COD sensor based on six-wavelength LED and its suspended matter interference dynamic correction method

Abstract

The present invention discloses a COD sensor based on a six-wavelength LED and a method for dynamically correcting suspended matter interference. The method comprises using the six-wavelength LED COD sensor to collect visible and ultraviolet light transmission signals of a water sample to be tested; calculating visible and ultraviolet absorbance data based on the intensity of the transmitted light signals; constructing a required characteristic function based on the visible light absorbance data; calculating suspended matter absorbance data at ultraviolet wavelengths based on the characteristic function; and subtracting the suspended matter absorbance data at ultraviolet wavelengths from the ultraviolet absorbance data to obtain net absorbance data for dissolved organic matter (DOM) after dynamic correction for suspended matter interference. The present invention eliminates suspended matter interference on spectral test results through multi-wavelength absorbance correction, corrects the absorbance of dissolved organic matter (DOM), and achieves accurate detection of dissolved organic matter and its associated chemical oxygen demand (COD) indicator.

Description

Technical Field

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

[0002] Chemical oxygen demand (COD) is a core evaluation indicator of water pollution. The national standard method uses potassium dichromate or permanganate as an oxidant to digest water samples under high temperature conditions for testing. However, this type of chemical detection method is difficult to meet the high-frequency online monitoring needs of scenarios such as sewage pipe networks and industrial wastewater treatment facilities.

[0003] Dissolved organic matter (DOM) in water is the main contributor to chemical oxygen demand (COD). Its absorbance at ultraviolet wavelengths of 250 nm to 300 nm (such as UV254 and UV276) can be used as an alternative indicator of COD. Optical COD detection technology analyzes the characteristic absorption peaks of DOM (such as UV254) through ultraviolet-visible spectroscopy, demonstrating significant advantages in real-time monitoring. DOM in water produces a characteristic absorption peak at an ultraviolet wavelength of 254 nm (UV254), and this absorbance value is significantly positively correlated with the COD value. This principle has been established as a rapid COD detection method for clarified water bodies in the industry standard DB37 / T 4149-2020.

[0004] While the industry standard DB37 / T 4149-2020 establishes UV254 as a surrogate for COD, its applicability is explicitly limited to clear water with suspended solids (SS) concentrations below 50 mg / L. Fundamentally, the scattering intensity of undissolved suspended solids (SS) in water exhibits significant wavelength dependence in the UV-visible band, resulting in absorbance measurements from traditional single- and dual-wavelength optical sensors containing difficult-to-remove SS interference signals.

[0005] In related technologies, optical COD detection is interfered with by suspended matter in practical applications, especially in sewage pipe networks and high-turbidity industrial wastewater. Existing anti-interference technologies have two inherent defects in the following two technical routes: (1) Physical isolation: For example, Chinese patent CN220603302U uses filtration and cleaning brushes to pre-treat water samples. 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 working conditions in the field; (2) Algorithm compensation: For example, Chinese patent CN117074333B uses a machine learning model to fuse multi-wavelength absorbance and turbidity parameters for correction, but the model training needs to cover complex variables such as SS particle size, mineral composition, and organic floc ratio. When the physicochemical characteristics of suspended matter in water exceed the range of the training set, the generalization ability of the model drops sharply; secondly, higher-precision continuous ultraviolet-visible spectroscopy Instruments such as Chinese patent CN112304875B analyze the SS scattering spectrum through full-band scanning, but their spectroscopic optical path is sensitive to vibration, and the deuterium lamp has a short life and high power consumption, making it difficult to implant in confined spaces such as pipeline monitoring wells. In addition, LED-based discrete wavelength probes, such as Chinese patent CN220603302U, although they have the advantages of low cost, low power consumption, and miniaturization, are unable to construct a mathematical characterization model for the SS scattering spectrum due to too few detection bands. Another example is Chinese patent CN114184549A, which attempts to improve anti-interference capability by adding Vis band auxiliary detection. However, the fixed empirical coefficient method it adopts does not take into account the dynamic changes in the physical and chemical properties of SS, and the problem of inaccurate correction factors still exists in long-term monitoring.

[0006] In summary, the fixed empirical coefficient method used in existing technologies does not take into account the dynamic changes in the physicochemical properties of SS, and the problem of inaccurate correction factors still exists in long-term monitoring. At the same time, the traditional algorithm compensation method requires SS gradient calibration of pre-collected water samples in the laboratory. The obtained fitting function is significantly different from the real-time SS characteristics of the water body on site. When the particle size distribution of suspended matter in the water body and the ratio of organic and inorganic components change with the season or operating conditions, the calibration model preset in the laboratory will completely fail. This "offline calibration-online application" model has become a fundamental obstacle to the on-site applicability of optical COD sensors. Summary of the Invention

[0007] 1. Technical problems to be solved

[0008] In response to the above-mentioned 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 matter interference thereof, which can directly construct a dynamic response model of SS interference at the monitoring site, and realize real-time stripping of SS influence without the need for full-spectrum scanning, thereby completing in-situ monitoring of COD in complex water bodies.

[0009] 2. Technical solution

[0010] The purpose of the present invention is achieved through the following technical solutions.

[0011] The content of this application is used to briefly introduce concepts that will be described in detail in the detailed description section below. The content of this application is not intended to identify key features or essential features of the technical solution for which protection is sought, nor is it intended to limit the scope of the technical solution for which protection is sought.

[0012] Some embodiments of the present application propose a COD sensor based on six-wavelength LEDs and a method for dynamic correction of suspended matter interference thereof to solve the technical problems mentioned in the above background technology section.

[0013] As a first aspect of the present application, some embodiments of the present application provide a COD sensor based on a six-wavelength LED, comprising a housing, and a light source, a flow cell, a light intensity detection component, and a control circuit mainboard disposed within the housing;

[0014] The flow cell is a transparent cavity that holds the environmental water sample to be tested and allows 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;

[0015] 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 source;

[0016] The light intensity detection component is used to detect the transmitted light signal emitted by the light source and absorbed by the environmental water sample to be tested in the flow cell, 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;

[0017] The control circuit mainboard is used to control the start-up of the light source, receive the electrical signals transmitted by the light intensity detection component, calculate the absorbance data of visible light and ultraviolet light based on the electrical signals, and communicate with the host computer.

