BIOLOGICAL NITRIFICATION KINETICS IN A FIXED-FILM REACTOR

The kinetic parameters for combined carbon/nitrogen removal in a four- stage aerated submerged fixed-film (ASFF) bio-reactor of 50 l volume w ere evaluated using a synthetic wastewater at 20 degrees C. Influent C OD concentrations were in the range of 0.057-1.8 g COD l(-1), and infl uent NH3-N concentrations were in the range of 0.0152-0.48 g NH3-N l(- 1) with hydraulic loaning ranging from 0.028 to 0.112 m(3) m(-2) day(- 1) coed nitrification was achieved even when high mass loadings were a pplied. The substrate (GOD or ammonia) removal in the reactor was desc ribed by a substrate-limiting phenomenon (reaction or mass transport). Substrate-removal rate followed Monod kinetics in the first stage of the reactor but was better described by first-order kinetics in the se cond to the fourth stages as the substrate concentration became much l ower: The order of the reaction was apparently a function of the hydra ulic lending, indicating the influence of mass transfer on the 'appare nt' order of the reaction. Copyright (C) 1996 Published by Elsevier Sc ience Ltd.