Choice of Technological Process and Chemical Medicine for the Disposal of Mixed Electroplating Wastewater by Chemical Methods

A technological process for the disposal of mixed electroplating wastewater under the alkaline condition was chosen by thermodynamic analysis, theoretical calculations, and experiment investigations. In this process, NaClO was chosen as oxidant, Na₂S and FeSO₄ as reducers. The optimal ratio of Na₂S and FeSO₄ was determined as Na₂S 80%-90%, FeSO₄ 10%-20%. Using Na₂S and FeSO₄ as oxidants can reduce the sludge quantity by 60%-70% comparing with using FeSO₄ only. A real project by this technology has already obained good results.