Dry anaerobic digestion of food waste under mesophilic conditions: Performance and methanogenic community analysis

The performance of dry anaerobic digestion (AD) of food waste was investigated under mesophilic conditions and the methanogenic community was investigated using 454 pyrosequencing. Stable dry AD was achieved by hydraulic retention time (HRT) control without the addition of alkali agents. The average CH4 production rate, CH4 content, and volatile solid reduction rate were 2.51 ± 0.17 m3/m3/d, 66 ± 2.1%, and 65.8 ± 1.22%, respectively, at an HRT of 40 d. The methanogenic community of the seed sludge experienced a significant reduction in genus diversity from 18 to 4 and a dominant methanogenic shift from hydrogenotrophic to acetoclastic groups after the acclimation under dry condition. Almost all sequences of the dry anaerobic digester were closely related with those of Methanosarcina thermophila with similarity of 96.4–99.1%. The experimental results would serve as useful information to understand the dry AD system.