Published: March 08, 2011 r2011 American Chemical Society 3665 dx.doi.org/10.1021/es104287n | Environ. Sci. Technol. 2011, 45, 3665–3671 ARTICLE pubs.acs.org/est Removal of Pharmaceutical and Personal Care Products from Reverse Osmosis Retentate Using Advanced Oxidation Processes Sihem Ben Abdelmelek, †,‡ John Greaves, § Kenneth P. Ishida, || William J. Cooper, † and Weihua Song ^,†, * † Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, California 92697-2175, United States ‡ Department of Chemistry, Facult  e des Sciences de Bizerte University of Carthage, Tunisia § Department of Chemistry, University of California, Irvine, California 92697-2025, United States ) Orange County Water District, Fountain Valley, California 92708, United States ^ Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, P. R. China b S Supporting Information ’ INTRODUCTION Reverse osmosis (RO) is an attractive method for the recla- mation of municipal wastewater because it removes a wide range of organic pollutants, bacteria and viruses, dissolved organic matter, and inorganic salts. 1-5 However, a concentrate (retentate or reject water) is produced and usually this represents as much as 20 to 30% of the influent. As a result of the RO process the retentate can contain high concentrations of contaminants, and further treatment may be required before its disposal into the environment. Various technologies for the treatment of RO retentate have been investigated, including coagulation/flocculation, 6 activated carbon adsorption, 7 ozone-biological activated carbon, 8 and river bank filtration. 9 The effectiveness of these processes is influenced by the amount and type of effluent organic matter (EfOM) and inorganic constituents, both of which are factors that influence treatment costs. Advanced oxidation processes (AOPs) are alternatives for the destruction of micropollutants in the RO retentate. Limited studies have been reported for this application. 6,10 AOPs involve the formation of the hydroxyl radical (HO•), as an oxidizing species, that is able to degrade a range of organic compounds in water. 11-14 However, one concern of AOPs is the competition for the HO• between the EfOM, the inorganic constituents, and the micropollutants of interest. This study focused on the feasibility of degrading pharmaceu- tical and personal care products (PPCPs) in RO retentate using AOPs. PPCPs are classified as emerging pollutants of concern due to their widespread use, incomplete removal during waste- water treatment, and the fact that they are not regulated. 15 The site studied, the Advanced Water Purification Facility (AWPF) at the Orange County Water District (Fountain Valley, California), treats wastewater effluent from the Orange County Sanitation Received: December 21, 2010 Accepted: February 14, 2011 Revised: February 10, 2011 ABSTRACT: The application of reverse osmosis (RO) in water intended for reuse is promising for assuring high water quality. However, one significant disadvantage is the need to dispose of the RO retentate (or reject water). Studies focusing on Pharmaceutical and Personal Care Products (PPCPs) have raised questions concern- ing their concentrations in the RO retentate. Advanced oxidation processes (AOPs) are alternatives for destroying these compounds in retentate that contains high concentration of effluent organic matter (EfOM) and other inorganic constituents. Twenty-seven PPCPs were screened in a RO retentate using solid phase extraction (SPE) and UPLC-MS/MS, and detailed degradation studies for 14 of the compounds were obtained. Based on the absolute hydroxyl radical (HO•) reaction rate constants for individual pharmaceutical com- pounds, and that of the RO retentate (EfOM and inorganic constituents), it was possible to model their destruction. Using excitation-emission matrix (EEM) fluorescence spectroscopy, the HO• oxidation of the EfOM could be observed through decreases in the retentate fluorescence. The decrease in the peak normally associated with proteins correlated well with the removal of the pharmaceutical compounds. These results suggest that fluorescence may be a suitable parameter for monitoring the degradation of PPCPs by AOPs in RO retentates.