Wastewater treatment from elctroplating shops is a special case in the metal industry. Apart from inorganic substances that are not in solution this wastewater may contain any of the following pollutants:

- cadmium                                                           - iron

- aluminum                                                          - fluoride

- ammonium compounds                                     - copper

- lead                                                                   - nickel

- chlorine                                                             - zinc

- cyanide                                                             - silver                   

Electroplating processes are either acid or alkaline. An electroplating shop usually has several processing tanks where the metal parts are immersed. Two kinds of wastewater occur:

-  water from rinsing tanks: here the concentration of toxic material is between 100 and 900 mg/l

 - salt solutions from exhausted baths: as the baths are emptied periodically the concentration of toxic material is    in the region of 1 to 10  mg/l

it is important to separate alkaline from acid wastewater. Should there by cyanides in the acid areas, highly poisonous prussic acid may escape from the wastewater. Depending on their concentration metals may be precipitated using milk of lime. The processes used are similar to those in the rest of the metal industry as described previously.