Removal and formation of chlorinated triclosan derivatives in wastewater treatment plants using chlorine and UV disinfection Jeffrey M. Buth a,1 , Michael R. Ross b , Kristopher McNeill a,⇑ , William A. Arnold c,⇑ a Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States b Department of Chemistry, College of St. Benedict, 37 South College Avenue, St. Joseph, MN 56374, United States c Department of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN 55455, United States article info Article history: Received 25 January 2011 Received in revised form 4 May 2011 Accepted 6 May 2011 Available online 8 June 2011 Keywords: Triclosan Wastewater Chlorination UV abstract Triclosan, a common antimicrobial agent, may react during the disinfection of wastewater with free chlo- rine to form three chlorinated triclosan derivatives (CTDs). This is of concern because the CTDs may be photochemically transformed to tri- and tetra-chlorinated dibenzo-p-dioxins when discharged into natural waters. In this study, wastewater influent, secondary (pre-disinfection) effluent, and final (post-disinfection) effluent samples were collected on two occasions each from two activated sludge wastewater treatment plants, one using chlorine disinfection and one using UV disinfection. Concentra- tions of triclosan and three CTDs were determined using ultra performance liquid chromatography–triple quadrupole mass spectrometry with isotope dilution methodology. Triclosan and the CTDs were detected in every influent sample at levels ranging from 453 to 4530 and 2 to 98 ng L 1 , respectively, though both were efficiently removed from the liquid phase during activated sludge treatment. Triclosan concentra- tions in the pre-disinfection effluent ranged from 36 to 212 ng L 1 , while CTD concentrations were below the limit of quantification (1 ng L 1 ) for most samples. In the treatment plant that used chlorine disinfec- tion, triclosan concentrations decreased while CTDs were formed during chlorination, as evidenced by CTD levels as high as 22 ng L 1 in the final effluent. No CTDs were detected in the final effluent of the treatment plant that used UV disinfection. The total CTD concentration in the final effluent of the chlo- rinating treatment plant reached nearly one third of the triclosan concentration, demonstrating that the chlorine disinfection step played a substantial role in the fate of triclosan in this system. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is an anti- microbial chemical widely-used in an assortment of consumer and medical products, including liquid hand soaps, textiles, and plastics. The use of many triclosan-containing products results in it being rinsed down drains and entering wastewater treatment plants. Typical influent concentrations have been measured on the lgL 1 level, reaching as high as 16.6 lgL 1 (McAvoy et al., 2002; Bester, 2003; Thomas and Foster, 2005; Heidler and Halden, 2007). Although triclosan is efficiently removed (>90%) by modern secondary wastewater treatment facilities due to its strong sorption to biosolids (Lindstrom et al., 2002; McAvoy et al., 2002; Singer et al., 2002; Bester, 2003; Sabaliunas et al., 2003; Thomas and Foster, 2005; Heidler and Halden, 2007), a significant amount persists through wastewater treatment, resulting in effluent con- centrations on the order of 10–100 ng L 1 (Lindstrom et al., 2002; McAvoy et al., 2002; Singer et al., 2002; Bester, 2003; Thomas and Foster, 2005; Heidler and Halden, 2007). Consequently, triclosan is discharged into aquatic environments via wastewater effluents. Triclosan has been detected in wastewater-impacted sur- face waters at concentrations on the order of 10 ng L 1 (Kolpin et al., 2002; Lindstrom et al., 2002; Singer et al., 2002; Tixier et al., 2002; Vanderford and Snyder, 2006), as well as in sediments of wastewater-impacted water bodies (Singer et al., 2002; Miller et al., 2008; Buth et al., 2010; Cantwell et al., 2010). The presence of triclosan in natural waters is of concern due to its potential to produce antimicrobial resistance (Singer et al., 2002), its potential endocrine-disrupting properties (Pothitou and Voutsa, 2008), and because it is photochemically transformed to 2,8- dichlorodibenzo-p-dioxin (2,8-DCDD) under natural sunlight (Kanetoshi et al., 1992; Latch et al., 2003; Mezcua et al., 2004; Aranami and Readman, 2007). Triclosan that remains in the secondary (pre-disinfection) effluent after activated sludge treatment may be chemically 0045-6535/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2011.05.017 ⇑ Corresponding authors. Present address: Department of Environmental Sci- ences, ETH Zurich, Universitätstrasse 16, 8092 Zurich, Switzerland. E-mail addresses: kris.mcneill@env.ethz.ch (K. McNeill), arnol032@umn.edu (W.A. Arnold). 1 Present address: Department of Chemistry, University of Wisconsin-Stevens Point, 2001 Fourth Avenue, Stevens Point, WI 54481, United States. Chemosphere 84 (2011) 1238–1243 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere