Multi-light-source device for COD measurement and detection method
阅读说明：本技术 一种用于cod测量的多光源装置及检测方法 (Multi-light-source device for COD measurement and detection method ) 是由 赵然 韩林辰 董子晨曦 刘应卫 于 2019-10-22 设计创作，主要内容包括：本发明提供一种用于COD测量的多光源装置及检测方法,所述多光源装置至少包括：进液口,用于接收待测样本；透光检测通道,与所述进液口连通,用于检测时存放待测样本；多个波长不同的紫外光源发生器,设于透光检测通道的同侧,用于发出紫外光源；紫外光源探测器,与紫外光源发生器相对设置。本发明所述的用于COD测量的多光源装置,可以形成对不同水体中COD进行准确的测量。测量简便快捷。(The invention provides a multi-light source device and a detection method for COD measurement, wherein the multi-light source device at least comprises the following components: the liquid inlet is used for receiving a sample to be detected; the light-transmitting detection channel is communicated with the liquid inlet and is used for storing a sample to be detected during detection; the ultraviolet light source generators with different wavelengths are arranged on the same side of the light transmission detection channel and are used for emitting ultraviolet light sources; and the ultraviolet light source detector is arranged opposite to the ultraviolet light source generator. The multi-light-source device for measuring COD can accurately measure COD in different water bodies. The measurement is simple, convenient and quick.)
1. A multiple light source apparatus for COD measurement, the multiple light source apparatus comprising at least:
the liquid inlet (1) is used for receiving a sample to be detected;
the light-transmitting detection channel (2) is communicated with the liquid inlet (1) and is used for storing a sample to be detected during detection;
the ultraviolet light source generators (3) with different wavelengths are arranged on the same side of the light transmission detection channel (1) and are used for emitting ultraviolet light sources;
and the ultraviolet light source detector (4) is arranged opposite to the ultraviolet light source generator (3).
2. The multi-light source device for COD measurement according to claim 1, further comprising one or more of the following features:
a. the number of the ultraviolet light source generators (3) is 4-10;
b. the multi-light source device further comprises a liquid outlet (5) communicated with the light transmission detection channel (2) and used for discharging a sample to be detected.
3. The multi-light source device for COD measurement according to claim 1, wherein the wavelength of the light emitted from the ultraviolet light source generator (3) is 200-400 nm.
4. The multi-light source device for COD measurement according to claim 3, wherein the number of the ultraviolet light source generators (3) is 4, and the wavelengths of the emitted light sources are 254nm, 275nm, 310nm, and 365nm, respectively.
5. The multi-light source device for COD measurement according to claim 1, further comprising one or more of the following features:
1) the multi-light source device also comprises a turbidity detection module which is arranged on the side surface of the light transmission detection channel;
2) the multi-light source device further includes: and the cleaning module (8) is arranged at one end of the light transmission detection channel and used for cleaning the light transmission detection channel.
6. Use of the multi-light source device for COD measurement according to any one of claims 1 to 5 in the field of COD measurement.
7. A modeling method of a COD measurement model at least comprises the following steps:
(1) using △ UVn and COD value of each modeling sample as input values to carry out machine learning to obtain a plurality of candidate models,
wherein, the COD value of each modeling sample is obtained by measuring a potassium dichromate COD detection method;
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
(2) and (4) respectively testing the fitting effects of different candidate models, and selecting the model with the highest fitting degree as the COD measurement model.
8. The modeling method of the COD measurement model of claim 7, further comprising one or more of the following features:
a. in the step (1), machine learning is carried out by utilizing any software of python, R or Matlab;
b. in step (1), the model for machine learning includes any one or more of the following: linear regression, stepwise regression, interactions linear regression, regression tree, support vector machines.
9. A modeling device of a COD measurement model at least comprises the following modules:
the machine learning module is used for performing machine learning by taking △ UVn and COD values of each modeling sample as input values to obtain a plurality of candidate models;
wherein, the COD value of each modeling sample is obtained by measuring a potassium dichromate COD detection method;
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
and the model screening module is used for respectively testing the fitting effects of different candidate models and selecting the model with the highest fitting degree as the COD measurement model.
10. A computer-readable storage medium on which a computer program is stored, which when executed by a processor, implements the modeling method of the COD measurement model according to any one of claims 7 to 8.
11. A computer processing device comprising a processor and the aforementioned computer readable storage medium, the processor executing a computer program on the computer readable storage medium to implement the steps of the method for modeling a COD measurement model according to any one of claims 7 to 8.
