Partial Nitritation/Anammox and biological phosphorus removal integration in a single bioreactor under mainstream conditions

Anammox-based nitrogen removal and enhanced biological phosphorus removal (EBPR) are increasingly applied for nutrient removal from wastewater, but are typically operated in separate reactors. Here, a novel process for integrated partial nitritation/anammox (PN/A) and EBPR in a single reactor employing integrated fixed film activated sludge was tested. The reactor was fed with mainstream municipal wastewater (5.4 +/- 1.3 g COD/g N) at 20 degrees C for 243 days. Robust ammonium, total inorganic nitrogen, and orthophosphate removal efficiencies of 94 +/- 4 %, 87 +/- 7 % and 92 +/- 7 % were achieved. Nitrite-oxidizing organisms suppression and ammonia -oxidizing organisms retention were achieved via solids retention time control, intermittent aeration, and sus-pended versus attached biomass population segregation. The contribution of anammox to nitrogen removal increased from 24 % to 74 %. In parallel, a substantial enrichment of Tetrasphaera polyphosphate accumulating organisms was observed. This work demonstrates a novel intensified bioprocess coupling PN/A and EBPR in the same reactor for efficient nutrient removal from wastewater.

Automated summary

In this study, a novel process for integrating partial nitritation/anammox (PN/A) and enhanced biological phosphorus removal (EBPR) in a single reactor was tested. The reactor was fed with mainstream municipal wastewater and achieved high removal efficiencies for ammonium, total inorganic nitrogen, and orthophosphate. By controlling the solids retention time, utilizing intermittent aeration, and segregating suspended and attached biomass populations, nitrite-oxidizing organisms were suppressed and ammonia-oxidizing organisms were retained. The integration of PN/A and EBPR in the same reactor showed promising results for efficient nutrient removal.