Multi-channel water quality online detection device and method based on fluorescence imaging system

Abstract

The present invention discloses a multi-channel water quality online detection device and method based on a fluorescence imaging system, the device comprises: a sample circulation pool, which is formed by connecting multiple sections of straight tubes with rectangular cross-sections end to end to form a channel for water sample circulation; an emission light window is provided on the outer wall of the straight tube, and an excitation light window is provided on the bottom surface of the straight tube; an emission light module, the emission light generated enters the sample circulation pool through the emission light window, and is used to excite fluorescent substances in the water sample to produce a fluorescence effect; a fluorescence imaging and detection module, including a dark light correction film, a CMOS photosensitive device and multiple groups of excitation light filters, the excitation light emitted from the excitation light window is received by the CMOS photosensitive device after passing through the filter; a control and analysis module, which analyzes the fluorescence intensity signal received by the CMOS photosensitive device and calculates the concentration of fluorescent organic pollutants in the water sample. The multi-channel water quality online detection device of the present invention can realize online real-time monitoring of fluorescent organic pollutants in water.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality detection, and in particular to a multi-channel water quality online detection device and method based on a fluorescence imaging system. Background Art

[0002] Water quality monitoring technology is a necessary condition for the control and treatment of environmental pollutants. Rapid and accurate detection of organic pollutants in water is crucial to ensure environmental safety and public health.

[0003] Traditional water quality testing methods usually rely on laboratory analysis, involving sample collection, transportation and cumbersome pre-treatment steps, which is not only time-consuming but also unable to achieve real-time monitoring, limiting its efficiency and response speed in practical applications. With the increasingly severe environmental pollution problem, the demand for more efficient and accurate water quality monitoring technology is becoming more urgent.

[0004] Online detection technology based on fluorescence imaging system can achieve efficient, rapid and real-time analysis and determination of organic pollutants with fluorescence effect. Fluorescence detection technology illuminates the sample with light of a specific wavelength to stimulate the target organic molecules to emit fluorescence, and uses the relationship between fluorescence intensity and pollutant concentration to achieve quantitative analysis of organic pollutants in water. Compared with traditional methods, the fluorescence imaging system can not only quickly obtain the fluorescence image of the sample, but also avoid possible changes in the sample during collection and transportation, and achieve non-destructive analysis, greatly improving the timeliness and accuracy of the data.

[0005] A Chinese patent document with publication number CN116818693A discloses an online monitoring method for secondary water supply quality based on the fusion of ultraviolet-visible spectra and three-dimensional fluorescence spectra, including: configuring s water samples as a training set, the water samples in the training set contain pollutants at different levels, and the pollutants are bacteria, nitrate, trivalent iron ions, trivalent aluminum ions, residual chlorine and humic acid; testing the ultraviolet-visible spectrum, three-dimensional fluorescence spectrum and conductivity of each water sample in the training set, and obtaining a matrix of the s water samples in the training set based on the ultraviolet-visible spectrum, three-dimensional fluorescence spectrum and conductivity, and taking each row of data in the training set as a sample; training the training set using a supervised classification algorithm and a k-fold cross-validation method in turn, building a classification model, and performing classification prediction on the test set.

[0006] A Chinese patent document with publication number CN109470667A discloses a method for tracing the source of pollutants by combining water quality parameters and three-dimensional fluorescence spectroscopy, the steps of which include: a water quality detection step, a fluorescence detection step, a pollution source type identification step, and a pollution source determination step.

[0007] The existing fluorescence imaging system can only detect organic pollutants in static water samples collected in the laboratory. The steps are complicated, the amount of data collected is too much, and it takes a long time to detect the concentration of organic pollutants in dynamic flowing water in actual production. Summary of the invention

[0008] The present invention provides a multi-channel water quality online detection device and method based on a fluorescence imaging system, which can realize continuous detection of water samples.

