Single-Cell Raman Spectroscopy-Based Phenotyping Revealed Metabolic Difference Between Side-Stream and Conventional Enhanced Biological Phosphorus Removal Systems

The anthropogenic discharge of phosphorus (P) needs to be managed as it will cause undesirable eutrophication and water quality deterioration in receiving waters (Cordell et al., 2009, Rittmann et al., 2011). As an alternative to conventional mainstream enhanced biological phosphorus removal (EBPR) process, the side-stream EBPR (S2EBPR) process involves a side-stream anaerobic reactor where the return activated sludge (RAS) or mixed liquor suspended solids (MLSS) undergoes hydrolysis and fermentation, and the overflow from this reactor is directed back to the mainstream biological process. Recent research breakthroughs and successful implementation of S2EBPR processes promise the potential to perform EBPR without reliance on influent carbon (Barnard et al., 2017, Tooker et al., 2017). Consequently, the incorporation of S2EBPR process with carbon conversion process could be expected as sustainable, low carbon-footprint, energy-efficient, and even energy-positive biological nutrient removal (BNR) processes.