Anammoxと部分亜硝酸化を活用する単一槽での窒素除去

摘要

sNitritation is an economically favorable aerobic process when used for nitrogen removal fromwastewater having a high ammonium concentration and a low C/N ratio. The combination of partialnitritation, by which half of the influent ammonia is oxidized to nitrite by ammonia oxidizing bacteria, andanaerobic ammonium oxidation (anammox)by anaerobic ammonium-oxidizing bacteria gives a costeffective ammonium removal process. Using a reactor packed with an acryl-fiber biomass carrier, theoptimum operational conditions for partial nitritation were determined to be 35℃at a pH of 7.5-7.7 withan NH4-N loading rate of 0.4kg-N/m3/d. During long-term operation of a lab-scale partial nitritationprocess, 60 to 80%of applied NH4-N was unexpectedly disappearing. Through DNA analyses of thebiomass attached on acryl-fiber carrier, ammonium-oxidizing and anammox bacteria were both found tobe present. Thus it was evident that favorable conditions for anammox bacteria had developed inside theattached immobilized nitrifying sludge. These results introduce a new wncept by which ammonium can beremoved using a one-stage process: Single-stage _Nitrogen removal using Anammox and Partial nitritation(SNAP).