[0009] The technical solution of the present invention is as follows:

[0010] A multi-channel water quality online detection device based on a fluorescence imaging system, comprising:

[0011] The sample circulation pool is formed by connecting multiple straight tubes with rectangular cross-sections end to end to form a channel for water sample circulation; the end to end of the sample circulation pool are connected but not connected, and are respectively a water sample inlet and a water sample outlet; an emission light window is opened on the outer wall of the straight tube, and an excitation light window is opened on the bottom surface of the straight tube, and the normal line at the geometric center of the emission light window is perpendicular to and intersects with the normal line at the geometric center of the corresponding excitation light window; the sample circulation pool is light-proof except for the emission light window and the excitation light window;

[0012] The emission light module includes multiple groups of emission light sources and condensing lenses. The emission light generated by the emission light source enters the sample flow cell through the emission light window after passing through the condensing lens, and is used to excite the fluorescent substance in the water sample to produce a fluorescent effect;

[0013] The fluorescence imaging and detection module includes a dark light correction film, a CMOS photosensitive device and multiple groups of excitation light filters. The excitation light emitted from the excitation light window is received by the CMOS photosensitive device after passing through the filter.

[0014] The control and analysis module analyzes the fluorescence intensity signal received by the CMOS photosensitive device and calculates the concentration of fluorescent organic pollutants in the water sample.

[0015] An emission light source, a corresponding condenser lens, a corresponding emission light window, a corresponding excitation light window, a corresponding excitation light filter, and a CMOS photosensitive device form a channel.

[0016] The emission light module, fluorescence imaging and detection module are controlled by the control and analysis module.

[0017] Preferably, the sample circulation pool has a U-shaped water sample circulation channel for testing.

[0018] Preferably, the sample flow cell is provided with 8 emission light windows and 8 excitation light windows; starting from the proximal end of the water sample inlet, the first to the eighth emission light windows are respectively provided along the flow direction of the water sample;

[0019] The first, fourth, fifth and eighth light emission windows are parallel to each other and form a first parallel group, wherein the first and eighth light emission windows are in the same side group, the fourth and fifth light emission windows are in the same side group, and the two groups of light emission windows are on opposite sides of each other;

[0020] The second, third, sixth and seventh light emission windows are parallel to each other and form a second parallel group, wherein the second and third light emission windows are in the same side group, the sixth and seventh light emission windows are in the same side group, and the two groups of light emission windows are on opposite sides of each other;

[0021] The light emission windows of the first parallel group and the second parallel group are perpendicular to each other.

[0022] The straight tubes where two adjacent light emission windows are perpendicular to each other are located are perpendicular to each other.

[0023] The normal line at the geometric center of the emission light window is perpendicular to and intersects with the normal line at the geometric center of the corresponding excitation light window. The perpendicular angle can prevent most of the emission light from affecting the detection of the excitation light.

[0024] In order to prevent the two light emitting windows on the same side from interfering with each other, preferably, the straight tubes where the two light emitting windows of the same side group are located are not collinear.

[0025] Furthermore, the straight tubes where the two light emitting windows of the same side group are located are connected through a connecting tube, and the axis of the connecting tube is perpendicular to the axis of the straight tubes where the two light emitting windows of the same side group are located.

[0026] Furthermore, the distance between the straight tube axes where the two light emitting windows of the same side group are located is greater than the length of the long side of the rectangle of the straight tube cross section.

[0027] This ensures that the emitted light from one of the emission windows cannot directly affect the water sample in the detection area of ​​the other emission window through primary scattering or refraction in the flow cell.

[0028] Except for the light path channel which remains light-transmissive, namely the emission light window and the excitation light window, the rest of the surface of the sample circulation pool pipeline is coated with an opaque coating to isolate the interference of external ambient light.

[0029] The emission wavelengths of the emission light sources are 260nm, 270nm, 390nm, and 400nm.

[0030] The emission light source is fixed in front of the emission light window, and the focusing lens is fixed between the emission light window and the emission light source. The specific wavelength light generated by the emission light source is focused by the lens and converted into parallel light and vertically enters the emission light window.

