Eficiência de floculantes químicos e naturais para a colheita de biomassa da microalga Scenedesmus obliquus cultivada em meio de cultura padrão

Abstract

Microalgae have been gaining increasing prominence in the biotechnology sector because they present versatility and potential for the generation of high added value products, due to their high growth rate, metabolic diversity, possibility of cultivation in different environments and carbon fixation. Therefore, the present study aimed to evaluate the flocculation efficiency of the microalga Scenedesmus obliquus with different flocculants and to determine the lipid content. The cultivation was carried out in triplicate in 20 L polyethylene reactors with a useful volume of 12 L, using standard Guillard f/2 medium, with constant aeration and lighting. Algal growth was monitored for 7 days by spectrophotometry (λ= 680 nm) and cell counting in a Neubauer chamber. Four types of flocculants were used to recover S. obliquus biomass: two natural flocculants, chitosan (1 g L-1) and moringa (10 g L-1), and two chemical flocculants, sodium hydroxide (0.5 M) and iron III chloride (1 gL-1). The lipid content was determined by the Bligh- Dyer method. Sodium hydroxide was the most efficient flocculant (99.42%), followed by chitosan (98.64%), whose biomass yields were 177 g L-1 and 170 g L-1. The lipid content in the biomass recovered with NaOH (0.5 M) was 5.0% and with moringa 11.0%. The most efficient flocculants were sodium hydroxide and chitosan.