Optimization of water replacement during leachate recirculation for two-phase food waste anaerobic digestion system with off-gas diversion

Luo, Liwen; Kaur, Guneet; Zhao, Jun; Zhou, Jun; Xu, Suyun; Varjani, Sunita; Wong, Jonathan W.C.

Optimization of water replacement during leachate recirculation for two-phase food waste anaerobic digestion system with off-gas diversion

2021

An integrated two-phase AD with acidogenic off-gas diversion from a leach bed reactor to an upflow anaerobic sludge blanket was developed for improving methane production. However, this system had its own technical limitation such as mass transfer efficiency for solid-state treatment. In order to optimize the mass transfer in this two phase AD system, leachate recirculation with various water replacement rates regulating the total solids contents (TS) at 12.5%, 15%, and 17.5% was aim to investigate its effect on methane generation. The solubilization of food waste was increased with decreasing TS content, while the enzymatic hydrolysis showed the opposite trend. A TS contents of 15% presented the best acidogenic performance with the highest hydrogen yield of 30.3 L H₂/kg VSₐddₑd, which subsequently resulted in the highest methane production. The present study provides an easy approach to enhance food waste degradation in acidogenic phase and energy conversion in methanogenic phase simultaneously.

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