Quaternary ammonium salt bactericide concentration on-line detection system and method based on circulating water system

Abstract

The invention discloses an online concentration detection system and method for quaternary ammonium salt bactericides based on a circulating water system, and belongs to the field of computer process.The method comprises the steps that a to-be-detected sample is obtained through a sampling pipeline connected with a circulating water pipeline, and a blank sample is obtained through a blank water sampling pipeline; calculating the electric signal of the to-be-detected sample in the sample light pool under the maximum absorption peak wavelength to obtain first absorbance, and calculating the electric signal of the blank sample in the blank light pool under the maximum absorption peak wavelength to obtain second absorbance; a pre-calibrated standard curve of absorbance and concentration is obtained, the concentration of the quaternary ammonium salt bactericide in the to-be-detected sample is determined according to the first absorbance, the second absorbance and the standard curve, and the standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions according to the maximum absorption peak wavelength. The online accurate detection of the concentration of the quaternary ammonium salt bactericide can be realized.

Description

Technical Field

[0001] This invention relates to the field of computer processing technology, and in particular to an online detection system and method for the concentration of quaternary ammonium salt bactericides based on a circulating water system. Background Technology

[0002] Quaternary ammonium salt bactericides are a class of non-oxidizing bactericides with broad-spectrum bactericidal capabilities. Examples include benzalkonium chloride, disdecyldimethylammonium chloride, and laurylamine dipropylenediamine. Besides their effectiveness against bacteria, quaternary ammonium salt bactericides are particularly effective against algae. Furthermore, as surfactants, they have a slime-removing effect, helping to keep circulating water systems clean. However, dosage control is crucial. Insufficient concentration will result in inadequate control, leaving the circulating water system at risk of microbial growth after a period of operation. Conversely, excessive concentration increases dosing costs and can lead to excessive foaming, negatively impacting system operation. Additionally, quaternary ammonium salts are toxic to shellfish; excessive dosage can cause ecological damage to surrounding water bodies.

[0003] Currently, quaternary ammonium salts are typically detected manually using spectrophotometry. However, manual detection systems cannot meet the requirements for continuous monitoring of chemical concentrations in circulating water, causing difficulties in chemical dosing and wastewater control. Alternatively, a fluorescence spectrophotometer can be used to measure the fluorescence intensity of fluorescent tracers in compound water treatment agents at different concentrations in circulating water, and a standard curve of fluorescence intensity versus concentration can be plotted. Based on the standard curve corresponding to fluorescence intensity, the content of water treatment agents in the circulating water system can be monitored. However, fluorescent tracers are expensive, and this system does not consider the influence of factors such as the detection instrument and reaction solution on the measurement results, resulting in large detection errors and low accuracy. Summary of the Invention

[0004] This invention provides an online detection system and method for the concentration of quaternary ammonium salt bactericides based on a circulating water system, which can solve the problems of large detection errors and low accuracy, and achieve accurate and continuous detection of the concentration of quaternary ammonium salt bactericides.

[0005] One embodiment of the present invention provides an online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system, comprising: a sample acquisition module, an absorbance detection module, and a concentration calculation module; The sample acquisition module is used to acquire the sample to be tested through a sampling pipe connected to the circulating water pipe, and to acquire a blank sample through a blank water inlet pipe. The sample to be tested and the blank sample are solutions obtained by mixing with a buffer solution and a target solution in sequence. The target solution includes any one of a colorimetric agent for colorimetric reaction with quaternary ammonium salt or a staining agent for decolorization reaction with quaternary ammonium salt. The light absorption detection module is used to calculate the electrical signal of the sample to be detected in the sample light cell at the wavelength of the maximum absorption peak to obtain the first absorbance, and to calculate the electrical signal of the blank sample in the blank water light cell at the wavelength of the maximum absorption peak to obtain the second absorbance. The concentration calculation module is used to obtain a pre-calibrated standard curve of absorbance and concentration, and to determine the concentration of quaternary ammonium salt bactericide in the sample to be tested based on the first absorbance, the second absorbance and the standard curve, so as to realize the online detection of the concentration of quaternary ammonium salt bactericide. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

[0006] This invention provides a method for detecting quaternary ammonium bactericides by acquiring a sample to be tested and a blank sample mixed with a buffer solution and a chromogenic agent (or dye), and then detecting the sample using the wavelength of the maximum absorption peak. Simultaneously, a pre-calibrated standard curve is used to determine the concentration of the quaternary ammonium bactericide. This system effectively eliminates the influence of the chromogenic agent or dye itself, as well as the detection instrument, on the measurement results, thereby achieving accurate detection of the quaternary ammonium bactericide concentration, improving detection precision, and reducing detection errors.

[0007] Furthermore, in the online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system, the sample acquisition module includes a sampling unit and a reagent unit, and the light absorption detection module includes a water sample detection unit and a blank water detection unit. The sampling unit is connected to the water sample detection unit, the reagent unit is connected to both the water sample detection unit and the blank water detection unit, and the water sample detection unit and the blank water detection unit are connected to the concentration calculation module. The sampling unit includes a sample water inlet pipe, a sample water sampling pump, a sampling electric valve, a buffer filter, a sample water discharge electric valve, and a sample water discharge pipe connected in sequence, and the buffer filter is connected in sequence to a backwash wastewater discharge pipe and a backwash wastewater discharge electric valve. The reagent unit includes a sample water buffer solution electric valve, a buffer solution injection pump, and a blank water buffer solution electric valve connected in sequence. The buffer solution injection pump is connected to a buffer solution storage tank. The reagent unit also includes a sample water colorimetric reagent electric valve, a colorimetric reagent injection pump, and a blank water colorimetric reagent injection electric valve connected in sequence. The colorimetric reagent injection pump is connected to a colorimetric reagent storage tank. The water sample detection unit includes a water sample inlet electric valve, a water sample inlet pump, a water sample-buffer solution mixer, a water sample-color reagent mixer, a water sample analysis inlet pump, and a water sample detection chamber connected in sequence. The water sample detection chamber includes a water sample ultraviolet-infrared variable light source, a water sample light cell, and a water sample light intensity detector. The water sample light cell is connected to the water sample analysis solution outlet pipe. The blank water detection unit includes a blank water injection tube, a blank water injection electric valve, a blank water injection pump, a blank water-buffer solution mixer, a blank water-color reagent mixer, a blank water analysis injection pump, and a blank water detection chamber connected in sequence. The blank water detection chamber includes a blank water ultraviolet-infrared variable light source, a blank water light cell, and a blank water light intensity detector, and the blank water light cell is connected to the blank water analysis solution outlet tube. The concentration calculation module includes a data processing and transmission unit, a quaternary ammonium salt dosing pump, and a quaternary ammonium salt dosing pipeline connected in sequence, and the quaternary ammonium salt dosing pump is connected to the quaternary ammonium salt storage tank.

[0008] By designing specialized sampling, reagent, water sample detection, and blank water detection units, this system enables continuous online monitoring of quaternary ammonium salt bactericides in circulating cooling water. The sampling unit continuously acquires circulating water samples, the reagent unit automatically adds buffer solution and colorimetric reagent, and the detection unit monitors the absorbance of the samples in real time, thus achieving continuous monitoring of quaternary ammonium salt concentration. The water sample detection and blank water detection units allow for simultaneous detection of the absorbance of both the test sample and the blank sample. By comparing the absorbance of the two samples and subtracting the absorption effects of the colorimetric reagent and buffer solution, the actual concentration of quaternary ammonium salt can be calculated more accurately, significantly improving detection precision and reducing errors caused by reagents and instruments. The system, through a variable light source (UV-IR variable light source) and data processing module, can automatically scan and determine the wavelength of the maximum absorption peak, making it suitable for various quaternary ammonium salts. The system's ability to detect colorimetric reagents gives it broad versatility and adaptability, meeting the detection needs of various application scenarios. Simultaneously, the automated sampling, dosing, mixing, detection, and data processing processes significantly reduce manual intervention. The sampling unit, reagent unit, and detection unit all operate automatically via electric valves and pumps. The data processing module automatically calculates concentrations and controls the dosing system. This highly automated system not only improves detection efficiency but also reduces human error, enhancing system reliability and stability. Furthermore, the system's direct connection between the concentration calculation module and the dosing system allows for automatic adjustment of the dosing amount based on real-time quaternary ammonium salt concentrations. When the detected concentration exceeds a set value, dosing is reduced or stopped; when the concentration falls below the set value, the dosing amount is increased. This real-time control function optimizes the dosing process, saves on reagent costs, and reduces potential environmental hazards.

[0009] Furthermore, obtaining the pre-calibrated standard curve of absorbance and concentration specifically involves: By performing blank detection on the sample light pool and the blank water light pool respectively, the first absorbance difference corresponding to the absorption wavelength of each detection light is obtained; and by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, the second absorbance difference corresponding to the absorption wavelength of each detection light is obtained. The wavelength of the maximum absorption peak is determined based on the maximum difference between each of the first absorbance differences and each of the second absorbance differences; For each quaternary ammonium salt standard solution, the attenuation detection light at the maximum absorption peak wavelength is detected for the quaternary ammonium salt standard solution in the sample optical cell and the blank sample in the blank water optical cell, respectively. The electrical signals at the maximum absorption peak wavelength in the sample optical cell and the blank water optical cell are obtained respectively. The electrical signals in the sample optical cell and the blank water optical cell are converted and calculated to obtain the third absorbance difference value between each quaternary ammonium salt standard solution and the maximum absorption peak wavelength. The absorbance difference of each quaternary ammonium salt standard solution is determined based on the third absorbance difference of each quaternary ammonium salt standard solution. According to the Lambert-Beer law, a linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve.

[0010] By performing blank detection and absorption peak wavelength scanning, the first and second absorbance differences under each detection light wavelength are obtained, thereby determining the maximum absorption peak wavelength. Furthermore, the electrical signals generated by the attenuation of the detection light at the maximum absorption peak wavelength in the quaternary ammonium salt standard solution and blank sample are converted and calculated to obtain the standard curve. Therefore, this embodiment also considers the influence of the chromogenic agent or dye itself and the detection instrument on the quaternary ammonium salt concentration during the standard curve determination process, improving the accuracy of the standard curve obtained from system calibration. This allows for more accurate detection results when subsequently using the standard curve to determine the concentration of quaternary ammonium salt bactericides in the sample to be tested, further reducing detection errors and improving detection precision.

[0011] Furthermore, by performing blank detection on the sample optical cell and the blank water optical cell respectively, a first absorbance difference corresponding to the absorption wavelength of each detection light is obtained. And by performing maximum absorption peak wavelength detection on the sample optical cell and the blank water optical cell respectively, a second absorbance difference corresponding to the absorption wavelength of each detection light is obtained, specifically as follows: The attenuation detection light under each detection light is detected for the blank calibration sample in the sample light pool and the blank water light pool respectively, and the electrical signal of each detection light under the sample light pool and the blank water light pool is obtained respectively. For each detection light, the electrical signals under the sample light cell and the blank water light cell are converted and calculated to obtain the first absorbance difference value corresponding to the absorption wavelength under each detection light. The buffer solution, target solution, and target quaternary ammonium salt standard solution are mixed in a preset ratio to obtain a mixed quaternary ammonium salt solution. The buffer solution, target solution, and blank calibration sample are then mixed in a preset ratio to obtain a mixed calibration sample. The mixed quaternary ammonium salt solution in the sample photocell and the mixed calibration sample in the blank photocell are respectively tested under the attenuation detection light of each detection light to obtain the second absorbance difference corresponding to the absorption wavelength under each detection light.

[0012] By separately detecting the blank calibration samples in the sample optical cell and the blank aqueous optical cell, and by sequentially mixing the buffer solution, the target solution with the target quaternary ammonium salt standard solution and the blank calibration sample before detection, the first absorbance difference and the second absorbance difference can be obtained more accurately, thereby more accurately determining the wavelength of the maximum absorption peak. This helps improve the accuracy of the standard curve, thus enabling more precise detection when determining the concentration of quaternary ammonium salt bactericides, further reducing detection errors and improving detection accuracy.

[0013] Furthermore, the standard curve is obtained by performing a linear regression on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions, specifically as follows: Linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the linear regression equation; Calculate the ratio of the intercept to the slope in the linear regression equation, and the correlation coefficient of the linear regression equation; If the ratio is less than or equal to a first preset threshold and the correlation coefficient is greater than a second preset threshold, then the linear regression equation is determined to be valid, and the standard curve is obtained. If the ratio is greater than the first preset threshold, or the correlation coefficient is less than or equal to the second preset threshold, the linear regression equation is determined to be invalid, and the linear regression is performed again.

[0014] By defining a standard curve based on the rule that the ratio between the first and second coefficients of the linear regression equation must be less than or equal to a first threshold, and the correlation coefficient must be greater than a second threshold, the calibration is considered valid. This ensures the high reliability and accuracy of the obtained standard curve, allowing it to more realistically reflect the relationship between quaternary ammonium salt concentration and absorbance. Using such a standard curve to determine the concentration of quaternary ammonium salt bactericides in a sample enables more precise detection, effectively reducing detection errors and improving accuracy.

[0015] Furthermore, the online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system further includes: The control command is determined based on the concentration of the quaternary ammonium salt bactericide. Input the actual operating data into the time prediction model to output the start and stop times corresponding to the control command; The control command is responded to based on the start time and the stop time to add a quaternary ammonium salt bactericide to the circulating water in the circulating water pipeline.

[0016] This approach, by accurately detecting the concentration of quaternary ammonium bactericides, further determines control commands based on the detected concentration and outputs the start and stop times corresponding to the control commands through a time prediction model. This allows for the addition of quaternary ammonium bactericides to the circulating water in the pipeline based on these time and control commands. This not only achieves accurate detection of quaternary ammonium bactericide concentrations but also enables precise dosing control based on the detection results, improving the operational efficiency and reliability of the circulating water treatment system.

[0017] Furthermore, the time prediction model includes a first time prediction model and a second time prediction model, specifically: A first deep learning model is established based on the decay function of circulating water quaternary ammonium salt concentration within a preset time period, and the first deep learning model is trained based on the first historical operating data to obtain the first time prediction model. The first time prediction model is used to predict the start time corresponding to the control command. The first historical operating data includes any multiple of the following within the preset time period: circulating water quaternary ammonium salt concentration, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate. The preset time period refers to the time period between the last time the dosing was stopped and the current time the dosing was started, or the time period between the last time the dosing was reduced and the current time the dosing was increased. A second deep learning model is established based on the incremental function of the quaternary ammonium salt concentration in the circulating water within a preset time period, and the second deep learning model is trained based on the second historical operating data to obtain the second time prediction model. The second time prediction model is used to predict the stop time corresponding to the control command. The second historical operating data includes any multiple of the following within the preset time period: quaternary ammonium salt concentration in the circulating water, dosing pump stroke, dosing pump frequency, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate.

[0018] By establishing a first deep learning model and a second deep learning model, and training them respectively using first and second historical operating data, a first time prediction model and a second time prediction model are obtained, enabling accurate prediction of the start and stop times corresponding to control commands. This time prediction method based on deep learning models can fully consider the influence of various operating parameters and conditions of the circulating water system on the changes in quaternary ammonium salt concentration, thus more accurately predicting the start and stop times of chemical dosing. This makes chemical dosing control more precise, further improving the operating efficiency and reliability of the circulating water treatment system, and also further enhancing the overall performance and benefits of online detection and control of quaternary ammonium salt bactericide concentration.

[0019] Furthermore, the acquisition of the sample to be tested through a sampling pipe connected to the circulating water pipe specifically involves: Initial samples were obtained through sampling pipes connected to the circulating water pipeline; The initial sample is filtered using a buffer filter to obtain the sample to be tested.

[0020] By adding a buffer filter to the initial sample during sample acquisition, suspended solids and other impurities in the circulating water can be effectively removed, reducing their interference with the test results. This helps improve the accuracy of the test, further reduces detection errors, and thus enables more precise online detection of quaternary ammonium bactericide concentrations, improving the accuracy of the detection.

[0021] This invention also provides an online detection method for the concentration of quaternary ammonium salt bactericides in a circulating water system, comprising: The sample to be tested is obtained through a sampling pipe connected to the circulating water pipe, and a blank sample is obtained through a blank water injection pipe. The sample to be tested and the blank sample are solutions obtained by mixing with a buffer solution and a target solution in sequence. The target solution includes any one of a colorimetric agent for colorimetric reaction with quaternary ammonium salt or a staining agent for decolorization reaction with quaternary ammonium salt. The electrical signal of the sample to be tested in the sample photocell at the wavelength of the maximum absorption peak is calculated to obtain the first absorbance, and the electrical signal of the blank sample in the blank photocell at the wavelength of the maximum absorption peak is calculated to obtain the second absorbance. A pre-calibrated standard curve of absorbance and concentration is obtained. Based on the first absorbance, the second absorbance, and the standard curve, the concentration of quaternary ammonium salt bactericide in the sample to be tested is determined to achieve online detection of the concentration of the quaternary ammonium salt bactericide. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

[0022] This invention provides an embodiment of a method for determining the concentration of quaternary ammonium bactericides by acquiring a sample to be tested and a blank sample mixed with a buffer solution and a chromogenic agent (or dye), detecting the sample using the wavelength of the maximum absorption peak, and simultaneously determining the concentration of the quaternary ammonium bactericide using a pre-calibrated standard curve. This method effectively eliminates the influence of the chromogenic agent or dye itself, as well as the detection instrument, on the measurement results, thereby achieving accurate detection of the concentration of quaternary ammonium bactericides, improving detection precision, and reducing detection errors.

[0023] Furthermore, obtaining the pre-calibrated standard curve of absorbance and concentration specifically involves: By performing blank detection on the sample light pool and the blank water light pool respectively, the first absorbance difference corresponding to the absorption wavelength of each detection light is obtained; and by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, the second absorbance difference corresponding to the absorption wavelength of each detection light is obtained. The wavelength of the maximum absorption peak is determined based on the maximum difference between each of the first absorbance differences and each of the second absorbance differences; For each quaternary ammonium salt standard solution, the attenuation detection light at the maximum absorption peak wavelength is detected for the quaternary ammonium salt standard solution in the sample optical cell and the blank sample in the blank water optical cell, respectively. The electrical signals at the maximum absorption peak wavelength in the sample optical cell and the blank water optical cell are obtained respectively. The electrical signals in the sample optical cell and the blank water optical cell are converted and calculated to obtain the third absorbance difference value between each quaternary ammonium salt standard solution and the maximum absorption peak wavelength. The absorbance difference of each quaternary ammonium salt standard solution is determined based on the third absorbance difference of each quaternary ammonium salt standard solution. According to the Lambert-Beer law, a linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve. Attached Figure Description

[0024] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system, provided in one embodiment. Figure 2 This is a schematic diagram of an online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system. Figure 3This is a schematic diagram of another online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system; Figure 4 This is a flowchart illustrating an online detection method for the concentration of quaternary ammonium salt bactericides based on a circulating water system. Figure 1 The components are: 1. Sample water inlet pipe; 2. Sample water sampling pump; 3. Sampling electric valve; 4. Backwash wastewater discharge pipe; 5. Backwash wastewater discharge electric valve; 6. Buffer filter; 7. Sample water discharge electric valve; 8. Sample water discharge pipe; 9. Calibration electric valve; 10. Calibration inlet pipe; 11. Sample water inlet electric valve; 12. Sample water inlet pump; 13. Sample water buffer solution electric valve; 14. Buffer solution inlet pump; 15. Buffer solution storage tank; 16. Blank water buffer solution electric valve; 17. Sample water-buffer solution mixer; 18. Sample water-chromogenic reagent mixer; 19. Sample water chromogenic reagent electric valve; 20. Chromogenic reagent inlet pump; 21. Blank water chromogenic reagent inlet electric valve; 22. Chromogenic reagent storage tank; 23. Sample water analysis inlet pump. 23. Sample water detection chamber; 24. Sample water UV-IR variable light source; 25. Sample water light cell; 26. Sample water light intensity detector; 27. Sample water analysis solution outlet tube; 28. Blank water inlet tube; 29. ​​Blank water inlet electric valve; 30. Blank water inlet pump; 31. Blank water-buffer solution mixer; 32. Blank water-chromogenic reagent mixer; 33. Blank water analysis inlet pump; 34. Blank water detection chamber; 35. Blank water UV-IR variable light source; 36. Blank water light cell; 37. Blank water light intensity detector; 38. Blank water analysis solution outlet tube; 39. Waste liquid tank; 40. Data processing and transmission unit; 41. Quaternary ammonium salt dosing pump; 42. Quaternary ammonium salt storage tank; 43. Quaternary ammonium salt dosing pipeline; 44. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0033] To address the issues of large detection errors and low accuracy in existing technologies, this application proposes an online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system. For ease of description, the structure of such an online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system is first described, as follows: Figure 1As shown, the system includes a sample acquisition module, an absorbance detection module, and a concentration calculation module. The sample acquisition module includes a sampling unit and a reagent unit. The absorbance detection module includes a water sample detection unit and a blank water detection unit. The sampling unit is connected to the water sample detection unit. The reagent unit is connected to both the water sample detection unit and the blank water detection unit. The water sample detection unit and the blank water detection unit are connected to the concentration calculation module. The sampling unit includes a sample water inlet pipe 1, a sample water sampling pump 2, a sampling electric valve 3, a buffer filter 6, a sample water discharge electric valve 7, and a sample water discharge pipe 8 connected in sequence. The buffer filter 6 is connected in sequence to a backwash wastewater discharge pipe 4 and a backwash wastewater discharge electric valve 5. The sampling unit is used to sample circulating water. The reagent unit includes a sample water buffer solution electric valve 13, a buffer solution injection pump 14, and a blank water buffer solution electric valve 16 connected in sequence. The buffer solution injection pump 14 is connected to a buffer solution storage tank 15. It also includes a sample water colorimetric reagent electric valve 19, a colorimetric reagent injection pump 20, and a blank water colorimetric reagent injection electric valve 21. The colorimetric reagent injection pump 20 is connected to a colorimetric reagent storage tank 22. The reagent unit is used to inject the buffer solution reagent and colorimetric reagent into the water sample to be tested. The buffer solution injection pump 14 and the colorimetric reagent injection pump 20 are dual-channel pumps, capable of quantitatively injecting solutions into the water sample detection unit and the blank water detection unit, respectively. The buffer solution storage tank 15 is soluble in the buffer solution required for color development and can also be used to store strong acid or strong alkali solutions required for color development. The colorimetric reagent storage tank is used to store the colorimetric reagent or dye. The water sample detection unit includes a sample water injection electric valve 11, a sample water injection pump 12, a sample water-buffer solution mixer 17, a sample water-chromogenic reagent mixer 18, and a sample water detection chamber 24 connected in sequence. The sample water detection chamber 24 includes a sample water ultraviolet-infrared variable light source 25, a sample water light cell 26, and a sample water light intensity detector 27. The sample water analysis solution outlet pipe 28 is connected to the sample water light cell 26. The water sample detection unit is used to introduce the water sample to be tested into the detection unit, so that the water sample, buffer solution, and chromogenic reagent are mixed in sequence and fully contacted, and sufficient color development time is reserved to ensure that the quaternary ammonium salt in the water sample and the chromogenic reagent are fully developed. The blank water detection unit includes a blank water injection tube 29, a blank water injection electric valve 30, a blank water injection pump 31, a blank water-buffer solution mixer 32, a blank water-chromogenic reagent mixer 33, a blank water analysis injection pump 34, and a blank water detection chamber 35, connected in sequence. The blank water detection chamber 35 includes a blank water UV-IR variable light source 36, a blank water fluorescence cell 37, and a blank water light intensity detector 38. The blank water fluorescence cell 37 is connected to the blank water analysis solution outlet tube 39 and is used to introduce blank water into the blank water detection unit, allowing the water sample, buffer solution, and chromogenic reagent to mix sequentially, thus eliminating the influence of the chromogenic reagent on the absorption of the light source to be tested. The blank water-buffer solution mixer 32 and the blank water-chromogenic reagent mixer 33 perform mixing functions. The blank water UV-IR variable light source 36 emits detection light of a specific wavelength. The detection light is attenuated after passing through the blank water fluorescence cell. The electrical signal generated by the attenuated detection light is measured in the blank water light intensity detector 38 and transmitted to the concentration calculation module for conversion into light intensity and absorbance data. The concentration calculation module includes a data processing and transmission unit 41, a quaternary ammonium salt dosing pump 42, and a quaternary ammonium salt dosing pipeline 44 connected in sequence. The quaternary ammonium salt dosing pump 42 is connected to the quaternary ammonium salt storage tank 43 and is used to process and calculate the electrical signals of the water sample detection unit and the blank water detection unit to obtain the concentration of quaternary ammonium salt in the water sample to be tested and to determine the control command for dosing operation. The sampling unit is connected to the water sample detection unit, and the reagent unit is also connected to the water sample detection unit. The water sample detection unit is connected to the concentration calculation module. After obtaining circulating water through the sampling unit, it is mixed with the target solution provided by the reagent unit to obtain the sample to be tested. The sample to be tested is input into the water sample detection unit for detection to obtain the electrical signal corresponding to the sample to be tested. The concentration calculation module processes the electrical signal to obtain the first absorbance. The reagent unit is connected to the blank water detection unit, which is connected to the concentration calculation module. The target solution provided by the reagent unit is mixed with the blank water obtained by the blank water detection unit to obtain a blank sample. The blank sample is then detected by the blank water detection unit to obtain the corresponding electrical signal. The concentration calculation module processes the electrical signal to obtain the second absorbance. Based on the first absorbance, the second absorbance, and a pre-calibrated standard curve of absorbance and concentration, the concentration calculation module obtains the concentration of quaternary ammonium salt bactericide in the sample to be tested.

