Chemical oxygen demand (COD) sensor based on six-wavelength light-emitting diode (LED) and suspended matter interference dynamic correction method thereof

Abstract

The invention discloses a COD (Chemical Oxygen Demand) sensor based on a six-wavelength LED (Light Emitting Diode) and a suspended matter interference dynamic correction method thereof. The COD sensor based on the six-wavelength LED is used for collecting transmission light signals of a to-be-detected environmental water sample in visible light and ultraviolet light; calculating absorbance data of visible light and absorbance data of ultraviolet light based on the light intensity value of the transmission light signal; constructing a required characteristic function based on the absorbance data of the visible light wavelength; calculating suspended matter absorbance data of the wavelength of the ultraviolet light based on the characteristic function; and subtracting the absorbance data of the suspended matter of the ultraviolet wavelength from the absorbance data of the ultraviolet wavelength to obtain net absorbance data of the dissolved organic matter DOM after dynamic correction of the interference of the suspended matter. According to the invention, through multi-wavelength absorbance correction, the interference of suspended solids on a spectrometric test result is eliminated, the absorbance of the dissolved organic matter DOM is corrected, and accurate detection of the dissolved organic matter and related chemical oxygen demand (COD) indexes thereof is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality detection, and more specifically, to a COD sensor based on six-wavelength LEDs and a dynamic correction method for suspended matter interference thereof. Background Art

[0002] Chemical Oxygen Demand (COD), as a core evaluation index of water pollution degree, is detected by using potassium dichromate or permanganate as an oxidant to digest a water sample under high temperature conditions according to the national standard method. However, such chemical detection methods are difficult to meet the high-frequency on-line monitoring requirements in scenarios such as sewage pipe networks and industrial wastewater treatment facilities.

[0003] Dissolved Organic Matter (DOM) in water is the main source of Chemical Oxygen Demand (COD). The absorbance generated at the ultraviolet wavelength of 250 nm to 300 nm (such as UV254 and UV276, etc.) can be used as a substitute index for COD. The optical method for COD detection shows significant advantages in the field of real-time monitoring by analyzing the characteristic absorption peak of DOM (such as UV254) through ultraviolet-visible spectroscopy. DOM in water produces a characteristic absorption peak at the ultraviolet wavelength of 254 nm (UV254). The absorbance value is significantly positively correlated with the value of COD. This principle is established as a rapid detection method for COD in clarified water by the industry standard DB37 / T 4149-2020.

[0004] Although the industry standard DB37 / T 4149-2020 establishes UV254 as a COD substitute index, its applicable range is clearly limited to clarified water with a suspended substance (SS) concentration of less than 50 mg / L. Fundamentally, the scattering intensity of non-dissolved suspended substances SS in water in the ultraviolet-visible light band shows significant wavelength dependence, resulting in the absorbance measurement value of traditional single / double-wavelength optical sensors containing SS interference signals that are difficult to separate.

[0005] In the related art, optical COD detection is interfered by suspended solids in practical applications, especially in sewage pipe networks and industrial wastewater with high turbidity. The existing anti-interference technologies have two inherent defects in two major technical routes: (1) Physical isolation: For example, Chinese Patent CN220603302U pre-treats water samples with filters and cleaning brushes. Although it can effectively intercept suspended particles, the frequent maintenance and high energy consumption caused by filter membrane blockage make it difficult to adapt to harsh field conditions; (2) Algorithm compensation: For example, Chinese Patent CN117074333B corrects by fusing multi-wavelength absorbance and turbidity parameters through a machine learning model. However, the model training needs to cover complex variables such as SS particle size, mineral composition, and organic floc proportion. When the physical and chemical characteristics of suspended solids in water exceed the range of the training set, the generalization ability of the model drops sharply; Secondly, for a higher-precision continuous ultraviolet-visible spectrometer, such as Chinese Patent CN112304875B, although it analyzes the SS scattering spectrum through full-band scanning, its spectroscopic optical path is sensitive to vibration, the deuterium lamp has a short lifespan and high power consumption, and it is difficult to be implanted into limited spaces such as pipe network monitoring wells; In addition, the discrete wavelength probe based on LED, such as Chinese Patent CN220603302U, although it has the advantages of low cost, low power consumption, and miniaturization, due to too few detection bands, it is impossible to construct a mathematical characterization model of the SS scattering spectrum; Another example is that Chinese Patent CN114184549A attempts to improve the anti-interference ability by adding Vis band auxiliary detection, but the fixed empirical coefficient method it uses does not consider the dynamic changes of the physical and chemical characteristics of SS, and there is still a problem of calibration factor inaccuracy in long-term monitoring.

[0006] To sum up, the fixed empirical coefficient method adopted in the prior art does not consider the dynamic changes of the physical and chemical characteristics of SS, and there is still a problem of calibration factor inaccuracy in long-term monitoring. At the same time, the traditional algorithm compensation method needs to perform SS gradient calibration on pre-collected water samples in the laboratory, and there are significant differences between the obtained fitting function and the real-time characteristics of SS in the on-site water body. When the particle size distribution, organic and inorganic component ratios of suspended solids in water change with seasons or working conditions, the calibration model preset in the laboratory will completely fail. This "offline calibration - online application" mode has become the fundamental obstacle restricting the on-site applicability of optical COD sensors. Summary of the Invention

[0007] 1. Technical problems to be solved In view of the above problems existing in the prior art, the present invention provides a COD sensor based on six-wavelength LEDs and a dynamic correction method for suspended solid interference, which can directly construct a dynamic response model of SS interference on-site, and realize real-time stripping of the influence of SS without full-spectrum scanning, so as to complete in-situ monitoring of COD in complex water bodies.

[0008] 2. Technical solutions The object of the present invention is achieved through the following technical solutions.

[0009] The content of this application is partially used to introduce concepts in a brief form, and these concepts will be described in detail in the following detailed implementation section. The content of this application is not intended to identify the key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0010] Some embodiments of this application propose a COD sensor based on a six-wavelength LED and its dynamic correction method for suspended matter interference to solve the technical problems mentioned in the above background art section.

