Ammonia Oxidizing Bacteria (AOB) kinetic parameters estimated using the actual maximum ammonia oxidation rate

The objective of this paper was to define a new and reliable approach to the Ammonia Oxidizing Bacteria kinetic parameters estimation process. The proposed approach is based on the use of the information provided by a continuous on-line differential titrimeter developed for the estimation of the Actual Maximum Ammonia Oxidation Rate. The instrument was tested in a 200000 p.e. WRRF (Water Resources Recovery Facility) treating urban and industrial (textile) sewage wastewater and truck-transported liquid wastes in the Tuscan textile district (Italy). Maximum Ammonia Oxidation Rate was used as an innovative data series for maximum specific growth rate (μmaxAOB) and decay coefficient (bAOB) estimation. Titrimetric tests were conducted under non-limiting condition for oxygen and substrate and half-saturation constant of ammonia (KNH) was calibrated referring to the effluent quality of the WRRF. The proposed procedure allows to define a new kinetic parameters data set for AOB biomass (μmaxAOB = 0.72 d−1, bAOB = 0.25 d−1, KNH = 0.4 mg N–NH4+ L−1). The new data set was used to produce a new model that allows to improve the accuracy of the description of the process efficiency of the WRRF when compared with a model using kinetic parameters estimated through conventional methods.