[0018] Furthermore, the light source includes a visible light LED chip packaged in a three-crystal form and an ultraviolet light LED chip packaged in a three-crystal form.

[0019] Furthermore, the visible light wavelengths integrated into the visible light LED chip include 456 nm, 524 nm and 615 nm, and the ultraviolet light wavelengths integrated into the ultraviolet light LED chip include 254 nm, 275 nm and 305 nm.

[0020] Furthermore, the control circuit mainboard includes a micro control unit and a light source driving circuit, a pre-processing circuit and a communication module electrically connected to the micro control unit;

[0021] The preprocessing circuit amplifies and filters the electrical signal converted from the transmitted light signal. The microcontroller unit controls the light source driving circuit to regulate the multi-wavelength composite packaged LED light source to output the corresponding multi-wavelength transmitted light signal and communicate with the host computer through the communication module.

[0022] Furthermore, the outer shell 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 circulation pool is installed at the center of the detection cavity and is connected to the outside, and 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 source and the circulation cell optical path are coaxially aligned, and the light intensity detection component is coaxially aligned with the light source.

[0023] Furthermore, the COD sensor based on six-wavelength LEDs also includes a cleaning brush head and a driving motor disposed in the housing; the driving motor is electrically connected to the microcontroller unit and is used to drive the cleaning brush head to rotate to remove pollutants.

[0024] As a second aspect of the present application, some embodiments of the present application provide a method for dynamic correction of suspended matter interference, comprising the following steps:

[0025] Step 1: Use the above-mentioned six-wavelength LED-based COD sensor to collect the transmitted light signals of the environmental water sample under visible light and ultraviolet light;

[0026] Step 2: Calculate the absorbance data of visible light and the absorbance data of ultraviolet light based on the light intensity value of the transmitted light signal;

[0027] Step 3: Construct the required characteristic function based on the absorbance data of visible light wavelengths;

[0028] Step 4: Calculate the absorbance data of the suspended matter at the ultraviolet wavelength based on the obtained characteristic function;

[0029] Step 5: Subtract the suspended matter absorbance data at the ultraviolet wavelength from the ultraviolet wavelength absorbance data calculated in step 1 to obtain the net absorbance data of dissolved organic matter (DOM) after dynamic correction of suspended matter interference.

[0030] Furthermore, step 1 specifically includes: the control circuit mainboard drives the LED light sources of each wavelength in sequence according to a preset order, each wavelength is independently lit and penetrates the environmental water sample to be tested, the light intensity detection component receives the transmitted light signal after being absorbed by the environmental water sample to be tested and converts it into an electrical signal, the electrical signal is amplified and filtered, and then 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.

[0031] Furthermore, when the light intensity detection component collects the transmitted light signal, each wavelength is illuminated for 1ms, and then the light source is turned off to enter a 50ms data collection interval. After 20 cycles, it automatically switches to the next wavelength and continuously collects 20 data points for each wavelength.

[0032] Furthermore, step 3 specifically includes: constructing a characteristic function, expressed as:

[0033] ;

[0034] Where, represents the wavelength, represents absorbance data, k is the absorbance amplitude coefficient, b is the decay rate coefficient, is the base of natural logarithms;

[0035] Based on the absorbance data of visible light wavelengths, the characteristic coefficients are solved by nonlinear fitting k and b , and thus obtain the required characteristic function;

[0036] Step 4 specifically includes: according to the constructed characteristic function, substituting the ultraviolet wavelength into the ultraviolet wavelength, and calculating the absorbance data of the suspended matter under the ultraviolet wavelength;

[0037] Step 5 specifically includes: substituting the ultraviolet wavelength into the characteristic function, calculating the suspended matter absorbance data at the ultraviolet wavelength, subtracting the suspended matter absorbance data at the ultraviolet wavelength from the measured absorbance data at the ultraviolet wavelength, and obtaining the net absorbance data of dissolved organic matter DOM after dynamic correction of suspended matter interference. The process is expressed as follows:

[0038] ;

[0039] Where, is the absorbance data of the measured environmental water samples, is the absorbance data of the suspended matter, It is the absorbance data of dissolved organic matter DOM in environmental water.

[0040] 3. Beneficial effects

[0041] Compared with the prior art, the advantages of the present invention are:

[0042] (1) The COD sensor based on six-wavelength LEDs adopts on-site adaptive dynamic correction. It solves the characteristic coefficient by real-time fitting of the absorbance data in the visible light band, and directly generates the optimal correction function in real time in the actual water environment. It does not require laboratory calibration or offline preprocessing, which significantly shortens the detection cycle. Combined with the dynamic compensation of interference signals in the ultraviolet band, it can quickly respond to changes in suspended matter concentration and physicochemical properties, ensuring the accuracy of COD measurement in complex water bodies.

[0043] (2) A multi-wavelength LED light source is driven in a time-sharing manner, and the start, stop, and switch of each wavelength light source are independently controlled by a microcontroller unit (MCU) according to a preset timing, thus avoiding the problem of crosstalk between multiple light sources. At the same time, the characteristic function is constructed in real time using visible light band data, and the interference signal is stripped off through differential correction in the ultraviolet band, thus solving the problem of calibration failure caused by insufficient detection bands in traditional single / dual wavelength sensors and ensuring measurement stability when the suspended matter concentration changes suddenly.