[0011] As the first aspect of this application, some embodiments of this application provide a COD sensor based on a six-wavelength LED, including a housing, and a light source, a flow cell, a light intensity detection component, and a control circuit main board disposed within the housing; The flow cell is a transparent cavity for accommodating the water sample of the environment to be measured and allowing the light path to pass through. The light source and the flow cell are coaxially aligned to ensure that the light beam converges at the center of the flow cell; The light source is a multi-wavelength composite packaged LED light source; the multi-wavelength composite packaged LED light source has at least one wavelength of ultraviolet light source and at least two wavelengths of visible light sources; The light intensity detection component is used to detect the transmitted light signal absorbed by the water sample of the environment to be measured in the flow cell after being emitted by the light source, and convert the transmitted light signal into an electrical signal; the light intensity detection component includes an ultraviolet detection photodiode and a visible detection photodiode; The control circuit main board is used to control the start of the light source, receive the electrical signal transmitted by the light intensity detection component, calculate the absorbance data of visible light and the absorbance data of ultraviolet light based on the electrical signal, and communicate with the upper computer.

[0012] Furthermore, the light source includes a visible light LED chip composite packaged in a three-chip form and an ultraviolet light LED chip composite packaged in a three-chip form.

[0013] Furthermore, the visible light wavelengths integrated by the visible light LED chip include 456 nm, 524 nm, and 615 nm, and the ultraviolet light wavelengths integrated by the ultraviolet light LED chip include 254 nm, 275 nm, and 305 nm.

[0014] Furthermore, the control circuit main board includes a micro control unit and a light source drive circuit, a preprocessing circuit, and a communication module electrically connected to the micro control unit; The preprocessing circuit amplifies and filters the electrical signal converted from the transmitted light signal. The micro control unit controls the light source drive circuit to regulate the multi-wavelength composite packaged LED light source to output a transmitted light signal corresponding to multiple wavelengths and communicates with the upper computer through the communication module.

[0015] Furthermore, the housing includes a light source chamber, a detection chamber, and a control chamber; the light source is installed at the front end of the light source chamber, the flow cell is installed at the center of the detection chamber and is connected to the outside, and the light intensity detection component is installed at the rear end of the detection chamber; the control circuit main board is installed in the control chamber; the optical path of the light source and the flow cell is coaxially aligned, and the light intensity detection component is coaxially aligned with the light source.

[0016] Furthermore, the COD sensor based on six-wavelength LEDs further includes a cleaning brush head and a driving motor disposed within the housing; the driving motor is electrically connected to the micro control unit and is used to drive the cleaning brush head to rotate to remove contaminants.

[0017] As a second aspect of the present application, some embodiments of the present application provide a method for dynamically correcting suspended matter interference, including the following steps: Step 1: Use the above-mentioned COD sensor based on six-wavelength LEDs to collect the transmitted light signals of the water sample to be measured in the visible light and ultraviolet light; Step 2: Calculate the absorbance data of the visible light and the absorbance data of the ultraviolet light respectively based on the light intensity values of the transmitted light signals; Step 3: Construct the required characteristic function based on the absorbance data of the visible light wavelength; Step 4: Calculate the absorbance data of the suspended matter at the ultraviolet light wavelength based on the obtained characteristic function; Step 5: Subtract the absorbance data of the suspended matter at the ultraviolet light wavelength calculated in Step 1 from the absorbance data of the ultraviolet light wavelength obtained in Step 1 to obtain the net absorbance data of the dissolved organic matter DOM after dynamic correction of the suspended matter interference.

[0018] Furthermore, Step 1 specifically includes: the control circuit main board drives each wavelength LED light source in a preset order, each wavelength is independently lit and penetrates the water sample to be measured, the light intensity detection component receives the transmitted light signal absorbed by the water sample to be measured and converts it into an electrical signal, and after the electrical signal is amplified and filtered, it is converted into a digital light intensity value, and the absorbance data of the visible light wavelength and the absorbance data of the ultraviolet light wavelength are calculated and stored according to the digital light intensity value.

[0019] Furthermore, during the process of the light intensity detection component collecting the transmitted light signal, the lighting duration of each wavelength is 1 ms, and then the light source is turned off and enters a 50 ms data acquisition interval period. After cycling 20 times, it automatically switches to the next wavelength, and 20 data points of each wavelength are continuously collected.

[0020] Furthermore, Step 3 specifically includes: constructing a characteristic function, expressed as: ; In the formula, represents the wavelength, represents the absorbance data, kis the absorbance amplitude coefficient, b is the attenuation rate coefficient, is the base of the natural logarithm; Based on the absorbance data at visible light wavelengths, the characteristic coefficients k and b are solved by non-linear fitting, and the required characteristic function is obtained therefrom; Step 4 specifically includes: According to the constructed characteristic function, substituting the ultraviolet light wavelength, and calculating the absorbance data of the suspended matter at the ultraviolet light wavelength; Step 5 specifically includes: Substituting the ultraviolet light wavelength into the characteristic function, calculating the absorbance data of the suspended matter at the ultraviolet light wavelength, subtracting the absorbance data of the suspended matter at the ultraviolet light wavelength from the measured absorbance data at the ultraviolet light wavelength, and obtaining the net absorbance data of the dissolved organic matter DOM after dynamic correction of the suspended matter interference, and the process is expressed as: ; In the formula, is the absorbance data of the measured environmental water sample, is the absorbance data of the suspended matter, is the absorbance data of the dissolved organic matter DOM in the environmental water body.

[0021] 3. Beneficial effects Compared with the prior art, the advantages of the present invention are as follows: (1) The COD sensor based on the six-wavelength LED adopts on-site adaptive dynamic correction, and the characteristic coefficients are solved by real-time fitting of the absorbance data in the visible light band, and the optimal corrected function is directly generated in real time in the actual water environment, without laboratory calibration or off-line preprocessing, significantly shortening the detection cycle; combined with the dynamic compensation of the interference signal in the ultraviolet band, it can quickly respond to the changes in the suspended matter concentration and physical and chemical characteristics, ensuring the accuracy of COD measurement in complex water bodies; (2) The time-division drive multi-wavelength LED light source is adopted, and the start, stop and switching of each wavelength light source are independently controlled by the micro control unit (MCU) according to the preset time sequence, avoiding the problem of multi-light source crosstalk; at the same time, the characteristic function is constructed in real time by using the visible light band data, and the interference signal is stripped by ultraviolet band differential correction, solving the problem of calibration failure caused by insufficient detection bands of traditional single / double wavelength sensors, and ensuring the measurement stability when the suspended matter concentration changes suddenly; (3) The six-wavelength LED light source is integrated by the three-crystal composite packaging technology, and the split waterproof shell and coaxial optical path design are adopted to ensure the long-term stable alignment of the light source, flow cell and detector; the integrated cleaning brush head is used to remove pollutants, which can meet the long-term monitoring requirements of complex water bodies, and realize long-term stable monitoring in harsh environments such as rivers and pipe networks with high turbidity and many suspended matters. Description of the drawings

