In-situ water quality analyzer and water quality analysis method

Abstract

This invention discloses an in-situ water quality analyzer and water quality analysis method, including a flow path switching control component, a feedback component, a media transport power component, an outflow component, a detection component, a return component, a waste discharge component, and a controller. The waste discharge component is used to connect to the return component to discharge or collect the media. The controller is electrically connected to the flow path switching control component, the feedback component, the media transport power component, the outflow component, the detection component, the return component, and the waste discharge component, and is used to control the flow path switching control component, the media transport power component, the outflow component, the detection component, and the return component to connect end to end to form a closed loop flow path. Compared with the prior art, it improves sampling accuracy, can offset the influence of interference factors such as tilting and shaking, eliminates signal errors during detection, has a simple internal flow path, can meet the requirements of detection, cleaning, and maintenance, has high reliability of detection results, is suitable for marine environments, has strong practicality, and is suitable for widespread promotion and application.

Description

Technical Field

[0001] This invention relates to the field of water quality testing technology, and in particular, to an in-situ water quality analyzer. Furthermore, this invention also relates to a water quality analysis method using the aforementioned in-situ water quality analyzer. Background Technology

[0002] Human activities and climate change have altered the concentration of nutrients in seawater, profoundly impacting marine biodiversity. Monitoring seawater nutrients is crucial for understanding marine ecosystem health, predicting red tides, and maintaining fishery resources. Monitoring typically involves the regular measurement of parameters such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and phosphate to ensure the sustainable development of the marine environment.

[0003] The in-situ seawater nutrient analyzer is a key device for monitoring seawater nutrients. It uses wet chemical reaction and spectrophotometric detection as its detection principle and is mainly composed of a metrology unit, a reaction unit, and a detection unit. The metrology unit is responsible for accurately delivering and quantitatively quantifying the water sample and reagents required for the chemical reaction. The reaction unit is the site where the water sample and reagents undergo the chemical reaction. The detection unit mainly consists of a light source detection device, which is used to detect the colorimetric signal value of the sample, thereby calculating the nutrient content in the water sample.

[0004] However, existing in-situ seawater nutrient analyzers have the following shortcomings:

[0005] 1. Due to interference factors such as tilting and shaking in marine application environments, existing in-situ seawater nutrient analyzers cannot use infrared sensing technology on both sides of the liquid level tube to determine the accuracy of the sampling volume. They can only rely solely on the number of motor rotation steps or time of a high-precision peristaltic pump or syringe pump to measure the extraction volume of water samples and reagents. This results in a lack of accurate and reliable sampling volume measurement and judgment measures when extracting water samples and reagents, making it impossible to ensure the accurate extraction and measurement of water samples and reagents, which significantly affects data repeatability and stability. When air bubbles or the corresponding liquid is missing in the water sample or reagent pipeline, relying solely on the pump motor step count cannot guarantee the actual sampling accuracy of water samples or reagents in the pipeline, leading to poor data repeatability and stability, and making the test results unreliable.

[0006] 2. During operation at sea, when the absorbance signal of the liquid inside the detection unit is collected and detected, the liquid inside the detection unit is easily affected by interference factors such as shaking and tilting. This causes some liquid inside the detection unit to be below the light path emitted by the light source, thereby interfering with the signal detection of Lambert's law, resulting in a very large signal error and making the detection results unreliable.

[0007] 3. When the in-situ seawater nutrient analyzer uses a plunger pump combined with a multi-channel switching valve for analysis and detection flow path, there are problems such as incomplete wet chemical reaction and time-consuming and water-intensive detection and cleaning processes. When the in-situ seawater nutrient analyzer uses a microflow path component or a three-way valve group combined with a power pump for analysis and detection flow path, the flow path structure is very complex. If any valve group fails, the entire flow path system will be paralyzed, and the equipment has high maintenance requirements. In summary, the internal flow path cannot meet the requirements for detection, cleaning and maintenance. Summary of the Invention

[0008] This invention provides an in-situ water quality analyzer and a water quality analysis method to solve the technical problems of existing in-situ seawater nutrient analyzers, such as inaccurate sampling, large signal errors, and internal flow paths that cannot meet the requirements for detection, cleaning, and maintenance.

[0009] According to one aspect of the present invention, an in-situ water quality analyzer is provided, comprising a flow path switching control component, a feedback component, a media transport power component, an effluent component, a detection component, a reflux component, a wastewater discharge component, and a controller. The flow path switching control component is connected to containers storing various detection media to control the sequential delivery of the media required during the detection process to the effluent component 400. The media transport power component provides transport power for the detection media. The wastewater discharge component is connected to the reflux component to discharge or collect the media. The controller is electrically connected to the flow path switching control component, the feedback component, the media transport power component, the effluent component, the detection component, the reflux component, and the wastewater discharge component, and is used to control the flow path switching control component, the media transport power component, the effluent component, the detection component, and the reflux component. The two ends are connected to form a closed loop flow path; the feedback component is used to collect the corresponding electrical signal according to the liquid state at the output end of the flow path switching control component when the medium conveying power component starts to work, and record the electrical signal collection time and the working time of the medium conveying power component, so as to feed the electrical signal, collection time and working time back to the controller. The controller is used to determine whether to issue a warning signal and / or control the medium conveying power component to stop working based on the electrical signal, collection time and working time; the detection component includes a reaction tank with the bottom surface tilted at a preset angle, an optical detection module arranged on the bottom side of the reaction tank to form a light detection channel at the bottom of the reaction tank, an input port that is opened at a preset height on the reaction tank and connected to the outflow component, and an air-sensing component connected to the reaction tank to connect to the outside.

[0010] As a further improvement to the above technical solution:

[0011] Furthermore, the feedback component includes a liquid sensor and a time recording unit. The liquid sensor is used to collect an electrical signal one when there is no liquid at the output of the flow path switching control component, or to collect an electrical signal two when there is liquid at the output of the flow path switching control component. The time recording unit is used to record the time when the liquid sensor collects the electrical signal two, the time when the medium conveying power component starts working, and the time when the medium conveying power component extracts a preset volume of liquid.

[0012] Furthermore, the optical detection module includes a mounting base disposed outside the reaction tank, a composite light source disposed outside the first bottom side of the reaction tank for independently emitting multi-band light sources, and a light signal detector disposed outside the second bottom side of the reaction tank and disposed opposite to the composite light source for detecting the light signals emitted by the light source.

[0013] Furthermore, the flow path switching control component is a multi-unit valve assembly, which includes a straight-through pipeline connected to the return component and the detection component respectively, and multiple valve ports arranged on the straight-through pipeline for controlling whether various detection media and air can flow into the straight-through pipeline respectively.

[0014] Furthermore, the in-situ water quality analyzer also includes a control valve five installed on the effluent assembly, a cadmium column connected to the control valve five, a return pipe connected to the output end of the cadmium column and the input end of the reaction tank respectively, a control valve six installed on the return pipe, and a waste liquid collection pipe one connected to the control valve six. The control valve five is used to connect the effluent assembly to the flow path switching control assembly and the reaction tank, or to connect the effluent assembly to the flow path switching control assembly and the cadmium column. The control valve six is ​​used to connect the cadmium column and the reaction tank, or to connect the cadmium column and the waste liquid collection pipe one.

[0015] Furthermore, the air supply component includes an air supply pipe connected to the reaction tank and a control valve installed on the air supply pipe.

[0016] Furthermore, the sewage discharge assembly also includes a control valve three installed on the return assembly, a main sewage discharge pipe connected to the control valve three, a control valve four installed on the main sewage discharge pipe, a waste liquid collection pipe two connected to the control valve four, and a waste liquid direct discharge pipe connected to the control valve four.

[0017] According to another aspect of the present invention, a water quality analysis method is also provided, which employs the above-mentioned in-situ water quality analyzer, comprising the following steps: S1, the controller controls the operation of the media delivery power component, controls the water sample to be drawn into the reaction tank through the flow path switching control component, and then controls the reagent required for detection to be drawn into the closed loop through the flow path switching control component, and then pushes the reagent in the closed loop into the reaction tank by evacuating air; S2, the controller controls the operation of the media delivery power component to ensure that the unmixed water sample and reagent in the reaction tank are fully circulated, mixed and reacted in the closed loop; S3, the controller controls the operation of the media delivery power component to push the mixture in the closed loop into the reaction tank by evacuating air, and then the optical detection module turns on the corresponding monochromatic light source according to the parameters to be detected to form a light detection channel in the reaction tank to detect the mixture in the reaction tank; S4, the controller controls the operation of the media delivery power component to discharge the waste liquid in the reaction tank to the sewage discharge component.

[0018] As a further improvement to the above technical solution:

[0019] Furthermore, after step S4, the following steps are also included: S5, the controller controls the operation of the medium delivery power component, controls the cleaning fluid to be drawn into the closed loop for circulation through the flow path switching control component, and then controls the air to be drawn into the closed loop through the flow path switching control component so as to discharge the cleaning fluid into the drain component through the air; S6, repeat steps S1-S5 until the detection of multiple parameters is completed.

[0020] Furthermore, sodium molybdate reagent is used to detect phosphate, and vanadium chloride reagent is used to detect nitrate nitrogen.

[0021] The present invention has the following beneficial effects:

[0022] The in-situ water quality analyzer of this invention connects to containers storing various detection media via a flow path switching control component. This controls the sequential delivery of the required media to the effluent component during the detection process. A media delivery power component provides the power for delivering the detection media. A controller connects the flow path switching control component, media delivery power component, effluent component, detection component, and return component end-to-end to form a closed-loop flow path. During water quality analysis, the media delivery power component draws various detection media into the closed-loop flow path for thorough mixing, thereby improving the repeatability and stability of the wet chemical reaction and the subsequent detection results. For reliability, the media delivery power assembly draws air to push the mixture into the reaction tank, and then vents the air to the outside through the air outlet. The optical detection module forms a light detection channel at the bottom of the reaction tank for detection. After detection, the media delivery power assembly draws cleaning fluid and circulates it in a closed loop for thorough cleaning, and then discharges it through the drain assembly. This achieves zero reagent residue and cleaning dead zones, eliminating reagent residue in the reaction system pipeline and interference from sample memory effects, thereby improving the stability of the reaction system and the accuracy and reliability of the analytical results. In marine environments, when disturbed by factors such as shaking and tilting, the feedback component... When the media transport power assembly starts working, it acquires corresponding electrical signals based on the liquid state at the output of the flow path switching control assembly, and records the electrical signal acquisition time and the working time of the liquid media transport power assembly. The electrical signals, acquisition time, and working time are then fed back to the controller. The controller determines whether to issue a warning signal and / or control the media transport power assembly to stop working based on the electrical signals, acquisition time, and working time, thereby improving the accuracy of actual sampling and ensuring the repeatability and stability of the detection data. Furthermore, the optical detection module, located at the bottom side of the reaction tank and positioned at a preset height within the reaction tank, further enhances the accuracy of the sampling. The inlet on the tank allows all the mixed liquid in the closed-loop flow path to be pushed into the reaction tank for photometric detection, ensuring that the liquid surface of the mixed liquid covers the light detection channel. The detection signal is not affected by liquid surface agitation within the reaction tank. Simultaneously, the reaction tank, tilted at a preset angle, ensures the normal operation of detection and cleaning. Compared to existing technologies, this solution improves sampling accuracy, counteracts the effects of tilting and shaking, eliminates signal errors during detection, has a simple and clear internal flow path, meets the requirements for detection, cleaning, and maintenance, provides highly reliable detection results, is suitable for marine environments, is highly practical, and is suitable for widespread promotion and application.

[0023] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of the in-situ water quality analyzer according to a preferred embodiment of the present invention;

[0026] Figure 2 This is a partial structural schematic diagram of the detection component in the in-situ water quality analyzer of a preferred embodiment of the present invention.

