This study evaluates the UV/H2O2 and UV/S2O82- (UV/PS) processes as alternative methods for the removal of ibuprofen (IBF) from wastewater destined for treatment and reuse. The second-order rate constants of IBF with HO center dot and SO4-center dot. were determined as k(HO center dot/IBF) = 5.57 x 10(9) M-1 s(-1) and k(SO4-center dot/IBF) = 1.32 x 10(9) M-1 s(-1). The IBF removal rate was higher in the UV/PS process than in the UV/H2O2 process for deionized water, while a higher IBF removal rate was seen with the UV/H2O2 process than with the UV/PS process for wastewater effluent. The suppression of IBF removal in wastewater effluent was verified by investigating the effects of background water quality using synthetic solutions (HCO3-, Cl-, NO3-, SO42-, humic acid, and fulvic acid); HCO3- and organic compounds showed stronger inhibitory effects on the UV/PS process than on the UV/H2O2 process. A mineralization test on the effluent organic matter (EfOM) revealed a higher efficiency for the UV/PS process than the UV/H2O2 process. A toxic by-product test showed a notably higher production yield of 4-isobutylacetophenone (4-IBAP) with the UV/PS process (eta(IBF -> IBAP)(UV/PS) = 0.23) than with the UV/H2O2 process (eta(IBF -> IBAP)(UV/H2O2) = 0.019), even though 4-IBAP was removed by both processes. (C) 2015 Elsevier B.V. All rights reserved.