Competition between PolyP and Non-PolyP Bacteria in an Enhanced Phosphate Removal System

The competition between polyphosphate accumulating bacteria (PolyP bacteria) and a group of microorganisms not accumulating polyphosphate (tentatively named "G bacteria") was observed in a laboratory sequencing batch reactor exhibiting enhanced biological phosphate removal (EBPR). The "G bacteria" were able to dominate the anaerobic-oxic system even though acetate was readily available. When acetate was used as the sole source of organic carbon, however, PolyP bacteria were able to compete successfully 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 PolyP bacteria to "G bacteria" in the activated sludge.