Sponsored by the Natural Processes and Systems for Hazardous Waste Treatment Task Committee of the Environmental Council of the Environmental and Water Resources Institute of ASCE. This report discusses the various natural processes for the attenuation and degradation of hazardous compounds and considers the application of these processes within inexpensive natural systems. New chemical compounds are continually being created to meet specific industrial applications and human uses. Release of these compounds into the environment is inevitable, and their contamination of natural resources, as well as their effect on human health, remain an important global ecological concern. Many compounds degrade in the presence of various natural processes, so there is a need to understand whether new compounds will persist in the environment or will eventually break down innocuously. Major attenuation processes that are covered include: sorption and sequestration, biodegradation and assimilation processes, photo-processes, phyto-processes, oxidation-reduction, and physical processes. Extensive up-to-date references are included, as well as numerous illustrations, tables, and case studies. This book serves as a reference for undergraduate or graduate students, as well as for practicing professionals.