Anaerobic ammonium oxidation (anammox) is a cost-effective, biological treatment process for the removal of reactive nitrogen from wastewater effluent. Today, over 100 full-scale anammox reactors have been installed across the globe and are in operation for the remediation of reactive nitrogen-rich wastewater effluent. These full-scale reactors consume 60% less energy and produce 90% less waste biomass than their conventional nitrification/denitrification counterparts. However, the bacteria responsible for anammox are easily inhibited by varying substrate and metabolite concentrations and have excruciatingly slow doubling times (7-22 days) under typical reactor configurations. While there is a substantial body of literature describing the performance of anammox reactors in response to various perturbations and operational conditions, very few studies have examined anammox bacteria’s response on a molecular level or the role of other bacteria in maintaining the functionality of anammox reactors. Insights into the anammox reactor’s bacterial community composition and functional profiles via metagenomic analyses are essential for understanding and optimizing reactor performance.<br/><br/>Here, we used genome-centric metagenomics in conjunction with 16S rRNA sequencing to gain insight into microbial community composition and function during 400 days of continuous operation of a laboratory-scale anammox reactor. Initial results reveal an intricately connected flow of reactive nitrogen through anammox, denitrifying, and dissimilatory nitrate reduction to ammonium (DRNA) bacteria. In particular, we find that shifts in organic carbon availability may destabilize the delicate balance between autotrophic and heterotrophic nitrogen-cycling populations, subsequently impacting the functionality of the reactor. In conclusion, we suggest strategies to manage shifts in organic carbon availability and mitigate their impacts on anammox reactor performance. Our findings improve the understanding of nitrogen-cycling within an anammox microbial community, and ultimately inform the more comprehensive control of anammox reactors.

Nitrogen flows in an anaerobic ammonium oxidation (anammox) reactor

255th National Meeting (2018)

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