[0044] (3) The six-wavelength LED light source is integrated through three-crystal composite packaging technology, and a split waterproof shell and coaxial optical path design are adopted to ensure the long-term stable alignment of the light source, circulation pool and detector; the integrated cleaning brush head removes pollutants, which can adapt to the long-term monitoring needs of complex water bodies and achieve long-term stable monitoring in harsh environments such as rivers with high turbidity and high suspended matter, and pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the steps of a method for dynamic correction of suspended matter interference according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the overall structure of a COD sensor based on six-wavelength LEDs in one embodiment of the present invention;

[0047] Figure 3 Schematic diagram of the detailed structure of a COD sensor based on six-wavelength LEDs in one embodiment of the present invention;

[0048] Figure 4 This is a circuit diagram of a control circuit mainboard of a COD sensor based on six-wavelength LEDs in one embodiment of the present invention;

[0049] Figure 5 This is a front view of a three-crystal composite packaged UV LED chip according to one embodiment of the present invention;

[0050] Figure 6 This is a schematic diagram of the back side of a three-crystal composite packaged UV LED chip in one embodiment of the present invention;

[0051] Figure 7 This is a front view of a three-crystal composite packaged visible light LED chip according to an embodiment of the present invention;

[0052] Figure 8 This is a schematic diagram of the back side of a three-crystal composite packaged visible light LED chip in one embodiment of the present invention;

[0053] Figures 5 to 8 The length units are all in millimeters, and the dark squares indicate the specific locations of the LED lamp packages and are marked with the corresponding wavelengths. Figures 5 to 8 The “+” and “-” signs on the left and right sides correspond to the direction of current flow.

[0054] Explanation of the numbers in the figure: 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 detection photodiode; 201, ultraviolet light LED; 202, visible light LED. DETAILED DESCRIPTION

[0055] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Optical detection technology based on ultraviolet absorption spectroscopy utilizes the positive correlation between the absorbance of characteristic wavelengths such as UV254 and COD (DB37 / T 4149-2020). Although it has been established as a rapid detection standard in clear water environments, its engineering application in turbid water bodies faces a fundamental technical obstacle - the wide-spectrum scattering interference caused by suspended solids (SS).

[0057] Because the currently used fixed empirical coefficient method does not take into account the dynamic changes in the physical and chemical properties of SS, the problem of inaccurate correction factors still exists in long-term monitoring. At the same time, the traditional algorithm compensation method requires SS gradient calibration of pre-collected water samples in the laboratory. The obtained fitting function is significantly different from the real-time SS characteristics of the water body on site. When the particle size distribution of suspended matter in the water body and the ratio of organic and inorganic components change with the season or operating conditions, the calibration model preset in the laboratory will completely fail. This "offline calibration-online application" model has become a fundamental obstacle to the on-site applicability of optical COD sensors.

[0058] This contradiction between hardware design and algorithm model forces existing technologies to make a difficult choice between "high-precision large-scale equipment" and "low-reliability micro-probes". The essential contradiction lies in the mismatch between the characterization capabilities of the limited detection wavelength and the wide-spectrum scattering characteristics of suspended matter, and the adaptive imbalance between the static compensation model and the dynamic physical and chemical characteristics of suspended matter, which seriously restricts the engineering application of optical COD sensors in complex water environments.

[0059] Based on this, this invention integrates multi-band optical detection with a physics-driven correction algorithm, abandoning the traditional passive compensation model of "pre-trained model + empirical coefficients" and eliminating laboratory calibration. Instead, it autonomously generates an optimal fit function from the multispectral data stream of field water bodies. By exploiting the resolvability of SS scattering spectra in the UVA-Vis band and constructing a mathematical transfer function for its interference intensity with the UVC-UVB band, this technical solution can achieve real-time removal of SS influence without requiring a full-spectrum scan, thus providing a solution for in-situ COD monitoring in complex water bodies that combines theoretical rigor with engineering practicality. 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 the ultraviolet spectrum. UVA-Vis refers to the combined range of ultraviolet A (UVA) and visible light (visible, Vis).

[0060] like Figures 2 to 8 As shown, the present invention provides a COD sensor based on six-wavelength LEDs, including a housing 100, a light source 200, a circulation cell, a light intensity detection component 300, a control circuit mainboard 400, and a cleaning brush head 500. The light source 200, the circulation cell, the light intensity detection component 300, the control circuit mainboard 400, and the cleaning brush head 500 are all disposed inside the housing 100.

[0061] The housing 100 adopts a split waterproof structure, including a light source cavity, a detection cavity and a control cavity. A detector receiving port is provided at the upper part of the detection cavity, and an LED light path incident port is provided at the lower part. The measurement is realized by the cross-reflection method. When the light passes through the solution to be tested, a light intensity difference is formed. The circulation pool is installed at the center of the detection cavity and is connected to the outside. The light intensity detection component 300 is fixedly installed at the rear end of the detection cavity corresponding to the detector receiving port, and the cleaning brush head 500 is installed on the side wall of the detection cavity. The light source 200 is installed at the front end of the light source cavity and corresponds to the LED light path incident port. The light source 200 is coaxially aligned with the light path of the circulation pool to ensure that the light beam converges at the center of the circulation pool. The light intensity detection component 300 is coaxially aligned with the light source 200. The control circuit mainboard 400 is fixedly installed inside the control cavity.

[0062] Light source 200 is a multi-wavelength composite-packaged LED light source, including both an ultraviolet light source and a visible light source. In this embodiment, a three-crystal composite package is used, comprising three visible light LED chips and three ultraviolet light LED chips. Ultraviolet light LED chips with emission wavelengths of 254 nm, 276 nm, and 305 nm are selected as the ultraviolet light source, while visible light LED chips with emission wavelengths of 456 nm, 524 nm, and 615 nm are selected as the visible light source.

[0063] like Figures 5 to 8As shown, the light source 200 adopts a three-crystal composite packaging structure, integrating three ultraviolet LED chips and three visible light LED chips on a substrate to form a six-wavelength composite light source. The ultraviolet LED chips and the visible light LED chips are arranged in a staggered manner. Within each packaging unit, the ultraviolet LED chips and the visible light LED chips are spaced apart, and the consistency of the optical axis 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 connected to the light source drive circuit in the control circuit main board 400 through the circuit board 600, realizing time-sharing independent control of each wavelength light source. This packaging method realizes six-wavelength time-sharing multiplexing by optimizing the chip layout and drive architecture, while meeting the heat dissipation requirements of the ultraviolet LED and the stability of the multi-spectral output.

[0064] The flow cell is a transparent cavity used to hold the water sample to be tested and for the light path to pass through. It provides a stable transmission path for the optical signal, ensuring that the light emitted by the light source 200 is accurately captured by the detector after passing through the water sample, thereby calculating the absorbance value. The light intensity detection component 300 is used to detect the light signal absorbed by the liquid in the flow cell, convert the light signal into an electrical signal, and transmit it to the control circuit mainboard 400. The light intensity detection component 300 includes two types of detectors: an ultraviolet detection photodiode 301 and a visible detection photodiode 302.

[0065] like Figure 4 As shown, the control circuit mainboard 400 is used to control the light source startup, detect photoelectric signals, and process the signals. The control circuit mainboard 400 integrates a microcontroller unit (MCU), a light source driver circuit, a preprocessing circuit, and a communication module. The control circuit mainboard 400 is connected to the six-wavelength LED light source and the light intensity detection component 300 via a circuit board 600. The control circuit mainboard 400 transmits the drive signal to the six-wavelength LED light source via the light source driver circuit. The photodiode in the light intensity detection component 300 converts the detected light signal into an electrical signal, which is then transmitted back to the control circuit mainboard 400 via the circuit board 600. Specifically, the microcontroller unit (MCU) controls the start and stop of the six-wavelength LED light source and the multi-wavelength switching through the light source driving circuit, and outputs a light signal. The light signal detected by the photodiode is converted into an electrical signal and then transmitted to the preprocessing circuit via the circuit board 600. In the preprocessing circuit, the electrical signal is amplified and filtered, and other preprocessing is performed. The microcontroller unit (MCU) converts the preprocessed electrical signal into a digital signal through the built-in analog-to-digital converter (ADC) and stores it. At the same time, it realizes data interaction with the host computer or monitoring platform through a communication module (such as RS-485), supporting remote command reception, status feedback, and real-time data upload.

[0066] The cleaning brush head 500 is used to remove suspended matter, algae, or sediment from the inner walls of the flow cell, preventing contaminants from obstructing the light path. The cleaning brush head 500 is connected to a drive motor fixed to the detection chamber via an embedded drive shaft. A microcontroller unit (MCU) controls the drive motor via PWM signals, driving the cleaning brush head 500 to rotate and remove contaminants.

[0067] Compared to traditional laboratory correction methods, this six-wavelength LED-based COD sensor eliminates the need to bring water samples back to the laboratory for pretreatment and can be deployed directly in actual surface water environments, generating a correction fitting function that matches the current suspended solids characteristics of the water. Multi-wavelength absorbance correction eliminates interference from suspended solids on spectroscopic test results, corrects the measured DOM absorbance, simplifies operation and maintenance, and enables rapid and accurate detection of DOM and its associated chemical oxygen demand (COD).

[0068] like Figure 1 As shown, based on the above-mentioned COD sensor based on six-wavelength LEDs, a method for dynamic correction of suspended matter interference of the present invention includes the following steps:

[0069] S1. Multi-wavelength data acquisition

[0070] A COD sensor based on six-wavelength LEDs was used to collect absorbance data of environmental water samples under visible and ultraviolet light.

[0071] Specifically, the COD sensor based on six-wavelength LED adopts a three-crystal composite package, integrating the ultraviolet LED chip and the visible light LED chip into the COD sensor based on six-wavelength LED, thereby building in six independent wavelength LED light sources.

[0072] In this embodiment, the UV LED chip emits UV wavelengths including 254 nm, 276 nm, and 305 nm, and the visible LED chip emits visible wavelengths including 456 nm, 524 nm, and 615 nm.

[0073] The COD sensor based on six-wavelength LEDs is driven by a microcontroller unit (MCU) in a preset order. Each wavelength is independently illuminated and penetrates the environmental water sample to be tested. The corresponding photodiode in the light intensity detection component 300 collects the transmitted light signal, outputs an analog current signal proportional to the transmitted light intensity, and transmits it to the pre-processing circuit of the control circuit mainboard 400. After pre-processing and photoelectric conversion, the ADC analog-to-digital conversion is performed to obtain the light intensity value in digital form and transmit it to the microcontroller unit (MCU). The microcontroller unit (MCU) uses the pre-stored reference light intensity data according to the formula Calculate the absorbance and store the absorbance data of visible light wavelength and ultraviolet light wavelength. represents the wavelength, Indicates the absorbance data of the environmental water sample measured at this wavelength. is the reference light intensity when there is no water sample to be tested, is the transmitted light intensity. Finally, a multi-wavelength absorbance data set of visible light and ultraviolet light is generated. =1, 2, ..., 6}. In this embodiment, =254nm, =276nm, =305nm; =456nm, =524nm, =615nm, corresponding to the above six wavelengths respectively.

[0074] Specifically, each wavelength is illuminated for 1ms, then turned off for a 50ms data acquisition interval. This process repeats 20 times before automatically switching to the next wavelength.

[0075] 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 the interval, the photodiode enters a reset state, and the gain of the preprocessing circuit is switched to the reference gear (1000 times gain); the above process is repeated to activate the 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.

[0076] During each LED activation cycle, the light intensity detection component 300 uses a GaN-based semiconductor photodiode, a SiC-based semiconductor photodiode, or an AlGaN-based deep ultraviolet photodiode to detect the light signal absorbed by the flow cell liquid. This light signal is converted into an electrical signal and transmitted to the control circuit mainboard 400. The analog-to-digital converter (ADC) built into the microcontroller unit converts the voltage signal into a digital signal. The preprocessing circuit performs signal filtering, sorting the 20 collected data points by numerical value, removing the maximum and minimum values, and using an average filter to obtain the arithmetic mean to generate a preliminary filtering result. Hampel filtering is then used to analyze the data distribution based on a sliding window, identifying and replacing outliers that deviate from statistical characteristics. Finally, a stable absorbance value is output.

[0077] The processed absorbance data is sorted by wavelength and stored in the corresponding registers. The register addresses are: 0x0000-0x0003: 254nm absorbance values ​​(2-byte floating-point numbers); 0x0004-0x0007: 276nm absorbance values ​​(2-byte floating-point numbers); and similarly for the remaining wavelengths, with 2-byte intervals. Furthermore, data can be transmitted via the RS-485 physical interface using the Modbus RTU protocol (suitable for long-distance, interference-resistant communication in industrial environments), ensuring reliable remote monitoring.

