Bio-Oxidation of Airborne Volatile Organic Compounds in an Activated Sludge Aeration Tank

摘要

An activated sludge aeration tank (40 x 40 x 300 cm, width x length x height) with a set of 2-mm orifice air spargers was used to treat gas-borne volatile organic compounds (VOCs; toluene, p-xylene, and dichloromethane) in air streams. The effects of liquid depth (Z), aeration intensity (G/A), the overall mass-transfer rate of oxygen in clean water (K_La_(O_2)), the Henry's law constant of the tested VOC (H), and the influent gaseous VOC concentration (C_o) on the efficiency of removal of VOCs were examined and compared with a literature-cited model. Results show that the measured VOC removal efficiencies and those predicted by the model were comparable at a G/A of 3.75-11.25 m~3/m~2 · hr and C_o of ～1000-6000 mg/m~3. Experimental data also indicated that the designed gas treatment reactor with K_La_(O_2) = 5-15 hr~(-1) could achieve > 85% removal of VOCs with H = 0.24-0.25 at an aerated liquid depth of 1 m and > 95% removal of dichloromethane with H = 0.13 at a 1-m liquid depth.