Functionally Relevant Microorganisms to Enhanced Biological Phosphorus Removal Performance at Full‐Scale Wastewater Treatment Plants in the United States

Abstract

The abundance and relevance of Accumulibacter phosphatis (presumed to be polyphosphate-accumulating organisms [PAOs]), Competibacter phosphatis (presumed to be glycogen-accumulating organisms [GAOs]), and tetrad-forming organisms (TFOs) to phosphorus removal performance at six full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plants were investigated. Coexistence of various levels of candidate PAOs and GAOs were found at these facilities. Accumulibacter were found to be 5 to 20% of the total bacterial population, and Competibacter were 0 to 20% of the total bacteria population. The TFO abundance varied from nondetectable to dominant. Anaerobic phosphorus (P) release to acetate uptake ratios (P rel /HAc up ) obtained from bench tests were correlated positively with the abundance ratio of Accumulibacter/(Competibacter 1TFOs) and negatively with the abundance of (Competibacter 1TFOs) for all plants except one, suggesting the relevance of these candidate organisms to EBPR processes. However, effluent phosphorus concentration, amount of phosphorus removed, and process stability in an EBPR system were not directly related to high PAO abundance or mutually exclusive with a high GAO fraction. The plant that had the lowest average effluent phosphorus and highest stability rating had the lowest P rel /HAc up and the most TFOs. Evaluation of full-scale EBPR performance data indicated that low effluent phosphorus concentration and high process stability are positively correlated with the influent readily biodegradable chemical oxygen demand-to-phosphorus ratio. A system-level carbon-distribution-based conceptual model is proposed for capturing the dynamic competition between PAOs and GAOs and their effect on an EBPR process, and the results from this study seem to support the model hypothesis. Water Environ. Res., 80, 688 (2008).

Long-term study on the impact of temperature on enhanced biological phosphorus and nitrogen removal in membrane bioreactor

“…The aerobic P uptake rates and anaerobic P release rates with the mixed liquor biomass were comparable to the values found in other studies for full-scale EBPR plants (Gu et al 2008;Gu et al 2005;Lopez-Vazquez et al 2008). …”

“…To investigate the PAOs activities in the different systems, batch P uptake and release tests (in duplicate) were carried out. Details of the P uptake and release tests can be found elsewhere (Gu et al 2008). Briefly, sodium acetate was added (80 mg/l as acetate) at the beginning of the anaerobic conditions (maintained with nitrogen gas purging for 45 minutes), then aerobic phase was maintained for 3 hrs.…”

“…When operated successfully, the EBPR process can be an inexpensive option to reach relatively high phosphorus removal efficiency. One main challenge remaining for effective application of EBPR process is how to further improve its reliability and stability since many full-scale EBPR facilities still experience unpredicted upsets and performance fluctuations (Amann et al 1990, Gu et al 2008, Gu et al 2005 due to factors that are not completely understood (Oehmen et al 2007). In some cases, external disturbances such as high rainfall, excessive nitrate loading to the anaerobic reactor, or nutrient limitation may explains these process upsets.…”

From macro to lab-scale: Changes in bacterial community led to deterioration of EBPR in lab reactor

“…The relative activity of PAOs and GAOs can be estimated on the basis of an analysis of P i release and C uptake rates [4,7]. The P rel /C upt ratio, which was determined in the current study on Day 1 as equal to 0.28 P-mol C-mol -1 , is quite low when compared to the values reported in the literature [4,29,54] for Accumulibacter and acetate (0.30-0.75 P-mol C-mol -1 ) or propionate (0.35-0.45 P-mol C-mol -1 ). However, these cited values were determined for reactors fed with a single VFA (acetate or propionate), whereas in the current study, the feed included a mixture of more complex organic substrates and not just acetate.…”

Granule Formation Mechanisms within an Aerobic Wastewater System for Phosphorus Removal

“…Probably more plausible in full-scale systems is the occurrence of microcolony aggregation. While there are lower abundances of "Candidatus Accumulibacter phosphatis" or other crucial organisms present during microcolony aggregation, full-scale systems typically have between 5 and 20% "Candidatus Accumulibacter phosphatis" and are still capable of successful nutrient removal (14). Further research is required to fully understand the fundamental microbial aspects related to both potential granulation mechanisms and whether they occur at full scale.…”