12. An electronic terminal, comprising: a processor, a memory, and a communicator; the memory is used for storing a computer program, the communicator is used for being in communication connection with an external device, and the processor is used for executing the computer program stored in the memory so as to enable the terminal to execute the modeling method of the COD measurement model according to any one of claims 7-8.
13. A COD measuring method comprises the following steps:
(1) putting a sample to be detected into the light-transmitting detection channel through the liquid inlet;
(2) receiving the optical signal by an ultraviolet light source detector and converting the optical signal into an electric signal to obtain a signal value UV0 of the ultraviolet light source detector when no ultraviolet light penetrates through the sample and a signal value UVn of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample, and obtaining an ultraviolet light source detector detection value △ UVn under the ultraviolet wavelength with the wavelength of n according to a formula △ UVn-UVn-UV 0;
(3) based on the measured value obtained in the step (2), obtaining a COD value through a COD measurement model of the sample to be measured; the COD measurement model of the sample to be measured is constructed by the modeling method according to any one of claims 8 to 9.
14. The COD measuring method according to claim 13, wherein in step (2), the method further comprises receiving the optical signal by an infrared light source detector and converting the optical signal into an electrical signal to obtain a signal value RV0 of the infrared light source detector when no infrared light source is irradiated and a signal value RV of the sample to be measured when the infrared light source is irradiated, and obtaining △ RV, wherein the △ RV is RV-RV 0.
Technical Field
The invention relates to the field of water quality analysis, in particular to a multi-light-source device for COD measurement and a detection method.
Background
Chemical Oxygen demand (cod) (chemical Oxygen demand) is a chemical method for measuring the amount of reducing substances to be oxidized in a water sample. The oxygen equivalent of a substance (typically an organic substance) that can be oxidized by a strong oxidizing agent in wastewater, wastewater treatment plant effluent, and contaminated water. It is an important and relatively fast measurable organic pollution parameter in the study of river pollution and properties of industrial wastewater and the management of operation of wastewater treatment plants. The chemical oxygen demand measured by using potassium permanganate solution as an oxidant is called permanganate index in the water quality environmental standard of China and is used for representing COD of surface water, drinking water and domestic sewage. The method has accurate measurement result, but has complex test process, fussy operation, higher analysis cost and difficult commercial application.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a multi-light source device and a detection method for COD measurement.
To achieve the above and other related objects, a first aspect of the present invention provides a multi-light source apparatus for COD measurement, the multi-light source apparatus comprising at least:
the liquid inlet is used for receiving a sample to be detected;
the light-transmitting detection channel is communicated with the liquid inlet and is used for storing a sample to be detected during detection;
the ultraviolet light source generators with different wavelengths are arranged on the same side of the light transmission detection channel and are used for emitting ultraviolet light sources;
and the ultraviolet light source detector is arranged opposite to the ultraviolet light source generator.
The second aspect of the invention provides the use of the multi-light source device for COD measurement in the field of COD measurement.
The third aspect of the invention provides a modeling method of a COD measurement model, which at least comprises the following steps:
(1) using △ UVn and COD value of each modeling sample as input values to carry out machine learning to obtain a plurality of candidate models,
wherein, the COD value of each modeling sample is obtained by measuring a potassium dichromate COD detection method;
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
(2) and (4) respectively testing the fitting effects of different candidate models, and selecting the model with the highest fitting degree as the COD measurement model.
The fourth aspect of the invention provides a modeling device of a COD measurement model, which at least comprises the following modules:
the machine learning module is used for performing machine learning by taking △ UVn and COD values of each modeling sample as input values to obtain a plurality of candidate models;
wherein, the COD value of each modeling sample is obtained by measuring a potassium dichromate COD detection method;
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
and the model screening module is used for respectively testing the fitting effects of different candidate models and selecting the model with the highest fitting degree as the COD measurement model.
A fifth aspect of the present invention provides a computer-readable storage medium on which a computer program is stored, which when executed by a processor, implements the aforementioned modeling method of the COD measurement model.
A sixth aspect of the present invention provides a computer processing device, which includes a processor and the aforementioned computer readable storage medium, wherein the processor executes a computer program on the computer readable storage medium to implement the aforementioned steps of the modeling method for the COD measurement model.
A seventh aspect of the present invention provides an electronic terminal, comprising: a processor, a memory, and a communicator; the memory is used for storing a computer program, the communicator is used for being in communication connection with an external device, and the processor is used for executing the computer program stored in the memory so as to enable the terminal to execute the modeling method of the COD measurement model.
