ABSTRACT
Enhanced biological phosphorus removal is one important strategy to protect natural waters from eutrophication. It is usually achieved through culturing an activated sludge with alternating anaerobic and oxic conditions, by which polyphosphate accumulating organisms (PAOs), the microorganisms responsible for phosphorus removal in wastewater treatment plants (WWTPs), can be largely enriched. To gain deep understandings regarding this biological phosphorus removal regime, numerous studies
have been made in the past two decades [1,2]. It is widely accepted that PAOs take up available carbon sources anaerobically and store them as poly-b-hydroxyalkanoates (PHAs), with the energy and reducing power mainly gained through polyphosphate cleavage and glycogen degradation, respectively. In the subsequent oxic phase, the stored PHAs are utilized for cell growth, glycogen replenishment, phosphorus uptake, and polyphosphate accumulation [2-4]. This metabolism behavior is considered to provide a selective advantage to PAOs over other populations.
