1. Ph.D. Student, Dept. of Environmental Engineering, Middle East Technical Univ., Inonu Bulvari 06531, Cankaya-Ankara/Turkey. E-mail: nates@metu.edu.tr
2. Professor, Dept. of Environmental Engineering, Middle East Technical Univ., Inonu Bulvari 06531, Cankaya-Ankara/Turkey. E-mail: uyetis@metu.edu.tr
3. Associated Professor, Dept. of Environmental Engineering, Suleyman Demirel Univ., 32260, Isparta/Turkey. E-mail: mkitis@mmf.sdu.edu.tr