AWWA WQTC64065

A bench-scale study of the degradation of four selected pharmaceuticals and personal care products (PPCPs) was carried out using ultraviolet (UV) and UV/H₂₂ treatment employing low pressure (LP) and medium pressure (MP) lamps. The target substances included the pharmaceutical compounds ibuprofen, naproxen, and gemfibrozil, along with the bactericide triclosan. The main objectives for the portion of the study reported in this paper were: to compare removals in ultra-pure water to results using partially treated water from a drinking water treatment plant; to determine the influence of water quality parameters on treatment efficacy; and, to estimate the kinetic parameters associated with the degradation of the selected compounds. Target compounds were spiked together into ultra-pure and pretreated water at levels (500-1000 ng/L) fairly close to the ones reported in the aquatic environment. The results for the LP lamp showed minimal, if any, removals with 40 mJ/cm² irradiation. At the same fluence, the addition of 10 mg/L H₂O₂ resulted in removals as high as 66%. Lower removals observed with one of the partially-treated waters may be attributed to higher alkalinity, although further investigation is required. In contrast, the MP lamp led to measurable degradation of all four compounds even at a low fluence of 40 mJ/cm². The highest removals observed were for triclosan, which has been shown to be susceptible to photolysis. The benefits of adding H₂O₂ when employing a MP lamp were not seen until the highest fluence (300 mJ/cm²) was applied, at which point removals were especially enhanced for ibuprofen and gemfibrozil when compared to UV alone. It is possible that the lower fluences were insufficient to produce a sufficient concentration of hydroxyl radicals to have an effect, under the matrix conditions. Overall, the removals in partially-treated water were lower than in ultra-pure water. Includes 18 references, figures.