CARBON-DIOXIDE FIXATION BY ALGAL CULTIVATION USING WASTE-WATER NUTRIENTS

Chlorella vulgaris was cultivated in wastewater discharged from a stee lmaking plant with the aim of developing an economically feasible syst em to remove ammonia from wastewater and CO, from flue gas simultaneou sly. Since no phosphorus compounds existed in wastewater, external pho sphate (15.3 - 46.0 g m(-3)) was added to the wastewater. After adapta tion to 5% (v/v) CO2, the growth of C. vulgaris was significantly impr oved at a typical concentration of CO, in flue gas of 15% (v/v). Growt h of C. vulgaris in raw wastewater was better than that in wastewater buffered with HEPES at 15% (v/v) CO,. CO, fixation and ammonia removal rates were estimated as 26.0 g CO2 m(-3) h(-1) and 0.92 g NH3 m(-3) h (-1), respectively, when the alga was cultivated in wastewater supplem ented with 46.0 g PO43 m(-3) without pH control at 15% (v/v) CO2.