Mixotrophic culture of Chlorella pyrenoidosa with olive-mill wastewater asthe nutrient medium

With olive-mill wastewater (`alpechin') as the nutrient medium, the influen ce of specific rate of aeration and initial alpechin concentration have bee n analysed in cultures of Chlorella pyrenoidosa, exposed both to continuous and intermittent illumination (12/12 h light/dark cycles). The stirring ra te in the bioreactor, as well as pH and temperature were fixed previously a t 180 rpm, 6.5 and 30 degreesC, respectively. The maximum specific growth r ate (mu (m)) and biomass productivity (b) were determined as kinetic parame ters. The chlorophyll, protein and carbohydrate contents were evaluated, as well as the fatty-acid composition of the lipid fraction. The experimental conditions most conducive to a balanced biomass composition with regard to proteins and lipids were: initial alpechin concentration of 10% (v/v), con tinuous illumination, and aeration rate of 1 L (litre cell suspension)(-1) min(-1). Under these conditions, the highest values of mu (m) and b were cl ose to 0.04 h(-1) and 1.4 10(-3) g L-1 h(-1), respectively.