CN101832918A - Ultraviolet photoelectric microsensor device for monitoring water quality on line and monitoring method - Google Patents

Abstract

An ultraviolet photoelectric micro sensor device for on-line monitoring of water quality, which includes an ultraviolet light source, an ultraviolet detector, a data acquisition and sending module, a bracket, and a sealing cover. The water flow sample to be monitored is placed between the ultraviolet light source and the ultraviolet detector. Among them, the ultraviolet light source and the ultraviolet detector are fixed on the bracket, the two ends of the ultraviolet light source are connected to the power supply through wires, and the two ends of the ultraviolet detector are connected with the data acquisition and transmission module through wires, which are characterized by ultraviolet light source, ultraviolet detector The ultraviolet detector is composed of GaN-based Schottky ultraviolet detector, and its response window corresponds to the central wavelength of the above-mentioned LED; the ultraviolet light source is composed of 3-7 ultraviolet LEDs, and the wavelength covers 200nm to 400nm range. The device is small in size and low in power consumption, can timely and accurately monitor changes in environmental pollution indicators (TOC, COD, etc.), and has broad application prospects.

Description

Ultraviolet photoelectric microsensor device and monitoring method for online monitoring of water quality

1. Technical field

The invention relates to a method for monitoring water quality pollution indicators and a water quality pollution indicator monitoring device using the method, which are used in the fields of water quality pollution monitoring and pollution treatment.

2. Background technology

Changes in water pollution will seriously affect the growth and balance of aquatic organisms. Therefore, monitoring changes in water pollution indicators is very important and has been widely used in various fields such as environmental monitoring and production process pollution monitoring. However, due to the national standard method (GB11914-89 The COD test method in ) has problems such as long test time, complicated operation, need for pretreatment, secondary pollution of chemical reagents, etc., making rapid detection difficult. Using the ultraviolet absorption spectrum of the water body to measure can achieve the goal of accurately testing the water body pollution indicators, but the traditional ultraviolet detection device is bulky and difficult to achieve multi-point online monitoring. Existing on-line monitoring instruments usually use a single wavelength (usually the 254nm wavelength of a low-pressure mercury lamp) detection method, and the disadvantage is that some organic compounds do not absorb at 254nm, which makes the detection data deviate from the actual data. Therefore, , it is particularly important to realize online rapid and accurate monitoring of water pollution.

3. Contents of the invention

The object of the present invention is to provide a method for quickly and accurately measuring water pollution indicators and a water pollution indicator monitoring device using this method. This monitoring method can accurately display the dynamic changes of monitoring indicators online, in real time.

The water quality on-line monitoring device provided by the present invention is an ultraviolet photoelectric microsensor device for on-line monitoring, which includes an ultraviolet light source 1 and an ultraviolet detector 2, and the water flow sample to be monitored is placed between the ultraviolet light source 1 and the ultraviolet detector 2, and the data It is composed of collection and sending module, source, bracket and sealing cover, wherein the ultraviolet light source and ultraviolet detector are fixed on the bracket, the two ends of the ultraviolet light source are connected to the power supply through wires, and the two ends of the ultraviolet detector are connected to the data acquisition and The transmitter modules are connected and the components are enclosed in a hermetic enclosure. The ultraviolet detector is composed of a GaN-based Schottky ultraviolet detector, and its response window corresponds to the central wavelength of the above-mentioned LED; the data acquisition and sending module is composed of a single-chip microcomputer, and the ultraviolet light source is a plurality of ultraviolet LED light sources, the wavelength coverage The entire range from 200nm to 400nm. For example, the ultraviolet light source is composed of 6 ultraviolet LEDs, and the typical center wavelengths are 220nm, 255nm, 280nm, 300nm, 365nm, 400nm; the data acquisition and transmission module is mainly AD and single-chip microcomputer system, which can include two functions of data acquisition and transmission.

The advantage of using 6 LED light sources for monitoring is obvious. Compared with the traditional low-pressure mercury lamp 254nm single-wavelength monitoring method, its monitoring range not only covers the entire ultraviolet band, but also can take into account all organic pollutants that absorb in the ultraviolet band to COD, etc. The contribution of parameters, and the 400nm LED light source is used for turbidity compensation, which can correct the absorption intensity. In this way, using 6 LED light sources for monitoring, the result is more accurate and reliable. The working voltage of the LED is 6-8V, and the current is 30-80mA. It is driven regularly by the constant current source circuit. The data collection of the ultraviolet detector is performed after the LED is lit for one minute each time, and it is automatically turned off after the data collection is completed.

The sealing cover is encapsulated by materials such as quartz glass and plastic, which can prevent water and corrosion.

The water quality online monitoring method provided by the present invention: the basic principle is to collect the spectral data of the sample and the basic water quality data, use the method of chemometrics to calculate and establish a mathematical model, and finally use the established mathematical model and the spectral graph of the measured sample to predict According to the relevant parameters of the measured object, according to different water quality and pollution indicators, the functional relationship between the spectral data and the measured object is established, and a variety of water quality basic data models and the functional relationship between spectral data and pollution indicators are preset in the data acquisition and sending module middle.

