Hassana Ibrahim Mustapha was born in Lokoja, Nigeria in 1974. Her first and second degrees were obtained at the Federal University of Technology, Minna, Nigeria in Agricultural Engineering (B.Eng.) and Soil and Water Conservation Engineering (M. Eng.) in year 2000 and 2005, respectively. Hassana joined the UNESCO-IHE, Institute for Water Education in the Netherlands in 2011 as a PhD Research Fellow. Her research work focused on the treatment of petroleum refining wastewater. Her PhD was supervised by Professor dr. ir. Piet N. L. Lens (Professor of Environmental Biotechnology). She has co-authored 12 papers on constructed wetlands for petroleum refining wastewater treatment, including 6 conference papers. Her research interests are in constructed wetlands, phytoremediation and treatment of wastewater. This book is a PhD dissertation and six of its chapters have been published separately in reputable journals.