I wish I had this book when I taught my graduate class on biological waste treatment! This is an excellent introduction to biological waste treatment in general. This book would also be extremely useful to wastewater treatment plant operators and could serve as the basis for short courses." --Richard A. Conway, Senior Corporate Fellow, Union Carbide Chemicals and Plastics Company, Inc. "An easily accessible book for both specialists and neophytes on the theory of activated sludge." --Sciences et techniques de l'eau