The steps are as follows: establish the functional relationship between the spectral data and the measured object, and preset the functional relationship between various water quality basic data models and spectral data and pollution indicators in the server 8; the ultraviolet light source 1 is a plurality of LED light sources, and the wavelength is discretely distributed at 200nm To the 400nm interval, multiple ultraviolet detectors 2 can accurately measure the absorbance at the corresponding wavelength; the data acquisition and sending module 3 obtains the multiple discrete absorbance values and sends them to the server 8, and the server selects the corresponding mode and preset basic data The spectral data in the range of 200nm to 400nm is obtained by fitting, and the relevant parameters of the measured object are obtained by calling the preset corresponding function relationship. Different wavelengths of ultraviolet light have different sensitivities to different measured object parameters, and multiple wavelengths can reflect the response of different wavelength bands to the same parameter, so multi-parameter and accurate measurement can be realized.

The beneficial effects of the present invention are: the monitoring device designed according to the online monitoring method of water quality pollution indicators of the present invention can realize fast, convenient, accurate and real-time online dynamic monitoring of a large area, can realize measurement under different conditions, and can monitor specified The water quality pollution index of the monitoring site; therefore, it has a wide application prospect in the fields of water quality environmental monitoring, governance, scientific research, industrial application and so on. The measurement system is small in size, low in power consumption, low in cost, can be placed underwater, and can realize convenient and safe multi-point measurement of large outdoor areas.

4. Description of drawings

Fig. 1 is a schematic cross-sectional view of the structure of the online monitoring device for water quality indicators of the present invention.

1-ultraviolet light source, 2-ultraviolet detector, 3-data acquisition and transmission module, 4-power supply, 5-support, 6-wire, 7-sealed cover, 8-server.

Figure 2 is a flow chart of the algorithm for obtaining parameters related to the function of absorbance and the item to be measured

Figure 3 is a flow chart of the specific water quality online monitoring algorithm

5. Specific implementation

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment 1: An embodiment of an ultraviolet photoelectric microsensor device for on-line monitoring, referring to FIG. 1 , the ultraviolet light source is a light source composed of a plurality of ultraviolet LEDs. The UV detector consists of 6 GaN-based Schottky UV detectors (including 5 AlGaN and 1 InGaN). AlGaN and InGaN can be used as laboratory samples or commercial products, and their response window covers the LED wavelength range; There is a water tank between the light source 1 and the ultraviolet detector 2, which can evenly flow the water flow samples to be monitored. The ultraviolet detector 2 data acquisition and transmission module, the above data acquisition and transmission module can also be composed of a data acquisition card and a wireless transmission module. Including data acquisition and transmission functions; the power supply can be solar cells, dry batteries or rechargeable batteries; the support 5 is made of metal materials; the sealing cover 7 is made of light-transmitting materials such as quartz glass; The server 8 is composed of a database and an operation program, and has the functions of data reading, analysis, storage, display, and alarm. Through the built-in reference absorption spectrum mode and pollution index correlation parameters of the server 8, select and set the appropriate mode according to the specific conditions of the measurement object, and call the corresponding special correlation function for different water quality pollution indicators, so that each water quality pollution Indicators are measured more precisely.

Example 2: Monitoring of water pollution index COD.

This method was applied to the water quality of Qinhuai River in Nanjing for on-line COD monitoring test. The ultraviolet light source (1) is composed of 6 ultraviolet LEDs, and the center wavelengths are 220nm, 255nm, 280nm, 300nm, 365nm, 400nm; the ultraviolet detector (2) is composed of 6 GaN-based Schottky ultraviolet detectors (5 AlGaN and 1 InGaN), the response wavelength corresponds to the center wavelength of the above-mentioned LED; the data acquisition and transmission module (3) is composed of a single-chip microcomputer, and the single-chip microcomputer is responsible for data collection and transmission; the power supply (4) is a solar cell, for ultraviolet The LED in the light source (1) and the data acquisition and transmission module (3) are powered, the solar panel is placed on the street light pole by the river, and the ultraviolet light source (1) and the data acquisition and transmission module (3) are connected through a wire (6); Bracket (5) is stainless steel, is used for fixing parts (1), (2), (3), (4), and the corresponding part of sealing cover (7) LED and detector is quartz glass, can see through ultraviolet light, and the rest The parts are corrosion-resistant plastics; the two ends of the ultraviolet detector (2) are connected with the data acquisition and sending module (3) through wires (6); the components (1), (2), (3), (4), ( 5), (6) are encapsulated in the sealed cover (7); the data acquisition and transmission module (3) transmits the collected data to the server (8) through wireless transmission, and the server is first installed in urban rivers, wild rivers, urban rivers, etc. The urban river mode is selected from lakes, wild lakes, rivers in chemical industry and other modes, and the measurement object is selected as COD measurement. The server reads and calculates online data, gives real-time measurement results and implements display, storage, and early warning functions. The monitoring results show that the correlation coefficient between the predicted value of COD and the measured value of the chemometric method is above 0.9, and the error is within ±5%.

