Definition
A water quality monitor is an instrumentation device used to continuously or intermittently measure specific physical, chemical, or biological parameters in a body of water. It provides data support for water quality assessment and management by conducting real-time or periodic analysis of key indicators of water samples through automated or semi-automated methods.
Principle
The working principle of the water quality monitor is based on sensor technology and analytical chemistry. The sensor converts the target parameters into measurable electrical signals such as potential, current, or optical signals. For example, electrochemical sensors reflect ion concentrations by measuring the potential change of ion-selective electrodes; optical sensors are measured according to Lambert-Beale's law, using the relationship between the absorption intensity of light at a specific wavelength and the concentration of substances. Instruments typically contain signal conditioning circuitry and data processing units that convert the original signal into standard concentration units.
Measurement method
Common measurement methods include electrochemical, optical, thermal, and biosensing. The electrochemical method is suitable for measuring parameters such as pH, dissolved oxygen, and conductivity. Optical methods are often used to detect turbidity, chromaticity and concentration of some chemicals; The thermal method can analyze the composition of water through thermal conductivity changes. Biosensing uses biosensitive components to respond to specific pollutants. Some instruments adopt multi-parameter integrated design, and multiple index measurements are completed synchronously through modular sensors.
Influencing factors
Measurement accuracy is influenced by various factors. Environmental conditions such as temperature fluctuations may change the sensitivity of the sensor and the rate of chemical reactions. Interfering substances in water bodies may cause sensor response biases; Drift or contamination from long-term use of the sensor needs to be controlled by regular calibration. In addition, the flow rate of the water sample, the change of pressure, and the position of the instrument can also affect the measurement stability.
Application:
Water quality monitors are widely used in environmental monitoring, industrial production, agricultural irrigation, aquaculture, and municipal water supply. In environmental monitoring, it can be used for long-term observation of surface water, groundwater and discharged water bodies. assist in controlling the quality of circulating water in industrial production; Agriculture guides irrigation water management; The municipal system is used to ensure the water quality of the water supply pipe network. Different scenarios have differentiated requirements for monitoring parameters, frequency and accuracy.
Selection
The selection should comprehensively consider the measurement parameters, range range, accuracy requirements, environmental adaptability and maintenance requirements. Firstly, the type of parameter to be measured and the concentration range are clarified, and the corresponding sensor type is selected. secondly, the protection level and material corrosion resistance are evaluated according to the on-site installation conditions; long-term monitoring needs to pay attention to instrument stability and calibration cycle; Integrated systems should also consider data interface compatibility and remote monitoring capabilities. It is recommended to refer to the performance requirements in international standards such as ISO, ASTM and relevant domestic industry standards.