Quantitative DNA Stable Isotope Probing To Identify Active Phosphate Accumulating Organisms Within a Side-stream Enhanced Biological Phosphorus Removal Process

The side-stream enhanced biological phosphorus removal (S2EBPR) process is an emerging technology for reliable and sustainable biological phosphorus removal in water resource recovery facilities. In S2EBPR facilities, a side-stream fermenter consistently provides volatile fatty acids (VFAs) to the mainstream reactors to tolerate fluctuating carbon loads among other advantages for optimal EBPR performance. Currently, the microbial community and activity of S2EBPR systems is not well characterized. This study investigated the influence of VFAs on the EBPR-related microbial communities in two full-scale facilities. We found that S2EBPR-related microbial community and their activity is influenced by the composition of VFAs, e.g., Tetrasphaera was active only with propionate as substrate, unlike Ca. Accumulibacter and Dechloromonas, which could uptake both acetate and propionate. Further, with propionate, Tetrasphaera was less active compared to Ca. Accumulibacter and Dechloromonas. This research expands our understanding of microbial ecophysiology of S2EBPR systems and has implications for optimizing EBPR performance.