1. Department of Civil and Environmental Engineering and Department of Chemical Engineering, Michigan Technological University, Houghton, Michigan 49931, Water Supply & Water Resources Division, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268, and DVGW-Technologiezentrum Wasser, Heinrich-Sontheimer-Laboratorium, Karlsruher Strasse 84, D-76139 Karlsruhe, Germany