Advanced nitrogen removal via anammox from municipal wastewater during the continuous flow anoxic/oxic process with an ultra-short hydraulic retention time

Anaerobic ammonium oxidation (anammox) as an autotrophic nitrogen removal process is a novel sustainability-relevant biotechnology. However, rapid enrichment and effective retention of anammox bacteria (AnAOB) in mainstream municipal wastewater treatment processes is challenging since the low-levels of ammonium and limited specific niche availability. Here, we show that by adding virgin carriers into the continuous-flow anoxic/oxic process with an ultra-short hydraulic retention time of 2.75 hours, anammox bacteria was in-situ rapidly and highly enriched (Ca. Brocadia; 10.6%) within anoxic biofilm carriers in 32 days for municipal wastewater treatment, scaling up to 200 L/d.