The Denizli-Kizildere geothermal power plant in western Anatolia, Turkey, has a capacity of 20 MW. The waste brine from the plant has a flow rate of 1500 ton/h and contains approximately 400 mg/dm(3) of silica, which causes scaling. This paper describes experimental work carried out to investigate the optimum conditions of silica removal from Denizfi-Kizildere geothermal wastewater by precipitation.