Data correction method and monitoring instrument for automatic online monitoring of water quality by ultraviolet absorption

Abstract

The invention relates to the field of water environment monitoring. In order to improve the accuracy of an automatic online ultraviolet absorption water quality monitor, a data correction method for automatic online ultraviolet absorption water quality monitoring and a monitor are provided. A test value is obtained by manually measuring a sample water sample, and the test value of the sample water sample at the same position and time is obtained by the monitor. A relationship model of and is constructed based on multiple measurement results. In the process of obtaining, a relationship model of turbidity and test value is established based on the turbidity collected during the static process and the corresponding test value. If the turbidity of the water sample does not drop to a turbidity correction threshold value within a preset time, the relationship model of turbidity and test value is used to obtain the test value corresponding to the turbidity correction threshold value. The above method improves the accuracy of the automatic online ultraviolet absorption water quality monitor.

Description

Technical Field

[0001] The invention relates to the field of water environment monitoring, in particular to an ultraviolet absorption water quality automatic online monitoring data correction method and a monitoring instrument. Background Art

[0002] The UV absorption water quality automatic online monitor monitors the COD (chemical oxygen demand) or permanganate index of water quality online based on the absorption spectrum characteristics of unsaturated organic molecules in water in the UV band (generally 254nm) and the principle of Lambert-Beer's law. Compared with chemical monitoring instruments, the UV absorption water quality automatic online monitor has the advantages of simple structure, low cost, no need for chemical reagents, no secondary pollution, and rapid response (the measurement time is generally within 1min). It is widely used in various small and simple water quality online monitoring stations.

[0003] Since the UV absorption water quality automatic online monitor uses the optical monitoring principle, the monitoring data is greatly affected by the turbidity of the water body. In order to mitigate and eliminate the impact of turbidity, the existing technical means generally adopt compensation and calibration of the monitoring equipment, mainly including: (1) using the UV-visible dual-wavelength measurement principle, using the characteristic absorbance of organic matter in the UV spectrum to detect the COD concentration in the water body, and using visible light as a reference beam to eliminate the impact of water sample turbidity. (2) using standard solutions of different turbidity to calibrate the equipment and compensate the monitoring data according to the calibration results. (3) regularly conducting laboratory manual comparison tests on water quality and calibrating the online monitor on-site according to the comparison test results. In general water bodies, the above measures can mitigate the impact of turbidity to a certain extent, but in high turbidity water bodies (turbidity above 100NTU), especially water bodies containing a large amount of sediment, the above compensation measures are not effective. The measured COD or permanganate index is often several times the laboratory manual comparison results, resulting in serious distortion of the monitoring data and unusable.

[0004] The reasons why the existing compensation and calibration technologies are ineffective are as follows: (1) The effect of water turbidity on UV absorbance is complex and nonlinear. Even if visible light is used as compensation, the compensation range and effect are limited. (2) To compensate for turbidity, standard solutions of different turbidities are often used to calibrate the equipment, and the monitoring data is compensated based on the calibration results. However, the substances that produce turbidity in actual monitoring and the substances that produce turbidity in standard solutions have different effects on UV absorbance, resulting in large errors in actual monitoring of UV absorption automatic online water quality monitors calibrated in the laboratory. (3) When the turbidity is high, the online monitoring data is very different from the manual comparison data, making it impossible to perform on-site calibration.

[0005] In addition to the compensation and calibration measures for the monitoring equipment itself, existing technical means also include: (1) measuring the water sample after it has settled for a period of time. (2) adding a high-efficiency filtration device to the sample inlet pipeline to filter the high-turbidity water sample before measuring. However, if the turbidity of the original water sample is high, even if it settles for a long time (such as 1 hour), its turbidity still cannot meet the measurement requirements. If the sedimentation time is too long, it will not only affect the monitoring efficiency, but also long-term static may cause changes in the COD or permanganate index detection value, resulting in reduced detection accuracy. If a filtration device is added, it is necessary to add filtration and backwashing equipment and pipelines, which not only increases the complexity and failure rate of the system, but also brings measurement errors. The filtration and backwashing devices are large in size, the pipelines are complex, and they are easy to clog, which is inconsistent with the design principle of small and simple online water quality monitoring stations. Summary of the invention

[0006] In order to improve the accuracy of an automatic online ultraviolet absorption water quality monitor, the present application provides an automatic online ultraviolet absorption water quality monitoring data correction method and a monitor.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] The method for correcting data of automatic online monitoring of water quality by ultraviolet absorption includes:

