Benzoapyrene of natural and anthropogenic sources is one of the toxic, mutagenic, polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants. This study focuses on an integrated treatment of benzoapyrene involving sequential chemical oxidation and biological degradation. The objectives are to (1) provide mechanistic details in the ozone-mediated degradation of benzoapyrene in the aqueous phase, (2) test the biodegradability of resultant intermediates, and (3) test the feasibility for the coupled chemical-biological treatment of the five-ring PAH. Batch and packed column reactors were used to examine the degradation pathways of benzoapyrene subject to ozonation in the aqueous phase. After different ozonation times, samples containing reaction intermediates and byproducts from both reactors were collected, identified for organic contents, and further biologically inoculated to determine their biodegradability. The O{sub}3-pretreated samples were incubated for 5, 10, 15, and 20 days; afterward biochemical oxygen demand (BOD), chemical oxygen demand (COD), and E. colitoxicity tests were conducted along with qualitative and quantitative determinations of benzoapyrene, intermediates, and reaction products by GCIFID and GC/ MS methods. Prevalent intermediates identified at different stages included ring-opened aldehydes, phthalic derivatives, and aliphatics. The degradation of benzoapyrene is primarily initiated via O{sub}3-mediated ring-opening, followed by O{sub}3 and hydroxyl radical fragmentation, and ultimately brought to complete mineralization primarily via hydroxyl radicals. Intermediates formed during chemical oxidation were biodegradable with a measured first-order rate constant (k{sub}0) of 0.18 day{sup}(-1). The integrated chemical-biological system seems feasible for treating recalcitrant compounds, while pretreatment by chemical oxidation appears useful in promoting soluble intermediates from otherwise highly insoluble, biologically inaccessible benzoapyrene.
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