Biodiesel, a promising renewable fuel, is produced mainly via catalytic transesterification and/or esterification reaction from various lipid sources. Primary and secondary sludges of municipal wastewater treatment facilities are potential lipid sources. In this study, factorial experimental analyses were used to study the influence of different variables on the lipid extraction and biodiesel production from primary and secondary sludges (Adelaide Pollution Control Plant, London, Canada). The maximum extracted lipids from the primary and secondary sludge sources were 14.46 (wt/wt) % and 10.04
(wt/wt) % (on the basis of dry sludge), respectively. The maximum biodiesel yield from extracted lipid by using homogeneous catalyst was 57.12 (wt/wt) % (on the basis of lipid) at 60°C for 14h of reaction. The biodiesel yield from the lipid of wastewater sludge by using mesoporous heterogeneous catalyst, SBA-15 impregnated with heteropolyacid (15% PW12), was 30.14 (wt/wt) % (on the basis of lipid) at 135°C and 135psi for 3h of reaction