The eighth aspect of the present invention provides a COD measuring method, comprising the steps of:
(1) putting a sample to be detected into the light-transmitting detection channel through the liquid inlet;
(2) receiving the optical signal by an ultraviolet light source detector and converting the optical signal into an electric signal to obtain a signal value UV0 of the ultraviolet light source detector when no ultraviolet light penetrates through the sample and a signal value UVn of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample, and obtaining an ultraviolet light source detector detection value △ UVn under the ultraviolet wavelength with the wavelength of n according to a formula △ UVn-UVn-UV 0;
(3) based on the measured value obtained in the step (2), obtaining a COD value through a COD measurement model of the sample to be measured; the COD measurement model of the sample to be measured is constructed by the modeling method according to any one of
As described above, the multi-light source device and the detection method for COD measurement according to the present invention have the following advantages:
the multi-light-source device for measuring COD can be used for more accurately measuring COD in different water bodies by combining a data analysis algorithm. The measurement is simple, convenient and quick. Because turbidity in the water can form certain influence to the measured value, so the infrared sensor that this device was arranged can carry out the analysis to the turbidity in the water, discharges the influence that the turbidity produced to measuring to obtain more accurate measured data. In a long-term measurement process, the tube wall of the light transmission detection channel can grow a biological film, including bacteria, blue algae and other substances which can influence the measurement, so that the biological film growing on the surface of the tube wall can be effectively cleaned by starting ultrasonic for 10-30 seconds before each measurement.
Drawings
FIG. 1 shows a diagram of a multi-light source apparatus for COD measurement according to the present invention.
FIG. 2 shows an exploded view of the multi-light source device for COD measurement according to the present invention.
FIG. 3 shows a schematic diagram of a turbidity module according to the present invention.
FIG. 4 is a flow chart of the modeling method of the COD measurement model of the present invention.
FIG. 5 is a diagram of a modeling apparatus for a COD measurement model according to the present invention.
Fig. 6 is a schematic diagram of an electronic terminal according to an embodiment of the invention.
FIG. 7 is a graph showing the COD values measured by the detection method of the present invention and the national standard method.
FIG. 8 shows a fitting graph of COD detection results of the detection method of the present invention and a national standard method of potassium dichromate.
Description of the element reference numerals
1 liquid inlet
2 light transmission detection channel
3 ultraviolet light source generator
4 ultraviolet light source detector
5 liquid discharge port
6 infrared light source generator
7 infrared light source detector
8 cleaning module
9 casing
A transmitted light
B scattered light
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.
Please refer to fig. 1 to 8. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
As shown in fig. 1 and 2, the present invention provides a multi-light source apparatus for COD measurement, the multi-light source apparatus at least comprising:
the
the light-transmitting
a plurality of ultraviolet
and the ultraviolet light source detector 4 is arranged opposite to the ultraviolet
The ultraviolet light source detector is used for receiving the optical signal of the ultraviolet light source generator and converting the optical signal into an electric signal for subsequent analysis and processing.
The number of the ultraviolet
The wavelength of the light emitted by the ultraviolet
In one embodiment, the number of the ultraviolet
In another embodiment, the number of the ultraviolet
Further, the multi-light source device further comprises a
The ultraviolet light source detector may be any of various devices or devices suitable for detecting ultraviolet light, such as an ultraviolet light sensor. The ultraviolet light source generator may be an ultraviolet lamp.
The light-transmissive detection channel can be made of various light-transmissive materials, and in one embodiment, the light-transmissive detection channel is a quartz tube.
In a preferred embodiment, the apparatus for multiple light sources further includes a turbidity detection module disposed on a side surface of the light transmission detection channel.
The turbidity detection module comprises:
an infrared
the turbidity detection module adopts a 90-degree scattering light principle. As shown in fig. 3, when the parallel light beams emitted from the infrared light source generator pass through the sample to be measured, a part of the parallel light beams is absorbed and scattered, and another part of the parallel light beams passes through the sample to be measured. The intensity of the scattered light at 90 ° to the incident light follows the rayleigh formula:
is ═ ((KNV2)/λ) × I0 wherein: i0 incident light intensity Is scattered light intensity N unit number of particles in solution
V-particle volume λ -incident light wavelength K-coefficient
Under constant incident light conditions, the scattered light intensity is directly proportional to the turbidity of the solution over a range of turbidity.
The above formula can be represented as: Is/I0 ═ K 'N (K' Is a constant)
The infrared
In one embodiment, an infrared
Specifically, the infrared light source detector is an infrared light sensor. The infrared light source generator is an infrared lamp.
The turbidity detection module is used for detecting the turbidity of a sample to be detected, and the influence of the turbidity on the measurement can be eliminated through subsequent data analysis.
