Keywords: anaerobic digestion, ASBR, anaerobic sequencing batch reactors, granular sludge, filamentous microorganisms, SMA, specific methanogenic activity, wastewater treatment, granules formation
Formation of granules with filamentous microorganisms abundant in anaerobic sequencing batch reactor
The start-up and granulation in a lab-scale Anaerobic Sequencing Batch Reactor (ASBR) fed with synthetic glucose wastewater were investigated. Sludge granulation proceeded after 110 days operation and was completed in approximately 140 days. Scanning electron microscope images showed that filamentous bacteria like Methanosaeta are abundant in the granule and exhibit in a uniform structure. The growth of Methanosaeta can predominate even if the acetate concentration is high in the ASBR. Short filamentous bacteria are observed in the effluent. Batch tests showed that the composition of these filamentous microorganisms included fermentative, syntrophic acetogenic and methanogenic bacteria, with an ecology similar to that of granular sludge.