Energy recovery from lipid extracted, transesterified and glycerol codigested microalgae biomass

Abstract

The production of methane (CH 4 ) via the anaerobic digestion of microalgae biomass residues from the biodiesel production process has the potential to meet some of the energy requirements of the primary biomass to fuel conversion process. This paper investigates the practical CH 4 yields achievable from the anaerobic conversion of the microalgae residues (as well as codigestion with glycerol) after biodiesel production using both the conventional and in situ transesterification methods. Results demonstrate that the type of lipid extraction solvent utilized in the conventional transesterification process could inhibit subsequent CH 4 production. On the basis of actual CH 4 production, a recoverable energy of 8.7–10.5 MJ kg −1 of dry microalgae biomass residue was obtained using the lipid extracted and transesterified microalgae samples. On codigesting the microalgae residues with glycerol, a 4–7% increase in CH 4 production was observed.