[0022] Figure 1 Schematic diagram of the steps of the suspended matter interference dynamic correction method in an embodiment of the present invention; Figure 2 Schematic diagram of the overall structure of the COD sensor based on six-wavelength LEDs in an embodiment of the present invention; Figure 3 Schematic diagram of the detailed structure of the COD sensor based on six-wavelength LEDs in an embodiment of the present invention; Figure 4 Circuit diagram of the control circuit main board of the COD sensor based on six-wavelength LEDs in an embodiment of the present invention; Figure 5 Front view of the three-crystal form composite packaged ultraviolet LED chip in an embodiment of the present invention; Figure 6 Back view of the three-crystal form composite packaged ultraviolet LED chip in an embodiment of the present invention; Figure 7 Front view of the three-crystal form composite packaged visible light LED chip in an embodiment of the present invention; Figure 8 Back view of the three-crystal form composite packaged visible light LED chip in an embodiment of the present invention; Figures 5 to 8 The length dimension units in [figures] are all millimeters (mm), and the dark squares indicate the specific positions of the LED lamp packages, and the corresponding wavelengths are marked at the same time; Figures 5 to 8 The "+" and "-" signs on the left and right sides in [figures] respectively correspond to the current flow directions.

[0023] Explanation of the reference numerals in the figures: 100, housing; 200, light source; 300, light intensity detection component; 400, control circuit main board; 500, cleaning brush head; 600, circuit board; 301, ultraviolet detection photodiode; 302, visible light detection photodiode; 201, ultraviolet LED; 202, visible light LED. Detailed implementation manners The present invention will be described in detail below in conjunction with the specification drawings and specific embodiments.

[0024] The optical detection technology based on ultraviolet absorption spectroscopy utilizes the positive correlation between the absorbance at characteristic wavelengths such as UV254 and COD (DB37 / T 4149-2020). Although it has been established as a rapid detection standard in a clear water environment, there are fundamental technical obstacles in its engineering application in turbid water bodies - the broadband scattering interference caused by suspended solids (SS).

[0025] Since the currently adopted fixed empirical coefficient method does not consider the dynamic changes in the physicochemical characteristics of SS, there is still a problem of calibration factor inaccuracy in long-term monitoring. At the same time, the traditional algorithm compensation method requires the SS gradient calibration of the pre-collected water samples in the laboratory, and there are significant differences between the obtained fitting function and the real-time characteristics of SS in the field water body. When the particle size distribution, organic and inorganic component ratios of the water body suspended matter change with seasons or working conditions, the calibration model preset in the laboratory will completely fail. This "offline calibration - online application" mode has become the fundamental obstacle restricting the on-site applicability of the optical COD sensor.

[0026] This contradiction between the hardware design and the algorithm model forces the existing technology to make a difficult choice between "high-precision large-scale equipment" and "low-reliability micro-probes". Its essential contradiction lies in the mismatch between the limited detection wavelength and the wide-spectrum scattering characteristics of suspended matter, and the maladaptation between the static compensation model and the dynamic physicochemical characteristics of suspended matter, which severely restricts the engineering application of the optical COD sensor in complex water environments.

[0027] Based on this, the present invention eliminates the laboratory calibration link by integrating multi-band optical detection and physically driven calibration algorithms, abandoning the passive compensation mode of the traditional "pre-trained model + empirical coefficient", and instead autonomously generating the optimal fitting function through the multi-spectral data stream of the field water body. This technical solution realizes the real-time stripping of the influence of SS by exploring the resolvability of the scattering spectrum of SS in the UVA-Vis band and constructing a mathematical transfer function between it and the interference intensity in the UVC-UVB band, thereby providing a solution with both theoretical rigor and engineering practicality for the in-situ monitoring of COD in complex water bodies. Among them, UVC refers to the ultraviolet C band (200 nm - 280 nm), UVB refers to the ultraviolet B band (280 nm - 315 nm), and the UVC-UVB band refers to the combined range of UVC and UVB in ultraviolet rays. UVA-Vis is the combined range of ultraviolet A band (UVA) and visible light (Visible, Vis).

[0028] As Figures 2 to 8 shown, the present invention provides a COD sensor based on six-wavelength LEDs, including a housing 100, a light source 200, a flow cell, a light intensity detection component 300, a control circuit main board 400, and a cleaning brush head 500. The light source 200, the flow cell, the light intensity detection component 300, the control circuit main board 400, and the cleaning brush head 500 are all arranged inside the housing 100.

[0029] The housing 100 adopts a split waterproof structure, including a light source chamber, a detection chamber and a control chamber. A detector receiving port is arranged at the upper part of the detection chamber, and an LED optical path incident port is arranged at the lower part. The measurement is realized by the opposed beam method. When the light passes through the solution to be measured, an optical intensity difference is formed. The flow cell is installed at the center of the detection chamber and is connected to the outside. The optical intensity detection component 300 is fixedly installed at the rear end of the detection chamber corresponding to the detector receiving port, and the cleaning brush head 500 is installed on the side wall of the detection chamber. The light source 200 is installed at the front end of the light source chamber and corresponds to the LED optical path incident port. The light source 200 is coaxially aligned with the optical path of the flow cell to ensure that the light beam converges at the center of the flow cell, and the optical intensity detection component 300 is coaxially aligned with the light source 200. The control circuit main board 400 is fixedly installed inside the control chamber.

[0030] The light source 200 is a multi-wavelength composite packaged LED light source, including an ultraviolet light source and a visible light source. In this embodiment, 3 visible light LED chips and 3 ultraviolet light LED chips are compound packaged in a three-chip form. The ultraviolet light LED chips with emission wavelengths of 254 nm, 276 nm, and 305 nm are selected as the ultraviolet light source, and the visible light LED chips with emission wavelengths of 456 nm, 524 nm, and 615 nm are selected as the visible light source.

[0031] As Figures 5 to 8 shown, the light source 200 adopts a three-chip composite packaging structure, integrating 3 ultraviolet light LED chips and 3 visible light LED chips on a substrate respectively to form a six-wavelength composite light source. The ultraviolet light LED chips and the visible light LED chips are arranged in an interleaved form. In each packaging unit, the ultraviolet light LED chips and the visible light LED chips are spaced apart, and the optical axis consistency is ensured. The cathodes of all chips are connected to the common ground terminal through copper wires; the anodes of each chip are independently led out and are respectively connected to the light source drive circuit in the control circuit main board 400 through the circuit board 600 to realize the time-division independent control of each wavelength light source. This packaging method realizes six-wavelength time-division multiplexing by optimizing the chip layout and drive architecture, and simultaneously meets the heat dissipation requirements of ultraviolet LEDs and the stability of multi-spectral output.

