Kinetics and dynamics of nitrification in a biofilm fluidized sand bed reactor

Abstract

A biofilm fluidized sand bed was used for the study of nitrification kinetics, in which NH4+ wastewater wat oxidized sequentially to NO2− and NO3−. After a 3 month startup period, a stable and active biofilm was obtained. Substrate inhibition for NH4+ and NO2− was not found. Double Michaelis-Menten kinetics described the data well. The oxygen saturation constant for the NO3− forming step was highest. This led to NO2− accumulation at low oxygen levels. Dynamic pulse experiments were used to determine O2 and NH4+ limitation. The limiting substrate can be predicted from the O2/NH4+ ratio. Repeated pulses of NH4 caused a reproducible and stable response of the reactor. Oxygen uptake provided a reliable monitoring method.