Coupling ultraviolet photolysis and bilofiltration for enhanced degradation of aromatic air pollutants

Coupling UV photolysis and biofiltration was evaluated as an effective treatment strategy for the enhanced degradation of hardly biodegradable aromatic volatile organic compounds (VOCs). o-Xylene, a recalcitrant and poorly water-soluble VOC, was used as a model compound and treated in two parallel treatment systems with and without UV pretreatment. Contaminated streams with flow rates of 0.186-0.384 m(3) h(-1) and inlet o-xylene concentrations of up to 0.22g m(-3) were passed through the treatment system. About 20% (between 10 and 35%) of o-xylene was converted into water-soluble intermediates during the UV photolysis stage, which partially oxidized o-xylene to more water-soluble and biodegradable byproducts. The untreated contaminant along with the byproducts of UV photolysis was then removed effectively in the biofiltration stage, with improvements of up to 100% compared with the control biofiltration process. The results suggested that combined UV photolysis-biofiltration is promising as an effective technique to eliminate hydrophobic and recalcitrant organic compounds from contaminated air steams. (c) 2005 Society of Chemical Industry.