[0032] The flow cell is a transparent cavity for accommodating the water sample to be measured and providing a stable transmission path for the optical path, ensuring that the light emitted by the light source 200 passes through the water sample and is accurately captured by the detector, so as to calculate the absorbance value. The optical intensity detection component 300 is used to detect the optical signal after being absorbed by the liquid in the flow cell, and after converting the optical signal into an electrical signal, it is transmitted to the control circuit main board 400. The optical intensity detection component 300 includes two types of detectors, namely an ultraviolet detection photodiode 301 and a visible detection photodiode 302.

[0033] As Figure 4As shown, the control circuit main board 400 is used to control the startup of the light source, detect photoelectric signals and process the signals. The control circuit main board 400 integrates a micro control unit (MCU), a light source drive circuit, a preprocessing circuit and a communication module. The control circuit main board 400 is connected to a six-wavelength LED light source and a light intensity detection component 300 through a circuit board 600. The control circuit main board 400 transmits a drive signal to the six-wavelength LED light source through the light source drive circuit. After the photodiode in the light intensity detection component 300 converts the detected optical signal into an electrical signal, it is transmitted back to the control circuit main board 400 through the circuit board 600. Specifically, the micro control unit (MCU) controls the start-stop and multi-wavelength switching of the six-wavelength LED light source respectively through the light source drive circuit to output an optical signal. The optical signal detected by the photodiode is converted into an electrical signal and then transmitted to the preprocessing circuit through the circuit board 600. In the preprocessing circuit, preprocessing such as amplifying and filtering the electrical signal is performed. The micro control unit (MCU) stores the preprocessed electrical signal after analog-to-digital conversion through a built-in analog-to-digital converter (ADC). At the same time, data interaction with a host computer or a monitoring platform is realized through a communication module (such as RS-485), supporting remote instruction reception, status feedback and real-time data upload.

[0034] The cleaning brush head 500 is used to remove suspended solids, algae or sediment attached to the inner wall of the flow cell to avoid contaminants blocking the optical path. The cleaning brush head 500 is connected to a drive motor fixed in the detection cavity through an embedded transmission shaft. The micro control unit (MCU) controls the drive motor through a PWM signal to drive the cleaning brush head 500 to rotate to remove contaminants.

[0035] Compared with the correction mode of traditional laboratories, the COD sensor based on six-wavelength LEDs of the present invention does not need to bring water samples back to the laboratory for pretreatment and can be directly deployed in the actual surface water environment to generate a correction fitting function matching the characteristics of the current water body suspended solids. Through multi-wavelength absorbance correction, the interference of suspended solids on the test results of the spectroscopic method is eliminated, the absorbance of the measured DOM is corrected, the operation and maintenance process is simplified, and the rapid and accurate detection of DOM and its associated chemical oxygen demand COD index is realized.

[0036] As Figure 1 shown, based on the above-mentioned COD sensor based on six-wavelength LEDs, a method for dynamically correcting the interference of suspended solids of the present invention includes the following steps: S1. Multi-wavelength data acquisition Using a COD sensor based on six-wavelength LEDs, absorbance data of environmental water samples in visible light and ultraviolet light are collected.

[0037] Specifically, the COD sensor based on six-wavelength LEDs adopts a three-crystal form composite package, integrating an ultraviolet LED chip and a visible light LED chip into the COD sensor based on six-wavelength LEDs, thereby having six independent-wavelength LED light sources built-in.

[0038] In this embodiment, the ultraviolet LED chip emits wavelengths of ultraviolet light, including 254 nm, 276 nm, and 305 nm, and the visible light LED chip emits wavelengths of visible light, including 456 nm, 524 nm, and 615 nm.

[0039] The COD sensor based on six-wavelength LEDs is driven by a micro-control unit (MCU) to sequentially drive each wavelength of LED light source in a preset order. Each wavelength is independently lit and penetrates the environmental water sample to be measured. The transmitted light signal is collected by the corresponding photodiode in the light intensity detection component 300, and an analog current signal proportional to the transmitted light intensity is output and transmitted to the preprocessing circuit of the control circuit main board 400 for preprocessing and photoelectric conversion. After ADC analog-to-digital conversion, the light intensity value in digital quantity is obtained and transmitted to the micro-control unit (MCU). The micro-control unit (MCU) calculates the absorbance based on the pre-stored reference light intensity data according to the formula and stores the absorbance data of the visible light wavelength and the absorbance data of the ultraviolet light wavelength. Among them, represents the wavelength, represents the absorbance data of the measured environmental water sample at this wavelength, is the reference light intensity when there is no water sample to be measured, is the transmitted light intensity. Finally, a multi-wavelength absorbance data set of visible light and ultraviolet light { = 1, 2,..., 6} is generated. In this embodiment, = 254 nm, = 276 nm, = 305 nm; = 456 nm, = 524 nm, = 615 nm, corresponding to the above six wavelengths respectively.

[0040] Specifically, the lighting duration of each wavelength is 1 ms (millisecond), and then the light source is turned off and enters a 50 ms data acquisition interval. After this process loops 20 times, it automatically switches to the next wavelength.

[0041] In a specific embodiment, the 254nm ultraviolet LED is first lit, and a constant current drive of 80.0mA±0.5mA is applied for 1ms; then the current LED is turned off and a 50ms interval period is entered, during which the photodiode enters a reset state, and the gain of the preprocessing circuit is switched to a reference position (1000 times gain); the above process is repeated to activate five LED light sources of 276nm, 305nm, 456nm, 524nm and 615nm in turn, and the absorbance data of the water sample at visible light wavelengths and ultraviolet wavelengths is collected cyclically.

[0042] During the activation cycle of each LED, the light intensity detection component 300 uses a GaN-based semiconductor photodiode or a SiC-based semiconductor photodiode or an AlGaN-based deep ultraviolet photodiode to detect the light signal absorbed by the liquid in the circulation pool, and after converting the light signal into an electrical signal, transmits it to the control circuit mainboard 400; the voltage signal is converted into a digital signal through an analog-to-digital converter (ADC) built into the microcontroller unit. The process of signal filtering by the preprocessing circuit includes sorting the 20 collected data by numerical value, removing the maximum and minimum values, using average filtering to take the arithmetic mean, and generating a preliminary filtering result; using Hampel filtering, analyzing the data distribution based on a sliding window, identifying and replacing abnormal values ​​that deviate from statistical characteristics; and finally outputting a stable absorbance value.

