Abstract:An anaerobic baffled reactor (ABR) provides spatial separation between acidogenic and methanogenic populations, and thus allows different bacterial groups to develop under their optimal conditions. It essentially behaves as a two-phase system. Most of the past studies on microbial populations had focused on methanogenesis. The most common observation is a shift between the two acetoclastic methanogens Methanosarcina sp. and Methanosaeta sp. However, little has been done on the population of acidogenesis. Be...