title: Exploring temporal variations of oxygen saturation constants of nitrifying bacteria.
abstract: Activated sludge models (ASM) are generally accepted as state-of-the-art in modeling wastewater treatment plants. In this paper, we assess the temporal variability of an ASM parameter-the oxygen half-saturation constant of autotrophic bacteria (K(O),(AUT)). A series of respirometric experiments is performed for conventional activated sludge and sludge from a membrane bioreactor. K(O) values are estimated for both ammonium-oxidizing and nitrite-oxidizing bacteria. For parameter estimation, the Monod kinetic model structure is extended by a sensor model. Still remaining systematic deviations between data and model are considered by a thorough residual analysis: (1) uncertainty estimates of K(O) are corrected to reflect model structure deficiencies and (2) the inter-experimental cross-correlation of residuals is taken into account to assess temporal changes. We conclude that K(O),(AUT) is a time variable parameter and should be considered accordingly.
authors.affiliation: Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland.
authors.forename: Helge
authors.initials: H
authors.lastname: Daebel
authors.forename: Reto
authors.initials: R
authors.lastname: Manser
authors.forename: Willi
authors.initials: W
authors.lastname: Gujer
mesh_terms: D000641:Ammonia; D001419:Bacteria / Q000378:metabolism*; D019149:Bioreactors; D007700:Kinetics; D008954:Models, Biological; D009573:Nitrites / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000379:methods*
chemical_list: D009573:Nitrites; D012722:Sewage; D000641:Ammonia; D010100:Oxygen