Real-time carbon monitoring of wastewater using bio-electrochemical sensors coupled with advanced data analysis methods provides WRRFs with an opportunity for efficient wastewater quality monitoring and an early warning tool for plant upsets.

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Enhanced biological phosphorus removal (EBPR) is strongly influenced by the influent ratio of readily biodegradable carbon to soluble phosphorus due to the preferences of phosphorus-accumulating organisms (PAO). The sidestream EBPR (S2EBPR) process redirects a portion of return activated sludge (RAS) to a sidestream fermenter, increasing the availability of biodegradable carbon. In this study, we assessed the performance and microbial community structure of a full-scale S2EBPR demonstration supplemented with external carbon dosing. By the end of the 10 month study period, the demonstration achieved a median effluent orthophosphate of 0.3 mg/L. The microbial community consisted of a common core microbiome in the RAS fermenter, EBPR basin, and nitrification basin. The most abundant PAO detected were Ca. “Dechloromonas phosphorivorans”, while the canonical PAO Ca. “Accumulibacter” and Tetrasphaera were observed in lower relative abundance. In addition to non-canonical PAO enrichment, the glycogen-accumulating organism Ca. “Competibacter” proliferated throughout the study and at some points outnumbered PAO taxa by 30 to 1 with no tangible performance impacts. This study provides insights into successful S2EBPR implementation at a low-carbon facility and improves our understanding of microbial community structure and key PAO and GAO in S2EBPR systems.

Reducing the solids retention time (SRT) of the enhanced biological phosphorus removal (EBPR) process can increase organic carbon diversion to the sidestream for energy recovery, thereby realizing some of the benefits of the high rate activated sludge (HRAS) process. Determining the washout (i.e. minimum) SRT of polyphosphate accumulating organisms (PAOs), therefore, allows for simultaneous phosphorus and carbon diversion for energy recovery from EBPR systems. However, few studies have investigated the washout SRT of PAOs in real wastewater, and little is known of the diversity of PAOs in high rate EBPR systems. Here we demonstrate efficient phosphorus removal (83% orthophosphate removal) in a high rate EBPR sequencing batch reactor fed real primary effluent and operated at 20 °C. Stable operation was achieved at a total SRT of 1.8 ± 0.2 days and hydraulic retention time of 3.7–4.8 hours. 16S rRNA gene sequencing data demonstrated that Accumulibacter were the dominant PAO throughout the study, with a washout aerobic SRT between 0.8 and 1.4 days. qPCR targeting the polyphosphate kinase gene revealed that Accumulibacter clades IIA, IIB and IID dominated the PAO community at low SRT operation, while clade IA was washed out at the lowest SRT values.

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