Biological Waste Treatment is the outgrowth of a course entitled ""Bio-oxidation of Organic Wastes—Theory and Design"" initiated at Manhattan College in 1955. The objective of the course was to present the fundamentals of bio-oxidation which would serve as a framework for the analysis, design, and operation of biological waste treatment facilities. This book reflects the authors' approach to the solution of waste treatment problems. It is intended as an engineering text that applies the principles of physics, chemistry, and biology of waste treatment to the design and operation of waste treatment facilities. The book begins with discussions of the pollutional characteristics of waste waters, the strength and flow of waste, waste treatment processes, and biochemical oxygen demand. Subsequent chapters cover the principles of biological oxidation, the theory and practice of aeration, stream and estuary analysis, and solid-liquid separation. The final chapters deal with aerobic and anaerobic biological treatment processes and sludge handling and disposal. Although this text is primarily intended to serve as a guide for the practicing engineer, it should also serve as a useful reference for graduate students in sanitary engineering.