Process to render water effluent containing nickel and zinc compounds arising from a surface treatment process

摘要

In a process to neutralise process effluent alkaline water free of cyanide arising from a coating process, the water is treated by the introduction of a large surplus of sulphide anions from a poorly soluble metal salt. The pH value of the effluent water is first adjusted to greater than 11, followed by the introduction of the anion-liberating reagent. The pH value is then adjusted to a value of greater than 5, followed by filtration and subsequent adjustment of the pH value to a legal discharge value.