As a form of waste management, composting is the process whereby organic waste matter is microbiologically degraded under aerobic conditions to achieve significant volume reduction while also producing a stable, usable end product. Co-composting refers to composting two or more waste types in the same vessel or process, thus providing cost and space savings. The most common type of co-composting practiced by counties and townships in the United States involves mixing sewage sludge and municipal solid waste to speed the process and increase the usefulness of the end product. The processing and ultimate use or disposal of cocomposting end products are regulated by federal and state environmental agencies.