Defatted algal biomass as feedstock for short chain carboxylic acids and biohydrogen production in the biorefinery format.

The objective of the study was to evaluate the potential application of defatted algal biomass (DAB) residue as a resource for biobased product synthesis in the biorefinery framework. Acid-catalyzed pretreatment of DAB residue resulted in higher reducing sugars (RS) solubilization (0.26 g RS/g DAB) than corresponding base method (0.19 g RS/g DAB). Subsequently, resulting RS were acidogenically fermented for the production of Bio-H and short chain carboxylic acids (SCA)/volatile fatty acids (VFA) at varying redox conditions (pH: 6, 7 and 10). Biosystem with pH-6 resulted in higher SCA (0.54 g SCA/g RS) and Bio-H production (0.83  l) followed by pH-10 (0.43 g SCA/g RS, 0.71  l) and pH-7 (0.27 g SCA/g RS, 0.48  l). Higher SCA production in pH-6 system resulted in maximum acidification (23%). Algal biomass majorly derived from CO and its residues after lipids extraction accounted as major feedstock for acidogenic product synthesis. Evaluation of these studies using DAB residues offers sustainability to algal refineries on its entirety use.