Biologically-based systems for handling waste are gathering international attention as a more reliable, less costly alternative to energy intensive mechanical systems, and are being used by increasing numbers of communities and municipalities. The natural process of waste treatment deals with processing waste and wastewater naturally in streams and the soil. The process in wastewater treatment plants is virtually the same process used in treating the material with bacteria only at a more rapid rate. This results in higher energy consumption and more accumulated sludge than the natural process. This edition features recent advances in the use of wetlands and aquatic systems, the treatment of sludges, and other areas in the field of waste management. It also includes current EPA regulations and coverage of small-scale on-site systems.