1. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
2. Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
3. School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, New South Wales 2006, Australia
4. Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
5. Ecological Engineering of Mine Wastes, Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
6. Department of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, Connecticut 06520, United States