[0009] Step 1: Collect water samples near the water inlet of the UV absorption water quality automatic online monitoring instrument, and measure the test value manually. The measured value is ;

[0010] Step 2: Use the UV absorption water quality automatic online monitor to test the sample water at the same time:

[0011] Step 21: Determine the turbidity correction threshold of the UV absorption water quality automatic online monitoring instrument ;

[0012] Step 22: If the sample water turbidity T ≤ turbidity correction threshold , then directly obtain the measurement result of the test value ;

[0013] If the sample water turbidity T> turbidity correction threshold , the sample water sample is left to stand, and the turbidity of the water sample and the corresponding test value are continuously collected during the standing process. Within the preset time,

[0014] If the turbidity T of the sample water drops to the turbidity correction threshold , then stop the water sample standing process and record the turbidity equal to The results of the test value at ;

[0015] If the turbidity T of the sample water does not drop to the turbidity correction threshold , then a relationship model between turbidity and test value is established based on the turbidity of the water sample collected during the static process and the corresponding test value measurement results; the turbidity of the sample water sample is calculated according to the relationship model between turbidity and test value: The results of the test value at ;

[0016] Step 3: Build based on multiple measurement results and Relationship model;

[0017] Step 4: Use the UV absorption water quality automatic online monitoring instrument to detect the water sample to obtain ,Will Substitution and The relationship model to obtain , This is the corrected detection value.

[0018] Furthermore, the preset time is 1 hour.

[0019] Furthermore, the relationship model between turbidity and detection value is a nonlinear regression model.

[0020] Further, and The relationship model between turbidity and detection value and the relationship model between turbidity and detection value are both established based on machine learning algorithms.

[0021] Furthermore, the turbidity correction threshold It is determined comprehensively based on the anti-turbidity interference ability of the ultraviolet absorption water quality automatic online monitoring instrument and the relationship between the detection value monitoring data and turbidity.

[0022] Further, the detection value is COD or permanganate index.

[0023] The ultraviolet absorption water quality automatic online monitoring instrument comprises: a control unit, an inlet pipe, an inlet valve, a sample circulation pool, a drainage pipe and a drainage valve connected in sequence, a detection value sensor and a turbidity sensor are arranged in the sample circulation pool, the detection value sensor and the turbidity sensor are connected to the control unit, the sample circulation pool has a sedimentation function, and the control unit is at least provided with and The control unit obtains the test value of the water sample to be tested according to the test results of the detection value sensor and the turbidity sensor. :

[0024] If the turbidity of the water sample to be tested is T≤ the turbidity correction threshold , then directly obtain the measurement result of the test value ; If the turbidity of the water sample to be tested T> turbidity correction threshold , then let the sample water sample stand for a preset time.

[0025] If the turbidity T of the water sample to be tested drops to the turbidity correction threshold , then stop the water sample standing process and record the turbidity equal to The results of the test value at ;

[0026] If the turbidity T of the water sample to be tested does not drop to the turbidity correction threshold , then according to the relationship model between turbidity and detection value, the turbidity of the water sample to be tested is calculated as The results of the test value at ;

[0027] Will Substitution and The relationship model to obtain , This is the corrected detection value.

[0028] Furthermore, the relationship model between turbidity and detection value is directly set in the control unit, or

[0029] During the static state of the water sample, the measurement results of the turbidity of the water sample and the corresponding detection value are continuously collected, and a relationship model between the turbidity and the detection value is established based on the collected measurement results of the turbidity of the water sample and the corresponding detection value.

[0030] Furthermore, the detection value sensor is a COD sensor or a permanganate index sensor.

[0031] Furthermore, a temperature sensor and / or a pH sensor is also provided in the sample circulation pool.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] Obtain test values ​​by manually measuring sample water samples , the detection value of the sample water sample at the same position and time is obtained through the monitoring instrument ; Based on multiple measurement results and The relationship model, in In the process of obtaining the turbidity, a relationship model between turbidity and detection value was established based on the turbidity collected during the static process and the corresponding detection value. If the turbidity of the water sample does not drop to the turbidity correction threshold within the preset time, , then the relationship model between turbidity and detection value is used to obtain the turbidity correction threshold The corresponding detection value In the process of monitoring data correction, this application also established the relationship model between turbidity and detection value and and The relationship model based on turbidity and test value not only improves the treatment efficiency, but also avoids the change of COD or permanganate index test value caused by long-term static, which further affects the test accuracy; and The monitoring results of the monitor are corrected based on the relationship model, which improves the accuracy of high turbidity water sample detection.

