Degradation of propionate and its precursor: the role of nutrient supplementation

Abstract

The role of nutrient supplementation on anaerobic degradation of propionate and its precursors was investigated in this study. Substrates used in this study were propionate, VFAs (from dog food-simulated primary sludge), and glucose. For propionate degradation, a pH-Stat system was used. Degradation of VFAs from dog food degradation was investigated by using a batch reactor while glucose degradation was investigated by using a semi-continuous fed system. Degradation of propionate and glucose were performed under mesophilic temperatures, while degradation of VFAs from dog food degradation was performed under both mesophilic and thermophilic temperatures. The results demonstrated that nutrient supplementation played an important role in degradation of all substrates tested. For propionate degradation, addition of iron, cobalt, and nickel (10, 1,1 mg/1, respectively) and/or yeast extract (100 mg/1) were found to enhance the propionate utilization rate by about double that of the control. For glucose, yeast extract addition caused higher gas production and lower effluent COD. For the degradation of VFAs produced from dog food degradation, daily calcium addition to a thermophilic batch-fed CSTR showed a higher gas production (75%) vs. the control.