In the last century global water demand has increased 6 folds and with current rate of water consumption by year 2025, 90% of fresh water resources will be consumed. So with increasing pressure on water resources worldwide, now there is need to consider recycling and reuse options for wastewater. Compact plants like membrane bioreactors (MBRs) are rapidly becoming popular and a promising technology for wastewater treatment. This book provides a detailed knowledge of this technology. Main focus of the research was to evaluate the effects of COD/N ratios on treatment performance and fouling propensity in MBR. Chapter 1 gives background and research objectives. Chapter 2 provides detailed information on main functional parameters of MBR, comparison of its performance with conventional wastewater treatment technologies, and description of fouling. Chapter 3 deals with detailed methodology adopted to achieve the research objectives. Chapter 4 provides results of this research. Chapter 5 gives conclusions of this study and future recommendations. This book will be very useful for students, professionals and researchers working in field of wastewater treatment.