Engineered and constructed wetland systems are gaining increased attention as market for decentralized wastewater management expands in developed and developing countries. This is more so as they are perceived as cost-effective and environmentally friendly. This book details series of experimental investigations leading to the conceptualization, design and development of a novel tidal vertical-flow alum sludge-based constructed wetland system aimed at concurrent enhancement of oxygen transfer and treatment performance during wastewater treatment. It represents the latest attempt at using engineering ingenuity to enhance the performance of constructed wetlands. The system holds great promise as a low-cost wastewater treatment system of choice particularly in isolated or scattered settlements. It is expected that the book will serve as a reference and useful guide for civil and environmental engineers, researchers, government and policy makers, environmental interest groups,students and others who have interest in engineered and constructed wetland systems and other novel low-cost technologies for wastewater treatment and environmental pollution control.