Example 3

Can refer to Chinese patent CN200810196207.5, the ultraviolet light source adopts the ultraviolet LED light source of Seoul Company. Establish the functional relationship between ultraviolet spectrum data and COD Embodiment, the functional relationship between COD and ultraviolet absorbance UVA preset by the server 8 is: COD=A+B*UVA255+C*UVA300, parameters A, B, and C are preset according to different modes Corresponding values (corresponding to the setting values of urban lake mode A=4.4, B=14, C=27). The ultraviolet light source is a light source composed of 3 ultraviolet LEDs, the center wavelengths are 255nm, 300nm, 400nm respectively, and the ultraviolet detector is composed of 3 GaN-based Schottky ultraviolet detectors (including 2 AlGaN and 1 InGaN), 2 The absorbance UV255 and UV300 at 255nm and 300nm measured by an AlGaN detector subtract the absorbance UV400 at 400nm measured by an InGaN detector to obtain the absorbance UVA255 and UVA300 values at 255nm and 300nm after deducting the influence of turbidity, after the preset COD The COD value is obtained as a function of the ultraviolet absorbance UVA. This method was applied to Nanjing Xuanwu Lake for COD measurement (the measurement time was September 2009), and the absorbance at 255nm, 300nm, and 400nm and the corresponding COD results are shown in Table 1.

Table 1 COD measurement results of water quality in Xuanwu Lake, Nanjing

Water sample serial number 1 2 3 4 5 6 7 UV255 0.13 0.14 0.15 0.18 0.18 0.25 0.29 UV300 0.08 0.10 0.11 0.12 0.13 0.18 0.22 UV400 0.04 0.07 0.08 0.06 0.08 0.12 0.15 UVA255 0.08 0.07 0.07 0.11 0.10 0.13 0.13 UVA300 0.04 0.03 0.03 0.05 0.04 0.06 0.06 COD 6.72 6.49 6.42 7.55 7.00 7.90 8.20

Claims (8)

1. the ultraviolet photoelectric microsensor device that is used for monitoring water quality on line, it comprises ultraviolet source, ultraviolet detector, data acquisition and sending module, support, seal closure is formed, current sample to be monitored places between ultraviolet source and the ultraviolet detector, wherein ultraviolet source and ultraviolet detector are fixed on the support, the two ends of ultraviolet source are connected with power supply by lead, the two ends of ultraviolet detector are connected with sending module with data acquisition by lead, it is characterized in that ultraviolet source, ultraviolet detector and support are encapsulated in the interior ultraviolet detector of seal closure to be made up of GaN base schottky type ultraviolet detector, and its response window is corresponding with the centre wavelength of above-mentioned LED; Ultraviolet source is that 3-7 ultraviolet LED formed, and wavelength covers the interval of 200nm to 400nm.

2. the ultraviolet photoelectric microsensor device of monitoring water quality on line according to claim 1, it is characterized in that described ultraviolet detector (2) is six GaN base ultraviolet light electric explorers, response wave length arrives the 400nm interval at 200nm, centre wavelength is respectively 220nm, 255nm, 280nm, 300nm, 365nm, 400nm.

3. the ultraviolet photoelectric microsensor of monitoring water quality on line according to claim 1 is characterized in that described data acquisition and sending module (3) are Single Chip Microcomputer (SCM) system, comprises data acquisition and sends two functions.

4. the ultraviolet photoelectric microsensor device of monitoring water quality on line according to claim 1 is characterized in that described seal closure (7) is quartz glass and plastic or other material encapsulation, can waterproof and anticorrosion.

5. method of utilizing the ultraviolet light photo micro sensing of the described monitoring water quality on line of claim 1, its method step is as follows: set up the funtcional relationship of spectroscopic data and measurand, multiple water quality basic data model and spectroscopic data and contamination index's funtcional relationship are preset in the server; Ultraviolet source (1) is a plurality of led light sources, and the wavelength Discrete Distribution is in 200nm to 400nm interval, and a plurality of ultraviolet detectors (2) can accurately be measured the absorbance at corresponding wavelength place; Data acquisition and sending module (3) obtain obtaining with the basic data match of presetting behind these a plurality of discrete absorbance numerical value the spectroscopic data in 200nm to 400nm interval, call the correlation parameter that the respective function relation that presets obtains measurand; The ultraviolet light of different wave length is to the susceptibility difference of different measurand parameters, and a plurality of wavelength reflect the response condition of different-waveband to same parameter again, realizes the accurate measurement of multiparameter.

6. the method for the ultraviolet light photo micro sensing of the described monitoring water quality on line of claim 5 is characterized in that dynamic on-line monitoring.

7. the method for the ultraviolet light photo micro sensing of the described monitoring water quality on line of claim 6 is characterized in that accurately monitoring simultaneously the numerical value of water pollution indexs such as TOC, COD.

8. the method for the ultraviolet light photo micro sensing of the described monitoring water quality on line of claim 6, it is characterized in that by referenced absorbance chart-pattern and contamination index's relevance parameter, select and be provided with suitable pattern according to the concrete condition of measuring object, at different quality contamination index, call corresponding special relevance function, make that the measurement of each water pollution index is more accurate.

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