Anaerobic co-digestion of kitchen waste and fruit/vegetable waste: lab-scale and pilot-scale studies.

The anaerobic digestion performances of kitchen waste (KW) and fruit/vegetable waste (FVW) were investigated for establishing engineering digestion system. The study was conducted from lab-scale to pilot-scale, including batch, single-phase and two-phase experiments. The lab-scale experimental results showed that the ratio of FVW to KW at 5:8 presented higher methane productivity (0.725 L CH4/g VS), and thereby was recommended. Two-phase digestion appeared to have higher treatment capacity and better buffer ability for high organic loading rate (OLR) (up to 5.0 g(VS) L(-1) d(-1)), compared with the low OLR of 3.5 g(VS) L(-1) d(-1) for single-phase system. For two-phase digestion, the pilot-scale system showed similar performances to those of lab-scale one, except slightly lower maximum OLR of 4.5 g(VS) L(-1) d(-1) was allowed. The pilot-scale system proved to be profitable with a net profit of 10.173$/ton as higher OLR (⩾ 3.0 g(VS) L(-1) d(-1)) was used.