Effects of culture medium recycling in the chemical composition of Spirulina platensis biomass cultivated in semi-continuous mode

Commercial microalgae cultivations use the semi-continuous mode, but there are no reports of using this cultivation mode to produce carbohydrate-rich biomass. It was evaluated biomass productivity and intracellular carbohydrates by Spirulina platensis in cultivation. Besides, reuse culture media after blend accomplished order obtain nutrient-depleted cultures. In first stage (Step 1), performed closed Erlenmeyer’s flasks, it verified that concentration renewal rate did not influence carbohydrates. However, interaction variables influenced cell yields, being best results obtained with 0.5 g/L 60%, respectively. Step 2, realized 10 L open mini raceways, cultures remained viable up 3 cycles obtaining mean carbohydrate contents 41.7% (w/w) yield 69.3 mg/L d Zarrouk 30% 70% rate. These values were higher than those observed experiments bioreactors. Therefore, demonstrated is for bioethanol production, which represents a possibility reusing nutrients from medium itself purpose.