Biogas energy production from tropical biomass wastes by anaerobic digestion

• Biogas energy yield of tropical biomass waste was evaluated.
• Liquid anaerobic digestion (L-AD) is effective for treating tropical food wastes.
• Solid-state anaerobic digestion (SS-AD) is suitable for treating albizia biomass.
• Albizia biomass showed higher methane yield than similar lignocellulosic biomass.

Anaerobic digestion (AD) is an attractive technology in tropical regions for converting locally abundant biomass wastes into biogas which can be used to produce heat, electricity, and transportation fuels. However, investigations on AD of tropical forestry wastes, such as albizia biomass and food wastes, such as taro, papaya, and sweet potato, are limited. In this study, these tropical biomass wastes were evaluated for biogas production by liquid AD (L-AD) and/or solid-state AD (SS-AD), depending on feedstock characteristics. When albizia leaves and chips were used as feedstocks, L-AD had greater methane yields (161 and 113 L kg−1 VS, respectively) than SS-AD (156.8 and 59.6 L kg−1 VS, respectively), while SS-AD achieved 5-fold higher volumetric methane productivity than L-AD. Mono-digestion and co-digestion of taro skin, taro flesh, papaya, and sweet potato achieved methane yields from 345 to 411 L kg−1 VS, indicating the robustness of AD technology.