title: Partial nitrification to nitrite using low dissolved oxygen concentration as the main selection factor.
abstract: Partial nitrification to nitrite (nitritation) can be achieved in a continuous process without sludge retention by wash out of nitrite oxidising bacteria (NOB) while retaining ammonia oxidising bacteria (AOB), at elevated temperatures (the SHARON process) and, as demonstrated in this paper, also at low dissolved oxygen (DO) concentrations. Enriched AOB was attained at a low DO concentration (0.4 mg l(-1)) and a dilution rate of 0.42 day(-1) in a continuous process. A higher oxygen affinity of AOB compared to NOB seemed critical to achieving this. This was verified by determining the oxygen half saturation constant, Ko, with similar oxygen mass transfer resistances for enriched AOB and NOB as 0.033+/-0.003 mg l(-1) and 0.43+/-0.08 mg l(-1), respectively. However, the extent of nitritation attained was found to be highly sensitive to process upsets.
authors.affiliation: Advanced Wastewater Management Centre, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Blackburne
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
authors.forename: Jürg
authors.initials: J
authors.lastname: Keller
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D019149:Bioreactors; D009573:Nitrites / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000032:analysis*; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D009573:Nitrites; D012722:Sewage; D014874:Water Pollutants, Chemical; D000641:Ammonia; D009584:Nitrogen; D010100:Oxygen