1. Bioresource Engineering Research Group (BioERG), Department of Chemical Engineering, Faculty of Engineering and the Built Environment, Cape Peninsula University of Technology, P.O. Box 1906, Bellville 7535, South Africa
2. Academic Support Programme for Engineering (ASPECT) & Water Research Group, Department of Civil Engineering, University of Cape Town, Private Bag X3, Rondebosch, Cape Town 7700, South Africa
3. Department of Chemical Engineering Technology, Doornfontein Campus, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa