A new pressurised biofilm reactor (PBR) process with a patented disc system that enables constant biofilm control has been developed to treat concentrated wastewater with respect to easily degradable organic matter under pressures of up to 6 bar. The pressurisation enables a six-fold increase of the O2 saturation level and aeration capacity, which potentially increases the reaction rate of COD as long as O2 is limiting the reaction rate. Experiments performed in a pilot-scale PBR-reactor fed by synthetic wastewater were conducted to verify the potential and kinetics of heterotrophic conversion of O2 and acetate. Under O2-limited conditions the maximum removal rate of O2 and CODf was measured to rA,O2=60 g O2/m2/d and rA,CODf=150 g CODf/m2/d at 70 mg O2/l. Experiments verified that half-order kinetics could be applied but liquid film diffusion apparently influenced the reaction rate considerably. The observed half-order rate constant was experimentally determined to K½A,O2=7.0 (g O2)1/2m−1/2d−1 but this value is underestimated by 15% due to the observed liquid film diffusion. Based on this the intrinsic zero-order reaction rate was estimated at k0f,O2=190 kg O2/m3 biofilm/d when both liquid film and biofilm diffusion were taken into account.

This content is only available as a PDF.