Shore-based hyper-spectral water quality monitor Vision-point

The shore-based hyper-spectral water quality monitor Vision-point is a water quality monitor launched by Wu Xi Spectrum Technology Co., LTD., which takes water quality parameter spectrum extraction technology as the core and integrates sensor, automatic measurement, automatic control and network communication technologies to carry out online real-time comprehensive evaluation of water quality. Can synchronously achieve such as total nitrogen, total phosphorus, ammonia nitrogen, suspended matter, chlorophyll a, chemical oxygen demand, dissolved oxygen, pH, transparency, turbidity, conductivity, temperature and other more than 20 kinds of water quality parameters real-time online display.

Vision-point, a shore-based hyper-spectral water quality monitor launched by Wu Xi Spectrum Technology Co., LTD., is a water quality monitor based on water quality parameter extraction technology, which integrates sensor, automatic measurement, automatic control and network communication technologies to carry out online real-time comprehensive evaluation of water quality. Can synchronously achieve such as total nitrogen, total phosphorus, ammonia nitrogen, suspended matter, chlorophyll a, chemical oxygen demand, dissolved oxygen, pH, transparency, turbidity, conductivity, temperature and other more than 20 kinds of water quality parameters real-time online display.

The complete water quality spectrum online monitoring system includes two parts: Vision-point, a shore-based hyper-spectral water quality monitoring instrument, and cloud data analysis service. Shore-based spectral water quality monitoring instrument can achieve real-time acquisition of spectral data at a fixed location, and then call the relevant model algorithm based on the built-in processor of the instrument for real-time interpretation and inversion. Calculate the index data of pH, turbidity, dissolved oxygen, ammonia nitrogen, total phosphorus, total nitrogen, suspended matter, chlorophyll a, chemical oxygen demand, Potassium permanganate index, five-day biochemical oxygen demand, nitrate nitrogen, nitrite nitrogen, transparency, eutrophication index, black odor grade, temperature and conductivity in water (currently supporting the monitoring of 21 common water quality indexes). The data will be uploaded to the data center of the cloud platform to realize 24-hour real-time online monitoring results display and automatic alarm when parameters exceed the standard.

1、Design idea of shore-based hyper-spectral water quality monitor: According to the principle of hyper-spectral water quality monitoring, the shore-based hyper-spectral water quality monitoring instrument needs to accurately measure the spectral reflectance of the water body, on this basis, perform the water quality parameters reversely according to the Preload model, and upload the monitoring results to the cloud for online display.In order to accurately measure the spectral reflectance of water, the shore-based hyper-spectral water quality monitoring instrument has two modules, namely, sky and earth. Among them, the sky module collects the sunlight (direct), sky light (diffuse), road light, diffuse light of vegetation and buildings from the top down incident on the horizontal plane (mainly ether sunlight and sky light in the open area), while the earth module receives the off-water radiation from the water body, including the diffuse light from inside the water body and the mirror reflected light from the water surface. The latter is the interference item that does not carry water information. The light path of the shore-based spectral water quality monitoring instrument to the ground module is specially designed, which can collect the off-water radiation from directly below the equipment with a very small field of view Angle, minimize the interference from the specular reflection of distant water surface and diffuse light from surrounding objects in the signal spectrum, improve the accuracy of the spectral measurement of the water body itself, and lay a data foundation for the accurate inversion of water quality parameters. The shore-based spectral water quality monitor uses a single spectral module to measure the spectrum from the opposite and the earth modules respectively. This design can ensure the accuracy of the data and significantly reduce the hardware cost.

Table 1 Parameters of the shore-based hyper-spectral water quality monitor Vision-point

2、Working principle of shore-based hyper-spectral water quality monitor：The working process of shore-based spectral water quality monitor mainly includes three steps: spectral acquisition, index inversion and data uploading.

In the spectral acquisition stage, the system first automatically determines the exposure according to the ambient light conditions to ensure that valid data can be measured under different illuminances (such as noon on sunny days and evening on rainy days). Then, the sky and earth module spectra and the dark noise of the system are measured respectively, and the reflectance spectra of the water body are calculated according to the reflectance calibration coefficient.

In the index inversion stage, according to the index inversion model carried by the system, the water reflectance spectrum is used to calculate the water quality parameters corresponding to the measurement. In view of the complexity of water components and the diversity of water types, targeted modeling must be carried out according to the principle of "one water, one level", that is, the corresponding water quality parameters should be obtained by on-site sampling and laboratory analysis while the reflectance spectrum of water is collected, and the water quality parameter inversion model should be constructed by various methods. These models can be carried on multiple similar equipment and deployed at different points (such as upstream and downstream), thus greatly expanding the monitoring radius. For data anomalies caused by precipitation, sewage and other emergencies, real-time sampling analysis can be used for model training to gradually improve the accuracy of the model.

Wu Xi Spectrum Horizon Technology Co., Ltd. has a special water quality analysis laboratory, equipped with multiple sets of multi-functional water quality analysis instruments, with the ability to analyze and test the collected water samples, and establish or upgrade the water quality inversion model based on the test results.