Feasibility of cultivating Hartbeespoort Dam microalgae

Abstract

Three cultivation experiments were conducted to grow microalgae in three consecutively scaled-up laboratory systems, which consisted of one, five and 135-litre bioreactors. The highest productivity achieved under optimum growth conditions was in the 5-litre Erlenmeyer bioreactors with 0.0862 g/L/d at an average bioreactor day-time temperature of 26.0oC and an aeration rate of 1.5 L/min. The three cultivation experiments revealed that closed­cultivation systems would not be feasible for the economic cultivation of micro-algal biomass from the Hartbeespoort Dam, as the highest biomass concentrations achieved under optimum laboratory conditions were too low. Open­cultivation systems are only feasible if the infrastructure already exists, like in the case of the Hartbeespoort Dam. It is recommended that designers of new micro-algal biomass-to-liquids (BtL) biodiesel processes first try to capitalize on existing cultivation infrastructure, like dams, by connecting their processes to them. This will reduce the capital and operating costs of a BtL process significantly