COMPETITION BETWEEN POLYPHOSPHATE AND POLYSACCHARIDE ACCUMULATING BACTERIA IN ENHANCED BIOLOGICAL PHOSPHATE REMOVAL SYSTEMS

The competition between polyphosphate accumulating bacteria (PP bacter ia) and another group of microorganisms (tentatively named ''G bacteri a'') has been observed in laboratory sequencing batch reactors exhibit ing enhanced biological phosphate removal (EBPR). The ''G bacteria'', which accumulate polysaccharide instead of polyphosphate, were able to dominate the anaerobic oxic system even though acetic acid was readil y available. When acetate was used as the sole source of organic carbo n in an anaerobic-oxic sequencing batch reactor, however, PP bacteria successfully competed for acetate with ''G bacteria''. The molar ratio of phosphate released to acetate taken up in the anaerobic stage vari ed from 0 to 0.78 and depended on the ratio of the numbers of PP bacte ria to ''G bacteria'' in the activated sludge.