Methane Fermentation of Coffee Waste by Thermophilic AnMBR

Abstract

 Coffee Grounds are deemed to be difficult substrates for thermophilic anaerobic digestion due to its complex composition and unknown system inhibition. This work investigated the biodegradability of coffee waste by batch experiment and the feasibility of long term operation of the AnMBR. COD conversion efficiency of 75% and methane yield of 290mlCH₄/g-COD_added was obtained in batch experiment. The amendments of alkalinity and micronutrients was obligatory to maintain process stability in long term experiment. Mixing sludge 15% into substrate enhanced the stability of system. Biogas production of 1.93L-Biogas/L-reactor·d and methane content of 60.6% was obtained in co-digestion process. Membrane operation continue 139 days without significant decrease of flux.