Impact of continuous leachate recirculation during solid state anaerobic digestion of Miscanthus

Continuous leachate recirculation was performed in a solid-state anaerobic digestion (SS-AD) in an attempt to enhance and improve the biogas (methane) production from Miscanthus sp. Furthermore, microbial community dynamics was analysed, and liaised with the process performance and stability. Results showed that the SS-AD process without leachate recirculation showed significantly higher degradation degree of cellulose/hemicellulose (35% higher) as well as methane yield (65% higher) compared to the leachate recirculation processes. Continuous recirculation led to the transpose of active microbial groups from the main reactor to the leachate holding vessel, a condition which could be attributed to the poor degradation efficiency. Therefore, for the enhancement of biogas production in a SS-AD of structural mono-substrate with leachate recirculated process, the recirculation speed should be carefully chosen and optimized to minimize the disturbance and wash-out of the viable microbial consortium.