[0034] The monitoring equipment hardware used in this application is basically the same as the existing small and micro water quality online monitoring stations. It only adds a sedimentation function on the basis of the sample circulation pool of the existing technology. It can be applied after a simple modification of the existing equipment. The implementation method is simple and there is no need to increase the hardware cost of the monitor. In addition, the correction method proposed in this application can realize the automation of the entire process after obtaining the manual comparison data, reduce manual intervention, and improve the level of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the method for correcting data of automatic online monitoring of water quality by ultraviolet absorption;

[0036] Figure 2 It is a schematic diagram of the partial structure of the ultraviolet absorption water quality automatic online monitoring instrument;

[0037] Figure 3 This is a schematic diagram of the relationship between manual comparative COD and online monitoring COD;

[0038] Figure 4 This is a schematic diagram of the relationship between turbidity and online monitoring COD;

[0039] Figure numerals: 1 is a water inlet pipeline, 2 is a water inlet valve, 3 is a detection value sensor, 4 is a turbidity sensor, 5 is other sensors, 6 is a sample circulation pool, 7 is a drainage pipeline, and 8 is a drainage valve. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] like Figure 1 As shown, the method for correcting data of automatic online monitoring of water quality by ultraviolet absorption includes:

[0042] Step 1: Collect water samples near the water inlet of the UV absorption water quality automatic online monitor, fix and store the water samples and send them to the laboratory for COD or permanganate index determination. The measured value is ;

[0043] Step 2: While collecting water samples manually, use the UV absorption water quality automatic online monitoring instrument to simultaneously carry out the detection of the same indicators, including:

[0044] Step 21: Determine the turbidity correction threshold of the UV absorption water quality automatic online monitoring instrument ; Turbidity correction threshold It represents the highest turbidity that the instrument is not affected by turbidity or is less affected and can correct itself. It should be determined comprehensively based on the anti-turbidity interference ability of the ultraviolet absorption water quality automatic online monitoring instrument and the relationship between the detection value (COD or permanganate index) monitoring data and turbidity.

[0045] Step 22: Use an ultraviolet absorption water quality automatic online monitoring instrument to test the sample water sample to obtain the test value measurement result :

[0046] If the sample water turbidity T≤ turbidity correction threshold , then directly obtain the measurement result of the test value ;

[0047] If the sample water turbidity T> turbidity correction threshold , the sample water sample is left to stand, and the turbidity of the water sample and the corresponding test value are continuously collected during the standing process. Within the preset time,

[0048] If the turbidity T of the sample water drops to the turbidity correction threshold , then stop the water sample standing process and record the turbidity equal to The results of the test value at ;

[0049] If the turbidity T of the sample water does not drop to the turbidity correction threshold , then a relationship model between turbidity and test value is established based on the turbidity of the water sample collected during the static process and the corresponding test value measurement results; the turbidity of the sample water sample is calculated according to the relationship model between turbidity and test value: The detection value at ; The relationship model between turbidity and detection value should adopt a nonlinear regression model.

[0050] The specific detection process is similar to step 1 to step 3.1 in the online monitoring process, except that the water samples used are different, and the water samples used for detection are water samples collected at the same time as the manually collected water samples. The specific steps are not described in detail here.

[0051] Step 3: Use the COD (or permanganate index) value measured by recent manual comparison is the dependent variable (y), and the online monitoring COD (or permanganate index) value at the same time as the manual measurement For the independent variable (x), establish and In order to ensure the accuracy of the relationship model, the number of manual comparison data used should be more than 6; manual comparison measurement should be carried out regularly, and the frequency of manual comparison measurement should be increased when the turbidity is high.

[0052] In order to achieve full process automated monitoring and avoid or reduce manual operation, the relationship model between turbidity and detection value and and The relationship models can be automatically established based on machine learning algorithms.

[0053] Step 4: Use the UV absorption water quality automatic online monitoring instrument to detect the water sample to obtain ,Will Substitution and The relationship model to obtain , This is the corrected detection value.

[0054] It should be noted that the sample water sample in the present invention refers to the water sample used to establish and The water sample of the relationship model, that is, the water samples used in step 1 to step 3 are all sample water samples. The water sample to be tested refers to the water sample to be tested by using and The relationship model is used to test water samples.