[0027] Legend:

[0028] 100. Flow path switching control component; 200. Feedback component; 300. Media conveying power component; 400. Outflow component; 500. Detection component; 510. Reaction tank; 520. Optical detection module; 521. Mounting base; 522. Composite light source; 523. Optical signal detector; 530. Input port; 540. Control valve one; 600. Return component; 610. Control valve two; 700. Sewage discharge component; 710. Control valve three; 720. Control valve four; 730. Waste liquid collection pipe two; 740. Waste liquid direct discharge pipe; 810. Control valve five; 820. Cadmium column; 830. Control valve six; 840. Waste liquid collection pipe one. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0030] like Figure 1 and Figure 2As shown, the in-situ water quality analyzer of this embodiment includes a flow path switching control component 100, a feedback component 200, a media transport power component 300, an outflow component 400, a detection component 500, a return component 600, a wastewater discharge component 700, and a controller. The flow path switching control component 100 is connected to containers storing various detection media to control the sequential delivery of the media required during the detection process to the outflow component 400. The media transport power component 300 provides transport power for the detection media. The wastewater discharge component 700 connects to the return component 600 to discharge or collect the media. The controller is electrically connected to the flow path switching control component 100, the feedback component 200, the media transport power component 300, the outflow component 400, the detection component 500, the return component 600, and the wastewater discharge component 700, and is used to control the flow path switching control component 100, the media transport power component 300, the outflow component 400, the detection component 500, the return component 600, and the wastewater discharge component 700. The 00 and the return component 600 are connected end to end to form a closed loop flow path; the feedback component 200 is used to collect the corresponding electrical signal according to the liquid presence state at the output end of the flow path switching control component 100 when the medium conveying power component 300 starts working, and record the electrical signal acquisition time and the working time of the medium conveying power component 300, so as to feed the electrical signal, acquisition time and working time back to the controller. The controller is used to determine whether to issue a warning signal and / or control the medium conveying power component 300 to stop working based on the electrical signal, acquisition time and working time; the detection component 500 includes a reaction pool 510 with the bottom surface tilted at a preset angle, an optical detection module 520 arranged on the bottom side of the reaction pool 510 to form a light detection channel at the bottom of the reaction pool 510, an input port 530 that is opened on the reaction pool 510 at a preset height and connected to the outflow component 400, and an air-sensing component connected to the reaction pool 510 for connecting to the outside.

[0031] like Figure 1 and Figure 2As shown, specifically, the in-situ water quality analyzer of the present invention is connected to containers storing various detection media via a flow path switching control component 100 to control the sequential delivery of the media required during the detection process to the outflow component 400. A media delivery power component 300 provides delivery power for the detection media. A controller connects the flow path switching control component 100, the media delivery power component 300, the outflow component 400, the detection component 500, and the return component 600 end-to-end to form a closed-loop flow path. During water quality detection and analysis, the media delivery power component 300 draws various detection media into the closed-loop flow path for thorough mixing, thereby improving the wet chemical reaction efficiency. To ensure the stability and reliability of subsequent test results, the media delivery power assembly 300 extracts air to push the mixture into the reaction tank 510, and then exhausts the air to the outside through the air outlet. The optical detection module 520 forms a light detection channel at the bottom of the reaction tank 510 for detection. After detection, the media delivery power assembly 300 extracts cleaning fluid and circulates it in a closed loop for thorough cleaning, and then discharges it through the drain assembly 700. This achieves zero reagent residue and cleaning dead zones, eliminating reagent residue in the reaction system pipeline and interference from sample memory effects, thereby improving the stability of the reaction system and the accuracy and reliability of the analytical results. In marine environments, it is susceptible to shaking and tilting. In the event of interference, when the media transport power assembly 300 starts working, the feedback component 200 collects the corresponding electrical signal based on the liquid state at the output of the flow path switching control component 100, and records the electrical signal acquisition time and the working time of the liquid media transport power assembly 300. This electrical signal, acquisition time, and working time are then fed back to the controller. The controller determines whether to issue a warning signal and / or control the media transport power assembly 300 to stop working based on the electrical signal, acquisition time, and working time, thereby improving the accuracy of actual sampling, ensuring the repeatability and stability of the detection data, and maintaining the preset... The inlet 530, located at a height on the reaction tank 510, allows all the mixed liquid in the closed-loop flow path to be pushed into the reaction tank 510 for photometric detection, ensuring that the liquid surface of the mixed liquid covers the photometric detection channel. The detection of the light source signal is not affected by the sloshing of the liquid surface within the reaction tank 510. Simultaneously, the reaction tank 510, tilted at a preset angle, ensures the normal operation of detection and cleaning. Compared to existing technologies, this solution improves sampling accuracy, counteracts the effects of tilting and sloshing, eliminates signal errors during detection, has a simple and clear internal flow path, meets the requirements of detection, cleaning, and maintenance, provides highly reliable detection results, is suitable for marine environments, is highly practical, and is suitable for widespread promotion and application.

[0032] It should be understood that the in-situ water quality analyzer of this embodiment can be used not only for monitoring seawater nutrients, but also for in-situ monitoring of ions such as silicates, hexavalent chromium, manganese, iron, and copper.

[0033] It should be understood that when the detection medium is a reagent, its quantity is relatively small, and in order to ensure detection efficiency, the cross-sectional area of ​​the closed-loop pipeline is relatively large. Therefore, the reagent needs to be pushed into the detection cell with the assistance of air to ensure flow efficiency.

[0034] Optionally, the controller is a PLC controller.

[0035] It should be understood that various testing media include cleaning solutions, water samples, reagents, standard solutions, and air.

[0036] Optionally, 20° ≤ preset angle ≤ 45°. Optionally, the preset angle is 30°, which can meet the normal detection and cleaning work of the in-situ water quality analyzer under the condition that the reaction tank 510 is shaken and tilted at an angle not exceeding 45°.

[0037] It should be understood that when the liquid in the reaction tank 510 is tilted at least 45°, the height at which the liquid is submerged in the reaction tank 510 is still less than or equal to the preset height, so as to ensure that the liquid in the reaction tank completely covers the optical detection channel.

[0038] Optionally, the media conveying power component 300 is a peristaltic pump, and is connected to the flow path switching control component 100 and the outflow component 400 respectively.

[0039] like Figure 1 As shown, optionally, the reflux assembly 600 includes a reflux pipeline and a control valve 610 disposed on the reflux pipeline for controlling the opening and closing of the reflux pipeline.