[0078] This step achieves precise acquisition of water absorbance by time-sharing the six-wavelength LED light source, combining photoelectric signal conversion with multi-stage filtering. Each wavelength LED is sequentially illuminated, and the transmitted light signal is collected. After being converted into an electrical signal by a photodiode, it undergoes de-extreme value filtering, mean calculation, and outlier correction to eliminate environmental noise and transient interference, ultimately outputting steady-state absorbance data for the six wavelengths. This eliminates crosstalk from multiple light sources and ensures independent measurement of each wavelength.

[0079] S2. Solving characteristic coefficients and establishing characteristic functions

[0080] Based on the absorbance data of the visible light wavelength obtained in step S1, the characteristic coefficient of the characteristic function is solved; based on the solved characteristic coefficient, the characteristic function is established, the ultraviolet light wavelength corresponding to the ultraviolet LED chip is substituted into the characteristic function, and the suspended matter absorbance data of the ultraviolet light wavelength is calculated.

[0081] First, construct the characteristic function, which is expressed as:

[0082] ;

[0083] represents the wavelength, represents absorbance data, k is the absorbance amplitude coefficient, b is the decay rate coefficient, is the base of natural logarithms.

[0084] According to the visible light wavelength and its corresponding absorbance data, that is ( , ), =4, 5, 6, solve the characteristic coefficients by nonlinear fitting methods (such as least squares method) k and b By fitting the suspended matter scattering process with visible light data, the interference of DOM absorption in the ultraviolet band can be avoided.

[0085] Substituting the solved characteristic coefficients into the equation, we get the final characteristic function.

[0086] This step uses the visible light absorbance data to solve the characteristic coefficients and obtain the required characteristic functions, providing a theoretical basis for ultraviolet band interference stripping.

[0087] S3. Calculation of suspended matter absorbance and DOM correction

[0088] Based on the characteristic function established in step S2, the ultraviolet light wavelength corresponding to the ultraviolet light LED chip is substituted to calculate the suspended matter absorbance at the ultraviolet light wavelength. The calculated suspended matter absorbance at the ultraviolet light wavelength is subtracted from the measured ultraviolet light wavelength absorbance to obtain the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of suspended matter interference.

[0089] Specifically, the absorbance interference of suspended solids (SS) is first removed by differential method to obtain the true absorbance of dissolved organic matter (DOM) at the ultraviolet wavelength. The specific process is as follows:

[0090] Based on the characteristic function established in step S2 , the absorbance of suspended solids at each UV wavelength can be calculated, forming three sets of data corresponding to the absorbance. The absorbance contribution of suspended solids (SS) in the UV band can be obtained.

[0091] Select the ultraviolet wavelength in the ultraviolet band (UVC-UVB band). Since the absorbance of the ultraviolet band includes the absorbance contribution of DOM and the absorbance contribution of SS, the absorbance of DOM is calculated by the difference method based on the absorbance of the measured ultraviolet wavelength and the absorbance data of the suspended matter at the ultraviolet wavelength. The calculated absorbance of the suspended matter at the ultraviolet wavelength is subtracted from the measured absorbance of the ultraviolet wavelength to obtain the absorbance data of the dissolved organic matter (DOM) in the environmental water body at the ultraviolet wavelength after the dynamic correction of the suspended matter interference. The process is expressed as follows:

[0092] ;

[0093] in, Indicates the absorbance data of the measured environmental water sample at the ultraviolet wavelength. Represents the absorbance data of suspended matter, that is, the fitted solution value of the absorbance of suspended matter obtained by calculating the characteristic function. Represents the absorbance data of DOM in environmental water at ultraviolet wavelength.

[0094] This step separates the suspended matter interference from the absorbance to obtain the true UV absorbance of DOM, that is, to obtain the net absorbance data of dissolved organic matter (DOM) in the environmental water body after dynamic correction of suspended matter interference.

[0095] More specifically, when When , it indicates that the following abnormal conditions may occur: (1) deviation in the fitting of the suspended matter characteristic function; (2) transient interference of the photoelectric signal; (3) sudden change in the optical characteristics of the water body. At this time, the abnormal handling mechanism can be enabled: assign , to avoid COD calculation anomalies caused by negative absorbance.

[0096] In a specific example, water samples were collected 50 cm below the water surface to avoid disturbing the bottom sediment, in accordance with the technical specifications of the National Surface Water Environmental Quality Standard (GB 3838-2002). The sampling points were located at three typical water bodies in Nanjing, Jiangsu Province. In this example, these three typical water bodies are named River 1, River 2, and River 3. The specific geographic coordinates and locations are described as follows:

[0097] River 1: The middle reaches of Jiuxiang River in Qixia District (32°06′12″N, 118°57′30″E), about 100 meters from the bridge pier on the south side of Xianlin Avenue;

[0098] River 2: Lower reaches of Bianmin River in Liuhe District (32°21′05″N, 118°50′15″E), 50 meters east of the bridge over the Ninglian Expressway;

[0099] River 3: The center of Xianlin Lake in Qixia District (32°06′08″N, 118°55′20″E), 200 meters away from the lakeshore.

[0100] The COD sensor based on six-wavelength LED of the present invention is used for on-site detection.

[0101] Example 1

[0102] Based on the aforementioned sampling point (River 1: middle reaches of Jiuxiang River, Qixia District, 32°06'12" N, 118°57'30" E), a COD sensor based on a six-wavelength LED was used to conduct on-site testing. The effectiveness of suspended matter interference correction was verified by comparing the measurement results of a continuous spectrometer with those of the sensor. The specific steps are as follows:

[0103] The COD sensor based on six-wavelength LEDs is used to sequentially drive the UV LED chip (UV wavelengths include 254nm, 276nm, and 305nm) and the visible light LED chip (visible light wavelengths include 456nm, 524nm, and 615nm) to collect the absorbance data of the water sample at each wavelength, which are as follows: =0.043, =0.040, =0.033; , .

[0104] Construct the characteristic function, expressed as: ; represents the wavelength, represents absorbance data, k is the absorbance amplitude coefficient, b is the decay rate coefficient, is the base of natural logarithms.

