Biological Nitrogen Removal Using Anaerobic Ammonium Oxidation

ANaerobic AMMonium OXidation (Anammox) is an efficient microbiological process for the removal of ammonia nitrogen from wastewater. Although several Anammox reactors have been operated successfully in European water pollution control plants, there are challenges associated with the process which must be addressed to ensure dependable performance when treating high strength wastestreams in New York City plants. Using the ammonia rich side stream emanating from the dewatering of anaerobically stabilized wastewater solids, it was possible to enrich Anammox performing bacteria in a sequencing batch reactor (SBR). Currently, the SBR is loaded with ≈7600 mg-N/day and achieves >85% nitrogen removal. Stable operation of the SBR resulted in the formation of red granular biomass as the dominant reactor morphotype. However, several process upsets occurred during the first seven months of reactor enrichment. The potential causes of these process upsets and the possible protective properties conferred by granulation are the focus of future research on Anammox.