Analysis of Phosphorus Fractions in EBPR Process and Metabolic Link with Polyphosphate

Polyphosphate (poly-P) is an energy rich biopolymer that plays significant role in enhanced biological phosphorus (P) removal (EBPR) process as an intracellular storage compound, the degradation of which is triggered by energy requirement and intracellular pH maintenance. As traditional assessment of EBPR process relies mainly on the released form of poly-P which is orthophosphate in solution, this study investigated the various fractions of P in EBPR that could be potentially present and are required to be considered for true evaluation of EBPR metabolism. Samples from a continuous flow lab scale EBPR process and from batch testing were subject to P fractionation to obtain the soluble and particulate forms of orthophosphate and poly-P in different EBPR metabolic stages. The results showed the unexpected presence of particulate orthophosphate with good correlation with soluble orthophosphate and also some level of soluble particulate poly-P correlating well with particulate poly-P. Considering the various possible sources of particulate orthophosphate and soluble poly-P, it was concluded that the presence of both particulate orthophosphate and soluble poly-P seems to be linked with poly-P metabolism and EBPR mechanism rather than background reasons. Further investigation is required to understand the significance of various P species in poly-P metabolism.