[0043] The processed absorbance data is classified by wavelength and stored in the corresponding register. The register address is assigned as follows: 0x0000-0x0003: 254nm absorbance value (2-byte floating point number); 0x0004-0x0007: 276nm absorbance value (2-byte floating point number); and the rest of the wavelengths are analogous, with intervals of 2 bytes. In addition, data can be transmitted through the RS-485 physical interface using the Modbus RTU protocol (suitable for long-distance, anti-interference communication in industrial environments) to ensure the reliability of remote monitoring.

[0044] This step achieves accurate collection of water absorbance by driving the six-wavelength LED light source in time-sharing mode, combining photoelectric signal conversion with multi-stage filtering. Each wavelength LED is lit in sequence and the transmitted light signal is collected. After being converted into an electrical signal by a photodiode, the environmental noise and instantaneous interference are eliminated through de-extreme value filtering, mean value calculation and outlier correction, and finally the steady-state absorbance data of the six wavelengths are output. This avoids crosstalk from multiple light sources and ensures independent measurement of each wavelength.

[0045] S2. Solving characteristic coefficients and establishing characteristic functions Based on the absorbance data of visible light wavelengths obtained in step S1, solve the characteristic coefficients of the characteristic function; establish a characteristic function based on the solved characteristic coefficients, substitute the ultraviolet light wavelengths corresponding to the ultraviolet LED chips into the characteristic function, and calculate the absorbance data of suspended matter at ultraviolet light wavelengths.

[0046] First, construct a characteristic function, expressed as: ; represents the wavelength, represents the absorbance data, k is the absorbance amplitude coefficient, b is the attenuation rate coefficient, is the base of the natural logarithm.

[0047] According to the visible light wavelengths and their corresponding absorbance data, that is, ( , ), =4, 5, 6, solve the characteristic coefficients k and b by non-linear fitting methods (such as the least squares method). By fitting the suspended matter scattering process using visible light data, the interference of DOM absorption in the ultraviolet band can be avoided.

[0048] Substitute the solved characteristic coefficients to obtain the final characteristic function.

[0049] In this step, the characteristic coefficients are solved through the absorbance data in the visible light band and the required characteristic function is obtained, providing a theoretical basis for ultraviolet band interference stripping.

[0050] S3. Suspended matter absorbance calculation and DOM correction Based on the characteristic function established in step S2, substitute the ultraviolet light wavelengths corresponding to the ultraviolet LED chips, calculate the absorbance of suspended matter at ultraviolet light wavelengths, subtract the calculated absorbance of suspended matter at ultraviolet light wavelengths from the measured absorbance at ultraviolet light wavelengths, and obtain the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of suspended matter interference.

[0051] Specifically, first, strip the absorbance interference of suspended solids (SS) by the difference method to obtain the true absorbance of dissolved organic matter (DOM) at ultraviolet light wavelengths. The specific process is as follows: Based on the characteristic function established in step S2 , the absorbance of suspended matter at each ultraviolet light wavelength can be calculated to form three groups of data corresponding one-to-one with the absorbance. Obtain the absorbance contribution of suspended solids (SS) in the ultraviolet band.

[0052] Select the ultraviolet light wavelength in the ultraviolet band (UVC-UVB band). Since the absorbance in the ultraviolet band includes the absorbance contribution of DOM and the absorbance contribution of SS, based on the absorbance of the measured ultraviolet light wavelength and the absorbance data of the suspended matter at the ultraviolet light wavelength calculated, the absorbance of DOM is calculated by the difference method. Subtract the absorbance of the suspended matter at the ultraviolet light wavelength calculated from the absorbance of the measured ultraviolet light wavelength to obtain the absorbance data of dissolved organic matter (DOM) in the environmental water body at the ultraviolet light wavelength after dynamic correction of the interference of the suspended matter. The process is expressed as: ; Among them, represents the absorbance data of the measured environmental water sample at the ultraviolet light wavelength, represents the absorbance data of the suspended matter, that is, the fitting solution value of the absorbance of the suspended matter calculated through the characteristic function, represents the absorbance data of DOM in the environmental water body at the ultraviolet light wavelength.

[0053] In this step, by separating the interference of the suspended matter from the absorbance, the true ultraviolet absorbance of DOM is obtained, that is, the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of the interference of the suspended matter is obtained.

[0054] More specifically, when , it indicates that the following abnormal situations may occur: (1) fitting deviation of the characteristic function of the suspended matter; (2) transient interference of the photoelectric signal; (3) sudden change of the optical properties of the water body. At this time, the abnormal handling mechanism can be enabled: assign a value to , to avoid abnormal COD calculation caused by negative absorbance.

[0055] In a specific embodiment, according to the technical specifications of the National Surface Water Environment Quality Standard (GB 3838-2002), water samples are collected at a depth of 50 cm below the water surface to avoid disturbing the bottom mud. The sampling points are located in three typical water bodies in Nanjing, Jiangsu Province. In this embodiment, these three typical water bodies are respectively named River 1, River 2, and River 3. The specific geographical coordinates and location descriptions are as follows: River 1: Middle reaches of the Jiuxiang River in Qixia District (32°06′12″ N, 118°57′30″ E), about 100 meters from the south side pier of Xianlin Avenue; River 2: Lower reaches of the Bianmin River in Liuhe District (32°21′05″ N, 118°50′15″ E), 50 meters east of the Ninglian Expressway cross-river bridge; River 3: Center of Xianlin Lake in Qixia District (32°06′08″ N, 118°55′20″ E), 200 meters in a straight line from the lake shore.

[0056] The COD sensor based on six-wavelength LEDs of the present invention is used for on-site detection.

[0057] Example 1 Based on the aforementioned sampling point (River 1: the middle reaches of Jiuxiang River in Qixia District, 32°06′12″N, 118°57′30″E), the COD sensor based on six-wavelength LEDs of the present invention is used for on-site detection. By comparing the measurement results of a continuous spectrometer and the sensor of the present invention, the effectiveness of the suspended solids interference correction is verified. The specific steps are as follows: The COD sensor based on six-wavelength LEDs is used to drive the ultraviolet LED chips (ultraviolet wavelengths include 254 nm, 276 nm, and 305 nm) and visible light LED chips (visible light wavelengths include 456 nm, 524 nm, and 615 nm) in sequence, and the absorbance data of the water sample at each wavelength are collected, which are respectively: = 0.043, = 0.040, = 0.033; , .

[0058] Construct a characteristic function, expressed as: ; represents the wavelength, represents the absorbance data, k is the absorbance amplitude coefficient, b is the attenuation rate coefficient, is the base of the natural logarithm.

