COMPETITION BETWEEN POLYP AND NON-POLYP BACTERIA IN AN ENHANCED PHOSPHATE REMOVAL SYSTEM

The competition between polyphosphate accumulating bacteria (PolyP bac teria) and a group of microorganisms not accumulating polyphosphate (t entatively named ''G bacteria'') was observed in a laboratory sequenci ng batch reactor exhibiting enhanced biological phosphate removal (EBP R). The ''G bacteria'' were able to dominate the anaerobic-oxic system even though acetate was readily available. When acetate was used as t he sole source of organic carbon, however, PolyP bacteria were able to compete successfully with ''G bacteria.'' The molar ratio of phosphat e released to acetate taken up in the anaerobic stage varied from 0 to 0.78 and depended on the ratio of the numbers of PolyP bacteria to '' G bacteria'' in the activated sludge.