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. The term is also sometimes used as a generic term for solids separated from suspension in a liquid; this 'soupy' material usually contains significant quantities of 'interstitial' water (between the solid particles).

Industrial wastewater solids are also referred to as sludge, whether generated from biological or physical-chemical processes. Surface water plants also generate sludge made up of solids removed from the raw water.

Sludge metal

Sludge metal (sometimes referred to simply as "sludge") is an extreme genre of music that melds elements of doom metal and hardcore punk, and sometimes Southern rock. Sludge metal is typically harsh and abrasive, often featuring shouted or screamed vocals, heavily distorted instruments and sharply contrasting tempos. While the style was anticipated by the Melvins from Washington, many of its earliest pioneers were from the city of New Orleans.

Characteristics

Sludge metal generally combines the slow tempos, heavy rhythms and dark, pessimistic atmosphere of doom metal with the aggression, shouted vocals and occasional fast tempos of hardcore punk. As The New York Times put it, "The shorthand term for the kind of rock descending from early Black Sabbath and late Black Flag is sludge, because it's so slow and dense." Many sludge bands compose slow-paced songs that contain brief hardcore passages (for example, Eyehategod's "Depress" and "My Name Is God"). Mike Williams, a founder of the sludge style and member of Eyehategod, suggests that "the moniker of sludge apparently has to do with the slowness, the dirtiness, the filth and general feel of decadence the tunes convey". However, some bands emphasize fast tempos throughout their music. The string instruments (electric guitar and bass guitar) are down-tuned and heavily distorted and are often played with large amounts of feedback to produce a thick yet abrasive sound. Additionally, guitar solos are often absent. Drumming is often performed in typical doom metal fashion. Drummers may employ hardcore d-beat or double-kick drumming during faster passages, or through the thick breakdowns (which are characteristic of the sludge sound). Vocals are usually shouted or screamed, and lyrics are generally pessimistic in nature. Suffering, drug abuse, politics and anger towards society are common lyrical themes.

Sludge (film)

Sludge is a 2005 documentary film by Appalshop filmmaker Robert Salyer chronicling the Martin County Sludge Spill that was an accident that occurred after midnight on October 11, 2000 when a coal sludge impoundment in Martin County, Kentucky, broke through an underground mine below, propelling 306 million gallons of sludge down two tributaries of the Tug Fork River. The movie documents the continuing story of the Martin County disaster, the resulting federal investigation, and the looming threat of coal sludge ponds throughout the coalfield region.

In the United States today, coal is the largest single source of fuel for energy production. Annually, the country mines over a billion tons of coal. Coal waste is a consequence of this consumption; the Mine Safety and Health Administration has estimated that there are over 235 sludge ponds throughout the region with the potential to break into an underground mine, as the Martin County pond did in 2000.

In the wake of the December 2008 release of coal ash at a Tennessee Valley Authority power plant, Appalshop provided a web stream of Sludge for the public for a limited time.