The quality of wastewater and waste liquid discharged from electroplating plant (or workshop), such as rinsing water for plating parts, waste tank liquid, equipment cooling water and surface water for washing, varies with the production process, some contain chromium, some contain nickel or cadmium, cyanide, acid, alkali, etc. Some metal ions in wastewater exist in the form of simple cations (such as Ni2+, Cu2+, etc.), and some are in the form of acid radical anions