Removal of sulfadiazine, sulfamethizole, sulfamethoxazole, and sulfathiazole from aqueous solution by ozonation Temesgen Garoma * , Shyam K. Umamaheshwar, Alison Mumper Department of Civil, Construction, and Environmental Engineering, 5500 Campanile Drive, San Diego State University, San Diego, CA 92182, United States article info Article history: Received 10 December 2009 Received in revised form 24 February 2010 Accepted 26 February 2010 Available online 19 March 2010 Keywords: Sulfonamides Ozonation Oxidation Reaction rates abstract The removal of sulfadiazine, sulfamethizole, sulfamethoxazole, and sulfathiazole from aqueous solution by ozonation was studied. The study was conducted experimentally in a semi-batch reactor under differ- ent experimental conditions, i.e., varying influent ozone gas concentration, bicarbonate ion concentra- tion, and pH. The results of the study indicated that ozonation could be used to effectively remove the sulfonamides from water. The sulfonamides exhibited moderate reactivity towards aqueous ozone, k O 3 >2  10 4 M 1 s 1 at pH of 2 and 22 °C. The mol of ozone absorbed by the solution per mol of sulfon- amides removed varied in the range of 5.5–12.0 with lower ranges representing ozone absorption by the solution at the beginning of the ozonation process whereas higher ratios correspond to >99.9% removal of the target sulfonamides. The removal rate of the sulfonamides improved with bicarbonate ion concentra- tion up to 8 mM but further increase in bicarbonate ion decreased removal efficiency. It was also observed that increasing the pH from 2.0 to 10.0 resulted in enhanced removal of the sulfonamides. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Scientific studies conducted in the US and worldwide have re- ported widespread occurrence of pharmaceuticals in treated drink- ing water (Ternes et al., 2002; Benotti et al., 2009), surface water (Focazio et al., 2008), groundwater (Holm et al., 1995), and waste- water treatment plant effluent and sludge (Lindberg et al., 2005). In particular, the detection of pharmaceuticals in drinking water sources (surface water and groundwater) and treated drinking water is causing great concern in the scientific communities and public health agencies. Because pharmaceuticals are designed to have certain physiological and biological effects, and uncontrolled ingestion may pose adverse health effects on humans and animals (Daughton and Ternes, 1999). Pharmaceuticals reach the environment through several path- ways. Pharmaceuticals ingested by humans and animals, for ther- apeutic effects, are partially absorbed by the body, and the rest are excreted in feces, urine or manure (Loffler and Ternes, 2003). The excreted pharmaceutical can be in the original form or as a metabolite (Heberer, 2002). For example, sulfamethizole, one of the focus chemicals for this study, can be excreted by the body at about 80% of the original (Scholar and Pratt, 2000). Besides hu- man and animal excretion, pharmaceuticals are released into the environment through effluent discharge from pharmaceutical manufacturing plants (Larsson et al., 2007), leachate from landfills containing medical waste (Holm et al., 1995), disposal of unused or expired pharmaceuticals (Ternes et al., 2002), leachate from animal manure used as fertilizer (Hirsch et al., 1999), treated wastewater used for irrigation (Hirsch et al., 1999), and recycled water used for groundwater recharge (Drewes et al., 2003). Current data available in the literature indicate that conven- tional treatment methods used in water treatment (coagulation, flocculation, sedimentation, sand filtration, and disinfection with chlorine) and wastewater treatment (primary settling, activated sludge or trickling filter, and secondary settling) are not effective for removal of all pharmaceuticals present in raw water and waste- water (Kim et al., 2007; Vieno et al., 2007). This is because pharma- ceuticals differ greatly in structure and in their physical and chemical properties which affect their rate of removal during treat- ment. In an activated sludge treatment process, the rate of removal of pharmaceuticals present in wastewater varied between 34% for clofibric acid to 78% for naproxen (Stumpf et al., 1999). In a pilot- scale drinking water treatment processes which used coagulation, sedimentation, rapid sand filtration, ozonation, granular activated carbon filtration, and UV disinfection, the removal rate of pharma- ceuticals present in the raw water varied in the range 16% for cip- rofloxacin to 99% for carbamazepine (Vieno et al., 2007). On the basis of data currently available in the literature, adsorp- tion to activated carbon, oxidation by ozonation, and separation by membrane processes using reverse osmosis (RO), microfiltration (MF), or nanofiltration (NF) seem to be the most promising meth- ods for the elimination of some pharmaceuticals (Ternes et al., 2002; Huber et al., 2003; Westerhoff et al., 2005). However, the 0045-6535/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2010.02.060 * Corresponding author. Tel.: +1 619 594 0957; fax: +1 619 594 8078. E-mail address: tgaroma@mail.sdsu.edu (T. Garoma). Chemosphere 79 (2010) 814–820 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere