The plant receives effluent water from the leaching plant and the cell house and waste water from ponds. The currents enter a large collecting tank. The composition of the solution from this tank has a zinc content of 1-3 g/l. From this tank the effluent is fed to the effluent treatment plant where lime milk is added to neutralize the acid content and to precipitate the zinc. Sulphide is added to precipitate the cadmium. The process takes place in a string of four reaction tanks. The pH values are adjusted automatically with two regulators which controls two lime pumps which adds lime milk in the first two tanks. After the reaction tanks the solution flows to two thickeners. The pH value is also measured in the overflow of the thickeners.