Production of scenedesmus sp. microalgae in cassava (cassava wastewater) for extraction of lipids

Microalgae are a renewable energy source and have been studied to obtain several bioproducts among which are lipids that can be applied in energy and food sectors. The production of lipids from microalgae has some bottlenecks such as their nutritional requirements, cultivation mode, and the need to break down the cell structure since lipid is an intracellular product. In light of this problem, this research seeks to analyze factors that influence the growth processes of Scenedesmus sp. microalgae biomass in the synthetic ASM-1 medium supplemented with cassava, an effluent from the pressing of cassava, and thus to assess the cultivation conditions, dry biomass, and lipid content through the study of cell lysis and forms of extraction. Scenedesmus sp. was cultivated in different concentrations of the effluent. Two types of pre-treatments for recovery of lipid (ultrasound and autoclave), two solvent systems (chloroform/ethanol and chloroform/methanol), and two methods of extraction (Bligh and Dyer with ultrasound and Soxhlet) were evaluated for cell disruption. Scenedesmus sp. microalgae showed better efficiency in dry biomass production in culture mediums supplemented with cassava (5% - 10%) compared to the synthetic growth medium. It was observed that for both solvent systems autoclave pre-treatment was more efficient; however, the Bligh and Dyer method adapted with the use of ultrasound and chloroform/ethanol solvent systems obtained the higher yield of 19.27% and lower cost of thermal energy, when compared to Soxhlet with the same solvent system that resulted in 15.71% of total extracted lipids. Analysis of the lipid profile suggests the possibility of using microalgae oil for biodiesel production due to low unsaturated content, lower than that of vegetable oils (soybean, cotton, and cinnamon).