Two-phase anaerobic digestion of a mixture of fruit and vegetable wastes

Abstract

Two-phase anaerobic digestion of a mixture of fruit and vegetable solid wastes was studied at laboratory scale, using digesters operated in the mesophilic range. An optimal configuration for a hybrid (up-flow anaerobic sludge bed-anaerobic filter) digester was determined, in order to improve the methanogenic step. Biodegradation achieved in two weeks was around 75%. The process was stable, even when the pH was at the lowest levels (around 5, in the hydrolyzer). The distribution and concentration of volatile fatty acids produced was also studied.