Carbon and phosphorus transformations in a full-scale enhanced biological phosphorus removal process

Carbon and phosphorus transformations in a full-scale enhanced biological phosphorus removal (EBPR) process was followed during 1 year. A correlation between the soluble phosphorus uptake in the process and the potential substrate for bio-P bacteria, measured as the volatile fatty acid (VFA) potential, in the influent wastewater was found. The results indicated that approximately 20 mg VFA-COD were required to remove 1 mg of soluble phosphorus. In the anaerobic stage of the process, poly-β-hydroxyalcanoic acids (PHA) were produced in an amount of 1.5 mg PHA-COD per mg of VFA-COD taken up by bio-P bacteria. Furthermore, a release of 0.31 mg of phosphate-P per mg of PHA-COD formed was observed in the anaerobic stage. Most of the released phosphate could be accounted for by a decrease in the polyphosphate content of the biomass in the anaerobic stage. Most of the results obtained were very well in agreement with the biochemical model for EBPR suggested by Smolders et al. (1994a).