Characterization of the denitrifying fraction of phosphate accumulating organisms in biological phosphate removal

Results of experimental investigations are presented that strongly support the hypothesis that PAO from activated sludge systems consist of two groups: a) denitrifying PAO (DNPAO) capable of using oxygen and nitrate and b) non-denitrifying PAO (non-DNPAO) only able to use oxygen. Batch experiments were performed in which activated sludge obtained from a pilot scale BiodeniphoTM was submitted to a sequence of anaerobic/anoxic/aerobic, …