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

This study focused on the extraction of lipids from sewage scum of dairy effluents and their subsequent con -version to biodiesel. Thermal-and solvent-based liquid extraction processes were compared under different conditions. Kinetic studies of lipid extraction were performed using hexane, ethyl acetate, propionate, and butyrate at 25-50 degrees C. The results showed that solvent-based extraction outperformed the thermal-based extraction method, achieving a lipid recovery of 71.9% using ethyl butyrate at 50 degrees C for 1 h. The experi-mental data from the extraction studies were modeled using first-and second-order extraction models, and the best fit was obtained using the former model. Two reaction routes were analyzed and compared to obtain bio-diesel from the lipids extracted from sewage scum. The best reaction conditions were identified by applying the Taguchi experimental design. It was found that the esterification/transesterification of scum lipids was the best alternative to obtain 94% FAME formation. This study contributes new findings to valorize the biomass gener-ated from the dairy industry to obtain biodiesel and, therefore, consolidate its supply chain in urban areas worldwide.

Automated summary

This study compared thermal-and solvent-based liquid extraction processes for extracting lipids from sewage scum of dairy effluents and converting them into biodiesel. The results showed that solvent-based extraction outperformed the thermal-based extraction method, achieving a lipid recovery of 71.9% using ethyl butyrate at 50 degrees C for 1 h. The best reaction conditions for obtaining biodiesel from the extracted lipids were identified using experimental design and esterification/transesterification of scum lipids was found to be the best alternative with 94% FAME formation.