Enhanced food waste degradation in integrated two-phase anaerobic digestion: Effect of leachate recirculation ratio

The aim of this study is to evaluate the effect of leachate recirculation at a ratio of 0%, 25%, 50% or 75% of collected leachate from the Leach Bed Reactor (LBR) on food waste digestion efficiency and its subsequent methane production in the second phase of a two-phase anaerobic system. Higher hydrolysis-acidogenesis efficiency and lower energy loss were achieved in LBR with higher leachate recirculation ratio. Better biochemical balance between metabolic products and microorganisms in leachate was revealed under 50% leachate recirculation ratio, which leads to the highest hydrogen production yield in LBR resulting the highest methane production yield in the corresponding methanogenic phase which was at least 15% higher than that in other conditions. This provides an easy approach to enhance the hydrolysis efficiency and in the same time a biochemical balanced leachate to enhance methanogenic reaction of a two-phase anaerobic digestion.