Kinetics of biological treatment of phenolic wastewater in three-phase fluidized bed containing biofilm and suspended sludge

Phenolic wastewater was treated in complete mixing type three-phase fluidized bed which contained both biofilm and suspended sludge. By considering the contributions of biofilm and suspended sludge to biodegradation of phenol separately, phenol removal rates with biofilm and with suspended sludge were evaluated both theoretically and experimentally. As a result, biodegradation of phenolic wastewater by biofilm process could be treated as a zero-order reaction. The volumetric biological removal rates with biofilm was proportional to the specific surface area of the biofilm with biodegradation coefficients (K) of 1.25 x 10^-2 kg-PhOH/m²-biofilm/d. At a lower suspended sludge concentration, bioparticle diameter and bioparticle hold-up in the three-phase fluidized bed reactor were decisive factors for the efficiency of phenol treatment, and it was also proved that almost 100% of phenol removal could be attained at a larger specific biofilm surface area per volumetric phenol loading rate than 80 m²/(kg-PhOH/d) without suspended sludge.