[0055] The present invention also provides an automatic online ultraviolet absorption water quality monitoring instrument, such as Figure 2 As shown, it includes: a control unit (not shown in the figure), an inlet pipe 1, an inlet valve 2, a sample circulation pool 6, a drainage pipe 7 and a drainage valve 8 connected in sequence, a detection value sensor 3 (COD sensor or permanganate index sensor), a turbidity sensor 4 and other sensors 5 (such as temperature, pH sensor, etc.) are arranged in the sample circulation pool 6, and the detection value sensor 3 and the turbidity sensor 4 are connected to the control unit. The above structure is basically the same as the existing small and micro water quality online monitoring station, the difference is that the sample circulation pool 6 of the present application has a sedimentation function, and the control unit is at least provided with and The control unit obtains the test value of the water sample to be tested according to the test results of the detection value sensor and the turbidity sensor. :If the turbidity of the water sample to be tested T≤ turbidity correction threshold , then directly obtain the measurement result of the test value ; If the turbidity of the water sample to be tested T> turbidity correction threshold , then let the sample water sample stand for a preset time.

[0056] If the turbidity T of the water sample to be tested drops to the turbidity correction threshold , then stop the water sample standing process and record the turbidity equal to The results of the test value at ;

[0057] If the turbidity T of the water sample to be tested does not drop to the turbidity correction threshold , then according to the relationship model between turbidity and detection value, the turbidity of the water sample to be tested is calculated as The results of the test value at ;

[0058] Will Substitution and The relationship model to obtain , This is the corrected detection value.

[0059] Among them, the relationship model between turbidity and detection value can be directly established by and In order to obtain more accurate test values, the turbidity of the water sample and the corresponding test value measurement results can also be continuously collected during the static process of the water sample, and the relationship model between turbidity and test value can be established based on the collected turbidity of the water sample and the corresponding test value measurement results.

[0060] The online monitoring process is as follows:

[0061] Step 1: The water inlet valve and the drain valve are opened, and the water sample enters the sample flow pool from the water inlet pipe and is discharged from the drain pipe to clean the sample flow pool. This step lasts for a period of time (such as 2 minutes) to ensure that the water sample in the sample flow pool is fully replaced by the water sample to be tested, and the sediment in the sample flow pool is discharged.

[0062] Step 2: The drain valve is closed, and the water level in the sample flow cell gradually rises. When the specified water level is reached, the inlet valve is closed.

[0063] Step 3: After the water sample has been placed in the sample flow cell for a period of time (e.g. 2 minutes), the detection value sensor, turbidity sensor and other sensors begin to collect data. The turbidity data T collected by the turbidity sensor is judged. If it is higher than the turbidity correction threshold , then go to step 3.1; if it is lower than or equal to the turbidity correction threshold , no turbidity correction is performed, and COD or permanganate index monitoring value is recorded , the drain valve opens and the sample flow cell is drained.

[0064] Step 3.1: The water sample continues to stand in the sample circulation pool. The standing time should be controlled within 1 hour (the standing time can be extended to 2 hours for water with particularly high turbidity). During this period, the COD sensor (or permanganate index sensor) and turbidity sensor monitor COD (or permanganate index) and turbidity at a higher monitoring frequency (such as 1-2 minutes / time) at the same time, and record the COD (or permanganate index) and turbidity monitoring data at the same time to form a COD (or permanganate index) and turbidity monitoring data series.

[0065] As the water sample is left to stand, the sediment gradually settles and the turbidity gradually decreases. If the turbidity decreases to the turbidity correction threshold within 1 hour, , then stop the water sample standing process and record the turbidity equal to COD or permanganate index monitoring value at , the drain valve opens and the sample flow cell is drained. If the turbidity cannot be reduced to the turbidity correction threshold within 1 hour, , then stop the water sample from standing for 1 hour, open the drain valve, and drain the sample flow pool; according to the COD (or permanganate index) and turbidity monitoring data series, take turbidity as the independent variable (x), and take COD (or permanganate index) at the same time as the dependent variable (y), establish the relationship model between turbidity and test value; according to the relationship model between turbidity and test value, deduce that turbidity is The corresponding COD (or permanganate index) value .

[0066] Step 4: The COD (or permanganate index) value of this online monitoring Substitution and The relationship model to obtain , That is the corrected COD (or permanganate index) value.

