In the art world, it is fostered by an incessant rain of numbers in the media whenever an art star comes to its attention. Graffiti Artists Turn on Banksy: The Rise of Art Hate Anthony Haden-Guest August 6, 2014
For the music genre, see Sludge metal. Sludge. Sludge is a semi-solid slurry and can be produced as sewage sludge from wastewater treatment processes or as a settled suspension obtained from conventional drinking water treatment and numerous other industrial processes.
Treatment Process. Activated sludge treatment is an aerobic (oxygen dependent) process that uses millions of microorganisms to remove waste materials from the water. There are two basic stages in the treatment of wastewater: the primary stage, in which most solids are removed, and the secondary stage, which removes organic materials and nutrients.