[0040] In this embodiment, the feedback component 200 includes a liquid sensor and a time recording unit. The liquid sensor is used to collect an electrical signal one when there is no liquid at the output of the flow path switching control component 100, or to collect an electrical signal two when there is liquid at the output of the flow path switching control component 100. The time recording unit is used to record the time when the liquid sensor collects the electrical signal two, the time when the medium conveying power component 300 starts working, and the time when the medium conveying power component 300 extracts a preset volume of liquid.

[0041] Specifically, the liquid sensor and time recording unit work together to determine the liquid extraction status: Electrical signal one is set as V0, and electrical signal two as V1. When there is no liquid at the output of the flow path switching control component 100, the liquid sensor collects V0; when liquid fills the output of the flow path switching control component 100, the liquid sensor collects V1. In the initial state, the time recording unit records the start time of the medium conveying power component 300 as T0, and the liquid sensor collects V0. When liquid is pumped to the liquid sensor position, the liquid sensor collects V1 and records the collection time as T1. Based on the liquid flow rate and pipe length in the closed-loop flow path, the controller presets a time threshold ΔT1 = T1 - T0. If the operating time of the medium conveying power component 300 exceeds this threshold ΔT1, and the liquid sensor still has not collected V1, then... If liquid extraction fails, the controller issues a fault alarm. The liquid sensor and time recording unit work together to determine the consistency of liquid extraction volume: Under the condition that other conditions are consistent, the working time of the medium conveying power component 300 is fixed each time it extracts a preset number of volumes of liquid. When the liquid is pumped to the position of the liquid sensor, the liquid sensor collects V1 and records the collection time as T1. The medium conveying power component 300 continues to work, and the electrical signal used by the liquid sensor remains V1 until the medium conveying power component 300 stops working after the preset number of extraction steps. At this time, the time is recorded as T2, and ΔT2 = T2 - T1 is calculated and the value of ΔT2 is recorded. If the value of ΔT2 is basically consistent with the controller's preset ΔT2, it indicates that the consistency of liquid extraction volume is good, and the controller does not alarm; otherwise, an alarm is triggered. Furthermore, if, during the continued operation of the media conveying power assembly 300, the electrical signal collected by the liquid sensor is not a continuous V1 signal but instead interspersed with V0 signals, the controller will also issue an alarm. If the total duration of the interspersed V0 signals exceeds a preset time threshold, the controller will control the media conveying power assembly 300 to stop operating and terminate the test.

[0042] It should be understood that when the media conveying power component 300 is a peristaltic pump, the peristaltic pump motor rotates a fixed number of steps each time it extracts a preset number of volumes of liquid. When the liquid is pumped to the position of the liquid sensor, the liquid sensor collects V1 and records the collection time as T1. The peristaltic pump continues to work, and the electrical signal used by the liquid sensor remains V1 until the peristaltic pump motor rotates a fixed number of steps. At this time, the time is recorded as T2, and ΔT2 = T2 - T1 is calculated and the value of ΔT2 is recorded. If the value of ΔT2 is basically consistent with the controller's preset ΔT2, it indicates that the consistency of the liquid extraction volume is good, and the controller will not alarm; otherwise, an alarm will be triggered.

[0043] like Figure 2As shown, in this embodiment, the optical detection module 520 includes a mounting base 521 disposed outside the reaction pool 510, a composite light source 522 disposed outside the first bottom side of the reaction pool 510 for independently emitting multi-band light sources, and a light signal detector 523 disposed outside the second bottom side of the reaction pool 510 and disposed opposite to the composite light source 522 for detecting the light signals emitted by the light source.

[0044] like Figure 2 As shown, specifically, a composite light source 522 and a light signal detector 523 can be installed via a mounting base 521 located outside the reaction tank 510. The composite light source 522 and the light signal detector 523 are respectively positioned opposite each other outside the first bottom side and the second bottom side of the reaction tank 510, thereby forming a light detection channel at the bottom of the reaction tank 510, ensuring that the liquid to be tested completely covers the light detection channel. Optionally, the composite light source 522 can be individually activated with single-band light sources at 700nm, 880nm, and 540nm. For example, 700nm can be used to detect ammonia nitrogen, 880nm to detect phosphate, and 540nm to detect nitrite nitrogen and nitrate nitrogen, allowing for the sequential detection of the four seawater nutrient parameters.

[0045] Optionally, the bottom surface of the reaction tank 510 is arranged in a conical shape and is provided with a bottom support port that is located at the bottom end when tilted or shaken and communicates with the reflux assembly 600, so as to ensure that the liquid in the reaction tank 510 can flow out smoothly from the bottom support port, thereby ensuring that closed-loop mixing and closed-loop cleaning can be carried out normally.

[0046] It should be understood that, in one embodiment, the reaction tank 510 has multiple bottom surfaces, which are arranged in a conical shape. One surface may be a conical surface, two surfaces may be conical surfaces, or multiple surfaces may be conical surfaces.

[0047] Optionally, the bottom support is centrally located on the bottom surface of the reaction tank 510 to ensure that the bottom support is at the lowest point of the bottom surface when tilted or shaken.

[0048] In this embodiment, the reaction tank 510 is arranged in a rectangular shape, and the bottom surface of the reaction tank 510 is arranged in a conical shape, with the bottom support opening in the center, so that the bottom surface is set at a preset inclined angle to ensure that the liquid in the reaction tank 510 can flow out smoothly from the bottom support opening, and is suitable for small volume detection.

[0049] In this embodiment, the reaction tank 510 has two bottom surfaces, both of which are conical, and the bottom support is located between the two bottom surfaces.

[0050] Alternatively, in another embodiment, the reaction tank 510 is arranged in a cylindrical shape, the bottom surface of the reaction tank 510 is arranged in a conical shape, and the bottom support is opened in the center so that the bottom surface is set at a preset inclined angle to ensure that the liquid in the reaction tank 510 can flow out smoothly from the bottom support.

[0051] Alternatively, in another embodiment, the reaction tank 510 is arranged in a cylindrical shape, the bottom surface of the reaction tank 510 is flat, and the reaction tank 510 is inclined so that the bottom surface of the reaction tank is inclined at a preset angle, and the bottom support is located at the lowest end of the bottom surface, so as to ensure that the liquid in the reaction tank 510 can flow out smoothly from the bottom support.

[0052] It should be understood that by tilting the reaction tank 510 at a preset angle, the medium in the reaction tank 510 can still flow out from the bottom support port under the interference of factors such as shaking and tilting, thereby ensuring that closed-loop mixing and closed-loop cleaning can be carried out normally.

[0053] like Figure 1 As shown, in this embodiment, the flow path switching control component 100 is a multi-valve assembly. The multi-valve assembly includes a straight-through pipe connected to the return component 600 and the detection component 500, respectively, and multiple valve ports arranged on the straight-through pipe for controlling whether various detection media and air can flow into the straight-through pipe. Specifically, during the detection process, according to the detection requirements, the valve port corresponding to the required detection medium is opened, so that the detection medium is pumped into the straight-through pipe under the action of the medium conveying power component 300, so that it flows in a closed loop flow path. Under the action of the multiple valve ports and the straight-through pipe, the detection media do not interfere with each other and can be shared.

[0054] like Figure 1 As shown, optionally, in this embodiment, the multi-port valve includes 7 reagent ports, 4 standard solution ports, 1 water sample port, 1 cleaning solution port, and 1 air port to meet the detection requirements of four seawater nutrient parameters.

[0055] like Figure 1As shown, in this embodiment, the in-situ water quality analyzer also includes a control valve 810 arranged on the outflow assembly 400, a cadmium column 820 connected to the control valve 810, a return pipe connected to the output end of the cadmium column 820 and the input end of the reaction tank 510 respectively, a control valve 830 arranged on the return pipe, and a waste liquid collection pipe 840 connected to the control valve 830. The control valve 810 is used to connect the outflow assembly 400 to the flow path switching control assembly 100 and the reaction tank 510, or to connect the outflow assembly 400 to the flow path switching control assembly 100 and the cadmium column 820. The control valve 830 is used to connect the cadmium column 820 and the reaction tank 510, or to connect the cadmium column 820 and the waste liquid collection pipe 840. Specifically, control valve 810 connects the outflow assembly 400 to the flow path switching control assembly 100 and the cadmium column 820, and control valve 830 connects the cadmium column 820 and the reaction tank 510, forming a closed-loop flow path consisting of the flow path switching control assembly 100, the media transport power assembly 300, the outflow assembly 400, the cadmium column 820, the reaction tank 510, and the return assembly 600. This flow path is used for seawater nitrate cadmium column reduction analysis. Compared to vanadium chloride reagent reduction analysis, this method has advantages such as high reduction efficiency, no interference from seawater substrate differences, and compatibility with standard marine testing methods. After the test is completed, control valve 830 connects the cadmium column 820 and the waste liquid collection pipe 840 to discharge and collect the waste liquid for unified treatment. Optionally, control valve 810 and / or control valve 830 are three-way solenoid valves.

[0056] like Figure 1 As shown, optionally, in this embodiment, when the control valve 810 is de-energized, the outflow component 400 is connected to the flow path switching control component 100 and the reaction tank 510; when the control valve 810 is energized, the outflow component 400 is connected to the flow path switching control component 100 and the cadmium column 820. In another embodiment, when the control valve 810 is de-energized, the outflow component 400 is connected to the flow path switching control component 100 and the cadmium column 820; when the control valve 810 is energized, the outflow component 400 is connected to the flow path switching control component 100 and the reaction tank 510.

[0057] like Figure 1 As shown, optionally, in this embodiment, when the control valve 830 is de-energized, the cadmium column 820 and the reaction tank 510 are connected; when the control valve 830 is energized, the cadmium column 820 and the waste liquid collection pipe 840 are connected. In another embodiment, when the control valve 830 is de-energized, the cadmium column 820 and the waste liquid collection pipe 840 are connected; when the control valve 830 is energized, the cadmium column 820 and the reaction tank 510 are connected.

[0058] like Figure 1As shown, in this embodiment, the air supply component includes an air supply pipe connected to the reaction tank 510 and a control valve 540 installed on the air supply pipe. Specifically, the air supply pipe connects to the outside world, and the control valve 540 controls the opening and closing of the air supply pipe. When reagents are being transported by air, the control valve 540 opens the air supply pipe to quickly discharge air after it enters the reaction tank 510. Under other circumstances, the control valve 540 closes the air supply pipe. Optionally, the control valve 540 is a solenoid valve.

[0059] like Figure 1 As shown, in this embodiment, the sewage discharge assembly 700 also includes a control valve 3 710 disposed on the return assembly 600, a sewage main pipe connected to the control valve 3 710, a control valve 4 720 disposed on the sewage main pipe, a waste liquid collection pipe 2 730 connected to the control valve 4 720, and a waste liquid direct discharge pipe 740 connected to the control valve 4 720. Specifically, after the test is completed, control valve three 710 connects the reflux assembly 600 to the reaction tank 510 and the main drain pipe, and control valve four 720 connects the main drain pipe and the waste liquid collection pipe two 730, so that the collected waste liquid can be centrally processed. Then, control valve three 710 causes the reflux assembly 600 to flow through the reaction tank 510 and the flow path switching control assembly 100, and the media conveying power assembly 300 pumps the cleaning fluid into the closed loop for circulation, so that the cleaning fluid is pushed into the reaction tank 510 after cleaning. Then, control valve three 710 connects the reflux assembly 600 and the main drain pipe, and control valve four 720 connects the main drain pipe and the waste liquid direct discharge pipe 740, so as to discharge the cleaning fluid. Optionally, control valve three 710 and / or control valve four 720 are three-way solenoid valves.

[0060] like Figure 1 As shown, optionally, in this embodiment, when the control valve 710 is de-energized, the reflux assembly 600 connects the reaction tank 510 and the flow path switching control assembly 100; when the control valve 710 is energized, the reflux assembly 600 connects the reaction tank 510 and the main drain pipe. In another embodiment, when the control valve 710 is de-energized, the reflux assembly 600 connects the reaction tank 510 and the main drain pipe; when the control valve 710 is energized, the reflux assembly 600 connects the reaction tank 510 and the flow path switching control assembly 100.