[0034] For this system, during blank detection, maximum absorption peak wavelength detection, calibration, and circulating water quaternary ammonium salt detection, the final waste liquid generated flows into the waste liquid tank 40 through the sample water analysis liquid outlet tube 28 and the blank water analysis liquid outlet tube 39 for collection.

[0035] Furthermore, to ensure sufficient color development time for the quaternary ammonium salt and the colorimetric reagent, the recommended volumes of the sample water-colorimetric reagent mixer 18 and the blank water-colorimetric reagent mixer 33 should not be less than 30 mL. However, this system does not limit their volumes; 30 mL is merely an example. If the time required for color development and stabilization is short, the volumes of the sample water-colorimetric reagent mixer 18 and the blank water-colorimetric reagent mixer 33 can be appropriately reduced; if the time required for color development and stabilization is long, the volumes of the sample water-colorimetric reagent mixer and the blank water-colorimetric reagent mixer can be appropriately increased.

[0036] Furthermore, to further increase the system's automation level, the system is equipped with an automatic cleaning function. The specific process is as follows: ① Replace the waste liquid in waste liquid tank 40 with demineralized water. Start the sample water analysis injection pump 23, sample water injection pump 12, sample water injection electric valve 11, sample water discharge electric valve 7, blank water injection electric valve 30, blank water analysis injection pump 34, and blank water injection pump 31. The pumps reverse, causing the colorimetric reagent and sample water in the water sample detection unit and blank water detection unit to be discharged from the sample water discharge pipe 8. The demineralized water is used to clean the pipeline at a flow rate of 15 ml / min for 20 minutes, and to loosen the suspended solids trapped on the buffer filter 6. ② Start the backwash wastewater discharge electric valve 5 and calibration electric valve 9, and close the other pumps and valves. Connect the calibration inlet pipe 10 to the demineralized water and backwash the buffer filter at a flow rate of 2 L / min for 5 minutes. The backwash water is discharged from the backwash wastewater discharge pipe 4. ① After backwashing is complete, open the sample water discharge electric valve 7, close the other valves and pumps, drain all the water from the buffer filter 6, and then close the valves to complete the entire process.

[0037] See Figure 2 An embodiment of the present invention provides an online detection system 200 for the concentration of quaternary ammonium salt bactericides based on a circulating water system, comprising: a sample acquisition module 210, an absorbance detection module 220, and a concentration calculation module 230; The sample acquisition module 210 is used to acquire a sample to be tested through a sampling pipe connected to a circulating water pipe, and to acquire a blank sample through a blank water inlet pipe. The sample to be tested and the blank sample are solutions obtained by mixing a buffer solution and a target solution in sequence. The target solution includes either a colorimetric agent for colorimetric reaction with a quaternary ammonium salt or a staining agent for decolorization reaction with a quaternary ammonium salt.

[0038] In this embodiment, taking nitrobenzene diazoaminoazobenzene as the colorimetric reagent as an example, the buffer solution storage tank 15 contains a sodium hydroxide solution with a pH of 12, and the colorimetric reagent storage tank 22 contains a 50 mg / L nitrobenzene diazoaminoazobenzene solution. Deionized water is used as blank water. The sample to be tested is obtained by mixing the circulating water with the buffer solution and the target solution in sequence. The blank sample is obtained by mixing the deionized water with the buffer solution and the target solution in sequence. During system operation, when it is necessary to obtain the sample to be tested and blank samples, circulating water and demineralized water must be obtained first. The following valves in the system are then opened: sample water electric valve, sample water injection pump 12, sample water analysis injection pump 23, blank water injection electric valve 30, blank water injection pump 31, blank water analysis injection pump 34, sample water buffer solution electric valve 13, buffer solution injection pump 14, blank water buffer solution electric valve 16, sample water colorimetric reagent electric valve 19, colorimetric reagent injection pump 20, and blank water colorimetric reagent injection electric valve 21. The remaining electric valves or pumps are closed. The sample water discharge electric valve 7 automatically opens after the buffer filter 6 is filled with water. The sample water injection pipe 1 is connected to the circulating water sampling pipe for sampling of the circulating water at a flow rate of 500 ml / L. The sample water injection pump 12 injects circulating water into the water sample detection unit at a flow rate of 0.5 mL / min. The remaining sample water is discharged through the sample water discharge pipe 8. The buffer solution injection pump 14... Sodium hydroxide solution is injected into the water sample detection unit at a flow rate of 0.5 mL / min, and nitrobenzene diazoaminoazobenzene solution is injected into the water sample detection unit at a flow rate of 0.5 mL / min to obtain the sample to be tested. Simultaneously, demineralized water is connected to the demineralized water injection pipeline as blank water. The blank water injection pump 31 injects demineralized water into the blank water detection unit at a flow rate of 0.5 mL / min, and the buffer solution injection pump 14 injects sodium hydroxide solution into the blank water detection unit at a flow rate of 1 mL / min, and nitrobenzene diazoaminoazobenzene solution is injected into the blank water detection unit at a flow rate of 0.5 mL / min to obtain the blank sample. The sample water analysis injection pump 23 and the blank water analysis injection pump 34 use a flow rate of 2 mL / min as power sources to extract the sample to be tested and the blank sample, respectively. The sample water analysis injection pump 23 extracts the sample to be tested into the sample water fluorescence cell 26, and the blank water analysis injection pump 34 extracts the blank sample into the blank water fluorescence cell 37. Testing begins after both the water sample detection unit and the blank water detection unit have been running stably for 10 minutes.

[0039] It should be noted that this system has broad compatibility with chromogenic agents (or staining agents), not limited to nitrobenzene diazoaminoazobenzene. It can be used with common chromogenic agents or staining agents such as bromophenol blue, eosin, aluminum mordant blue 29, and acid red 94. It also has broad compatibility with quaternary ammonium salts; single-chain, double-chain, and compound quaternary ammonium salts can all be used. Only appropriate chromogenic agents (or staining agents) need to be selected, and the maximum absorption peak wavelength needs to be determined by detection. Furthermore, the nitrobenzene diazoaminoazobenzene and sodium hydroxide mentioned above are just examples; reagent concentration, dosing flow rate, and the wavelength of the maximum absorption peak can be determined through debugging and testing. In addition, this system can be used not only for chromogenic agents in colorimetric reactions but also for measuring the absorbance of the maximum absorption peak wavelength of the staining agent after a fading reaction between the quaternary ammonium salt and the staining agent. It can also achieve online detection of quaternary ammonium salt concentration. Given a buffer solution concentration and injection flow rate, chromogenic agent concentration, chromogenic agent injection flow rate, and quaternary ammonium salt solution injection flow rate, a series of absorbance attenuation values ​​versus quaternary ammonium salt concentrations can be obtained at various quaternary ammonium salt concentrations. A linear regression calculation is performed on the relationship between absorbance attenuation values ​​and quaternary ammonium salt concentrations to obtain the linear regression equation for the reagent on that quaternary ammonium salt, which is used to detect the quaternary ammonium salt concentration in circulating water. The staining agent can be brominated thymol blue.

[0040] As an example of an embodiment of the present invention, obtaining the sample to be tested through a sampling pipe connected to a circulating water pipe specifically involves: obtaining an initial sample through a sampling pipe connected to a circulating water pipe; filtering the initial sample through a buffer filter to obtain the sample to be tested.

[0041] In this embodiment, the sampling unit includes a buffer filter 6, which can filter suspended solids in the circulating water to reduce the impact of scattering of suspended solids on the detection results. At the same time, it serves as a buffer container to reduce the impact of water flow and water quality on the detection system. Its filtration accuracy is not less than 5μm and its volume is 500ml.

[0042] The light absorption detection module 220 is used to calculate the electrical signal of the sample to be tested in the sample light cell at the wavelength of the maximum absorption peak to obtain the first absorbance, and to calculate the electrical signal of the blank sample in the blank water light cell at the wavelength of the maximum absorption peak to obtain the second absorbance.