[0031] Preferably, the emission wavelength corresponding to the first and third emission light windows is 260nm, the emission wavelength corresponding to the second and fourth emission light windows is 270nm, the emission wavelength corresponding to the fifth and seventh emission light windows is 390nm, and the emission wavelength corresponding to the sixth and eighth emission light windows is 400nm.

[0032] Preferably, the filters corresponding to the first, second, fifth and sixth excitation light windows filter out light with a wavelength above 400 nm, and the filters corresponding to the third, fourth, seventh and eighth excitation light windows filter out light with a wavelength above 450 nm.

[0033] The grayscale of the dark light correction film is known and is used for absolute grayscale calibration.

[0034] The entire detection module is in a light-proof environment, and no external ambient light enters except the light emitting window.

[0035] The multi-channel water quality online detection device of the present invention also includes a filtering device for filtering out particles in the water sample before the water sample enters the sample circulation pool.

[0036] The multi-channel water quality online detection device of the present invention further comprises a sampling peristaltic pump, which collects water samples and sends them into the sample circulation pool.

[0037] The present invention also provides a multi-channel water quality online detection method based on a fluorescence imaging system, comprising:

[0038] The water sample to be tested is passed through the inlet of the sample flow cell, and the emission light module emits emission light to excite the fluorescent substance in the water sample to produce a fluorescence effect. The CMOS photosensitive device collects the fluorescence intensity signals of the first to eighth excitation light windows in real time. The control and analysis module analyzes the fluorescence intensity signals received by the CMOS photosensitive device to calculate the concentration of fluorescent organic pollutants in the water sample;

[0039] The calculation process is as follows:

[0040] (1) Calculate the fluorescence intensity of the area where the dark light correction film is located and calculate its arithmetic mean, which is recorded as t 0;

[0041] (2) Calculate the excitation light window i The fluorescence intensity of the area is calculated and its arithmetic mean is recorded as t i , i is an integer from 1 to 8; then the channel i Fluorescence parameters X i for:

[0042] ①;

[0043] (3) Calculate the concentration parameters based on the fluorescence parameters of channels 1, 3, 5, and 6 Y 1:

[0044] ②;

[0045] in a 1. a 3. a 5. a 6 are the conversion coefficients of channels 1, 3, 5, and 6 respectively. b 1 is the offset parameter;

[0046] (4) Calculate the concentration parameters based on the fluorescence parameters of channels 2, 4, 7, and 8 Y 2:

[0047] ③;

[0048] in a 2. a 4. a 7. a 8 are the conversion coefficients of channels 2, 4, 7, and 8 respectively. b 2 is the offset parameter;

[0049] (5) Calculate the concentration of fluorescent pollutants in the sample flow cell Y , in ng / g:

[0050] ④.

[0051] Preferably, a 1- a 8 and b 1. b 2 is calculated as:

[0052] (a) Prepare 10 sets of fluorescent substance solutions with known concentrations;

[0053] (b) Ten groups of fluorescent substance solutions with known concentrations are introduced into the sample flow cell inlet respectively, and the emission light module emits emission light to excite the fluorescent substances in the water sample to produce a fluorescence effect. The CMOS photosensitive device collects the fluorescence intensity signals of the first to eighth excitation light windows in real time;

[0054] (c) Solve according to formulas ①-④ a 1- a 8 and b 1. b 2.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The present invention does not require the collection of water samples and the sending of them to the laboratory for pre-treatment and post-testing, thus avoiding changes in water quality and enabling on-site continuous online testing of the concentration of organic pollutants in actual flowing sewage;

[0057] (2) The space requirement is small, which can realize the miniaturization of equipment; the requirements for the tested site are low, and it can be quickly applied to most production environments without additional modification;

[0058] (3) It uses a small number of fixed-band LED light sources, which have stable light emission, low component cost and maintenance cost, and no need to switch bands for scanning, which is conducive to rapid detection;

[0059] (4) The fluorescence imaging system based on CMOS photosensitive devices has fast data acquisition speed and high imaging quality. Through the dark light correction film, fluorescence information and correction data can be obtained simultaneously in one imaging, which can accurately reflect the concentration of organic pollutants in the tested water body in real time and realize rapid detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the implementation process of the multi-channel water quality online detection device;

