Enhanced Food Waste Hydrolysis for Integrated Biofuel Production

In recent years, there has been an increasing interest in using anaerobic digestion as a means of reducing the volume of municipal solid waste (MSW) and generating methane biogas for energy recovery. In order to increase process efficiency of food waste treatment and obtain valuable product, hydrolysis of food waste were enhanced by optimizing pH and total solids (TS), then two strategies of volatile fatty acid (VFA) utilization for biofuel production were proposed in this study.  One of the strategies was methanization of VFA abundant liquid in high rate anaerobic digester, such as up-flow anaerobic sludge bed reactor (UASB) as the methanogenic reactor. Another strategy was production of single cell oil (SCO) or microbial lipid by oleaginous yeast Cryptococcus curvatus to be used as biodiesel feedstocks. High concentration of VFA production was the optimizing objective during the hydrolysis of food waste. After 20 d incubation time at pH 6.0 and 12% TS, VFA concentration, VFA yield and volatile solids (VS) reduction were reached to 53.9g/L, 0.38gVFA/gVS and 59.2%, respectively. Biofuel production of two strategies was compared and the mass balance of two systems was calculated. At steady-state, methane production rate of 2.28L/L/d and lipid production of 1.1g/L/d were achieved in two systems, respectively. Ammonia and phosphor recovery were added into these two systems to produce valuable products and alleviate inhibition.