[0061] like Figure 1 As shown, optionally, in this embodiment, when the control valve 4 720 is de-energized, it connects the main sewage pipe and the waste liquid direct discharge pipe 740; when the control valve 4 720 is energized, it connects the main sewage pipe and the waste liquid collection pipe 2 730. In another embodiment, when the control valve 4 720 is de-energized, it connects the main sewage pipe and the waste liquid collection pipe 2 730; when the control valve 4 720 is energized, it connects the main sewage pipe and the waste liquid direct discharge pipe 740.

[0062] The water quality analysis method of this embodiment uses the above-mentioned in-situ water quality analyzer and includes the following steps: S1, the controller controls the operation of the media delivery power assembly 300, controls the water sample to be drawn into the reaction tank 510 through the flow path switching control assembly 100, and then controls the reagent required for detection to be drawn into the closed loop through the flow path switching control assembly 100, and then pushes the reagent in the closed loop into the reaction tank 510 by evacuating air; S2, the controller controls the operation of the media delivery power assembly 300 to ensure that the water in the reaction tank 510 is not mixed with water. The homogeneous water sample and reagents are fully circulated, mixed, and reacted in a closed-loop flow path; S3, the controller controls the media conveying power component 300 to operate, and pushes the mixture in the closed-loop flow path into the reaction tank 510 by extracting air. Then, the optical detection module 520 turns on the corresponding monochromatic light source according to the parameters to be detected, so as to form a light detection channel in the reaction tank 510 to detect the mixture in the reaction tank 510; S4, the controller controls the media conveying power component 300 to operate, so that the waste liquid in the reaction tank 510 is discharged to the sewage discharge component 700.

[0063] Specifically, by adopting the above steps in conjunction with an in-situ water quality analyzer, interference factors such as shaking and tilting during operation in a marine environment can be overcome, enabling the analysis and detection of seawater nutrients. This improves the reliability of the test results, making it highly practical and suitable for widespread promotion and application.

[0064] It should be understood that the water quality analysis method of this embodiment can be used not only for monitoring seawater nutrients, but also for in-situ monitoring of ions such as silicates, hexavalent chromium, manganese, iron, and copper.

[0065] In this embodiment, after step S4, the following steps are also included: S5, the controller controls the operation of the medium delivery power assembly 300, controls the cleaning fluid to be drawn into a closed loop for circulation through the flow path switching control assembly (100), and then controls the air to be drawn into the closed loop through the flow path switching control assembly 100, so that the cleaning fluid is discharged into the sewage discharge assembly 700 by the air; S6, repeat steps S1-S5 until the detection of multiple parameters is completed. Specifically, by cleaning after parameter detection, the residue of detection reagents is avoided during subsequent parameter detection, eliminating the interference of reagent residues in the reaction system pipeline and the memory effect between samples, improving the accuracy of the detection results, and completing the detection of multiple parameters with one in-situ water quality analyzer, which greatly reduces the detection cost and operation and maintenance cost.

[0066] Optionally, in one embodiment, an in-situ water quality analyzer is used to detect four seawater nutrient parameters to greatly reduce the monitoring cost of marine water nutrients. The four seawater nutrients include ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and phosphate.

[0067] In this embodiment, sodium molybdate reagent is used for phosphate detection, and vanadium chloride reagent is used for nitrate nitrogen detection. Specifically, using sodium molybdate reagent for phosphate detection avoids introducing the ammonia nitrogen to be tested into the reagent, thus preventing interference with the accuracy of the ammonia nitrogen parameter data; using vanadium chloride reagent for nitrate nitrogen detection avoids introducing the ammonia nitrogen to be tested into the cadmium column 820 ammonium chloride buffer solution, thus preventing interference with the accuracy of the ammonia nitrogen parameter data. This avoids mutual interference between reagents during the detection process, thereby enabling the sequential detection of the four seawater nutrient parameters.

[0068] In this embodiment, through the combined effect of the multi-valve assembly, the composite light source 522, and the optimized adjustment of the reagent formula, four seawater nutrient parameters were detected sequentially in one in-situ water quality analyzer without mutual interference, ensuring the reliability of the detection results.

[0069] like Figure 1 As shown, in one embodiment, the specific steps of the water quality analysis method are as follows:

[0070] Sampling process:

[0071] The controller controls the peristaltic pump to rotate forward and simultaneously opens the water sample valve and control valve 540 (the valve closes when the pump stops, as will not be described later) to draw a quantitative water sample into the reaction tank 510, and then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the reagent valve and control valve 540 to draw a quantitative reagent into the closed loop, and then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540, using the air drawn into the closed loop to push the reagent in the original closed loop into the reaction tank 510.

[0072] Mixing process:

[0073] The controller controls the peristaltic pump to rotate forward and simultaneously opens control valve 610. The water sample and reagents in reaction tank 510 are fully circulated, mixed and reacted in the closed loop. Then the peristaltic pump is turned off.

[0074] Optical inspection process:

[0075] The controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540. Air drawn into the closed loop pushes the mixed liquid from half of the closed loop into the reaction tank 510, and then the peristaltic pump is shut off. The controller then controls the peristaltic pump to rotate in reverse and simultaneously opens the air valve and control valve 540. Air drawn into the closed loop pushes the mixed water sample from the other half of the closed loop into the reaction tank 510, and then the peristaltic pump is shut off. The optical detection module 520 activates the corresponding monochromatic light source according to the nutrient parameters to be detected, forming a light detection channel within the reaction tank 510 to detect the mixed liquid. The absorbance of the liquid in the reaction tank 510 is detected according to Lambert's law, and the nutrient parameters are detected using a standard curve calibration method.

[0076] Waste liquid discharge process:

[0077] Before opening control valve 4 720, the controller controls the peristaltic pump to rotate forward, and at the same time opens the air valve port and control valve 3 710 to use air to discharge the waste liquid in the reaction tank 510. The waste liquid is then collected and treated uniformly through waste liquid collection pipe 2 730. After discharge, the peristaltic pump and control valve 4 720 are closed.

