Research in the area of bacteriological studies of biogical nutrient r
emoval (BNR) systems has emphasized the role of Acinetobacter spp. in
phosphorus removal. The present study was undertaken to enumerate, iso
late and identify bacterial populations from a BNR/activated sludge sy
stem. The most probable numbers (MPN) of volatile fatty acid (VFA) uti
lizers and denitrifiers were determined. Bacterial populations were is
olated from the MPN tubes. Pure cultures of Gram-negative bacteria wer
e identified. Acinetobacter spp. were not the dominant group of bacter
ia recovered from the system. Bacteria belonging to Aeromonas/Vibrio,
coliforms, Pseudomonas and Acinetobacter groups were recovered both on
VFA media and denitrification medium, indicating an overlap in their
role. In the system studied, both phosphorus and nitrogen removal was
carried out by more than one group of bacteria.