Denitrification kinetics in a rotating disk biofilm reactor

Denitrification kinetics of a synthetic substrate containing molasses, sodium nitrate, Na2HPO4. 12H202kH2PO4, and tap water treated with Na2,SO3was studied in a rotating disk biofilm reactor( RDBR). Experiments were performed at various conditions:biofilm thickness in the range 100-I 100k Mm and nitrate concentration in the feed of 5 to 50 mg N^1- ‘. Biofilm density decreases with increasing biofilm thickness. Most experiments were in the kinetic controlled regime or fully penetrated Biofilms.The intrinsic zero-order kinetic constant Was found to be k0=7.96 X10^-6 kg NO(3)-N * kg biofilm ^-1 S^-1 (at 25 “C). Some runs were in the diffusion controlled regime or partially partially penetrated biofilms;the effective diffusivity of nitrate in the biofilm which fitted experimental results was Db=1.5 X10^-9 m^2S^-1 The efficiency of the RDBR, considered as a CSTR, predicted by a model based on a zero-order reaction and diffusion inside the biofilm, reasonably agrees with experimental data.