[0043] In this embodiment, with both the light source and the detection wavelength being the maximum absorption peak wavelength i, the sample water ultraviolet-infrared variable light source 25 and sample water light intensity detector 27 in the sample water detection chamber 24, and the blank water ultraviolet-infrared variable light source 36 and blank water light intensity detector 38 in the blank water detection chamber 35 begin synchronous detection. Specifically, the sample water ultraviolet-infrared variable light source 25 provides the light source and detection light corresponding to the maximum absorption peak wavelength to the sample water light cell 26, and the blank water ultraviolet-infrared variable light source 36 provides the light source and detection light corresponding to the maximum absorption peak wavelength to the blank water light cell 37. Since the detection light is attenuated after passing through the sample water light cell 26 and the blank water light cell 37, the electrical signal generated by the detection light after attenuation by the sample to be tested is measured in the sample water light intensity detector 27, and the electrical signal generated by the detection light after attenuation by the blank sample is measured in the blank water light intensity detector 38. The two electrical signals are transmitted to the concentration calculation module to obtain the first absorbance A corresponding to the sample to be tested and the second absorbance B corresponding to the blank sample. Among them, the sample water ultraviolet-infrared variable light source 25 and the blank water ultraviolet-infrared variable light source 36 have the ability to emit light sources with wavelengths in the range of 220-760nm, and the sample water light intensity detector 27 and the blank water light intensity detector 38 have the ability to detect absorbance with wavelengths in the range of 220-760nm.

[0044] The concentration calculation module 230 is used to obtain a pre-calibrated standard curve of absorbance and concentration, and to determine the concentration of quaternary ammonium salt bactericide in the sample to be tested based on the first absorbance, the second absorbance, and the standard curve, so as to realize the online detection of the concentration of quaternary ammonium salt bactericide. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

[0045] like Figure 3 As shown, the online concentration detection system 300 for quaternary ammonium salt bactericides based on a circulating water system specifically comprises: The sample acquisition module 310 includes a sampling unit 312 and a reagent unit 314. The absorbance detection module 320 includes a water sample detection unit 322 and a blank water detection unit 324. The sampling unit 312 is connected to the water sample detection unit 322. The reagent unit 314 is connected to both the water sample detection unit 322 and the blank water detection unit 324. The water sample detection unit 322 and the blank water detection unit 324 are connected to the concentration calculation module 330. The sampling unit 312 includes a sample water inlet pipe, a sample water sampling pump, a sampling electric valve, a buffer filter, a sample water discharge electric valve, and a sample water discharge pipe connected in sequence, and the buffer filter is connected in sequence to a backwash wastewater discharge pipe and a backwash wastewater discharge electric valve. The reagent unit 314 includes a sample water buffer solution electric valve, a buffer solution injection pump, and a blank water buffer solution electric valve connected in sequence. The buffer solution injection pump is connected to a buffer solution storage tank. It also includes a sample water colorimetric reagent electric valve, a colorimetric reagent injection pump, and a blank water colorimetric reagent injection electric valve connected in sequence. The colorimetric reagent injection pump is connected to a colorimetric reagent storage tank. The water sample detection unit 322 includes a water sample inlet electric valve, a water sample inlet pump, a water sample-buffer solution mixer, a water sample-color reagent mixer, a water sample analysis inlet pump, and a water sample detection chamber connected in sequence. The water sample detection chamber includes a water sample ultraviolet-infrared variable light source, a water sample light cell, and a water sample light intensity detector. The water sample light cell is connected to the water sample analysis liquid outlet pipe. The blank water detection unit 324 includes a blank water injection tube, a blank water injection electric valve, a blank water injection pump, a blank water-buffer solution mixer, a blank water-color reagent mixer, a blank water analysis injection pump, and a blank water detection chamber connected in sequence. The blank water detection chamber includes a blank water ultraviolet-infrared variable light source, a blank water light cell, and a blank water light intensity detector. The blank water light cell is connected to the blank water analysis solution outlet tube. The concentration calculation module 330 includes a data processing and transmission unit, a quaternary ammonium salt dosing pump, and a quaternary ammonium salt dosing pipeline connected in sequence, and the quaternary ammonium salt dosing pump is connected to the quaternary ammonium salt storage tank.

[0046] In this embodiment, the first absorbance difference value A corresponding to the wavelength of the maximum absorption peak determined by blank detection before calibration is obtained. i0 -B i0 Based on the first absorbance A and the second absorbance B, the target absorbance AA corresponding to the sample to be tested is determined. i0 -(BB) i0 Then, based on the pre-calibrated standard curve of absorbance and concentration (formula: y = ax + b), the concentration of quaternary ammonium salt in the circulating water is calculated, and the operating data is recorded. The operating data includes, but is not limited to, sampling time, sample water injection pump flow rate, sample water analysis injection pump flow rate, blank water injection pump flow rate, blank water analysis injection pump flow rate, buffer solution injection pump flow rate, colorimetric reagent injection pump flow rate, sample water discharge electric valve flow rate, sample water absorbance, blank water absorbance, and calculated concentration. Wherein, y is the quaternary ammonium salt concentration of the sample to be tested, a is the slope coefficient of absorbance and concentration, x is the target absorbance, and b is the intercept.

[0047] As an example of an embodiment of the present invention, the method of obtaining a first absorbance difference corresponding to the absorption wavelength of each detection light by performing blank detection on the sample light pool and the blank water light pool respectively, and obtaining a second absorbance difference corresponding to the absorption wavelength of each detection light by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, specifically involves: detecting the attenuation detection light of the blank calibration sample in the sample light pool and the blank water light pool under each detection light, respectively obtaining the electrical signal of each detection light under the sample light pool and the blank water light pool; and for each detection light, respectively... The electrical signals under the sample light cell and the blank water light cell are converted and calculated to obtain the first absorbance difference corresponding to the absorption wavelength under each detection light. The buffer solution, the target solution and the target quaternary ammonium salt standard solution are mixed in a preset ratio to obtain a mixed quaternary ammonium salt solution. The buffer solution, the target solution and the blank calibration sample are mixed in a preset ratio to obtain a mixed calibration sample. The attenuation detection light under each detection light is detected for the mixed quaternary ammonium salt solution in the sample light cell and the mixed calibration sample in the blank water light cell to obtain the second absorbance difference corresponding to the absorption wavelength under each detection light.

[0048] In this embodiment, a blank test is required before detecting the maximum absorption peak wavelength. The procedure is as follows: Calibration inlet pipe 10 and blank water inlet pipe 29 are respectively connected to demineralized water as blank calibration samples. Calibration electric valve 9, sample water inlet electric valve 11, sample water inlet pump 12, sample water analysis inlet pump 23, blank water inlet electric valve 30, blank water inlet pump 31, and blank water analysis inlet pump 34 are opened. Other electric valves or pumps are closed. After the demineralized water has entered the water sample detection unit and blank water detection unit for 30 minutes, the sample water in the sample water detection chamber 24 is analyzed using ultraviolet-infrared spectroscopy. The variable light source 25 and sample water intensity detector 27, as well as the blank water ultraviolet-infrared variable light source 36 and blank water intensity detector 38 in the blank water detection chamber 35, begin scanning the absorption spectrum peaks with a scanning accuracy of 1 nm. This allows for the detection of attenuation of the demineralized water in the sample water detection unit and the blank water detection unit under each detection light beam. The electrical signals of the demineralized water under the conditions of the sample water detection unit and the blank water detection unit are then transmitted to the concentration calculation module, where they are converted into absorbance values ​​A corresponding to the sample water detection unit and the blank water detection unit, respectively. i0 With B i0 Where i is the corresponding wavelength, the data is input into the concentration calculation module, and the absorbance A is calculated. i0 With B i0 The difference is used to obtain the first absorbance difference.