[0078] Cleaning process:

[0079] The controller controls the peristaltic pump to rotate forward and simultaneously opens the cleaning fluid valve and control valve 1 540 to draw the cleaning fluid into the reaction tank 510, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens control valve 2 610, allowing the water in the reaction tank 510 to circulate and clean fully in the closed loop, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 1 540 to push half of the cleaning fluid in the closed loop into the reaction tank 510, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate in reverse and simultaneously opens control valve 1 540 and control valve 2 610 to push the other half of the cleaning fluid in the closed loop into the reaction tank 510, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 3 710 to discharge the cleaning fluid in the reaction tank 510 through the waste liquid direct discharge pipe 740.

[0080] like Figure 1 As shown, in one embodiment, the specific steps for analyzing and detecting nitrates in seawater using the cadmium column 820 cyclic reduction method are as follows:

[0081] Sampling process:

[0082] The controller controls the peristaltic pump to rotate forward and simultaneously opens the water sample valve and control valve 540 (the valve closes when the pump stops, as will not be described later) to draw a quantitative water sample into the reaction tank 510, and then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the ammonium chloride buffer reagent valve and control valve 540 to draw a quantitative ammonium chloride buffer reagent into the closed loop, and then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540, using the air drawn into the closed loop to push the reagent in the original closed loop into the reaction tank 510.

[0083] Mixing process:

[0084] The controller controls the peristaltic pump to rotate forward and simultaneously opens control valve 610. The water sample and ammonium chloride buffer in reaction tank 510 are fully circulated, mixed, and reacted in the closed loop. Then the peristaltic pump is turned off. The controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540. The air drawn into the closed loop is used to push half of the mixed solution in the closed loop into reaction tank 510. Then the peristaltic pump is turned off. The controller controls the peristaltic pump to rotate in reverse and simultaneously opens the air valve and control valve 540. The air drawn into the closed loop is used to push the other half of the mixed solution in the closed loop into reaction tank 510. Then the peristaltic pump is turned off.

[0085] Cadmium column 820 reduction process:

[0086] Open control valve 5 810, the controller controls the peristaltic pump to rotate forward, and at the same time open control valve 2 610, so that the mixture in reaction tank 510 repeatedly circulates and reduces in a closed loop flow path of detection tank → control valve 3 710 → control valve 2 610 → multi-unit valve group → peristaltic pump → control valve 5 810 → cadmium column 820 → control valve 6 830 → detection tank.

[0087] Colorimetric reaction process:

[0088] When control valve 510 is closed, the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540. Air drawn into the closed loop is used to push the water sample reduced by cadmium column 820 in half of the closed loop into the reaction tank 510, and then the peristaltic pump is closed. The controller then controls the peristaltic pump to rotate in reverse and simultaneously opens the air valve and control valve 540. Air is used to push the water sample reduced by cadmium column 820 in the other half of the closed loop into the reaction tank 510, and then the peristaltic pump is closed. The controller then controls the peristaltic pump to rotate forward and simultaneously opens the nitrate colorimetric reagent valve and control valve 540 to draw the nitrate colorimetric reagent into the closed loop, and then the peristaltic pump is closed. Finally, the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540. Air drawn into the closed loop is used to push the reagent in the original closed loop into the reaction tank 510.

[0089] Optical inspection process:

[0090] The optical detection module 520 turns on the corresponding monochromatic light source according to the nutrient parameters to be detected, so as to form a light detection channel in the reaction tank 510 to detect the mixed liquid in the reaction tank 510. The absorbance value of the liquid in the reaction tank 510 is detected according to Lambert's law. The purpose of detecting nutrient parameters is achieved by using the standard curve calibration method.

[0091] Waste liquid discharge process:

[0092] Before opening control valve 4 720, the controller controls the peristaltic pump to rotate forward, and at the same time opens the air valve port and control valve 3 710 to use air to discharge the waste liquid in the reaction tank 510. The waste liquid is then collected and treated uniformly through waste liquid collection pipe 2 730. After discharge, the peristaltic pump and control valve 4 720 are closed.

[0093] Cleaning process:

[0094] The controller controls the peristaltic pump to rotate forward and simultaneously opens the cleaning fluid valve and control valve 540 to draw the cleaning fluid into the reaction tank 510, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the ammonium chloride buffer reagent valve and control valve 610 to draw the ammonium chloride buffer reagent into the closed loop, then shuts off the peristaltic pump; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540, using the air drawn into the closed loop to push the reagent in the original closed loop into the reaction tank 510; the controller controls the peristaltic pump to rotate forward and simultaneously opens the air valve and control valve 540. Open control valve 2 610, and the unmixed cleaning solution and ammonium chloride buffer in reaction tank 510 will fully circulate, mix and react in the closed loop; pre-open control valve 5 810 and control valve 6 830, the controller controls the peristaltic pump to rotate forward, and simultaneously open control valve 1 540 and control valve 2 610, the mixed cleaning solution and ammonium chloride buffer in reaction tank 510 will be flushed with cadmium column 820 in the line of detection tank → control valve 5 810 → control valve 2 610 → multi-unit valve group → peristaltic pump → control valve 5 810 → cadmium column 820 → control valve 6 830 → waste liquid collection pipe 1 840.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An in-situ water quality analyzer, characterized in that, The system includes a flow path switching control component (100), a feedback component (200), a media conveying power component (300), an outflow component (400), a detection component (500), a return component (600), a drain component (700), and a controller. The flow path switching control component (100) is connected to containers storing various detection media to control the sequential delivery of the media required during the detection process to the outflow component (400). The media conveying power component (300) provides conveying power for the detection media. The drain component (700) is used for... The recirculation assembly (600) is connected to discharge or collect the medium. The controller is electrically connected to the flow path switching control assembly (100), the feedback assembly (200), the medium conveying power assembly (300), the outflow assembly (400), the detection assembly (500), the recirculation assembly (600), and the sewage discharge assembly (700), and is used to control the flow path switching control assembly (100), the medium conveying power assembly (300), the outflow assembly (400), the detection assembly (500), and the recirculation assembly (600) to connect end to end to form a closed loop flow path. The feedback component (200) is used to collect the corresponding electrical signal according to the liquid presence state at the output end of the flow path switching control component (100) when the medium conveying power component (300) starts working, and record the electrical signal acquisition time and the working time of the medium conveying power component (300) so as to feed the electrical signal, acquisition time and working time back to the controller. The controller is used to determine whether to issue a warning signal and control the medium conveying power component (300) to stop working based on the electrical signal, acquisition time and working time. The detection assembly (500) includes a reaction cell (510) with its bottom surface tilted at a preset angle, an optical detection module (520) arranged on the bottom side of the reaction cell (510) for forming a light detection channel at the bottom of the reaction cell (510), an input port (530) that is opened on the reaction cell (510) at a preset height and communicates with the outflow assembly (400), and an air-access component that is connected to the reaction cell (510) for communicating with the outside world. The feedback component (200) includes a liquid sensor and a time recording unit. In the initial state, the time recording unit records the start time of the medium conveying power component (300) as T0, and the liquid sensor acquires an electrical signal V0. When the liquid is pumped to the position of the liquid sensor, the liquid sensor acquires an electrical signal V1 and records the acquisition time as T1. Based on the liquid flow rate and pipeline length in the closed loop, the controller presets a time threshold ΔT1 = T1 - T0. When the start time of the medium conveying power component (300) exceeds this threshold ΔT1, and the liquid sensor still has not acquired V1... If the liquid extraction fails, it is determined to be a liquid extraction failure, and the controller will issue a fault alarm. The liquid sensor and the time recording unit work together to determine the consistency of the liquid extraction volume: Under the condition that other conditions are consistent, the working time of the media conveying power component (300) is fixed each time it extracts a preset number of steps of liquid volume; when the liquid is pumped to the position of the liquid sensor, the liquid sensor collects V1 and records the collection time as T1, the media conveying power component (300) continues to work, and the electrical signal collected by the liquid sensor remains V1 until the media conveying power component (300) works to the preset time. Stop after the number of extraction steps. Record the time as T2 and calculate ΔT2 = T2 - T1. Record the value of ΔT2. If the value of ΔT2 is basically consistent with the controller's preset ΔT2, it indicates that the consistency of liquid extraction is good and the controller will not alarm. Otherwise, an alarm will be triggered. If, during the continued operation of the media conveying power component (300), the electrical signal collected by the liquid sensor is not a continuous V1 signal but an interspersed V0 signal, the controller will also trigger an alarm. When the total time of the interspersed V0 signal is greater than the preset time threshold, the controller will control the media conveying power component (300) to stop working and terminate the test.

