Bio-hydrogen and methane production from two-phase anaerobic digestion of food waste under the scheme of acidogenic off-gas reuse

Anaerobic hydrolysis of food wastes sourced from bakery (T1), Chinese restaurant (T2), western-style restaurant (T3), and wet market (T4) were performed in leach bed reactors under the scheme of acidogenic off-gas reuse in methanogenic reactor. Results showed that food waste in T3 achieved the highest hydrogen production of 61.0 L/kg.VSadded. Highest activity of hydrogenase in both leachate and digestate samples confirmed the superior performance of H-2 production in T3. Mixed acid fermentation with domination of acetate and butyrate was observed in all four treatments, whereas variations in quantification and speciation of the acidogenic products were closely related to the composition of substrates. High volatile solids (VS) removal (76.7%) was observed in T3 while VS reduction rates of the other treatments ranged from 37 to 55%. High COD production of 0.65 gCOD /g.VSadded together with the reuse of elevated acidogenic off-gas ensured the highest specific CH4 production of 0.42 L/g.VS(added )in T3.