METABOLIC MODEL OF THE AEROBIC METABOLISM OF POLYPHOSPHATE ACCUMULATING ORGANISMS WITH A PROPIONATE CARBON SOURCE

In enhanced biological phosphorus removal (EBPR) systems, polyphosphate accumulating organisms (PAOs) are primarily responsible for removing phosphate from wastewater. Propionate is an abundant carbon substrate in many EBPR plants. It has been suggested in some studies to be a more favourable substrate than acetate for EBPR processes, through providing PAOs an advantage over their carbon competitors, the glycogen accumulating organisms (GAOs). The aerobic metabolism of PAOs enriched with a propionate carbon source is studied in this paper. A metabolic model is proposed and experimentally validated to characterise the aerobic biochemical transformations by PAOs. The model predicts very well the experimental data obtained from the enriched PAO culture through solid, liquid and gas-phase analysis. This model may be combined with previously formulated metabolic models to better describe the biochemical activity of PAOs in full-scale treatment systems with acetate and propionate as the primary carbon sources. Furthermore, it can also facilitate the study on the impact of different carbon sources on the PAO and GAO competition.