[0061] Figure 2 It is a schematic diagram of the structure of a multi-channel water quality online detection device;

[0062] Figure 3 It is a top view schematic diagram of a multi-channel water quality online detection device;

[0063] Figure 4 is a side view schematic diagram of the flow cell;

[0064] Figure 5 Schematic diagram of the bottom of the flow cell;

[0065] Figure 6 Fluorescence intensity images of different concentrations of 2-ITX in the example, (a)-(f) are 0 ng / g, 100 ng / g, 200 ng / g, 400 ng / g, 500 ng / g, and 1000 ng / g, respectively. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0067] In order to analyze the concentration of fluorescent organic matter in water samples online, the present invention proposes an online detection method and device for organic pollutants in water based on a fluorescence imaging system. Through a sample sampling and pre-processing module, a multi-channel detection module, an imaging module and a data processing algorithm, the fluorescence intensity of the water sample is monitored in real time to achieve continuous monitoring of fluorescent target organic matter.

[0068] like Figure 1-Figure 3 As shown, the multi-channel water quality online detection device based on the fluorescence imaging system of the present invention specifically includes:

[0069] 1. Pre-filter device: The pre-filter device consists of a filter membrane holder and a hydrophilic filter membrane, which is mainly used to filter particles in water samples and reduce the interference of excitation light and fluorescence scattering caused by suspended particles. The main medium of the filter membrane can be polyethersulfone (PES) or hydrophilic modified polytetrafluoroethylene (PTFE), and the pore size of the filter membrane can be selected according to the size of suspended particles in the actual sample. For example, for environmental water samples, a PES filter membrane with a pore size of 0.45um and a thickness of 0.18mm can be used. The diameter of the filter membrane is 47mm.

[0070] 2. Sample circulation pool 3: The sample circulation pool 3 is made of quartz material and is used to maintain the circulation of the water sample to be tested and to assist in the generation of high-quality fluorescence effect.

[0071] like Figure 4 and Figure 5 As shown, the circulation pool 3 is formed by connecting straight pipes of rectangular cross-section end to end, but the end is not connected. The geometric center of the pipe cross section is always in the same horizontal plane, which is called the circulation plane. The plane is parallel to the top and bottom surfaces of the circulation pool. A circular tube perpendicular to the circulation plane extends out from the same side of the circulation pool, which serves as the entrance and exit of the analysis channel, that is, the channel for the water sample to be tested to flow in and out. Eight equal rectangular areas are marked out on the outer side of the circulation pool as emission light windows 3-1, starting from the proximal end of the entrance and numbered 1-8 along the flow direction of the water sample. Emission windows 1, 4, 5, and 8 are parallel to each other and form a parallel group, of which 1 and 8 are the same side group, 4 and 5 are the same side group, and the two groups of windows are on opposite sides; emission windows 2, 3, 6, and 7 are parallel to each other and form a parallel group, of which 2 and 3 are the same side group, 6 and 7 are the same side group, and the two groups of windows are on opposite sides; the windows of the above two parallel groups are perpendicular to each other. Therefore, the pipes where two adjacent windows that are perpendicular to each other are located are perpendicular to each other, such as 1 and 2.

[0072] Similarly, eight equal rectangles are drawn on the bottom surface of the pipe at the emission window as excitation light windows (3-2-1 to 3-2-8). The normal line at the geometric center of the emission light window is perpendicular to and intersects with the normal line at the geometric center of the excitation light window. The vertical angle can avoid the influence of most emission light on the detection of excitation light. In order to prevent the two emission light windows on the same side from interfering with each other, the pipes where the two are located are not colinear. By using a common vertical pipe for connection, the distance between the two pipes is greater than the length of the long side of the pipe cross-section rectangle, ensuring that the emission light of one window cannot directly affect the water sample in the detection area of ​​the other window through a single scattering or refraction in the flow cell.

