Electroplating is a process applied to metals or alloys to enhance properties such as wear resistance and corrosion resistance. However, the wastewater discharged from electroplating contains chromium, a heavy metal that is relatively widespread. If the chromium content exceeds permissible levels, it can pose risks to human health. In this chapter, let’s explore three solutions for treating electroplating wastewater containing chromium together with Hangzhou Modi.
1.Chemical Precipitation Method
This method addresses excessive chromium in wastewater using lead salts, barium salts, or neutralization precipitation. The barium salt method, for instance, involves a chemical reaction between barium salt cations and chromic acid in the wastewater, forming insoluble barium chromate precipitate. Residual barium ions are removed by filtration through gypsum, and then polyvinyl chloride microporous tubes are used to eliminate barium sulfate precipitate. This approach is mainly used for treating wastewater containing chromium (Cr), with a process that is simple and effective. Its advantage lies in enabling a scientific approach to wastewater treatment.
2.Electrolysis Method
This technique removes chromium while retaining iron ions as the main mechanism in the wastewater. Hexavalent chromium is reduced to trivalent chromium under acidic conditions. As the hydrogen ion concentration decreases, the pH rises, which facilitates the treatment of trivalent chromium. At the same time, it is essential to maintain the hydroxide content in the wastewater to prevent an increase in pH, allowing chromium ions to form precipitates and be separated. However, this method has drawbacks, such as significant energy consumption. To reduce energy usage, salts are often added to the wastewater to increase conductivity. But this increase in salt content makes the treated wastewater unrecyclable, indicating that this method still requires improvement.
3.Activated Carbon Treatment
Activated carbon can effectively adsorb hexavalent chromium in wastewater. When using this method, it is necessary to adjust the specific adsorbent properties of the activated carbon to ensure it gradually cleans surface contaminants and allows the wastewater to be recycled.
“Extra Knowledge”
How can we monitor the levels of pollutants in water? Using online water quality monitoring instruments allows real-time tracking of pollutant concentrations. For chromium, as mentioned in this article, the T8000-Cr Total Chromium Online Analyzer can be used to monitor changes in chromium levels in wastewater in real time.
