Acidogenic fermentation of food waste in a leachate bed reactor (LBR) at high volumetric organic Loading: Effect of granular activated carbon (GAC) and sequential enrichment of inoculum

This study investigated the impact of different granular activated carbon (GAC) loadings and inoculum enrichment on acidogenic fermentation of food waste in a leachate bed reactor (LBR) operated at a high volumetric organic loading of 49 g VS/L_reactor. LBR with a high GAC loading of 0.51 g GAC/g VS_{food waste} achieved hydrolysis yield of 620 g SCOD/kg VS_added, significantly (P ≤ 0.05) higher to that obtained for LBRs with low or no GAC loading. A high GAC loading also resulted in a higher acidification yield of 507 g COD_SCFA/kg VS_added. Butyrate dominated the short-chain fatty acid (SCFA) composition by constituting 57-60 % of total SCFA at high GAC loadings, while the composition of acetate (38-40 %) and butyrate (36-38 %) were similar at lower GAC loadings. Inoculum enrichment further improved the hydrolysis and acidogenesis yields by 10-22 % resulting in the final hydrolysis yield of 683 g SCOD/kg VS_added and acidification yield of 617 g COD_SCFA/kg VS_added.