[0105] Based on the absorbance data of the measured visible light wavelength ( =0.043, =0.040 and =0.033), the negative exponential function of the suspended matter scattering absorbance was fitted by the nonlinear least squares method, and the characteristic coefficient was solved as follows: = 0.0944, = -0.002. Based on the solved characteristic coefficient, the characteristic function is expressed as:

[0106] .

[0107] Based on the established characteristic function, the UV wavelength corresponding to the UV LED chip is substituted to calculate the absorbance of the suspended matter at the UV wavelength: , , that is, the absorbance value of suspended matter SS at ultraviolet light wavelengths of 254 nm and 275 nm.

[0108] From this, the absorbance contribution of suspended solids (SS) in the UV band was calculated. Since the absorbance in the UV band includes the absorbance contribution of DOM and SS, by subtracting the calculated absorbance of suspended solids at the UV wavelength from the measured absorbance at the UV wavelength, the net absorbance data of dissolved organic matter (DOM) in the environmental water body can be obtained after dynamic correction for suspended solid interference.

[0109] According to the measured absorbance of the total UV wavelength and the calculated absorbance data of the suspended matter at the UV wavelength, the absorbance of DOM is calculated by the difference method to obtain the absorbance of DOM at the UV wavelength. The process is expressed as follows:

[0110] ;

[0111] in, is the wavelength of ultraviolet light, is the absorbance data of the environmental water sample at the ultraviolet wavelength. is the absorbance data of the suspended matter, that is, the fitted solution value of the absorbance of the suspended matter, It is the absorbance data of DOM in environmental water at ultraviolet wavelength.

[0112] In this example, the absorbance of DOM at 254 nm of the water sample from River 1 is calculated as:

[0113] ;

[0114] in, is the actual measured absorbance value of the water sample from River 1 at the ultraviolet wavelength of 254 nm, is the fitted solution value of the absorbance of suspended matter SS at the ultraviolet light wavelength of 254 nm.

[0115] Specifically, the absorbance of the water sample from River 1 at a wavelength of 254 nm on a continuous UV-visible spectrometer is * = 0.063. Comparing the absorbance of the water sample from River 1 at a wavelength of 254 nm on a continuous UV-visible spectrometer, we can conclude that *= .

[0116] Similarly, the absorbance of DOM at 276 nm in the water sample of River 1 is calculated as:

[0117] ;

[0118] Specifically, the absorbance of the water sample from River 1 at the ultraviolet wavelength of 276 nm on a continuous ultraviolet-visible spectrometer is * = 0.045. The calculated absorbance of DOM at 276 nm for the River 1 water sample is Comparing with the absorbance of the water sample from River 1 at the wavelength of 276nm on the continuous UV-visible spectrometer, it can be concluded that ≈ .

[0119] It can be seen that the DOM absorbance data corrected by this method are highly consistent with the measurement results of the continuous UV-visible spectrometer, verifying that this technical solution can effectively separate the absorbance contributions of dissolved organic matter and suspended matter and solve the correction failure problem of traditional methods caused by changes in water turbidity.

[0120] The detection method proposed in the present invention, based on the three-wavelength fitting method in the visible light band, realizes the direct measurement of the absorbance of suspended solids in water by optimizing the spectral analysis algorithm, and has constructed a breakthrough "pretreatment-free and high-precision" detection system. It adopts three-crystal composite packaging technology to integrate visible LED and ultraviolet LED chips, and combines multi-wavelength signal acquisition with intelligent analysis algorithms. It not only eliminates the sample filtration pretreatment step required by traditional methods, but also shortens the detection process from the original 30-50 minute sample preparation cycle to real-time detection, and more effectively solves the technical problem of the loss of colloidal dissolved organic matter DOM during the pretreatment process.

[0121] This technical solution dynamically fits visible light band data to solve characteristic coefficients, generating an optimal correction function in real time and achieving on-site adaptive correction. The six-wavelength LED COD sensor can directly analyze water quality characteristics in real time in actual water environments and automatically generate the optimal correction function. This technology successfully establishes a new paradigm for rapid and accurate detection of water pollutants, significantly improving detection efficiency while ensuring data accuracy, and providing reliable technical support for online monitoring of complex water bodies such as rivers and lakes.

[0122] Example 2

[0123] Based on the aforementioned sampling point (River 2: downstream of the Bianmin River in Liuhe District, 32°21'05" N, 118°50'15" E), a COD sensor with six wavelength LEDs was used for on-site testing. The effectiveness of suspended matter interference correction was verified by comparing the measurement results of a continuous spectrometer with those of the sensor. The specific steps are as follows:

[0124] The COD sensor using six-wavelength LEDs drives the UV LED chip and the visible light LED chip in sequence to collect the absorbance data of the water sample at each wavelength, which are: , ; =0.242, =0.209, =0.176.

[0125] Based on the absorbance data of the measured visible light wavelength ( =0.242, =0.209 and =0.176), the negative exponential function of the suspended matter scattering absorbance was fitted by nonlinear least squares method, and the characteristic coefficient was solved as follows: = 0.5991, = -0.002. Based on the solved characteristic coefficient, the characteristic function is expressed as:

[0126] .

[0127] Based on the established characteristic function, the UV wavelength corresponding to the UV LED chip is substituted to calculate the absorbance of the suspended matter at the UV wavelength: , , that is, the absorbance value of suspended matter SS at ultraviolet light wavelengths of 254 nm and 275 nm.

[0128] From this, the absorbance contribution of suspended solids (SS) in the UV band was calculated. Since the absorbance in the UV band includes the absorbance contribution of DOM and SS, by subtracting the calculated absorbance of suspended solids at the UV wavelength from the measured absorbance at the UV wavelength, the net absorbance data of dissolved organic matter (DOM) in the environmental water body can be obtained after dynamic correction for suspended solid interference.

