Efficient anaerobic digestion of whole microalgae and lipid-extracted microalgae residues for methane energy production

The primary aim of this study was to completely investigate extensive biological methane potential (BMP) on both whole microalgae and its lipid-extracted biomass residues with various degrees of biomass pretreatment. Specific methane productivities (SMP) under batch conditions for non-lipid extracted biomass were better than lipid-extracted biomass residues and exhibited no signs of ammonia or carbon/nitrogen (C/N) ratio inhibition when digested at high I/S ratio (I/S ratio ⩾ 1.0). SMP for suitably extracted biomass ranged from 0.30 to 0.38 L CH4/g VS (volatile solids). For both whole and lipid-extracted biomass, overall organic conversion ranged from 59.33 to 78.50 as a measure of %VS reduction with greater percentage biodegradability in general found within the lipid-extracted biomass. Higher production levels correlated to lipid content with a linear relationship between SMP and ash-free lipid content being developed at a R2 of 0.814.