Real-time recovery strategies for volatile fatty acid-inhibited anaerobic digestion of food waste for methane production

[Display omitted] •Instability of long-term anaerobic digestion of FW was verified.•Propionate appeared as the main inhibitory VFA.•Recovery was reestablishment of dynamic balance of acetogenesis and methanogenesis.•Trace elements were key drivers of process recovery and rebalance.•Real-time recovery strategies for VFA-inhibited anaerobic system of FW were given. This study investigated effects of real-time recovery strategies on VFA (volatile fatty acid)-inhibited anaerobic system of FW (food waste) and identified key driver of process recovery. The long-term anaerobic system of FW encountered serious VFA (mainly propionate) inhibition. The pH adjustment (PA) strategy could not reverse process imbalance but only delayed the process failure. The short-term effect of reinoculation (RI) strategy was greatly effective, but its long-term effect was non-sustainable. Trace elements were key drivers of process recovery owing to their indispensable roles in activating methanogenesis and therefore stimulating propionate conversion. From the viewpoint of economic feasibility, the single strategy of trace elements supplementation (TE) and the combinational strategy of PA + TE were respectively recommended in the initial and medium VFA-inhibition stages. The three-in-one strategy of PA + TE + RI was always effective but was costly. This study provided practical guidance on real-time recovery of VFA-inhibited anaerobic system of FW.