Competition between polyphosphate and polysaccharide accumulating bacteria in enhanced biological phosphate removal systems

Abstract The competition between polyphosphate accumulating bacteria (PP bacteria) and another group of microorganisms (tentatively named “G bacteria”) has been observed in laboratory sequencing batch reactors exhibiting 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 readily available. When acetate was used as the sole source of organic carbon 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 varied from 0 to 0.78 and depended on the ratio of the numbers of PP bacteria to “G bacteria” in the activated sludge.