[0049] The maximum absorption peak wavelength detection process is as follows: Open calibration electric valve 9, sample water injection electric valve 11, sample water injection pump 12, sample water analysis injection pump 23, blank water injection electric valve 30, blank water injection pump 31, blank water analysis injection pump 34, sample water buffer solution electric valve 13, buffer solution injection pump 14, blank water buffer solution electric valve 16, sample water colorimetric reagent electric valve 19, colorimetric reagent injection pump 20, and blank water colorimetric reagent injection electric valve 21. Close the remaining electric valves or pumps. Taking nitrobenzene diazoaminoazobenzene as the colorimetric reagent as an example, and using a 5 mg / L quaternary ammonium salt standard solution as the target quaternary ammonium salt standard solution, calibration inlet pipe 10 is connected to a 5 mg / L quaternary ammonium salt standard solution. Buffer solution storage tank 15 contains sodium hydroxide solution with a pH of 12. Colorimetric reagent storage tank 22 contains 50... A 5 mg / L quaternary ammonium salt standard solution is injected into the water sample detection unit by sample water injection pump 12 at a flow rate of 0.5 mL / min. A sodium hydroxide solution is injected into the water sample detection unit by buffer solution injection pump 14 at a flow rate of 1 mL / min, and a nitrobenzene diazonium aminoazobenzene solution is injected into the water sample detection unit at a flow rate of 0.5 mL / min, resulting in a mixed quaternary ammonium salt solution. Simultaneously, demineralized water is connected to the demineralized water injection pipeline as a blank calibration sample. A demineralized water injection pump 31 injects demineralized water into the blank water detection unit at a flow rate of 0.5 mL / min, a sodium hydroxide solution is injected into the blank water detection unit by buffer solution injection pump 14 at a flow rate of 1 mL / min, and a nitrobenzene diazonium aminoazobenzene solution is injected into the blank water detection unit at a flow rate of 0.5 mL / min. Sample water analysis injection pump 23 and blank water analysis injection pump 34 use 2 mL / min as a power source to extract the solution to be tested, resulting in a mixed calibration sample. After both the water sample detection unit and the blank water detection unit have been running stably for 10 minutes, the sample water UV-IR variable light source 25 and sample water light intensity detector 27 in sample water detection chamber 24, and the blank water UV-IR variable light source 36 and blank water light intensity detector 38 in blank water detection chamber 35, begin synchronous scanning of the absorption peak wavelength with a scanning accuracy of 1 nm. At this time, the target quaternary ammonium salt standard solution-buffer solution-chromogenic agent in the water sample detection unit and the blank water detection unit containing blank calibration sample-buffer solution-chromogenic agent generate corresponding electrical signals at specific wavelengths. The two electrical signals are transmitted to the concentration calculation module and converted into absorbance values ​​A corresponding to the water sample detection unit and the blank water detection unit. i1 With B i1 Where i is the corresponding wavelength, the data is input into the concentration calculation module, and the absorbance A is calculated. i1 With B i1 The difference is used to obtain the second absorbance difference.

[0050] As an example of an embodiment of the present invention, the acquisition of the pre-calibrated standard curve of absorbance and concentration specifically involves: performing blank detection on the sample light cell and the blank water light cell respectively to obtain a first absorbance difference corresponding to the absorption wavelength of each detection light; and performing maximum absorption peak wavelength detection on the sample light cell and the blank water light cell respectively to obtain a second absorbance difference corresponding to the absorption wavelength of each detection light; determining the maximum absorption peak wavelength based on the maximum difference between each of the first absorbance difference and each of the second absorbance differences; and for each quaternary ammonium salt standard solution, respectively testing the quaternary ammonium salt standard solution in the sample light cell and... The blank sample in the blank photoluminescence cell is detected by attenuation detection light at the wavelength of the maximum absorption peak, and the electrical signals of the maximum absorption peak wavelength at the sample photoluminescence cell and the blank photoluminescence cell are obtained respectively. The electrical signals at the sample photoluminescence cell and the blank photoluminescence cell are converted and calculated to obtain the third absorbance difference between each quaternary ammonium salt standard solution and the wavelength of the maximum absorption peak. Based on the third absorbance difference of each quaternary ammonium salt standard solution, the absorbance difference of each quaternary ammonium salt standard solution is determined. According to the Lambert-Beer law, the absorbance difference and concentration of each quaternary ammonium salt standard solution are linearly regressed to obtain the standard curve.

[0051] In this embodiment, the first absorbance difference and the second absorbance difference obtained according to the foregoing embodiment are used to calculate a series of absorbance differences A of the detection light at the absorption wavelength. i1 -A i0 -(B i1 -B i0 The absorbance difference is the actual absorbance of the quaternary ammonium salt reacting with the chromogenic reagent solution at a specific wavelength after subtracting the instrument blank and the absorption wavelength of the chromogenic reagent itself. Take A i1 -A i0 -(B i1 -B i0 The absorption wavelength corresponding to the maximum value in () is the wavelength i of the maximum absorption peak.

[0052] The calibration procedure based on the maximum absorption peak wavelength i is as follows: Taking nitrobenzene-diazoaminoazobenzene as the colorimetric reagent as an example, the calibration inlet pipe 10 is connected to quaternary ammonium salt standard solutions of 1, 3, 5, 10, 15, and 20 mg / L. The buffer solution storage tank 15 contains a sodium hydroxide solution with a pH of 12, and the colorimetric reagent storage tank 22 contains a 50 mg / L nitrobenzene-diazoaminoazobenzene solution. The sample water injection pump 12 injects the quaternary ammonium salt standard solutions of each concentration into the water sample detection unit at a flow rate of 0.5 mL / min. The buffer solution injection pump 14 injects sodium hydroxide solution into the water sample detection unit at a flow rate of 1 mL / min and nitrobenzene-diazoaminoazobenzene solution into the water sample detection unit at a flow rate of 0.5 mL / min. Simultaneously, the demineralized water injection pipeline is connected to demineralized water as a blank sample. Blank water injection pump 31 injects demineralized water into the blank water detection unit at a flow rate of 0.5 mL / min, buffer solution injection pump 14 injects sodium hydroxide solution into the blank water detection unit at a flow rate of 1 mL / min, and nitrobenzene diazoaminoazobenzene solution into the blank water detection unit at a flow rate of 0.5 mL / min. Sample water analysis injection pump 23 and blank water analysis injection pump 34 use a flow rate of 2 mL / min as the power source to extract the solution to be tested. After both the water sample detection unit and the blank water detection unit have been running stably for 10 minutes, at the maximum absorption peak wavelength i for both the light source and the detection wavelength, the sample water UV-IR variable light source 25 and sample water light intensity detector 27 in sample water detection chamber 24 and blank water UV-IR variable light source 36 and blank water light intensity detector 38 in blank water detection chamber 35 begin synchronous detection. This yields a series of electrical signals generated by 1, 3, 5, 10, 15, and 20 mg / L quaternary ammonium salt standard solutions at this maximum absorption peak wavelength. These electrical signals are then transmitted to the concentration calculation module and converted into absorbance values ​​A. c B c c represents the concentration of the quaternary ammonium salt standard solution. The concentration calculation module records the absorbance value A. i0 B i0 The absorbance values ​​A of a series of 1, 3, 5, 10, 15, and 20 mg / L quaternary ammonium salt standard solutions at the wavelength of maximum absorption peak were calculated. c -A i0 -(B c -B i0 According to the Lambert-Beer theorem, for c and A c -A i0 -(B c -B i0 Linear regression calculations were performed to obtain the linear regression formula y=ax+b for c and absorbance with nitrobenzene diazoaminoazobenzene as the colorimetric reagent, which is the standard curve.

[0053] As an example of an embodiment of the present invention, the step of performing linear regression on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve specifically involves: performing linear regression on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain a linear regression equation; calculating the ratio of the intercept to the slope in the linear regression equation, and the correlation coefficient of the linear regression equation; if the ratio is less than or equal to a first preset threshold and the correlation coefficient is greater than a second preset threshold, then the linear regression equation is determined to be valid, and the standard curve is obtained; if the ratio is greater than the first preset threshold, or the correlation coefficient is less than or equal to the second preset threshold, then the linear regression equation is determined to be invalid, and linear regression is performed again.

[0054] In this embodiment, if the calibrated linear regression equation is y=ax+b, the ratio of the intercept b to the slope a is calculated. The first preset threshold can be set to 5%, and the second preset threshold can be set to 0.99. If the ratio of b to a is less than or equal to 5%, the correlation coefficient R... 2 If the value is greater than 0.99, the above linear regression equation is valid. If the above threshold condition is not met, the linear regression equation is invalid, and the standard curve should be redone, that is, the linear regression should be performed again until the above threshold condition is met. The linear regression equation that meets the threshold condition is then used as the standard curve.

[0055] As an example of an embodiment of the present invention, the online detection system for the concentration of quaternary ammonium salt bactericide based on a circulating water system further includes: determining a control command based on the concentration of the quaternary ammonium salt bactericide; inputting actual operating data into a time prediction model to output the start time and stop time corresponding to the control command; and responding to the control command based on the start time and the stop time to add the quaternary ammonium salt bactericide to the circulating water in the circulating water pipeline.

[0056] In this embodiment, after completing the online detection of quaternary ammonium salt concentration in the circulating water, control commands for guiding the dosing and discharge of circulating water can be determined. The actual operating data is input into the time prediction model to obtain the start and end times corresponding to the control commands. Based on the start and end times, the control responds to the control commands. The process of determining the control commands includes: the data processing and transmission unit is set with an allowable dosing concentration range for circulating water. If the detected quaternary ammonium salt concentration is greater than the set value, the quaternary ammonium salt dosing pump is controlled to reduce or stop dosing, and the circulating water system valve is started or the discharge valve opening is increased. If the detected quaternary ammonium salt concentration is less than the set value, the quaternary ammonium salt dosing pump is controlled to increase or start dosing, and the circulating water system valve is closed or the discharge valve opening is decreased.

