Rethinking the Mechanisms of Biological Phosphorus Removal

Abstract

Enhanced biological phosphorus removal (EBPR) was observed in high-rate, non-nitrifying plants in the United States that were operated in a plug-flow mode. In facilities designed for nitrification and denitrification, a first-stage anaerobic zone, free of nitrate and nitrite was needed to accomplish EBPR, and this is referred to as the Phoredox (a.k.a. the AO and A2O) process. When a biological mechanism responsible for EBPR was proposed, these treatment configurations were accepted as normal practice, but many later observations showed that more reliable phosphorus removal could be achieved with alternative configurations. This paper discusses the development of alternative configurations for EBPR and the likelihood that a host of phosphate accumulating organisms (PAOs) that react to different environmental conditions might play a much bigger role in reliable and sustainable biological phosphorus removal. The conclusion is that conventional designs might have inadvertently selected for less efficient PAOs, while alternative configurations allowed for the growth of multiple PAO species such as Tetrasphaera, which can ferment higher carbon forms and take up phosphorus under anoxic conditions.

Survey of full‐scale sidestream enhanced biological phosphorus removal (S2EBPR) systems and comparison with conventional EBPRs in North America: Process stability, kinetics, and microbial populations

“…During a pilot test at the Pinery Water Facility in Colorado, the average secondary effluent TP concentration was less than 0.5 mg P/L, without chemical addition (Barnard et al, 2010). The intermittent mixing operation at this facility resulted in an estimated SRT in the UMIF reactor of approximately 3 days (Barnard, Dunlap, & Steichen, 2016). Two facilities near Minneapolis, Minnesota (Seneca and St.…”

Microbiome engineering: enhancing climate resilience in corals

“…Cycling in this way results in a selection of microorganisms with a higher capacity for intracellular accumulation of polyphosphates (Blackall et al 2002). The discovery of microorganisms as the main drivers for wastewater treatment was a revelation, and modern methods are now informed by more rigorous microbiological and microbial ecological studies to enhance treatment efficiency (Barnard et al 2017). Although wastewater treatment is a closed system, as opposed to the natural system in which corals are found, this built-environment example clearly demonstrates that working backward from experimental manipulations can result in important advances in ME techniques, and provides a unique view on using indirect selection pressure to manipulate a microbial community to select a targeted function.…”

Sidestream RAS Fermentation for Stable Bio-P Combined with Short Cut Nitrogen Removal in an A/B Process

“…By using the information presented by J. Barnard et al (2017) and Tooker et al (2017), a sidestream biological phosphorus removal (SBPR) reactor was implemented to accept a small portion of RAS and ferment it before returning it to the main stream process.…”

“…Some Tetrasphaera have shown to be capable of taking up VFA, but not all, and those that have the ability to take up VFA do not cycle polyP, effectively rendering them useless to removing orthoP (J. Barnard et al, 2017). Even though Tetrasphaera have not been known to utilize VFA in an effective manner for taking up orthoP like Accumulibacter, they are able to produce VFA during fermentation that could be used by other PAOs.…”