2. The in-situ water quality analyzer according to claim 1, characterized in that, The optical detection module (520) includes a mounting base (521) disposed outside the reaction cell (510), a composite light source (522) disposed outside the first bottom side of the reaction cell (510) for independently emitting multi-band light sources, and a light signal detector (523) disposed outside the second bottom side of the reaction cell (510) and disposed opposite to the composite light source (522) for detecting the light signals emitted by the light source.

3. The in-situ water quality analyzer according to claim 1, characterized in that, The flow path switching control component (100) is a multi-unit valve assembly, which includes a straight-through pipeline connected to the return assembly (600) and the detection assembly (500) respectively, and a multi-port valve installed on the straight-through pipeline for controlling whether various detection media and air can flow into the straight-through pipeline respectively.

4. The in-situ water quality analyzer according to claim 1, characterized in that, The in-situ water quality analyzer also includes a control valve five (810) installed on the outflow assembly (400), a cadmium column (820) connected to the control valve five (810), a return pipe connected to the output end of the cadmium column (820) and the input end of the reaction tank (510) respectively, a control valve six (830) installed on the return pipe, and a waste liquid collection pipe one (840) connected to the control valve six (830). The control valve five (810) is used to connect the outflow assembly (400) to the flow path switching control assembly (100) and the reaction tank (510), or to connect the outflow assembly (400) to the flow path switching control assembly (100) and the cadmium column (820). The control valve six (830) is used to connect the cadmium column (820) and the reaction tank (510), or to connect the cadmium column (820) and the waste liquid collection pipe one (840).

5. The in-situ water quality analyzer according to any one of claims 1-4, characterized in that, The air supply unit includes an air supply pipe connected to the reaction tank (510) and a control valve (540) installed on the air supply pipe.

6. The in-situ water quality analyzer according to any one of claims 1-4, characterized in that, The sewage discharge assembly (700) also includes a control valve three (710) installed on the return assembly (600), a sewage main pipe connected to the control valve three (710), a control valve four (720) installed on the sewage main pipe, a waste liquid collection pipe two (730) connected to the control valve four (720), and a waste liquid direct discharge pipe (740) connected to the control valve four (720).

7. A water quality analysis method, characterized in that, The in-situ water quality analyzer according to claim 3 includes the following steps: S1, the controller controls the operation of the medium delivery power assembly (300), controls the water sample to be drawn into the reaction tank (510) through the flow path switching control assembly (100), and then controls the reagent required for detection to be drawn into the closed loop flow path through the flow path switching control assembly (100), and then pushes the reagent in the closed loop flow path into the reaction tank (510) by evacuating air; S2, the controller controls the operation of the medium delivery power assembly (300) to ensure that the unmixed water sample and reagent in the reaction tank (510) are fully circulated, mixed and reacted in the closed loop; S3, the controller controls the operation of the medium conveying power assembly (300), and pushes the mixed liquid in the closed circulation path into the reaction tank (510) by drawing air. Then, the optical detection module (520) turns on the corresponding monochromatic light source according to the parameters to be detected, so as to form a light detection channel in the reaction tank (510) to detect the mixed liquid in the reaction tank (510). S4, the controller controls the operation of the medium conveying power assembly (300) to discharge the waste liquid in the reaction tank (510) to the sewage discharge assembly (700).

8. The water quality analysis method according to claim 7, characterized in that, Step S4 is followed by the following steps: S5, the controller controls the operation of the medium conveying power assembly (300), controls the cleaning fluid to be drawn into the closed circulation flow path through the flow path switching control assembly (100), and then controls the air to be drawn into the closed circulation flow path through the flow path switching control assembly (100) so that the cleaning fluid can be discharged into the sewage discharge assembly (700) through the air. S6. Repeat steps S1-S5 until all parameters have been detected.

9. The water quality analysis method according to claim 8, characterized in that, Sodium molybdate reagent is used to detect phosphate, and vanadium chloride reagent is used to detect nitrate nitrogen.

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