The wavelength of the light emitted by the infrared
In one embodiment, the infrared
In a preferred embodiment, the multi-light source device further comprises a cleaning module connected to the transparent detection channels for cleaning the transparent detection channels. In one embodiment, the cleaning module comprises an
The multi-light source apparatus further includes a housing 9 for placing the respective components.
The multi-light source device can also comprise a controller, wherein the controller can be a single chip microcomputer, and the single chip microcomputer can be an 8-bit minimum system. The controller may also be a different brand and model, or a higher number of controllers or processors. The controller may be used to install the associated control program. After the relevant control programs are installed, the controller is in signal connection with the ultraviolet light source detector and the infrared light source detector, and signals of the ultraviolet light source detector and the infrared light source detector can be collected and processed according to needs.
The multi-light source device for COD measurement can be used in the field of COD measurement.
The COD measuring method provided by the invention comprises the following steps:
(1) putting a sample to be detected into the light-transmitting detection channel through the liquid inlet;
(2) receiving the optical signal by an ultraviolet light source detector and converting the optical signal into an electric signal to obtain a signal value UV0 of the ultraviolet light source detector when no ultraviolet light penetrates through the sample and a signal value UVn of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample, and obtaining an ultraviolet light source detector detection value △ UVn under the ultraviolet wavelength with the wavelength of n according to a formula △ UVn-UVn-UV 0;
(3) and (3) obtaining the COD value through the COD measurement model of the sample to be measured based on the measured value obtained in the step (2).
In one embodiment, as shown in fig. 3, step (2) further includes:
and receiving the optical signal by an infrared light source detector and converting the optical signal into an electric signal to obtain a signal value RV0 of the infrared light source detector when no infrared light source irradiates and a signal value RV of the sample to be detected when infrared light irradiates, and obtaining △ RV, wherein the △ RV is RV-RV 0.
Accordingly, the measured values in step (3) at this time were △ UV and △ RV.
In one embodiment, the infrared light source detector can be used to directly measure the turbidity in water: and (3) placing the turbidity standard reagent into the device, calibrating to obtain a calibration curve, and comparing the measured value of the sample to be measured with the calibration curve in the actual measurement process to obtain a turbidity value.
As shown in fig. 4, the COD measurement model in step (3) can be constructed by the following method:
(1) using △ UVn and COD value of each modeling sample as input values to carry out machine learning to obtain a plurality of candidate models,
wherein the COD value of each modeling sample is obtained by measuring the COD detection method of potassium dichromate (HJ/T399-2007);
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
(2) and (4) respectively testing the fitting effects of different candidate models, and selecting the model with the highest fitting degree as the COD measurement model.
The highest fitting degree means that the fitting value has the lowest standard deviation and the highest R with the COD value of the sample2。
In one embodiment, in step (1), machine learning is performed using any of python, R or Matlab software;
in one embodiment, in step (1), the model for machine learning comprises any one or more of: linear regression, stepwise regression, interactions linear regression, regression tree, support vector machines.
As shown in fig. 5, the modeling apparatus of the COD measurement model provided by the present invention at least includes the following modules:
the machine learning module is used for performing machine learning by taking △ UVn and COD values of each modeling sample as input values to obtain a plurality of candidate models;
wherein, the COD value of each modeling sample is obtained by measuring a potassium dichromate COD detection method;
△UVn＝UVn-UV0；
UV 0: the signal value of the ultraviolet light source detector when no ultraviolet light penetrates through the sample;
UVn: the signal value of the ultraviolet light source detector when the ultraviolet light with the wavelength of n penetrates through the sample;
△ UVn, detecting the detection value of the ultraviolet light source detector of each modeling sample under the ultraviolet wavelength with the wavelength of n, and respectively detecting the signal values of the ultraviolet light source detector when the ultraviolet light with various wavelengths respectively penetrates through the samples;
and the model screening module is used for respectively testing the fitting effects of different candidate models and selecting the model with the highest fitting degree as the COD measurement model.
In one embodiment, the machine learning module performs machine learning using any one of python, R or Matlab software;
in one embodiment, in the machine learning module, the model for machine learning includes any one or more of: linear regression, stepwise linear regression, interactions linear regression, regression tree, support vector machines.
It should be noted that the division of the modules of the above apparatus is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. These modules may all be implemented in software invoked by a processing element; or may be implemented entirely in hardware; and part of the modules can be realized in the form of calling software by the processing element, and part of the modules can be realized in the form of hardware. For example, the obtaining module may be a processing element that is set up separately, or may be implemented by being integrated in a certain chip, or may be stored in a memory in the form of program code, and the certain processing element calls and executes the functions of the obtaining module. Other modules are implemented similarly. In addition, all or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software.
