Enhancing anaerobic digestion performance of crude lipid in food waste by enzymatic pretreatment

- Three lipases were applied to hydrolyze the floatable grease in the food waste.
- Animal fat and vegetable oil are applied as substrates for anaerobic digestion.
- Three lipids are hydrolyzed in the conditions of 24 h, 1000-1500 μL and 40-50 °C.
- The digestion time was shortened by 10-40 d for three lipids treated by lipases.
- The biomethane production rate of the hydrolysis products was enhanced 26.9-157.7%.

Three lipases were applied to hydrolyze the floatable grease (FG) in the food waste for eliminating FG inhibition and enhancing digestion performance in anaerobic process. Lipase-I, Lipase-II, and Lipase-III obtained from different sources were used. Animal fat (AF) and vegetable oil (VO) are major crude lipids in Chinese food waste, therefore, applied as substrates for anaerobic digestion tests. The results showed that Lipase-I and Lipase-II were capable of obviously releasing long chain fatty acid in AF, VO, and FG when hydrolyzed in the conditions of 24 h, 1000-1500 μL and 40-50 °C. Compared to the untreated controls, the biomethane production rate were increased by 80.8-157.7%, 26.9-53.8%, and 37.0-40.7% for AF, VO, and FG, respectively, and the digestion time was shortened by 10-40 d. The finding suggests that pretreating lipids with appropriate lipase could be one of effective methods for enhancing anaerobic digestion of food waste rich in crude lipid.