Performance and kinetic evaluation of a semi-continuously fed anaerobic digester treating food waste: Effect of trace elements on the digester recovery and stability

This study investigated the effects of trace elements (TEs: Fe, Co, and Ni) on the anaerobic digestion of food waste in laboratory scale semi-continuously fed anaerobic digesters. The digesters were operated for approximately 460 d at organic loading rates (OLRs) ranging from 1.0 to 5.0 g VS L-1 d(-1) at 37 degrees C. Results showed that methane production was severely inhibited when volatile fatty acids (VFAs) concentration was 30000 mg L-1 at OLR of 4.0 g VS L-1 d(-1) without the addition of TEs. However, the inhibition was gradually decreased and the methane production increased from 0.13 up to 0.44 L g(-1) VSadded when the TEs was added. Fe was proved to be the essential element in maintaining the stability of the digester. The conversion coefficient of substrate into biogas (Y-S/G) was 1.00 and 1.26 g VSremoved L-1 biogas with and without TEs addition, respectively. The estimated biomass yield with feeding TEs (0.06 g VSS g(-1) CODremoved) was higher three times than that without TEs (0.02 g VSS g(-1) CODremoved). (C) 2014 Elsevier Ltd. All rights reserved.