[0059] Based on the measured absorbance data of the visible light wavelengths ( = 0.043, = 0.040, and = 0.033), the negative exponential function of the suspended solids scattering absorbance is fitted by the non-linear least squares method, and the characteristic coefficients obtained by solving are: = 0.0944, = -0.002. Based on the solved characteristic coefficients, the characteristic function is expressed as: .

[0060] Based on the established characteristic function, substitute the ultraviolet wavelengths corresponding to the ultraviolet LED chips to calculate the absorbance of the suspended solids at the ultraviolet wavelengths: , , that is, the absorbance values of the suspended solids SS at the ultraviolet wavelengths of 254 nm and 275 nm.

[0061] Thus, the absorbance contribution of suspended solids (SS) in the ultraviolet band is calculated. Since the absorbance in the ultraviolet band includes the absorbance contribution of DOM and the absorbance contribution of SS, subtracting the calculated absorbance of suspended solids at the ultraviolet wavelength from the measured absorbance at the ultraviolet wavelength can obtain the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of the interference of suspended solids.

[0062] According to the measured absorbance at the total ultraviolet wavelength and the calculated absorbance data of suspended solids at the ultraviolet wavelength, the absorbance of DOM is calculated by the difference method to obtain the absorbance of DOM at the ultraviolet wavelength. The process is expressed as: ; Among them, is the ultraviolet wavelength, is the absorbance data of the measured environmental water sample at the ultraviolet wavelength, is the absorbance data of suspended solids, that is, the fitting solution value of the absorbance of suspended solids, is the absorbance data of DOM in the environmental water body at the ultraviolet wavelength.

[0063] In this embodiment, the absorbance of DOM in the water sample of River 1 at 254 nm is calculated as: ; Among them, is the actually measured value of the absorbance of the water sample of River 1 at the ultraviolet wavelength of 254 nm, is the fitting solution value of the absorbance of suspended solids SS at the ultraviolet wavelength of 254 nm.

[0064] Specifically, the absorbance of the water sample of River 1 at the ultraviolet wavelength of 254 nm in the continuous ultraviolet-visible spectrometer is * = 0.063. Comparing the calculated with the absorbance of the water sample of River 1 at the ultraviolet wavelength of 254 nm in the continuous ultraviolet-visible spectrometer, it can be obtained that * = .

[0065] Similarly, the absorbance of DOM in the water sample of River 1 at 276 nm is calculated as: ; Specifically, the absorbance of the water sample of River 1 at the ultraviolet wavelength of 276 nm in the continuous ultraviolet-visible spectrometer is * = 0.045. Comparing the calculated absorbance of DOM in the water sample of River 1 at 276 nm Comparing with the absorbance of the water sample from River 1 at the ultraviolet wavelength of 276 nm in a continuous ultraviolet-visible spectrometer, it can be obtained that ≈ 。

[0066] Thus, it can be seen that the DOM absorbance data corrected by this method is highly consistent with the measurement results of the continuous ultraviolet-visible spectrometer, verifying that this technical solution can effectively separate the light absorption contributions of dissolved organic matter and suspended solids and solve the problem of calibration failure caused by changes in water turbidity in traditional methods.

[0067] The detection method based on the three-wavelength fitting method in the visible light band proposed by the present invention realizes the direct determination of the absorbance of suspended solids in water by optimizing the spectral analysis algorithm, and breakthroughly constructs a "pretreatment-free - high-precision" detection system. By integrating visible LED and ultraviolet LED chips using the three-crystal composite packaging technology and combining multi-wavelength signal acquisition and intelligent analysis algorithms, not only the sample filtration pretreatment link required by traditional methods is eliminated, shortening the detection process from the original 30 - 50-minute sample preparation cycle to real-time detection, but also the technical problem of the loss of colloidal dissolved organic matter DOM during the pretreatment process is effectively solved.

[0068] This technical solution solves for the characteristic coefficients by dynamically fitting the data in the visible light band, generates the optimal correction function in real time, and realizes on-site adaptive correction. The six-wavelength LED COD sensor of the present invention can directly analyze the water quality characteristics in the actual water environment in real time and automatically generate the optimal correction function. This technology has successfully constructed a new paradigm for rapid and accurate detection of water quality pollutants, significantly improving the detection efficiency while ensuring data accuracy, and providing reliable technical support for on-line monitoring of complex water bodies such as rivers and lakes.

[0069] Example 2 Based on the aforementioned sampling point (River 2: downstream of the Bianmin River in Liuhe District, 32°21′05″N, 118°50′15″E), the six-wavelength LED COD sensor of the present invention was used for on-site detection. By comparing the measurement results of the continuous spectrometer and the sensor of the present invention, the effectiveness of suspended solid interference correction was verified. The specific steps are as follows: The six-wavelength LED COD sensor was used to drive the ultraviolet LED chip and the visible light LED chip in sequence to collect the absorbance data of the water sample at each wavelength, which were respectively: , ; =0.242、 =0.209, =0.176。

[0070] Based on the measured absorbance data at visible light wavelengths ( =0.242、 = 0.209 and = 0.176), fitting the negative exponential function of the scattering absorbance of suspended matter by non - linear least squares method, the characteristic coefficients obtained are: = 0.5991, = - 0.002. Based on the obtained characteristic coefficients, the characteristic function is expressed as: .

[0071] Based on the established characteristic function, substituting the ultraviolet light wavelength corresponding to the ultraviolet light LED chip, calculate the absorbance of suspended matter at the ultraviolet light wavelength: , , that is, the absorbance values of suspended solids SS at ultraviolet light wavelengths of 254 nm and 275 nm.

[0072] Thus, the absorbance contribution of suspended solids (SS) in the ultraviolet band is calculated. Since the absorbance in the ultraviolet band includes the absorbance contribution of DOM and the absorbance contribution of SS, subtracting the calculated absorbance of suspended matter at the ultraviolet light wavelength from the measured absorbance at the ultraviolet light wavelength, the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of suspended matter interference can be obtained.

[0073] According to the measured absorbance at the ultraviolet light wavelength and the calculated absorbance data of suspended matter at the ultraviolet light wavelength, calculate the absorbance of DOM by the difference method, and obtain the absorbance of DOM at the ultraviolet light wavelength. The process is expressed as: ; where, is the ultraviolet light wavelength, is the absorbance data of the measured environmental water sample at the ultraviolet light wavelength, is the absorbance data of suspended matter, that is, the fitting solution value of the absorbance of suspended matter, is the absorbance data of DOM in the environmental water body at the ultraviolet light wavelength.