[0067] Example

[0068] In a certain river, the turbidity is below 30NTU during the dry season, and the turbidity reaches 100~300NTU during the flood season due to the large amount of sediment entering the river. A small water quality station is set up at a section of the river, and the COD is monitored using an ultraviolet absorption water quality automatic online monitor. The COD of the section is manually monitored at 10~30mg / L. The online COD monitoring results during the dry season are not much different from the manual monitoring results, but the online COD monitoring during the flood season is as high as 60 mg / L, which is 2~3 times the manual monitoring COD. Because the online monitoring COD deviation is too large, it cannot be calibrated and can only be used as invalid data. The correction method of the present invention is used to correct the monitoring data, as follows:

[0069] According to the anti-turbidity interference capability of the ultraviolet absorption automatic online water quality monitor selected by this station, combined with the monitoring data analysis, it was found that when the turbidity is higher than 50NTU, the monitored COD value is obviously affected by the turbidity, so 50NTU is determined as the turbidity correction threshold.

[0070] 1. Manual comparison and modeling

[0071] Step 1: Collect water samples near the water inlet of the online monitoring equipment, fix and store the water samples, and send them to the laboratory for COD determination. The laboratory determination value is While the water samples are collected by manual comparison test, the online monitoring equipment also carries out COD monitoring to obtain the online monitoring COD value at the same time as the manual comparison test. . Manual comparison is conducted every 5 days.

[0072] Online monitoring of COD value There are three situations:

[0073] If the sample water turbidity T≤ turbidity correction threshold , then directly obtain the measurement result of the test value ①;

[0074] If the sample water turbidity T> turbidity correction threshold , the sample water sample is left to stand, and the turbidity of the water sample and the corresponding test value are continuously collected during the standing process. Within the preset time,

[0075] If the turbidity T of the sample water drops to the turbidity correction threshold , then stop the water sample standing process and record the turbidity equal to The results of the test value at ②;

[0076] If the turbidity T of the sample water does not drop to the turbidity correction threshold , then a relationship model between turbidity and test value is established based on the turbidity of the water sample collected during the static process and the corresponding test value; the turbidity of the sample water sample is calculated according to the relationship model between turbidity and test value: The results of the test value at ③.

[0077] Step 2: COD value measured by the last 6 manual comparisons is the dependent variable (y), and the online monitoring COD value at the same time as the manual measurement For the independent variable (x), establish and According to the characteristics of the data, and The relationship model uses linear regression, such as Figure 3 shown.

[0078] 2. Online Monitoring

[0079] Step 1: The water inlet valve and the drain valve are opened, and the water sample enters the sample flow pool from the water inlet pipe and is discharged from the drain pipe to clean the sample flow / sedimentation pool. This step lasts for 2 minutes to ensure that the water sample in the sample flow pool is fully replaced by the water sample to be tested, and the sediment in the sample flow / sedimentation pool is discharged.

[0080] Step 2: The drain valve is closed, and the water level in the sample circulation / sedimentation tank gradually rises. When the specified water level is reached, the inlet valve is closed.

[0081] Step 3: After the water sample has been placed in the sample flow cell for 2 minutes, the detection value sensor, turbidity sensor and other sensors begin to collect data. The turbidity data T collected by the turbidity sensor is judged, and the measured T=119NTU, which is higher than the turbidity correction threshold, then go to step 3.1.

[0082] Step 3.1: The water sample continues to stand in the sample flow cell for less than 1 hour. During this period, the COD sensor and turbidity sensor monitor COD and turbidity at a monitoring frequency of 2 minutes per time, forming a COD and turbidity monitoring data series.

[0083] As the water sample was left standing, the sediment gradually settled and the turbidity gradually decreased. Within 1 hour, the turbidity decreased from 119NTU to 68NTU, which was still higher than the turbidity correction threshold. Therefore, the water sample was stopped standing after 1 hour, the drain valve was opened, and the sample flow pool was drained. Based on the COD and turbidity monitoring data series, the relationship model between turbidity and detection value was established with turbidity as the independent variable (x) and the online monitored COD at the same time as the dependent variable (y). According to the data characteristics, the relationship model between turbidity and detection value adopts quadratic polynomial regression, such as Figure 4 According to the relationship model between turbidity and detection value, the corresponding COD value when the turbidity is 50NTU is deduced. =18.9mg / L.

[0084] Step 4: =18.9mg / L input and The relationship model corresponding to the independent variable value =18.9mg / L dependent variable value =16.0mg / L. Then =16.0mg / L is the corrected COD value.

