Improved volatile fatty acid and biomethane production from lipid removed microalgal residue (LRμAR) through pretreatment

Renewable energy from lipid removed microalgal residues (LRμARs) serves as a promising tool for sustainable development of the microalgal biodiesel industry. Hence, in this study, LRμAR from Ettlia sp. was characterized for its physico-biochemical parameters, and applied to various pretreatment to increase the biodegradability and used in batch experiments for the production of volatile fatty acids (VFA) and biomethane. After various pretreatments, the soluble organic matters were increased at a maximum of 82% in total organic matters in alkali-autoclaved sample. In addition, VFA and methane production was enhanced by 30% and 40% in alkali-sonicated and alkali-autoclaved samples, respectively. Methane heating value was recovered at maximum of 6.6 MJ kg−1 VS in alkali-autoclaved conditions with comparison to non-pretreated samples. The pretreatment remarkably improved LRμAR solubilization and enhanced VFA and biomethane production, which holds immense potential to eventually reduce the cost of algal biodiesel.