The performance and microbial community structure of two bench-scale enhanced biological phosphorous removal (EBPR) reactors were monitored during their startup and subsequent operation. Near-complete phosphate removal was achieved in both reactors within 7 days of inoculation and corresponded with increases in putative PAOs (Candidatus Accumulibacter and Dechloromonas spp.) and glycogen accumulating organisms (GAOs; Ca. Competibacter and Defluviccoccus spp.), as determined by 16s rRNA amplicon sequencing analysis. In one of the experiments a crash in total phosphate removal was observed on the 35th day of operation. Differential abundance testing revealed that drastic increases in organic carbon degraders within the Cytophagia, predatory bacteria (e.g., Bdellovibrio spp.) and endosymbionts and parasites of protists (Ca. Protochlamydia and Aquicella spp.) coincided with a rapid decline in PAOs and the crash in reactor performance. The changes in microbiome composition during the start-up and operation of these lab-scale EBPRs indicate that predation and parasitism is more likely to affect stability in EBPR performance than the presence of GAOs.

Predation and parasitism induces community stability and performance within EBPR reactors

2019 Spring National Meeting

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