[0074] In this embodiment, calculate the absorbance of DOM in the water sample of River 2 at 254 nm as: ; where, is the actually measured value of the absorbance of the water sample of River 2 at the ultraviolet light wavelength of 254 nm, is the fitting solution value of the absorbance of suspended solids SS at the ultraviolet light wavelength of 254 nm.

[0075] Specifically, the absorbance of the water sample of River 2 at the ultraviolet light wavelength of 254 nm in the continuous ultraviolet - visible spectrometer is * = 0.105. The calculated is compared with the absorbance of the ultraviolet light wavelength at 254 nm of the water sample of River 2 in a continuous ultraviolet-visible spectrometer, and it can be obtained that *≈ .

[0076] Similarly, the absorbance of DOM of the water sample of River 2 at 276 nm is calculated as: ; Specifically, the absorbance of the water sample of River 2 at the ultraviolet light wavelength of 276 nm in a continuous ultraviolet-visible spectrometer is * = 0.083. The calculated absorbance of DOM of the water sample of River 2 at 276 nm is compared with the absorbance of the ultraviolet light wavelength at 276 nm of the water sample of River 2 in a continuous ultraviolet-visible spectrometer, and it can be obtained that *≈ .

[0077] The present invention realizes the direct determination of the absorbance of suspended solids in water by optimizing the spectral analysis algorithm. Through the built-in machine learning algorithm, on-site adaptive correction is realized, the water quality characteristics are directly analyzed in real time in the actual water environment, and the optimal correction function is automatically generated. At the same time, the multi-wavelength cross-validation technology and the dynamic compensation mechanism are adopted to respond to the change of the suspended solid concentration immediately to ensure the measurement accuracy.

[0078] Example 3 Based on the sampling point (River 3: the center of Xianlin Lake, Qixia District, 32°06′08″ N, 118°55′20″ E), the COD sensor with six-wavelength LEDs of the present invention is used for on-site detection. By comparing the measurement results of the continuous spectrometer and the sensor of the present invention, the effectiveness of the suspended solid interference correction is verified. The specific steps are as follows: The COD sensor with six-wavelength LEDs is used to drive the ultraviolet light LED chip (the ultraviolet light wavelengths include 254 nm, 276 nm, and 305 nm) and the visible light LED chip (the visible light wavelengths include 456 nm, 524 nm, and 615 nm) in sequence, and the absorbance data of the water sample at each wavelength are collected, which are respectively: , .; = 0.210, = 0.181, = 0.153.

[0079] Based on the measured absorbance data of the visible light wavelengths ( = 0.210, = 0.181, and = 0.153), the negative exponential function of the scattering absorbance of suspended matter was fitted by the non - linear least - squares method, and the characteristic coefficients obtained by solving were: = 0.5163, = - 0.002. Based on the solved characteristic coefficients, the characteristic function is expressed as: .

[0080] Based on the established characteristic function, substituting the ultraviolet light wavelength corresponding to the ultraviolet light LED chip, the absorbance of suspended matter at the ultraviolet light wavelength is calculated: , , that is, the absorbance values of suspended solids SS at the ultraviolet light wavelengths of 254 nm and 275 nm.

[0081] Thus, the absorbance contribution of suspended solids (SS) in the ultraviolet band is calculated. Since the absorbance in the ultraviolet band includes the absorbance contribution of DOM and the absorbance contribution of SS, subtracting the calculated absorbance of suspended matter at the ultraviolet light wavelength from the measured absorbance at the ultraviolet light wavelength, the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction for suspended matter interference can be obtained.

[0082] According to the measured absorbance at the ultraviolet light wavelength and the calculated absorbance data of suspended matter at the ultraviolet light wavelength, the absorbance of DOM is calculated by the difference method, and the absorbance of DOM at the ultraviolet light wavelength is obtained. The process is expressed as: ; Among them, is the ultraviolet light wavelength, is the absorbance data of the measured environmental water sample at the ultraviolet light wavelength, is the absorbance data of suspended matter, that is, the fitting solution value of the absorbance of suspended matter, is the absorbance data of DOM in the environmental water body at the ultraviolet light wavelength.

[0083] In this embodiment, the absorbance of DOM in the water sample of River 3 at 254 nm is calculated as: ; Among them, is the actual measured value of the absorbance of the water sample of River 3 at the ultraviolet light wavelength of 254 nm, is the fitting solution value of the absorbance of suspended solids SS at the ultraviolet light wavelength of 254 nm.

[0084] Specifically, the absorbance of the water sample of River 3 at the ultraviolet light wavelength of 254 nm in the continuous ultraviolet - visible spectrometer is * = 0.053. Substituting the calculated By comparing the absorbance of the water sample from River 3 at a wavelength of 254 nm on a continuous UV-visible spectrometer, it can be concluded that *≈ .

[0085] Similarly, the absorbance of DOM at 276 nm in the water sample of River 3 was calculated as: ; Specifically, the absorbance of the water sample from River 3 at the ultraviolet wavelength of 276 nm on a continuous ultraviolet-visible spectrometer is * = 0.043. The calculated absorbance of DOM of River 3 water sample at 276 nm is By comparing the absorbance of the water sample from River 3 at the wavelength of 276nm on a continuous UV-visible spectrometer, it can be concluded that ≈ .

[0086] Experimental verification shows that this technical solution can remove SS interference through visible light band modeling and ultraviolet band differential correction, quantitatively deduct SS absorption contribution in UVC-UVB band, improve DOM / COD detection accuracy, and directly detect in situ without filtering or digestion. It overcomes the limitations of traditional single-wavelength correction, reduces the pretreatment steps of filtering through filter membranes or suction filters compared to traditional filtration methods, reduces the loss of DOM in the filtration process, and thus reduces the relative error of DOM detection; secondly, by using deep ultraviolet probes to achieve high-precision real-time measurement of high-attenuation wavelengths such as 254 nm, the measurement volatility of the online monitoring system is reduced, the response time is shortened, and the data dependence is reduced, taking into account both cost reduction and enhanced anti-interference ability.

[0087] The present invention realizes real-time online monitoring of COD indicators in water bodies through innovative in-situ detection technology, completely abandoning the sample collection, transportation and pretreatment links required for traditional laboratory analysis. The deep ultraviolet probe integrated with three-crystal composite packaging technology can be directly immersed in the water to be tested. Through the synchronous acquisition of multi-wavelength optical signals and intelligent analysis algorithms, the whole process from data collection to result output is completed within 30 seconds. This technology is particularly aimed at the problem of suspended matter interference in natural water bodies, and a dynamic compensation mechanism for SS absorbance based on a negative exponential model is established, which improves the detection efficiency by an order of magnitude compared with the traditional filtration method. The whole system can work directly in complex water environments such as rivers, lakes, etc., truly realizing the breakthrough technological innovation of "sampling and detection", and providing a reliable technical means for emergency monitoring and long-term online supervision of water environment.