[0129] According to the measured absorbance of ultraviolet wavelength and the calculated absorbance data of suspended matter at ultraviolet wavelength, the absorbance of DOM is calculated by the difference method to obtain the absorbance of DOM at ultraviolet wavelength. The process is expressed as follows:

[0130] ;

[0131] in, is the wavelength of ultraviolet light, is the absorbance data of the environmental water sample at the ultraviolet wavelength. is the absorbance data of the suspended matter, that is, the fitted solution value of the absorbance of the suspended matter, It is the absorbance data of DOM in environmental water at ultraviolet wavelength.

[0132] In this example, the absorbance of DOM at 254 nm of the water sample from River 2 is calculated as:

[0133] ;

[0134] in, is the actual measured absorbance value of the water sample from River 2 at the ultraviolet wavelength of 254 nm, is the fitted solution value of the absorbance of suspended matter SS at the ultraviolet light wavelength of 254 nm.

[0135] Specifically, the absorbance of the water sample from River 2 at a wavelength of 254 nm on a continuous UV-visible spectrometer is *= 0.105. Comparing the absorbance of the water sample from River 2 at a wavelength of 254 nm on a continuous UV-visible spectrometer, we can conclude that *≈ .

[0136] Similarly, the absorbance of DOM at 276 nm in the water sample of River 2 is calculated as:

[0137] ;

[0138] Specifically, the absorbance of the water sample from River 2 at a wavelength of 276 nm on a continuous UV-visible spectrometer is * = 0.083. The calculated absorbance of DOM at 276 nm for the River 2 water sample is Comparing with the absorbance of the water sample from River 2 at the wavelength of 276nm on the continuous UV-visible spectrometer, it can be concluded that *≈ .

[0139] This method directly measures the absorbance of suspended solids in water by optimizing a spectral analysis algorithm. A built-in machine learning algorithm enables on-site adaptive correction, analyzing water quality characteristics in real time within the actual water environment and automatically generating an optimal correction function. Multi-wavelength cross-validation technology and a dynamic compensation mechanism simultaneously respond to changes in suspended solids concentration, ensuring measurement accuracy.

[0140] Example 3

[0141] Based on the sampling point (River 3: Center of Xianlin Lake, Qixia District, 32°06'08" N, 118°55'20" E), a COD sensor with six wavelength LEDs was used for on-site testing. The effectiveness of suspended matter interference correction was verified by comparing the measurement results of a continuous spectrometer with those of the sensor. The specific steps are as follows:

[0142] The COD sensor using six-wavelength LEDs sequentially drives the UV LED chip (UV wavelengths include 254nm, 276nm, and 305nm) and the visible light LED chip (visible light wavelengths include 456nm, 524nm, and 615nm) to collect the absorbance data of the water sample at each wavelength, which are: , . ; =0.210, =0.181, =0.153.

[0143] Based on the absorbance data of the measured visible light wavelength ( =0.210, =0.181 and =0.153), the negative exponential function of the suspended matter scattering absorbance was fitted by nonlinear least squares method, and the characteristic coefficient was solved as follows: = 0.5163, = -0.002. Based on the solved characteristic coefficient, the characteristic function is expressed as:

[0144] .

[0145] Based on the established characteristic function, the UV wavelength corresponding to the UV LED chip is substituted to calculate the absorbance of the suspended matter at the UV wavelength: , , that is, the absorbance value of suspended matter SS at ultraviolet light wavelengths of 254 nm and 275 nm.

[0146] From this, the absorbance contribution of suspended solids (SS) in the UV band was calculated. Since the absorbance in the UV band includes the absorbance contribution of DOM and SS, by subtracting the calculated absorbance of suspended solids at the UV wavelength from the measured absorbance at the UV wavelength, the net absorbance data of dissolved organic matter (DOM) in the environmental water body can be obtained after dynamic correction for suspended solid interference.

[0147] According to the measured absorbance of ultraviolet wavelength and the calculated absorbance data of suspended matter at ultraviolet wavelength, the absorbance of DOM is calculated by the difference method to obtain the absorbance of DOM at ultraviolet wavelength. The process is expressed as follows:

[0148] ;

[0149] in, is the wavelength of ultraviolet light, is the absorbance data of the environmental water sample at the ultraviolet wavelength. is the absorbance data of the suspended matter, that is, the fitted solution value of the absorbance of the suspended matter, It is the absorbance data of DOM in environmental water at ultraviolet wavelength.

[0150] In this example, the absorbance of DOM at 254 nm of the water sample from River 3 was calculated as:

[0151] ;

[0152] in, is the actual measured absorbance value of the water sample from River 3 at the ultraviolet wavelength of 254 nm. is the fitted solution value of the absorbance of suspended matter SS at the ultraviolet light wavelength of 254 nm.

[0153] Specifically, the absorbance of the water sample from River 3 at a wavelength of 254 nm on a continuous UV-visible spectrometer is * = 0.053. Comparing the absorbance of the water sample from River 3 at a wavelength of 254 nm on a continuous UV-visible spectrometer, we can conclude that *≈ .

[0154] Similarly, the absorbance of DOM at 276 nm in the water sample of River 3 was calculated as:

[0155] ;

[0156] Specifically, the absorbance of the water sample from River 3 at a wavelength of 276 nm on a continuous UV-visible spectrometer is * = 0.043. The calculated absorbance of DOM of River 3 water sample at 276nm is Comparing with the absorbance of the water sample from River 3 at the wavelength of 276nm on the continuous UV-visible spectrometer, it can be concluded that ≈ .

[0157] Experimental verification has shown that this technical solution can remove SS interference through visible light band modeling and ultraviolet band differential correction, quantitatively deduct the SS absorption contribution in the UVC-UVB band, and improve the accuracy of DOM / COD detection. It also eliminates the need for filtration or digestion, allowing direct in-situ detection. This overcomes the limitations of traditional single-wavelength correction and reduces the pretreatment step of filtering through a filter membrane or a vacuum filter compared to traditional filtration methods, reducing DOM loss during the filtration process and, in turn, the relative error of DOM detection. Secondly, by using a deep ultraviolet probe to achieve high-precision real-time measurement at high-attenuation wavelengths such as 254 nm, the measurement volatility of the online monitoring system is reduced, response time is shortened, and data dependence is reduced, achieving a balance between cost reduction and enhanced anti-interference capabilities.

[0158] 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 steps 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 entire 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.