For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), among others. For another example, when one of the above modules is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).
The present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the aforementioned modeling method of a COD measurement model.
The computer processing device provided by the invention comprises a processor and the computer readable storage medium, wherein the processor executes a computer program on the computer readable storage medium to realize the steps of the modeling method of the COD measurement model.
The invention provides an electronic terminal, comprising: a processor, a memory, and a communicator; the memory is used for storing a computer program, the communicator is used for being in communication connection with an external device, and the processor is used for executing the computer program stored in the memory so as to enable the terminal to execute the modeling method of the COD measurement model.
As shown in fig. 6, a schematic diagram of an electronic terminal provided by the present invention is shown. The electronic terminal comprises a
The above-mentioned system bus may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The system bus may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus. The communication interface is used for realizing communication between the database access device and other equipment (such as a client, a read-write library and a read-only library). The memory may include a Random Access Memory (RAM), and may further include a non-volatile memory (non-volatile memory), such as at least one disk memory.
The processor may be a general-purpose processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like; the integrated circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic device, or discrete hardware components.
Those of ordinary skill in the art will understand that: all or part of the steps for implementing the above method embodiments may be performed by hardware associated with a computer program. The aforementioned computer program may be stored in a computer readable storage medium. When executed, the program performs steps comprising the method embodiments described above; the computer-readable storage medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs (compact disc-read only memories), magneto-optical disks, ROMs (read-only memories), RAMs (random access memories), EPROMs (erasable programmable read only memories), EEPROMs (electrically erasable programmable read only memories), magnetic or optical cards, flash memory, or other type of media/machine-readable medium suitable for storing machine-executable instructions. The computer readable storage medium may be a product that is not accessed by the computer device or may be a component that is used by an accessed computer device.
In particular implementations, the computer programs are routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
Example data analysis:
1.1 sample sources: a certain rural sewage treatment station.
1.2 sample number: and 76 pieces.
1.3 data verification method after sampling:
and sending to a qualified laboratory for COD test of national standard GB 11914-89. (the national standard method COD test is divided into a potassium permanganate method and a potassium dichromate method). the test adopts the potassium dichromate method. The potassium dichromate method is that firstly potassium dichromate is used for digesting a water sample, and the COD concentration in the water sample can be calculated by quantifying the consumption of the potassium dichromate.
1.4 ultraviolet lamp bead used:
3 ultraviolet bulbs were used for this test at wavelengths of 280nm (UV1),275nm (UV2) and 310nm (UV 3). Three lamp beads share one sensor. Each time the detection sensor reads 4 signals, firstly, the electric signals of the ultraviolet light emitted by the ultraviolet lamp after penetrating through the sample are directly read one by one, and finally, the background voltage signal (UV0) is read once again, which means the signals read by the sensor when the ultraviolet lamp is not turned on.
After the sensor signal is read, a table with 4 columns, namely UV0, UV1, UV2 and UV3, is generated in the background of the system directly by the system. The actual value of the sample submitted to the laboratory for national standard method testing can be manually input into the system through the UI, the system can generate a new 4-column table by matching the actual measurement sample with the previous 4-column table through time and point location, and the table header and partial data shown in the table 1 are as follows
TABLE 1
All signals need to have the dark current signal subtracted in order to remove their background voltage interference.
According to the 4 rowsAccording to the method, machine learning (machinelearning) is carried out on the model in a system background by utilizing Matlab or Python to respectively check the fitting effect of different models on the model, and finally, the optimal model is selected. Models that can be considered include (linear regression, stepwise regression, iterative linear regression, regression tree, support vector machines, etc.). After machine learning aiming at the data, the fitting degree of stepwise linear regression is the best, and the fitting value has the lowest standard deviation (18) and the highest R with the true value of the sample2(75%). the resulting formula is:
Predicted＝373.015-74.8747*(UV1-UV0)-595.4812*(UV2-UV0)-1373.5*(UV3-UV0)+2601.6*(UV2-UV0)*(UV3-UV0)
fig. 7 shows the difference between the true value (blue) and the predicted value (yellow) after fitting by the above method, and the trends are basically the same, so as to meet the requirements of the users. The model is selected to analyze subsequent sensor measurements and give a COD measurement.
As shown in FIG. 8, compared with the COD detection method of the potassium dichromate national standard method, the water sample subjected to the multi-light source COD analysis of the invention can achieve higher fitting degree, which exceeds 94.7%.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
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