2007 Volume 43 Issue 1 Pages 51-62
To evaluate the effectiveness of the separation of polyphosphate-accumulating organisms (PAOs) and glycogen accumulating organism (GAOs)/G-bacteria from the phylogenetically high-diverse activated sludge using the buoyant density separation, activated sludge was collected from the acetate-fed SBR and the microbial community was determined. The activated sludge sample collected at the end of the aerobic phase was subjected to the buoyant density separation. The microbial communities of separated sludge were fingerprinted by terminal restriction fragment length polymorphism (T－RFLP) analysis. The microbial community analysis exhibited that Candidatus ‘Accumulibacter phosphatis’ known as PAOs, Defluvicoccus- relative G-bacteria and the group GB known as GAOs and some organisms playing an important role for nitrogen removal existed in the SBR. The T－RFLP analysis for each fraction of the buoyant density separation revealed that Cand. ‘Accumulibacter phosphatis’ was selectively concentrated in the high-density fraction. Although some unidentified peaks were also the prominent, Defluvicoccus vanus-relative G-bacteria were failed to concentrate. The unique T－RF derived from organisms including the group GB was the prominent in the high-density fraction. The Acidobacteria, the Bacteroidetes and the Nitrospira were disappeared in the high-density fraction. Even though some bacteria related to phosphorus removal were eliminated, most of bacterial strains which do not play an important role for phosphorus removal could be eliminated by the buoyant density separation.