[0073] Except for the light path channel that remains light-transmissive, namely the emission light window and the excitation light window, the rest of the surface of the circulation pool pipeline is coated with an opaque coating to isolate it from interference from external ambient light.

[0074] 3. Emission light generator: The emission light generator consists of a specific wavelength emission light LED1 and a focusing lens 2, which is used to generate emission light that can excite fluorescent substances to produce fluorescence effects. The emission light LED1 is preferably a Thorlabs light source, and there are four models: LED260J, LED275W, LED395L, and LED405L, which can generate emission light with wavelengths of 260nm, 270nm, 390nm, and 400nm, respectively. The peak intensity of this type of light source at wavelengths deviating from -10nm, -5nm, 0nm, +5nm, +10nm, and +15nm is 10%, 50%, 100%, 60%, 30%, and 10%, respectively. The wavelength range is narrow, there is less interference, and the excitation efficiency is higher. The emission light LED1 is fixed in front of the emission light window, and the focusing lens 2 is fixed between the emission light window and the emission light LED1, so that the specific wavelength light generated by the LED is converted into parallel light after being focused by the lens and vertically injected into the emission light window. Among them, the LED wavelength corresponding to windows 1 and 3 is 260nm, the LED wavelength corresponding to windows 2 and 4 is 270nm, the LED wavelength corresponding to windows 5 and 7 is 390nm, and the LED wavelength corresponding to windows 6 and 8 is 400nm.

[0075] 4. Fluorescence imaging and detection module: The fluorescence imaging and detection module consists of an excitation light filter 4, a dark light correction film 6 and a CMOS photosensitive device 5, which are used to filter and obtain the fluorescence of the required band, and convert the fluorescence intensity signal into a digital image signal. The four excitation light filters are divided into two groups, each with four pieces, one of which can filter light with a wavelength of more than 400nm (referred to as 400nm filter), and the other group can filter light with a wavelength of more than 450nm (referred to as 450nm filter). The filter is fixed below the excitation window, where excitation windows 1, 2, 5, and 6 correspond to 400nm filters, and excitation windows 3, 4, 7, and 8 correspond to 450nm filters, so that after the excitation light is emitted through the excitation window, the light of irrelevant bands is filtered out by the filter and received by the CMOS below it. The CMOS photosensitive device is fixed directly below the sample flow cell, and its field of view includes the complete bottom surface of the sample flow cell, and can fully receive the excitation light filtered by the filter. The dark light correction film is a square film with known grayscale, which is used for absolute grayscale calibration and is located in the center of the sample flow cell, parallel to the CMOS. The entire detection module is in a light-proof environment, and no external ambient light is injected except the excitation window.

[0076] 5. Sampling peristaltic pump: The micro air pump is a 12V micro peristaltic pump, designed with a sampling flow rate of 100cc per minute.

[0077] The multi-channel water quality online detection method based on the fluorescence imaging system of the present invention specifically includes:

[0078] 1. Sampling: Connect two hoses to the inlet and outlet of the sample flow cell respectively, and immerse the other end of the hose at the inlet into the water to be tested. Start the sampling peristaltic pump to allow the water sample to enter the sample flow cell for real-time sampling of the water sample.

[0079] 2. Real-time determination of the concentration of organic pollutants in the sample circulation pool: The fluorescent organic molecules in the sample will absorb the emission light of a specific frequency emitted by the emission light generator, produce a fluorescence effect, and emit fluorescence outward. A total of eight LED light sources that can generate four wavelengths of 260nm, 270nm, 390nm, and 400nm are used to continuously irradiate the circulating water sample through the emission light window at different parts of the sample circulation pool. The fluorescent substance in the water sample absorbs the emission light and emits excitation light. After the excitation light passes through the excitation light window, it is filtered by two filters of 400nm and 450nm, respectively, and is captured by the CMOS image sensor. The CMOS records the excitation light intensity of each channel and the grayscale of the dark light correction film in the center of the field of view in real time. After the CMOS collects the data, the main controller completes the data analysis and calculates the concentration of the fluorescent organic pollutants in the current circulating sample. The specific calculation process is as follows:

