This fourth edition of Writer Supply and Pollution Control has been updated significantly. Approximately 40% of the material is new. In particular, the presentation of many topics has been modernized, and several are introduced for the first time. These changes include new or newly updated treatments of toxic substances; sedimentation; filtration; demineralization processes; chemical kinetics; oxygen transfer; viruses; biological kinetics; rotating biological contactors; pressure filtration of sludges; wastewater reclamation and reuse; water quality modeling; and the technical, social, and environmental dimensions of managing water in a modern society. As in earlier editions, the emphasis is on the application of scientific methods to solve problems related to the development, movement, and treatment of water and wastewateu