Survey of Full Scale Side-Stream EBPR Facilities and Comparison with Conventional EBPR: Process Stability, Kinetics and Microbial Ecology

Abstract

12Side-stream EBPR process (S2EBPR) is a new alternative to address the common challenges in 13 EBPR related to weak wastewater influent and to improve EBPR process stability. A systematic 14 evaluation and comparison of the process performance and microbial community structure 15 between four S2EBPR with conventional EBPR configurations in US was conducted. The 16 statistical analysis suggested higher performance stability in S2EBPR than the conventional 17 EBPRs, although possible bias is recognized due to variations in the target permit levels and 18 plant-specific factors among the plants. Total and known PAOs and GAOs abundance and 19 identities were investigated with FISH, DAPI, 16S rRNA gene sequencing and Raman 20 microspectroscopy. The results suggested comparable relative PAO and Candidatus 21Accumulibacter abundances in S2EBPR and conventional EBPR systems. Tetrasphaera, a 22 putative PAO, was also found at similar abundance in S2EBPR as in conventional facilities, 23 whereas the relative abundance of known GAOs was lower in S2EBPR than those typically seen 24 at conventional EBPRs. Microbial community analyses via 16S rRNA gene amplicon sequencing 25 revealed differences in the community phylogenetic fingerprints between S2EBPR and 26 conventional plants. Shannon and Inverse Simpson indices, which are combined measures of 27 Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted:

Modeling Versatile and Dynamic Anaerobic Metabolism for PAOs/GAOs Competition Using Agent-based Model and Verification via Single Cell Raman Micro-spectroscopy

“…4–8 . Meanwhile, the existence of GAOs does not necessarily deteriorate EBPR performance as long as PAOs are kinetically favored 1,9,10 .…”

“…The performance stability of EBPR has been a concern for its wide implementation in practice and its sustainability advantages are often offset by the needs to have chemicals standby for ensuring reliable P removal performance to consistently meet compliance 1,9,11 . Many facilities still suffer from inconsistent performance with unpredicted upsets, particularly for those with relatively weak influent readily biodegradable COD (rbCOD) 1,5,6,12 .…”

“…Many facilities still suffer from inconsistent performance with unpredicted upsets, particularly for those with relatively weak influent readily biodegradable COD (rbCOD) 1,5,6,12 . An emerging technology that has been demonstrated to successfully address this common stability challenge is side-stream RAS and mixed liquor hydrolysis/fermentation-based side-stream EBPR (S2EBPR) 1,9 , 11,13–18 . S2EBPR refers to modified EBPR configurations that include diversion of a portion of RAS or anaerobic mixed liquor to a side-stream reactor, where simultaneous VFA production via sludge hydrolysis and fermentation and PAO activity-related P release and carbon uptake occur.…”

“…S2EBPR refers to modified EBPR configurations that include diversion of a portion of RAS or anaerobic mixed liquor to a side-stream reactor, where simultaneous VFA production via sludge hydrolysis and fermentation and PAO activity-related P release and carbon uptake occur. Compared to conventional EBPR design, the S2EBPR offers a suite of advantages including influent-carbon independent condition for PAO enrichment that eliminates the influences of fluctuating influent loads, more controllable lower-redox environment with more complex VFA composition that provides more favorable selection of PAOs over GAOs, flexible implementation configurations and potential reduction of carbon footprint and denitrification enhancement by diverting more influent carbon to denitrification 1,9,11,19–22 ..…”

“…While full-scale processes demonstrated the potential promises and advantages of S2EBPR 9,11,13–18 , existing knowledge gaps in fundamental understanding of the biochemical mechanisms and microbial ecology involved in S2EBPR hampers its wider application and implementation. Design and optimization of S2EBPR requires adequate EBPR models that can capture the underlying key mechanisms involved in the S2EBPR such as the VFA production via hydrolysis and fermentation, and PAO and GAO competition in the extended-anaerobic side-stream reactor.…”