A new bioreactor with a semi-fixed packing: investigation of degradation of phenol

Abstract

 A new bioreactor using a semi-fixed packing of frames with “sacks” made of a fabric of “Raschell” type stretched on them is proposed. The construction provides not only a large surface area of the biofilm carrier per unit volume of the apparatus, but also the possibility for an easy removal of the biomass after reaching a certain thickness of the biofilm increasing the gas velocity. Aerobic degradation of phenol in the new bioreactor, using microorganisms of the strain Pseudomonas putida, was studied. The experiments are carried out using water containing 0.7 g/l of phenol at a temperature of 27–30 °C. Different specific surface area of the packing (within 176 and 387 m²/m³) are studied. Degradation rates from 60 to 140 mg/(1 h) are attained. A retardation of the process at the end is observed, probably due to inhibition effect. This rate is 5–6 times higher than the rate observed when using free cells. At air velocity of 0.03–0.035 m/s (related to the total cross section of the bioreactor) the vibrations of the packing material lead to destruction and removal of the old biomass.