Biological Fluidized Bed Denitrification of Wastewater

Abstract

<p> A half-order kinetic model (8-48 mg NO3+NO2-N/l), coupled with a temperature dependency described by the Arrhenius relationship (4°-27° C), adequately described biological denitrification of municipal wastewater in a pilot scale fluidized bed reactor. Biofilm support media (activated carbon or sand) and hydraulic flux (0.25-1.7 m^3/m^2·min) were not found to be significant factors in controlling denitrification rate within the reactor. Control of biofilm thickness on the support media was essential for satisfactory operation of the process; excess thickness contributed to elutriation of media and attached biofilm. Under similar influent wastewater conditions, the fluidized bed process was capable of equivalent NO3+NO2-N removal in about one-tenth of the time necessary in a suspended growth or a rotating biological contactor (RBC) process. Temperature dependency of the NO3+NO2-N removal rate appeared to be less than the dependency in a suspended growth or a RBC process, but similar to the dependency observed in a packed column.</p>