This textbook offers a complete comprehensive coverage of wastewater engineering from pollutant classification, design of collection systems and treatment systems including operational guidelines for the treatment plants. Apart from the primary and conventional secondary wastewater treatment, this book covers the details and design of advanced biological treatment systems such as sequencing batch reactor (SBR), up-flow anaerobic sludge blanket (UASB) reactors and hybrid reactor, with design examples and photographs of actual working reactors which is useful for students and practicing engineers. This textbook is designed to provide complete solution for the wastewater engineering for easy reference to the users. This textbook is an ideal reference for courses taught at the university undergraduate and postgraduate level in the field of civil/environmental engineering, chemical engineering, water management and environmental science. It should also appeal to practicing engineers in the wastewater engineering and effluent treatment plant designers.