Claims

1. A method for correcting data of automatic online monitoring of water quality by ultraviolet absorption, characterized in that: include: Step 1: Collect water samples near the water inlet of the UV absorption water quality automatic online monitoring instrument, and measure the test value manually. The measured value is R L , where the detection value is COD or permanganate index; Step 2: Use the UV absorption water quality automatic online monitor to test the sample water at the same time: Step 21: Determine the turbidity correction threshold T of the ultraviolet absorption water quality automatic online monitoring instrument t ; Step 22: If the sample water turbidity T≤ turbidity correction threshold T t , then directly obtain the test value R M ; If the sample water turbidity T> turbidity correction threshold T t , the sample water sample is left to stand, and the turbidity of the water sample and the corresponding test value are continuously collected during the standing process. Within the preset time, If the turbidity of the sample water T drops to the turbidity correction threshold T t , then stop the water sample standing process and record the turbidity equal to T t The measurement result of the detection value R M ; If the turbidity T of the sample water does not drop to the turbidity correction threshold T t , then a relationship model between turbidity and test value is established based on the turbidity of the water sample collected during the static process and the corresponding test value measurement results; the turbidity of the sample water sample is calculated as T according to the relationship model between turbidity and test value t The measurement result of the detection value R M ; Step 3: Construct R based on multiple measurement results L With R M Relationship model; Step 4: Use the UV absorption water quality automatic online monitoring instrument to detect the water sample to obtain R M ', R M 'Substitute into R L With R M Relational model to obtain R L ', R L ' is the corrected detection value.

2. The method for correcting data of automatic online ultraviolet absorption water quality monitoring according to claim 1, characterized in that: The default time is 1 hour.

3. The method for correcting data of automatic online ultraviolet absorption water quality monitoring according to claim 1, characterized in that: The relationship model between turbidity and detection value is a nonlinear regression model.

4. The method for correcting data of automatic online ultraviolet absorption water quality monitoring according to claim 1, characterized in that: R L With R M The relationship model between turbidity and detection value and the relationship model between turbidity and detection value are both established based on machine learning algorithms.

5. The method for correcting data of automatic online ultraviolet absorption water quality monitoring according to claim 1, characterized in that: Turbidity correction threshold T t It is determined comprehensively based on the anti-turbidity interference ability of the ultraviolet absorption water quality automatic online monitoring instrument and the relationship between the detection value monitoring data and turbidity.

6. Ultraviolet absorption water quality automatic online monitoring instrument, including: The control unit is provided with a water inlet pipeline, a water inlet valve, a sample circulation pool, a drainage pipeline and a drainage valve connected in sequence, a detection value sensor and a turbidity sensor are arranged in the sample circulation pool, the detection value sensor is a COD sensor or a permanganate index sensor, and the detection value sensor and the turbidity sensor are both connected to the control unit, characterized in that the sample circulation pool has a precipitation function, and the control unit is provided with at least R L With R M The control unit obtains the test value of the water sample to be tested according to the test results of the detection value sensor and the turbidity sensor. M ': If the turbidity of the water sample to be tested is T≤ the turbidity correction threshold T t , then directly obtain the test value R M '; If the turbidity of the water sample to be tested T> turbidity correction threshold T t , then let the sample water sample stand for a preset time. If the turbidity T of the water sample to be tested drops to the turbidity correction threshold T t , then stop the water sample standing process and record the turbidity equal to T t The measurement result of the detection value R M '; If the turbidity T of the water sample to be tested does not drop to the turbidity correction threshold T t , then according to the relationship model between turbidity and detection value, the turbidity of the water sample to be tested is calculated as T t The measurement result of the detection value R M '; R M 'Substitute into R L With R M Relational model to obtain R L ', R L ' is the corrected detection value.

7. The ultraviolet absorption water quality automatic online monitoring instrument according to claim 6, characterized in that: The relationship model between turbidity and test value is set directly in the control unit, or During the static state of the water sample, the measurement results of the turbidity of the water sample and the corresponding detection value are continuously collected, and a relationship model between the turbidity and the detection value is established based on the collected measurement results of the turbidity of the water sample and the corresponding detection value.

8. The ultraviolet absorption water quality automatic online monitoring instrument according to claim 6 or 7, characterized in that: A temperature sensor and / or a pH sensor is also provided in the sample circulation pool.

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