Methane production from acidic effluent obtained from hydrogen fermentation process of food waste using continuous stirred tank reactor

Abstract

This study investigated the effect of hydraulic retention time (HRT) on methane production from the acidic effluent of a hydrogen fermentation process of food waste using a continuous stirred tank reactor (CSTR). The CSTR was operated at 35 ± 3°C with HRTs of 12, 10, 8 and 6 days (d). The hydrogen content, methane yield (MY) and methane production rate (MPR) were increased with a decrease in HRT from 12 to 10 d. At the HRT of 10 d, the maximum methane content of 71.3%, MY of 155 mL CH4/g-COD and MPR of 4629.1 mL CH4/L d were achieved. However, a further decrease in HRT from 10 to 8 and 6 d resulted in a decrease of methane content, MY and MPR. The main soluble metabolite products obtained at the HRT of 10 d were butyric and acetic acids. The maximum energy production rate obtained at the optimum HRT of 10 d was 185.31 kJ/L d.