[0088] The above has schematically described the present invention and its implementation manners. This description is not restrictive. Without departing from the spirit or basic features of the present invention, the present invention can be implemented in other specific forms. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Any reference signs in the claims should not limit the claims involved. Therefore, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of this creation, design similar structural manners and embodiments to this technical solution without creative efforts, they should all fall within the protection scope of this patent. In addition, the term "comprising" does not exclude other elements or steps, and the term "a" before an element does not exclude including "a plurality of" such elements. The multiple elements stated in the product claims can also be implemented by one element through software or hardware. The terms such as "first" and "second" are used to represent names and do not indicate any specific order.

Claims

1. COD sensor based on six-wavelength LEDs, characterized in that: It includes a housing, as well as a light source, a flow cell, a light intensity detection component, and a control circuit main board placed inside the housing; The flow cell is a transparent cavity for accommodating the water sample of the environment to be measured and allowing the light path to pass through. The light source and the flow cell are coaxially aligned to ensure that the light beam converges at the center of the flow cell; The light source is a multi-wavelength composite packaged LED light source; the multi-wavelength composite packaged LED light source has at least one wavelength of ultraviolet light source and at least two wavelengths of visible light sources; The light intensity detection component is used to detect the transmitted light signal absorbed by the water sample of the environment to be measured in the flow cell by the light source and convert the transmitted light signal into an electrical signal; the light intensity detection component includes an ultraviolet detection photodiode and a visible detection photodiode; The control circuit main board is used to control the startup of the light source, receive the electrical signal transmitted by the light intensity detection component, calculate the absorbance data of visible light and the absorbance data of ultraviolet light according to the electrical signal, and communicate with the host computer.

2. The COD sensor based on six-wavelength LED according to claim 1, wherein: The light source includes a visible light LED chip composite packaged in a three-chip form and an ultraviolet light LED chip composite packaged in a three-chip form.

3. The COD sensor based on a six-wavelength LED according to claim 2, characterized in that: The visible light wavelengths integrated by the visible light LED chip include 456 nm, 524 nm, and 615 nm, and the ultraviolet light wavelengths integrated by the ultraviolet light LED chip include 254 nm, 275 nm, and 305 nm.

4. The COD sensor based on a six-wavelength LED according to claim 1, wherein: The control circuit main board includes a micro control unit, as well as a light source drive circuit, a preprocessing circuit, and a communication module electrically connected to the micro control unit; For the micro control unit, the preprocessing circuit amplifies and filters the electrical signal converted from the transmitted light signal. The micro control unit controls the light source drive circuit to regulate the multi-wavelength composite packaged LED light source to output the transmitted light signal corresponding to multiple wavelengths, and communicates with the host computer through the communication module.

5. The COD sensor based on six-wavelength LED according to claim 1, wherein: The housing includes a light source cavity, a detection cavity, and a control cavity; the light source is installed at the front end of the light source cavity, the flow cell is installed at the center of the detection cavity and is connected to the outside, the light intensity detection component is installed at the rear end of the detection cavity; the control circuit main board is installed in the control cavity; the light path of the light source and the flow cell is coaxially aligned, and the light intensity detection component is coaxially aligned with the light source.

6. The COD sensor based on a six-wavelength LED according to claim 5, wherein: It further includes a cleaning brush head and a drive motor arranged inside the housing; The drive motor is electrically connected to the micro control unit and is used to drive the cleaning brush head to rotate to remove pollutants.

7. A method for dynamically correcting interference of suspended matter, characterized in that: It includes the following steps: Step 1: Use the COD sensor based on six-wavelength LED according to any one of claims 1 to 6 to collect the transmitted light signals of visible light and ultraviolet light of the water sample of the environment to be measured; Step 2: Calculate the absorbance data of visible light and the absorbance data of ultraviolet light respectively based on the light intensity values of the transmitted light signals; Step 3: Construct the required characteristic function based on the absorbance data of visible light wavelengths; Step 4: Calculate the absorbance data of suspended matter of ultraviolet light wavelengths based on the obtained characteristic function; Step 5: Subtract the absorbance data of suspended matter at the ultraviolet light wavelength from the absorbance data of dissolved organic matter (DOM) obtained in Step 1 to obtain the net absorbance data of DOM with dynamic correction for suspended matter interference.

8. The method for dynamically correcting suspended matter interference according to claim 7, wherein: Step 1 specifically includes: The control circuit main board drives each wavelength LED light source in sequence according to a preset order. Each wavelength is independently lit and penetrates the water sample of the environment to be measured. The light intensity detection component receives the transmitted light signal absorbed by the water sample of the environment to be measured and converts it into an electrical signal. After the electrical signal is amplified and filtered, it is converted into a digital light intensity value, and the absorbance data at the visible light wavelength and the absorbance data at the ultraviolet light wavelength are calculated and stored according to the digital light intensity value.

9. The method for dynamically correcting suspended matter interference according to claim 8, wherein: During the process of the light intensity detection component collecting the transmitted light signal, the lighting duration of each wavelength is 1 ms, and then the light source is turned off and enters a 50-ms data collection interval period. After cycling 20 times, it automatically switches to the next wavelength, and 20 data points are continuously collected for each wavelength.

10. The method for dynamically correcting suspended matter interference according to claim 7, wherein: Step 3 specifically includes: Construct a characteristic function, expressed as: ； In the formula, represents the wavelength, represents the absorbance data, k is the absorbance amplitude coefficient, b is the attenuation rate coefficient, is the base of the natural logarithm; Based on the absorbance data at visible light wavelengths, solve for the characteristic coefficients through non-linear fitting k and b , and thus obtain the required characteristic function; Step 4 specifically includes: According to the constructed characteristic function, substitute the ultraviolet light wavelength to calculate the absorbance data of suspended matter at the ultraviolet light wavelength; Step 5 specifically includes: Substitute the ultraviolet light wavelength into the characteristic function to calculate the absorbance data of suspended matter at the ultraviolet light wavelength, subtract the absorbance data of suspended matter at the ultraviolet light wavelength from the measured absorbance data at the ultraviolet light wavelength to obtain the net absorbance data of DOM with dynamic correction for suspended matter interference, and the process is expressed as: ； In the formula, is the absorbance data of the measured environmental water sample, is the absorbance data of suspended solids, is the absorbance data of dissolved organic matter (DOM) in environmental water bodies.

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