Evaluation of Intracellular Polyphosphate Distribution in the PAOs Using Raman Microscopy

A newly developed Raman microscopy method was applied to evaluate the intracellular inclusion and dynamics of polyphosphate in PAOs in EBPR processes. Observation of polyphosphate at individual cell level indicated that there are distributed states of cells in terms of polyphosphate content at any given time, suggesting that agent-based distributive modeling would more accurately reflect the behavior of an EBPR process than the traditional average-state based modeling. In this study, we applied this method to reveal the intracellular polyphosphate content distribution among different lab-scale and full-scale EBPR systems. The results, for the first time, showed that the level of inclusion of polyphosphate quantity in individual PAO cell and the distribution of intracellular polyphosphate vary for different EBPR systems. Whether this difference is due to the process variables, diversity of PAOs organisms and/or due to the heterogeneity of metabolic status among individual cells remains unclear. The advantage of the Raman method is that it allows for the evaluation of kinetics for cellular polyphosphate metabolism to a very detailed extent and at the cellular level, which will lead to more fundamental and better understanding of the mechanisms of phosphorus removal in EBPR processes.