Groundwater denitrification was carried out in a laboratory scale flui
dized bed reactor using sand particles as the biomass carrier. This pa
per is concentrated on the fluidized bed reactor operation at very hig
h nitrate loading rates (between 30 to 100 kg.NO3/m(3) reactor/day) wi
th corresponding short retention times (5 to 1.5 minutes). The effects
of nitrate loading rate on nitrate and nitrite removal, as well as on
reactor biomass profiles and biofilm characteristics, are presented i
n this article. The results of the present study indicate that this ty
pe of reactor can operate efficiently at retention times shorter than
3 minutes and at nitrate loading rates higher than 70 kg.NO3/m(3)/day.
However, this system requires careful control of the biofilm thicknes
s to achieve a reliable reactor operation.