1. Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
2. Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06520-8286, USA.
3. Department of Civil Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
4. Department of Chemistry, University of Minnesota, Minneapolis, MN 55455-0431, USA.