Performance and dynamic characteristics of microbial communities in an internal circulation reactor for treating brewery wastewater

<div><p>A laboratory-scale internal circulation (IC) anaerobic reactor fed with brewery wastewater was operated at 35°C±1°C. The influent was pumped into the bottom of the IC reactor by a pulse pump, whereas the effluent was drawn from the upper outlet and allowed to flow into the effluent tank. The biogas volume was recorded using a gas container connected to a biogas metre. The results indicated that the maximum organic loading rate (OLR) of the IC reactor was 19.5 kg chemical oxygen demand (COD)/m <sup>3</sup>/day; at which point, the dominant archaeal populations found in the sludge using the polymerase chain reaction with denaturing gradient gel electrophoresis were <i>Methanosaeta</i> species. The COD removal efficiencies of the reactor exceeded 85%, with a maximum specific methane production rate of 210 mL CH<sub>4</sub>/g volatile suspended solids (VSS)/day and a coenzyme F<sub>420</sub> content of 0.16 μmol/g VSS, respectively. The main archaeal species in the sludge samples at different OLRs varied greatly, as compared with the organisms in the inoculated sludge. The dominant archaeal species in the treated sludge at low OLRs were <i>Methanosarcina</i> species, whereas those at high OLRs were <i>Methanosaeta</i> species.</p></div>