Wastewater treatment is a process through which wastewater is converted into usable form with minimal impact on the environment. The by-products generated from wastewater treatment plants like grit, sewage sludge and screenings, are also treated in the wastewater treatment plant. It involves various phase separation processes such as sedimentation and filtration, polishing, biochemical oxidation and chemical oxidation. Treatment of wastewater depends on the type of wastewater. Accordingly, wastewater treatment plants can be categorized as industrial wastewater, agricultural wastewater, sewage and leachate treatment plants. This book outlines the processes and applications of wastewater treatment in detail. It presents this complex subject in the most easy to understand language. This book attempts to assist those with a goal of delving into the field of wastewater treatment.