlet of the flow channel.

5. The in-situ water body plastic detection device according to claim 1, wherein: the filter screen is a large-aperture filter screen; the large-aperture filter screen comprises a filter screen main body and a plurality of first filter holes arranged on the filter screen main body, wherein the aperture of the first filter holes ranges from 1mm to 1cm; the large-aperture filter screen is a stainless steel filter screen.

6. The in-situ water body plastic detection device according to claim 1, wherein: the filter membrane is a small-aperture filter membrane; the small-aperture filter membrane comprises a filter membrane main body and a plurality of second filter holes formed in the filter membrane main body, and the aperture of the second filter holes ranges from 1nm to 10 microns; the small-aperture filter membrane adopts an ion microporous membrane.

7. The in-situ water body plastic detection device according to claim 1, wherein: the optical detection instrument adopts any one of a visible light detector, an infrared spectrometer or a Raman spectrometer.

8. The detection method of the in-situ water body plastic detection device according to any one of claims 1 to 7, characterized by comprising the following steps: the method comprises the following steps:

s1, sample introduction

Opening a water pump, extracting a water body to be detected with a set volume, enabling the water body to be detected to enter a flow channel from a flow channel inlet, filtering part of impurities in the water body to be detected by a large-aperture filter screen when the water body to be detected passes through the large-aperture filter screen, and collecting the volume of the water body to be detected of each sample introduction by using a flowmeter arranged on the water pump;

s2, pretreatment

The water body to be detected after being filtered by the large-aperture filter screen continuously flows forwards along the flow channel, when the water body to be detected flows through the biological cracking sprinkler, the biological cracking sprinkler sprays biological cracking liquid to the water body to be detected in the flow channel, the biological cracking liquid kills part of microorganisms in the water body to be detected, and when the water body to be detected flows through the ultrasonic generator, the ultrasonic waves emitted by the ultrasonic generator are utilized to vibrate and crush the microorganisms, plankton or microorganism corpses in the water body to be detected;

s3, enrichment

The pretreated water body to be detected reaches the small-aperture filter membrane, the micro-plastic in the water body to be detected is enriched on the small-aperture filter membrane, and the rest substances flow out of the runner outlet after passing through the small-aperture filter membrane along with the water body to be detected; air-drying the micro-plastics enriched on the small-aperture filter membrane by using a fan, and heating and drying the micro-plastics enriched on the small-aperture filter membrane by using a heating resistance net;

s4, optical detection

And detecting the micro-plastic enriched on the small-aperture filter membrane by using an optical detection instrument to obtain the type and the concentration of the micro-plastic.

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