Enzymatic production of biodiesel from waste cooking oil in a packed-bed reactor: An engineering approach to separation of hydrophilic impurities

► An engineering approach to produce biodiesel enzymatically from waste cooking oil. ► The yields of methyl esters and glycerol reached 94.3% and 99.7%, respectively. ► The reactor system was modified to improve the separation of hydrophilic impurities. ► Water generated during esterification of free fatty acids was removed efficiently. ► Long-term operation was possible with less than 0.2% residual triglyceride.