Lipase pre-hydrolysis enhance anaerobic biodigestion of soap stock from an oil refning industry

Abstract

A novel alcalophilic Staphylococcus haemolyticus strain with the lipolytic activity was used to perform enzymatic hydrolysis pretreatment of soap stock: a lipid rich solid waste from an oil refining industry. The culture liquid of the selected bacteria and an enzymatic preparation obtained by precipitation with ammonium sulphate from a fltrate of the same culture liquid were used for enzymatic pretreatment. The hydrolysis was carried with different incubation concentrations (10, 20 and 30%) of soap stock and the pretreatment effciency was verifed by running comparative biodegradability tests (crude and treated lipid waste). All pretreated assays showed higher reaction rate compared to crude lipid waste, which was confirmed by the increased levels of biogas production. The pretreatment of solutions containing 10% emulsifed soap stock was optimized for 24 h hydrolysis time, enabling high-biogaz formation (800 ml). The use of enzymatic pre-treatment seemed to be a very promising alternative for treating soap stock having high fat contents. © 2013 by Japan Oil Chemists' Society.