Electroplating is an important industry for China’s economic development, but it is also one of the highly polluting industries. Wastewater generated from electroplating plants is a major source of pollution, making electroplating wastewater treatment a critical process. This article explains electroplating wastewater treatment processes.
First, let’s look at the main sources, characteristics, and classification of electroplating wastewater.
1.Main sources of electroplating wastewater:
alkaline degreasing solutions, coarsening solutions for plastic electroplating, laboratory water, aged and discarded electroplating baths, rinsing water from plated parts, stripping solutions, etc. Among these, rinsing water accounts for the largest proportion.
2.Characteristics:
complex composition, wide variety of pollutants, large fluctuations in water quality, high toxicity, and poor biodegradability.
3.Classification:
By pollutant type, it is mainly divided into acidic/alkaline wastewater, organic wastewater, oily wastewater, and heavy metal wastewater.
Based on treatment processes discussed in this article, it is classified into cyanide-bearing wastewater, chromium-bearing wastewater, and combined wastewater.
Main Electroplating Wastewater Treatment Processes
1.Treatment of cyanide in electroplating wastewater
The common method is the chemical process. Depending on the oxidant used, specific methods include ozone oxidation, chlorine dioxide synergistic oxidation for cyanide destruction, and alkaline chlorination. Among these, alkaline chlorination is the most widely used.
(The cyanide content is monitored using the T8000 – CN Online Cyanide Analyzer.)
2.Treatment of chromium in wastewater
Two main approaches are available:
– Reduce hexavalent chromium to trivalent chromium, then remove it by chemical precipitation.
– Recover chromium resources.
(Total chromium is monitored using the T8000 – Cr Online Total Chromium Analyzer.)
3.Treatment of nickel in electroplating wastewater
Main technologies include ion exchange, biological treatment, and membrane separation.
Nickel is a scarce resource, so it is usually purified and recycled; ion exchange is the most common method.
(Total nickel is measured using the T8000 – Ni Online Total Nickel Analyzer.)
4.Treatment of combined wastewater
Treatment must be designed according to the specific characteristics of the wastewater.
One important point to remember:
During the entire wastewater treatment process, online monitoring of water quality parameters is essential and forms a key step in evaluating water quality.
