ABSTRACT
An attempt to improve process efficiency was carried out by applying recirculation of methanogenic sludge to the influent of an acidogenic reactor during two-phase anaerobic digestion of a soluble organic wastewater. It was intended to investigate its impact as well as to determine its performance at different hydraulic retention times (HRTs). The two-phase system used consisted of an anaerobic packed bed reactor (APBR) as the acidogenic reactor and an upflow anaerobic reactor (UAR) as the methanogenic reactor.