[0080] A. Calculate the arithmetic mean value of the fluorescence brightness of the area where the dark light correction film is located in the obtained image, and record it as t 0;

[0081] B. Excitation window in the obtained image i The fluorescence brightness of the area is calculated and its arithmetic mean is recorded as t i , then the channel i Fluorescence parameters X i According to the following calculation formula, i The value range is an integer from 1 to 8:

[0082]

[0083] C. Based on the fluorescence parameters of channels 1, 3, 5, and 6, calculate the concentration parameters as follows Y 1:

[0084]

[0085] in a 1. a 3. a 5. a 6 are the conversion coefficients of the corresponding channels, b 1 is the offset parameter.

[0086] D. Based on the fluorescence parameters of channels 2, 4, 7, and 8, calculate the concentration parameters as follows Y 2:

[0087]

[0088] in a 2. a 4. a 7. a 8 are the conversion coefficients of the corresponding channels. b 2 is the offset parameter, and the concentration of fluorescent pollutants in the flow cell is calculated by the following formula: Y , in ng / g:

[0089] 3. Specific embodiments

[0091] In this example, water samples containing the fluorescent substance 2-isopropyl-thioxanthen-9-one (2-ITX) at different concentrations were used for testing. The specific process is as follows:

[0092] 1. Parameter calibration:

[0093] 1) Prepare ten sets of 2-ITX solutions with different known concentrations.

[0094] 2) Allow the above solutions to pass through the sample flow cell at a flow rate of 10cc / min, and collect data.

[0095] 3) Calculation of fluorescence parameters X i .

[0096] 4) Solve the coefficients a 1- a 8 and parameters b 1. b 2. In this example, a 1=-31725.2, a 3=27721.49, a 5=132751.4, a 6=-30569, b 1=33.8, a 2=-24201.0, a 4=-23110.1, a 7=1471905, a 8=-1189147.5, b 2=142.8.

[0097] 2.2-ITX concentration test:

[0098] 1) Configure 2-ITX solutions of 0ng / g, 100 ng / g, 200 ng / g, 400 ng / g, 500 ng / g, and 1000 ng / g.

[0099] 2) Allow the above solutions to pass through the sample flow cell at a flow rate of 10cc / min, and collect data.

[0100] 3) Calculation of fluorescence parameters X i and the concentration of fluorescent pollutants Y , the detection error is ±5-20%.

[0101] Figure 6 The grayscale images obtained after CMOS acquisition when the concentration of 2-ITX in the real water body is (a) 0 ng / g, (b) 100 ng / g, (c) 200 ng / g, (d) 400 ng / g, (e) 500 ng / g, and (f) 1000 ng / g. The image viewing angle is the same as the bottom view of the device. The fluorescence intensity of each acquisition window increases with the increase of 2-ITX concentration; at the same concentration, the measured signal intensity of each window is different due to the different excitation light bands and filters.