[0159] The above schematically describes the invention and its implementation methods. This description is not restrictive. Without departing from the spirit or basic features of the invention, the invention can be implemented in other specific forms. What is shown in the accompanying drawings is only one of the implementation methods of the invention. The actual structure is not limited to this. Any figure mark in the claims should not limit the claims involved. Therefore, if a person of ordinary skill in the art is inspired by it and designs a structural method and embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the scope of protection of this patent. In addition, the word "including" does not exclude other elements or steps, and the word "one" before an element does not exclude the inclusion of "multiple" elements. The multiple elements stated in the product claim can also be implemented by one element through software or hardware. Words such as first and second are used to indicate names and do not indicate any specific order.

Claims

1. COD sensor based on six-wavelength LED, characterized by: It includes a housing, and a light source, a flow cell, a light intensity detection component and a control circuit mainboard placed in the housing; The flow cell is a transparent cavity that holds the environmental water sample to be tested and allows 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 source; The light intensity detection component is used to detect the transmitted light signal emitted by the light source and absorbed by the environmental water sample to be tested in the circulation pool, 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 mainboard is used to control the start-up of the light source, receive the electrical signal transmitted by the light intensity detection component and calculate the absorbance data of visible light and ultraviolet light according to the electrical signal, and communicate with the host computer; The dynamic correction of suspended matter interference includes: calculating the absorbance data of visible light and the absorbance data of ultraviolet light based on the light intensity value of the transmitted light signal; The characteristic function is constructed based on the absorbance data of visible light wavelengths and is expressed as: ； Where, represents the wavelength, represents absorbance data, k is the absorbance amplitude coefficient, b is the decay rate coefficient, is the base of natural logarithms; Based on the absorbance data of visible light wavelengths, the characteristic coefficients are solved by nonlinear fitting k and b , get the characteristic function; Substitute the UV wavelength into the characteristic function to calculate the absorbance data of the suspended matter at the UV wavelength; Subtract the absorbance data of suspended matter at ultraviolet wavelength from the absorbance data of ultraviolet wavelength to obtain the net absorbance data of dissolved organic matter DOM after dynamic correction of suspended matter interference. The process is expressed as: ； Where, To determine the absorbance data of environmental water samples, is the absorbance data of the suspended matter, It is the absorbance data of dissolved organic matter DOM in environmental water.

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

3. The COD sensor based on 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 six-wavelength LED according to claim 1, characterized in that: The control circuit mainboard includes a micro control unit and a light source driving circuit, a pre-processing circuit and a communication module electrically connected to the micro control unit; The microcontrol unit and the preprocessing circuit amplify and filter the electrical signal converted from the transmitted light signal. The microcontrol unit controls the light source driving circuit to regulate the multi-wavelength composite packaged LED light source to output the corresponding multi-wavelength transmitted light signal, and communicates with the host computer through the communication module.

5. The COD sensor based on six-wavelength LED according to claim 1, characterized in that: 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 circulation pool is installed at the center of the detection cavity and is connected to the outside, and 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 source is coaxially aligned with the optical path of the circulation pool, and the light intensity detection component is coaxially aligned with the light source.

6. The COD sensor based on six-wavelength LED according to claim 5, characterized in that: Also included are a cleaning brush head and a drive 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 pollutants.

7. A method for dynamic correction of suspended matter interference, characterized by: The following steps are involved: Step 1: using the COD sensor based on six-wavelength LEDs as described in any one of claims 1 to 6 to collect the transmitted light signals of the environmental water sample to be tested under visible light and ultraviolet light; Step 2: Calculating the absorbance data of visible light and the absorbance data of ultraviolet light based on the light intensity value of the transmitted light signal; Step 3: Construct the required characteristic function based on the absorbance data of visible light wavelengths; Step 4: Calculate the absorbance data of the suspended matter at the ultraviolet wavelength based on the obtained characteristic function; Step 5: Subtract the suspended matter absorbance data at the ultraviolet wavelength from the ultraviolet wavelength absorbance data calculated in step 1 to obtain the net absorbance data of dissolved organic matter (DOM) after dynamic correction of suspended matter interference.

8. The method for dynamic correction of suspended matter interference according to claim 7, characterized in that: Step 1 specifically includes: The control circuit mainboard drives the LED light sources of each wavelength in sequence according to a preset order. Each wavelength is independently lit and penetrates the environmental water sample to be tested. The light intensity detection component receives the transmitted light signal after being absorbed by the environmental water sample to be tested and converts it into an electrical signal. After amplification and filtering, the electrical signal is converted into a digital light intensity value. Based on the digital light intensity value, the absorbance data of the visible light wavelength and the absorbance data of the ultraviolet light wavelength are calculated and stored.

9. The method for dynamic correction of suspended matter interference according to claim 8, characterized in that: When the light intensity detection component collects the transmitted light signal, each wavelength is illuminated for 1ms, and then the light source is turned off to enter a 50ms data collection interval. After 20 cycles, it automatically switches to the next wavelength and continuously collects 20 data points for each wavelength.

10. The method for dynamic correction of suspended matter interference according to claim 7, characterized in that: Step 3 specifically includes: Construct the characteristic function, expressed as: ； Where, represents the wavelength, represents absorbance data, k is the absorbance amplitude coefficient, b is the decay rate coefficient, is the base of natural logarithms; Based on the absorbance data of visible light wavelengths, the characteristic coefficients are solved by nonlinear fitting k and b , and thus obtain the required characteristic function; Step 4 specifically includes: According to the constructed characteristic function, the wavelength of ultraviolet light is substituted to calculate the absorbance data of the suspended matter under the ultraviolet wavelength; Step 5 specifically includes: Substitute the UV wavelength into the characteristic function, calculate the suspended matter absorbance data at the UV wavelength, subtract the suspended matter absorbance data at the UV wavelength from the measured absorbance data at the UV wavelength, and obtain the net absorbance data of dissolved organic matter DOM after dynamic correction of suspended matter interference. The process is expressed as: ； Where, is the absorbance data of the measured environmental water samples, is the absorbance data of the suspended matter, It is the absorbance data of dissolved organic matter DOM in environmental water.

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