This thoroughly revised Second Edition presents a comprehensive account of the principles of operation and design of wastewater treatment plants. Beginning with the basic concepts of treatment of wastewater and the design considerations required of an efficient treatment plant, the book moves on to spotlight the design criteria for domestic wastewater treatment units. In essence, the text gives the detailed procedures for design computations of all units of a wastewater treatment plant. It also describes the most common types of reactors used for physical operations and biological processes in wastewater treatment plants. Besides additional examples and exercises, this edition also includes a new chapter on "Disinfection of Wastewater". The book is intended for the undergraduate students of Civil and Environmental Engineering. It will also be useful to the practising professionals involved in the design of wastewater treatment plants. Key Features Provides several examples supported by graphs and sketches to highlight the various design concepts of wastewater treatment units. Encapsulates significant theoretical and computational information and useful design hints in Note and Tip boxes. Includes well-graded practice exercises to help students develop the skills in designing treatment plants.