As phosphorus limits are becoming increasingly stringent in biological wastewater treatment processes, the number of treatment plants that are striving to achieve enhanced biological phosphorus removal (EBPR) is increasing. In summary, maintaining stable EBPR involves sustaining adequate populations of bacteria that are recognized to store higher percentages of phosphorus (polyphosphate) by weight than other bacteria that generally compete in treatment systems.
For EBPR microbes — polyphosphate accumulating organisms (PAOs) — to manifest, optimal conditions must be achieved. These conditions most often involve a designated anaerobic selector zone in which PAOs store volatile fatty acids under anaerobic conditions, which are then converted