[0057] As an example of an embodiment of the present invention, the time prediction model includes a first time prediction model and a second time prediction model. Specifically, a first deep learning model is established based on the decay function of circulating water quaternary ammonium salt concentration within a preset time period, and the first deep learning model is trained based on first historical operating data to obtain the first time prediction model. The first time prediction model is used to predict the start time corresponding to the control command. The first historical operating data includes any multiple of the following within the preset time period: circulating water quaternary ammonium salt concentration, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate. The preset time period refers to the last shutdown... The time interval between stopping the dosing and starting the current dosing, or the time interval between the last decrease in dosing and the current increase in dosing; a second deep learning model is established based on the incremental function of the circulating water quaternary ammonium salt concentration within the preset time interval, and the second deep learning model is trained based on the second historical operating data to obtain the second time prediction model, wherein the second time prediction model is used to predict the stop time corresponding to the control command, wherein the second historical operating data includes any multiple of the following within the preset time interval: circulating water quaternary ammonium salt concentration, dosing pump stroke, dosing pump frequency, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate.

[0058] In this embodiment, the timing of the next dosing cycle can be predicted using a first deep learning model. The specific method is as follows: During the time period between the last time dosing was reduced or stopped and the current time dosing was increased or started, first historical operating data is acquired. This first historical operating data includes any multiple of the following: circulating water quaternary ammonium salt concentration, unit load, circulating water temperature, circulating water conductivity, circulating water pH, circulating water makeup flow rate, or circulating water wastewater discharge flow rate. A deep learning model is established, comparing the decay function of the circulating water quaternary ammonium salt concentration with other parameters during the time period between the last time dosing was reduced or stopped and the current time dosing was increased or started. The model is trained using the first historical operating data to complete the dosing control prediction.

[0059] The end time of the current dosing cycle can be predicted using a second deep learning model. The specific method is as follows: Acquire second historical operating data within the time period between the last time dosing was reduced or stopped and the current time dosing was increased or started. This second historical operating data includes any multiple parameters such as circulating water quaternary ammonium salt concentration, dosing pump stroke, dosing pump frequency, unit load, circulating water temperature, circulating water conductivity, circulating water pH, and circulating water makeup flow or circulating water discharge flow. Establish a deep learning model of the circulating water quaternary ammonium salt concentration increment function and other parameters within the time period between the last time dosing was reduced or stopped and the current time dosing was increased or started. Train the model using the second historical operating data to achieve dosing control prediction.

[0060] As an example of an embodiment of the present invention, the online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system further includes: acquiring the operating status signal of the system to be cooled, and responding to the shutdown status signal in the operating status signal to stop the online concentration detection of quaternary ammonium salt bactericides based on the circulating water system.

[0061] It should be noted that when the colorimetric reagent is aluminum-mordant blue 29, the buffer solution can be an acetate-sodium acetate buffer solution with a pH of 5.5, and the other detection steps are the same.

[0062] It should be noted that circulating water with high calcium and magnesium hardness may interfere with the color development of the chromogenic agent (or staining agent). A color-changing hydrogen ion exchanger can be installed between the buffer filter and the sample water inlet electric valve to remove calcium and magnesium ions from the water. After the exchange, the pH of the circulating water will be slightly lower. The buffer solution in the system then maintains pH stability, ensuring the reliability of the detection. Using a color-changing hydrogen ion exchanger indicates resin failure when the resin changes color, allowing for timely replacement with new resin. Alternatively, complexing agents such as EDTA and DTPA can be added to the buffer solution storage tank as masking agents to eliminate the influence of calcium and magnesium.

[0063] like Figure 4 As shown, based on the above system item embodiments, corresponding method item embodiments are provided; the online detection method 400 for the concentration of quaternary ammonium salt bactericides based on circulating water systems includes steps 401-403; Step 401: Obtain the sample to be tested through the sampling pipe connected to the circulating water pipe, and obtain the blank sample through the blank water inlet pipe. The sample to be tested and the blank sample are solutions obtained by mixing with the buffer solution and the target solution in sequence. The target solution includes any one of the following: a colorimetric agent for colorimetric reaction with quaternary ammonium salt, or a staining agent for decolorization reaction with quaternary ammonium salt. Step 402: Calculate the electrical signal of the sample to be tested in the sample photocell at the wavelength of the maximum absorption peak to obtain the first absorbance, and calculate the electrical signal of the blank sample in the blank photocell at the wavelength of the maximum absorption peak to obtain the second absorbance. Step 403: Obtain a pre-calibrated standard curve of absorbance and concentration. Determine the concentration of quaternary ammonium salt bactericide in the sample to be tested based on the first absorbance, the second absorbance, and the standard curve. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

[0064] As an example of an embodiment of the method of the present invention, obtaining the pre-calibrated standard curve of absorbance and concentration specifically involves: By performing blank detection on the sample light pool and the blank water light pool respectively, the first absorbance difference corresponding to the absorption wavelength of each detection light is obtained; and by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, the second absorbance difference corresponding to the absorption wavelength of each detection light is obtained. The wavelength of the maximum absorption peak is determined based on the maximum difference between each of the first absorbance differences and each of the second absorbance differences; For each quaternary ammonium salt standard solution, the attenuation detection light at the maximum absorption peak wavelength is detected for the quaternary ammonium salt standard solution in the sample optical cell and the blank sample in the blank water optical cell, respectively. The electrical signals at the maximum absorption peak wavelength in the sample optical cell and the blank water optical cell are obtained respectively. The electrical signals in the sample optical cell and the blank water optical cell are converted and calculated to obtain the third absorbance difference value between each quaternary ammonium salt standard solution and the maximum absorption peak wavelength. The absorbance difference of each quaternary ammonium salt standard solution is determined based on the third absorbance difference of each quaternary ammonium salt standard solution. According to the Lambert-Beer law, a linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve.

[0065] It is understood that the above method embodiments correspond to the system embodiments of the present invention. The method embodiments of this application should include the online detection step of the concentration of quaternary ammonium salt bactericide based on the circulating water system provided by any of the above system embodiments of the present invention, which will not be repeated here.

[0066] It should be noted that in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any inventive effort.

[0067] Based on the above embodiments of the online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the online concentration detection method for quaternary ammonium salt bactericides based on a circulating water system according to any embodiment of the present invention.

[0068] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0069] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0070] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0071] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium, including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the online detection method for the concentration of quaternary ammonium salt bactericides based on a circulating water system as described in any of the above-described method embodiments of the present invention.

[0072] The modules / units integrated into the system / terminal device, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or system capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0073] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system, characterized in that, include: Sample acquisition module, absorbance detection module, and concentration calculation module; The sample acquisition module is used to acquire the sample to be tested through a sampling pipe connected to the circulating water pipe, and to acquire a blank sample through a blank water inlet pipe. The sample to be tested and the blank sample are solutions obtained by mixing with a buffer solution and a target solution in sequence. The target solution includes any one of a colorimetric agent for colorimetric reaction with quaternary ammonium salt or a staining agent for decolorization reaction with quaternary ammonium salt. The light absorption detection module is used to calculate the electrical signal of the sample to be detected in the sample light cell at the wavelength of the maximum absorption peak to obtain the first absorbance, and to calculate the electrical signal of the blank sample in the blank water light cell at the wavelength of the maximum absorption peak to obtain the second absorbance. The concentration calculation module is used to obtain a pre-calibrated standard curve of absorbance and concentration, and to determine the concentration of quaternary ammonium salt bactericide in the sample to be tested based on the first absorbance, the second absorbance and the standard curve, so as to realize the online detection of the concentration of quaternary ammonium salt bactericide. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

2. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The sample acquisition module includes a sampling unit and a reagent unit, and the absorbance detection module includes a water sample detection unit and a blank water detection unit. The sampling unit is connected to the water sample detection unit, the reagent unit is connected to both the water sample detection unit and the blank water detection unit, and the water sample detection unit and the blank water detection unit are connected to the concentration calculation module. The sampling unit includes a sample water inlet pipe, a sample water sampling pump, a sampling electric valve, a buffer filter, a sample water discharge electric valve, and a sample water discharge pipe connected in sequence, and the buffer filter is connected in sequence to a backwash wastewater discharge pipe and a backwash wastewater discharge electric valve. The reagent unit includes a sample water buffer solution electric valve, a buffer solution injection pump, and a blank water buffer solution electric valve connected in sequence. The buffer solution injection pump is connected to a buffer solution storage tank. The reagent unit also includes a sample water colorimetric reagent electric valve, a colorimetric reagent injection pump, and a blank water colorimetric reagent injection electric valve connected in sequence. The colorimetric reagent injection pump is connected to a colorimetric reagent storage tank. The water sample detection unit includes a water sample inlet electric valve, a water sample inlet pump, a water sample-buffer solution mixer, a water sample-color reagent mixer, a water sample analysis inlet pump, and a water sample detection chamber connected in sequence. The water sample detection chamber includes a water sample ultraviolet-infrared variable light source, a water sample light cell, and a water sample light intensity detector. The water sample light cell is connected to the water sample analysis solution outlet pipe. The blank water detection unit includes a blank water injection tube, a blank water injection electric valve, a blank water injection pump, a blank water-buffer solution mixer, a blank water-color reagent mixer, a blank water analysis injection pump, and a blank water detection chamber connected in sequence. The blank water detection chamber includes a blank water ultraviolet-infrared variable light source, a blank water light cell, and a blank water light intensity detector, and the blank water light cell is connected to the blank water analysis solution outlet tube. The concentration calculation module includes a data processing and transmission unit, a quaternary ammonium salt dosing pump, and a quaternary ammonium salt dosing pipeline connected in sequence, and the quaternary ammonium salt dosing pump is connected to the quaternary ammonium salt storage tank.

3. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The process of obtaining the pre-calibrated standard curve of absorbance and concentration is as follows: By performing blank detection on the sample light pool and the blank water light pool respectively, the first absorbance difference corresponding to the absorption wavelength of each detection light is obtained; and by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, the second absorbance difference corresponding to the absorption wavelength of each detection light is obtained. The wavelength of the maximum absorption peak is determined based on the maximum difference between each of the first absorbance differences and each of the second absorbance differences; For each quaternary ammonium salt standard solution, the attenuation detection light at the maximum absorption peak wavelength is detected for the quaternary ammonium salt standard solution in the sample optical cell and the blank sample in the blank water optical cell, respectively. The electrical signals at the maximum absorption peak wavelength in the sample optical cell and the blank water optical cell are obtained respectively. The electrical signals in the sample optical cell and the blank water optical cell are converted and calculated to obtain the third absorbance difference value between each quaternary ammonium salt standard solution and the maximum absorption peak wavelength. The absorbance difference of each quaternary ammonium salt standard solution is determined based on the third absorbance difference of each quaternary ammonium salt standard solution. According to the Lambert-Beer law, a linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve.

4. The online detection method for the concentration of quaternary ammonium salt bactericides based on a circulating water system as described in claim 3, characterized in that, The process involves performing blank detection on both the sample optical cell and the blank water optical cell to obtain a first absorbance difference corresponding to the absorption wavelength of each detection light, and then performing maximum absorption peak wavelength detection on both the sample optical cell and the blank water optical cell to obtain a second absorbance difference corresponding to the absorption wavelength of each detection light. Specifically: The attenuation detection light under each detection light is detected for the blank calibration sample in the sample light pool and the blank water light pool respectively, and the electrical signal of each detection light under the sample light pool and the blank water light pool is obtained respectively. For each detection light, the electrical signals under the sample light cell and the blank water light cell are converted and calculated to obtain the first absorbance difference value corresponding to the absorption wavelength under each detection light. The buffer solution, target solution, and target quaternary ammonium salt standard solution are mixed in a preset ratio to obtain a mixed quaternary ammonium salt solution. The buffer solution, target solution, and blank calibration sample are then mixed in a preset ratio to obtain a mixed calibration sample. The mixed quaternary ammonium salt solution in the sample photocell and the mixed calibration sample in the blank photocell are respectively tested under the attenuation detection light of each detection light to obtain the second absorbance difference corresponding to the absorption wavelength under each detection light.

5. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The standard curve is obtained by performing a linear regression on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions, specifically as follows: Linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the linear regression equation; Calculate the ratio of the intercept to the slope in the linear regression equation, and the correlation coefficient of the linear regression equation; If the ratio is less than or equal to a first preset threshold and the correlation coefficient is greater than a second preset threshold, then the linear regression equation is determined to be valid, and the standard curve is obtained. If the ratio is greater than the first preset threshold, or the correlation coefficient is less than or equal to the second preset threshold, the linear regression equation is determined to be invalid, and the linear regression is performed again.

6. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system further includes: The control command is determined based on the concentration of the quaternary ammonium salt bactericide. Input the actual operating data into the time prediction model to output the start and stop times corresponding to the control command; The control command is responded to based on the start time and the stop time to add a quaternary ammonium salt bactericide to the circulating water in the circulating water pipeline.

7. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 6, characterized in that, The time prediction model includes a first time prediction model and a second time prediction model, specifically: A first deep learning model is established based on the decay function of circulating water quaternary ammonium salt concentration within a preset time period, and the first deep learning model is trained based on the first historical operating data to obtain the first time prediction model. The first time prediction model is used to predict the start time corresponding to the control command. The first historical operating data includes any multiple of the following within the preset time period: circulating water quaternary ammonium salt concentration, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate. The preset time period refers to the time period between the last time the dosing was stopped and the current time the dosing was started, or the time period between the last time the dosing was reduced and the current time the dosing was increased. A second deep learning model is established based on the incremental function of the quaternary ammonium salt concentration in the circulating water within a preset time period, and the second deep learning model is trained based on the second historical operating data to obtain the second time prediction model. The second time prediction model is used to predict the stop time corresponding to the control command. The second historical operating data includes any multiple of the following within the preset time period: quaternary ammonium salt concentration in the circulating water, dosing pump stroke, dosing pump frequency, unit load, circulating water temperature, circulating water conductivity, circulating water pH value, circulating water makeup flow rate, or circulating water sewage discharge flow rate.

8. The online concentration detection system for quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The process of obtaining the sample to be tested through a sampling pipe connected to the circulating water pipe is as follows: Initial samples were obtained through sampling pipes connected to the circulating water pipeline; The initial sample is filtered using a buffer filter to obtain the sample to be tested.

9. A method for online detection of the concentration of quaternary ammonium salt bactericides based on a circulating water system, characterized in that, include: The sample to be tested is obtained through a sampling pipe connected to the circulating water pipe, and a blank sample is obtained through a blank water injection pipe. The sample to be tested and the blank sample are solutions obtained by mixing with a buffer solution and a target solution in sequence. The target solution includes any one of a colorimetric agent for colorimetric reaction with quaternary ammonium salt or a staining agent for decolorization reaction with quaternary ammonium salt. The electrical signal of the sample to be tested in the sample photocell at the wavelength of the maximum absorption peak is calculated to obtain the first absorbance, and the electrical signal of the blank sample in the blank photocell at the wavelength of the maximum absorption peak is calculated to obtain the second absorbance. A pre-calibrated standard curve of absorbance and concentration is obtained. Based on the first absorbance, the second absorbance, and the standard curve, the concentration of quaternary ammonium salt bactericide in the sample to be tested is determined. This is an online detection system for the concentration of quaternary ammonium salt bactericide in a circulating water system. The standard curve is determined by calibrating multiple quaternary ammonium salt standard solutions based on the wavelength of the maximum absorption peak.

10. The online detection method for the concentration of quaternary ammonium salt bactericides based on a circulating water system as described in claim 1, characterized in that, The process of obtaining the pre-calibrated standard curve of absorbance and concentration is as follows: By performing blank detection on the sample light pool and the blank water light pool respectively, the first absorbance difference corresponding to the absorption wavelength of each detection light is obtained; and by performing maximum absorption peak wavelength detection on the sample light pool and the blank water light pool respectively, the second absorbance difference corresponding to the absorption wavelength of each detection light is obtained. The wavelength of the maximum absorption peak is determined based on the maximum difference between each of the first absorbance differences and each of the second absorbance differences; For each quaternary ammonium salt standard solution, the attenuation detection light at the maximum absorption peak wavelength is detected for the quaternary ammonium salt standard solution in the sample optical cell and the blank sample in the blank water optical cell, respectively. The electrical signals at the maximum absorption peak wavelength in the sample optical cell and the blank water optical cell are obtained respectively. The electrical signals in the sample optical cell and the blank water optical cell are converted and calculated to obtain the third absorbance difference value between each quaternary ammonium salt standard solution and the maximum absorption peak wavelength. The absorbance difference of each quaternary ammonium salt standard solution is determined based on the third absorbance difference of each quaternary ammonium salt standard solution. According to the Lambert-Beer law, a linear regression was performed on the absorbance difference and concentration of each of the quaternary ammonium salt standard solutions to obtain the standard curve.

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