Microbial ecology in long-term up-flow anaerobic reactor operation treating municipal wastewater at low temperatures and variable loadings
Microbial community characterization of the low temperature in anaerobic granules were presented in this study. Granules were taken from up-flow granulated anaerobic reactors at 12, 8.5, 5.5 and 2.5 ?C which were operated continuously over 1025 days by applying a stepwise increase of organic loading rate by intermittent increases to 15.2±0.2 g COD·l-1·d-1. In this study, methanogen communities showed temperature change effected the degradation pathway of organic matter with acetoclastic methanogen and H2-dependent methylotrophic methanogens played significant roles. At 2.5 °C, acetate might be the main precursor of methanogenesis. This successful operation at low temperatures along with microbial community confirmation, the prevalence of psychrotolerant communities was observed throughout long-term reactor operation, indicating the long-term adaptation of the microbial community in granulated biomass through changes in the community structure and low temperature anaerobic treatment potential in pilot and/or full-scale application for treating municipal wastewater.