Pretreatment Of Lipid-rich Food Waste Using Klebsiella Strain LZU10 Can Enhance The Methane Production Of Anaerobic Co-digestion Of Food Waste And Straw

Food waste causes harmful effects to human health and environment. Compared with traditional physical and chemical treatment methods, anaerobic digestion is an environmental friendly method in treating food waste. In this study, a bacterium named LZU10 was isolated from soil contaminated by lipid. It can use waste cooking oil as the sole carbon source. 16 S rRNA analysis revealed that it belonged to the genus of kleblsiella. LZU10 can degrade 58% of waste cooking oil in 66 hours in M9 medium added with 1% waste cooking oil. The results of gas chromatography showed that lipid could be degraded by strain LZU10. Thin layer chromatography reveald that the lipid was degraded into free fatty acids, diglycerides and monoglycerides. Strain LZU10 could degrade different types of edible oils, such as rapeseed oil, sesame oil, lard and salad oil. It also could use different long-chain fatty acids including oleic acid, linoleic acid, linolenic acid, stearic acid and palmitic acid as the carbon source. Strain LZU10 showed the ability to degrade different concentrations of waste cooking oil and different kinds of waste oils such as hotpot oil, frying waste oil and hot chili waste oil. It exhibited higher growth rate at temperatures between 25℃ and 42℃ and at pH levels from 5 to 8. Strain LZU10 resistant to some heavy metals and antibiotics. Because the lipids in food waste inhibit the methane production of anaerobic digestion of food waste, LZU10 was used to pretreat lipid-rich food waste to eliminate the inhibitory effect. The result of anaerobic digestion experiment showed that co-digestion of food waste and straw had higher stability and methane production than individual digestion of food waste or straw. When food waste(67%(VS/VS) of lipid) was co-digested with straw, the lipid concentration in anaerobic digestion system was 15 g VS/L causing inhibition effect on anaerobic digestion process. The methane production of co-digestion of straw and pretreated food waste was 67.57% higher than control. Therefore, using biological method to treat lipid-rich food waste provides an effective approach to solve the lipid inhibition problem in anaerobic digestion of lipid-rich food waste or lipid-rich wastes.