Klebsiella pneumoniae sp. LZU10 degrades oil in food waste and enhances methane production from co-digestion of food waste and straw

Abstract

High content of lipid in food waste (FW) often causes inhibition on anaerobic digestion (AD) and methane production. To facilitate the transformation of oily FW to biogas, a bacterial strain Klebsiella pneumoniae sp. LZU10 (hereafter LZU10) which could degrade waste cooking oil to soluble chemical oxygen demand (sCOD) was isolated from restaurant FW-contaminated soil. The strain also demonstrated high resistance to heavy metals, whose level were found elevated in FW. Thus LZU10 was used to pretreat FW prior to anaerobic co-digestion (coAD) with straw. Results showed that after pretreatment by LZU10 the lipid content decreased from 59.6% to 39.5%, and sCOD increased by 25.03%. The methane production and methane recovery rate were increased by 41% and 58%, respectively, after pretreatment with LZU10, compared with those of untreated FW. The present study suggests that pretreatment of lipid-rich FW with lipolytic bacteria is a promising solution to reduce lipid inhibition and enhance methane production.