Biodiesel production from wastewater scum of dairy industry: Lipid extraction studies and reaction routes

•Lipids from residual dairy effluents are a low-cost feedstock to obtain biodiesel.•Solvent extraction using ethyl butyrate achieved 72% of sewage scum lipid recovery.•Valorization of dairy scum waste via thermal and solvent extraction was analyzed.•Taguchi experimental design was used to improve the FAME formation.