Sludge 11 : Any muddy or slushy mass. Specifically, mud from a drill hole in boring, muddy sediment in the steam boiler, or precipitated solid matter arising from sewage treatment processes
Barbara A. Plog, Patricia J. Quinlan, Jodey B. Schonfeld and Patricia M. Dewey (editors), Fundamentals of industrial hygiene 5th ed., Appendix E - Glossary (Michael Horowitz, MS, CIH - Compiler), National Safety Council, Illinoise, USA 2002. http://www.wbcsd.org/web/projects/cement/tf3/fihAp pendices.pdf, (Env and Occupn Sfty and Hlth - Amer) {680}