With the continuous progress of China’s economy, heavy metal pollution incidents occur from time to time. Among them, heavy metals such as lead, cadmium, mercury and arsenic are all harmful to the ecological environment and human health. In this chapter, the editor will study together with everyone to understand the “tools” for monitoring heavy metals in industrial wastewater.

When it comes to the “props” for monitoring heavy metals in industrial wastewater, water quality detectors naturally come to mind. The methods to be noted for online monitoring of heavy metals in water include colorimetric analysis and electrochemical analysis. Colorimetric analysis is limited by its own technology and cannot simultaneously detect multiple ions. Electrochemical analysis is mainly suitable for “relatively” clean water bodies and is not appropriate for detecting heavy metals in industrial wastewater because it is affected by detection conditions, resulting in reduced accuracy and, in severe cases, secondary pollution.

The water quality heavy metal monitoring equipment produced by Hangzhou Modi uses the colorimetric method, which can serve as a “tool” for monitoring heavy metals in industrial wastewater. Of course, the instruments used to detect different parameters in water are also different. The working principle is that the water sample is injected into the digestion tank through an injection pump, and then a reducing agent is added to reduce different forms of heavy metals in the water to the same valence state. After that, a buffer solution is injected to adjust the pH value to an appropriate level, and a characteristic chromogenic agent is added to make the heavy metals in the water and the chromogenic agent form an orange-yellow complex. Then, the photoelectric ratio design is used to measure the color change of the orange-yellow complex at a certain wavelength. This way, the content of heavy metals in water can be calculated according to Lambert-Beer’s law.