1. Department
of Environmental Engineering, College of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
2. Department
of Engineering and Technical Service, D. C. Water and Sewer Authority, Washington, D.C. 20032, United States
3. Department
of Chemical, Bioengineering, and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States