Sequential Reactivity Studies Of B[A]P And B[E]P By Chemical And Biological Processes.

Benzo pyrene, a and e isomers (B[a]P, B[e]P), are polycyclic aromatic hydrocarbons (PAHs) originating from natural and anthropogenic sources and listed as priority pollutants being toxic, mutagenic, and recalcitrant compounds.This paper focuses on the sequential treatment of these PAHs, involving chemical followed by biological oxidation to reach the following objectives: (i) to obtain mechanistic reactivity aspects of the ozone-initiated degradation of B[a]P and B[e]P in the aqueous phase, (ii) to test the biodegradability of resultant intermediates and (iii) to test the feasibility of the integrated chemical-biological treatment of the five-ring PAHs.Batch reactors were used, and after different ozonation times, samples containing reaction intermediates and byproducts were collected, The samples were identified for organic contents, then biologically inoculated to determine their biodegradability. The (O3)-pretreated samples were incubated from five to twentyfive days; afterward biochemical oxygen demand (BOD), chemical oxygen demand (COD), and toxicity tests were conducted. Further qualitative and quantitative determinations of B[a]P and B[e]P, intermediates, and reaction products by HPLC and GC/MS techniques were conducted. Major intermediates identified at different stages were ring-opened aldehydes, phthalic derivatives, and hydrocarbons. The degradation of B[a]P and B[e]P is primarily initiated viaO(3)-mediated ring-opening, followed by 03 and hydrohyl radical fragmentation. The last step is the complete mineralization via OHdegrees radicals.The proposed approach seems suitable for treating recalcitrant compounds, while pretreatment by chemical oxidation appears useful to generate soluble intermediates from otherwise highly insoluble, biologically unavailable B[a]P and B[e]P.