A Full-Scale Comparative Study of Conventional and Side-Stream Enhanced Biological Phosphorus Removal Processes

Abstract

In this study, a full-scale pilot testing was performed with side-by-side operation of a conventional enhanced biological phosphorus removal (EBPR) process and a side-stream EBPR (S2EBPR) process. A comparison of the performance, activities and population dynamics of key functionally relevant populations between the two configurations were carried out. The results demonstrated that, with the same influent wastewater characteristics, S2EBPR configuration showed more effective and stable orthophosphate (PO4-P) removal performance (up to 94% with average effluent concentration down to 0.1 mg P/L) than conventional EBPR, especially when the mixers in side-stream reactor were operated intermittently. Mass balance analysis illustrated that both denitrification and EBPR performance have been enhanced in S2EBPR configuration through diverting primary effluent to anoxic zone and producing additional carbon (~40%) via fermentation in side-stream reactor. Microbial characterization showed that there was no significant difference in the relative abundances of Ca. Accumulibacter (~5.9%) and Tetrasphaera (~16%) putative polyphosphate-accumulating organisms (PAOs) between the two configurations. However, lower relative abundance of known GAOs was observed in S2EBPR configuration (1.1%) than the conventional one (2.7%). A relatively higher PAO activity and increased degree of dependence on glycolysis pathway than TCA cycle was observed in S2EBPR configuration using P release and uptake batch test. Adequate anaerobic solid retention time (SRT) and conditions that generate continuous and slow feeding/production of volatile fatty acid (VFA) with higher composition percentage of propionate in the side-stream reactor of S2EBPR process likely provide a competitive advantage for PAOs over GAOs.

Microbial synergies and dynamics in biological nutrient removal processes

“…On the other hand, a low carbon environment was always maintained, which was considered to encourage the growth of PAO than GAO as the latter could not survive well in low carbon environment (Tu, 2012). A recent study also reported that PAO could be favored against GAO by the side-stream sludge hydrolysis or a longer anaerobic period (Wang et al, 2018), which agreed the previous work of Stokholm-Bjerregaard et al (2015). Further study would be required to investigate on the competition between PAO and GAO with continuous low carbon supply under warm climate.…”

Molecular Evidence of Internal Carbon-Driven Partial Denitrification Annamox (PdNA) in a mainstream Pilot A-B System Coupled with Side-stream EBPR treating municipal wastewater

“…2). Second, our previous study via Ramanbased observation suggested that the PHA-containing cells were significantly higher in the S2EBPR system in comparison to those in the conventional EBPR systems (Wang et al, 2021;Wang et al, 2018). Coupling of internal carbon (PHA) utilization and partial denitrification were also observed by others (Ji et al, 2017;Krasnits et al, 2013;Tu et al, 2019;Wang et al, 2019b).…”

Assessing the performance of polyphosphate accumulating organisms in a full‐scale side‐stream enhanced biological phosphorous removal

“…Before performing the activity test, a 30‐min aeration was applied to deplete the sludge from remaining organics to obtain a soluble COD <20 mg/L (Wang et al, 2018). This pre‐aeration step ensures the designed initial COD concentration is achieved in the batches.…”