[0102] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-channel water quality online detection device based on a fluorescence imaging system, characterized in that: include: The sample flow cell is composed of a plurality of straight pipes with rectangular cross-sections connected end to end to form a U-shaped flow channel for the water sample to be tested for the flow of the water sample; The sample flow cell is connected end to end but not connected, and is respectively a water sample inlet and a water sample outlet; the outer wall of the straight tube is provided with 8 emission light windows, and the bottom surface of the straight tube is provided with 8 excitation light windows, and the normal line at the geometric center of the emission light window is perpendicular to and intersects with the normal line at the geometric center of the corresponding excitation light window; Starting from the proximal end of the water sample inlet, the first to eighth light emission windows are arranged along the flow direction of the water sample; the first, fourth, fifth, and eighth light emission windows are parallel to each other and form a first parallel group, wherein the first and eighth light emission windows are in the same side group, the fourth and fifth light emission windows are in the same side group, and the two groups of light emission windows are on opposite sides of each other; The second, third, sixth and seventh emission light windows are parallel to each other and form a second parallel group, wherein the second and third emission light windows are in the same side group, the sixth and seventh emission light windows are in the same side group, and the two groups of emission light windows are on opposite sides of each other; the emission light windows of the first parallel group and the second parallel group are perpendicular to each other; the straight tubes where the two emission light windows of the same side group are located are not collinear; the straight tubes where the two emission light windows of the same side group are located are connected by a connecting tube, and the axis of the connecting tube is perpendicular to the axis of the straight tubes where the two emission light windows of the same side group are located; the distance between the axes of the straight tubes where the two emission light windows of the same side group are located is greater than the length of the long side of the rectangle of the straight tube cross section; the sample circulation pool is lightproof except for the emission light window and the excitation light window; The emission light module includes multiple groups of emission light sources and condensing lenses. The emission light generated by the emission light source enters the sample flow cell through the emission light window after passing through the condensing lens, and is used to excite the fluorescent substance in the water sample to produce a fluorescent effect; The fluorescence imaging and detection module includes a dark light correction film, a CMOS photosensitive device and multiple groups of excitation light filters. The excitation light emitted from the excitation light window is received by the CMOS photosensitive device after passing through the filter. The control and analysis module analyzes the fluorescence intensity signal received by the CMOS photosensitive device and calculates the concentration of fluorescent organic pollutants in the water sample.

2. The multi-channel water quality online detection device based on the fluorescence imaging system according to claim 1 is characterized in that: The emission wavelengths of the first and third emission light windows are 260 nm, the emission wavelengths of the second and fourth emission light windows are 270 nm, the emission wavelengths of the fifth and seventh emission light windows are 390 nm, and the emission wavelengths of the sixth and eighth emission light windows are 400 nm.

3. The multi-channel water quality online detection device based on the fluorescence imaging system according to claim 1 is characterized in that: The filters corresponding to the first, second, fifth and sixth excitation light windows filter out light with a wavelength of more than 400nm, and the filters corresponding to the third, fourth, seventh and eighth excitation light windows filter out light with a wavelength of more than 450nm.

4. A method for online water quality detection using the multi-channel online water quality detection device according to any one of claims 1 to 3, characterized in that: include: The water sample to be tested is passed through the inlet of the sample flow cell, and the emission light module emits emission light to excite the fluorescent substance in the water sample to produce a fluorescence effect. The CMOS photosensitive device collects the fluorescence intensity signals of the first to eighth excitation light windows in real time. The control and analysis module analyzes the fluorescence intensity signals received by the CMOS photosensitive device to calculate the concentration of fluorescent organic pollutants in the water sample; The calculation process is as follows: (1) Calculate the fluorescence intensity of the area where the dark light correction film is located and calculate its arithmetic mean, which is recorded as t 0; (2) Calculate the excitation light window i The fluorescence intensity of the area is calculated and its arithmetic mean is recorded as t i , i is an integer from 1 to 8; then the channel i Fluorescence parameters X i for: ①； (3) Calculate the concentration parameters based on the fluorescence parameters of channels 1, 3, 5, and 6 Y 1: ②； in a 1. a 3. a 5. a 6 are the conversion coefficients of channels 1, 3, 5, and 6 respectively. b 1 is the offset parameter; (4) Calculate the concentration parameters based on the fluorescence parameters of channels 2, 4, 7, and 8 Y 2: ③； in a 2. a 4. a 7. a 8 are the conversion coefficients of channels 2, 4, 7, and 8 respectively. b 2 is the offset parameter; (5) Calculate the concentration of fluorescent pollutants in the sample flow cell Y , in ng / g: ④。 5. The method according to claim 4, characterized in that a 1- a 8 and b 1. b 2 is calculated as: (a) Prepare 10 sets of fluorescent substance solutions with known concentrations; (b) Ten groups of fluorescent substance solutions with known concentrations are introduced into the sample flow cell inlet respectively, and the emission light module emits emission light to excite the fluorescent substances in the water sample to produce a fluorescence effect. The CMOS photosensitive device collects the fluorescence intensity signals of the first to eighth excitation light windows in real time; (c) Solve according to formulas ①-④ a 1- a 8 and b 1. b 2.

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