1. a Department of Materials and Energy Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania
2. b Water Infrastructure and Sustainable Energy Futures (WISE-Futures), African Centre of Excellence, Nelson Mandela African Institution of Science and Technology, Nelson Mandela Road, Tengeru, P.O. Box 9124, Arusha, Tanzania
3. c Department of Water and Environmental Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania