Semi continuous Cultivation of Chlorella

Microalgal biomass composition can be modulated by changing the type of bioreactor and cultivation conditions. Besides, these microorganisms can produce valuable biomass components from unconventional culture media, including effluents and wastes. Our objective was to evaluate the production and composition of biomass in an airlift bioreactor operated in a semi-continuous mode to cultivate the microalgae Chlorella minutissima in a landfill leachate-based medium. Chlorella minutissima was cultivated in an airlift bioreactor operated in semi-continuous mode, applying a Taguchi L9 orthogonal arrangement and analyzing the effects of factors landfill leachate concentration (LC), percentage flux of CO2 added to the gas stream (GP), aeration flow in the reactor (AF), and feed flow (FR), on the cellular composition of biomass. The microalgae produced high protein levels, reaching a maximum content of 69.60% (LC: 10%, GP: null, AF: 0.30 vvm and FR: 0.9 J hmax). The highest contents of lipid and carbohydrate were 17.4% (LC: 15%, GP: null, AF: 0.45 vvm and FR: 0.7 J hmax) and 11.6% (LC: 10%, GP: 15%, AF: 0.15 vvm and FR: 0.7 J hmax), respectively. Statistical analysis showed LC was the most influential factor. GP did not show significance for any response, while the variables AF and FR showed significance in the productivity of proteins. The use of unconventional cultivation media in airlift bioreactor operated in semi-continuous mode was shown as a system with potential to be used to valorize leachate by producing valuable biomass, allowing to obtain different cell composition by varying the process conditions.