BACTERIAL-POPULATIONS IN A BIOLOGICAL NUTRIENT REMOVAL PLANT

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.