mud
Sludge refers to a mixture of finely divided, predominantly very fine-grained solids and a comparatively small amount of liquid , mostly, but not necessarily, caused by sedimentation .
Etymology and colloquial usage
The word Schlamm is derived from the late Middle High German slam (soft, wet sediment) or the Middle Low German slam ( dirt , morass). The colloquial meaning still corresponds to this today. Mud is often synonymous with swamp , damp earth, dirt and in this sense is also referred to as feces .
More specific use of the term
Technical definition
In general, a sludge arises from a suspension , i.e. from predominantly microscopic particles of a solid substance that are finely distributed in a liquid - here mostly water - in suspension. If such a mixture remains still for some time, the suspended matter will settle on the bottom, provided that they have a higher density than the surrounding liquid. The resulting very fine-grain sediment (see → Sediment ) is called sludge. The solid particles are no longer in suspension, but tightly packed and only separated from each other by a thin film of liquid . One example of this is sewage sludge that settles in the clarifier of a sewage treatment plant .
Geoscientific Definitions
Sedimentology
In sedimentology , the definition is narrower. There, a very fine-grained sediment is called sludge, which is formed from natural mineral and organic matter through natural sedimentation in standing, but not necessarily permanent, water. The inorganic sludge particles consist of various minerals and are of different origins. The clay muds belong to the terrigenous muds , as they have their origin in the weathering and erosion of rocks on dry land and are washed into lakes and into the sea by streams and rivers or, mediated by floods, accumulate in alluvial plains . The particles in a clay sludge typically consist of clay minerals . On the other hand, there are sludges, the particles of which come directly from the water at the bottom of which they settle. These often consist of the remains of microorganisms that live in the water. Many of these microorganisms are able to form skeletons from mineral substances. Depending on the prevailing substance, one can differentiate between lime sludge (mainly made of calcium carbonate , CaCO 3 ) and silica sludge ( made mainly of silicon dioxide , SiO 2 ). Often the sludge is named directly after the microorganisms, of whose skeletons it mainly consists, in the case of a silica sludge z. B. as radiolarian sludge or in the case of a lime sludge z. B. as globigerin sludge .
If, in the course of time, many layers of mud are deposited on top of each other, the bottom layers come under increasing pressure. This drains them and solidifies them, sometimes with the help of chemical processes. A fine-grained, brittle sedimentary rock is created from a soft mud. The geological process of solidification of a mud into a rock falls under the generic term diagenesis . Depending on the starting material is produced mudstone , fine-grained limestone ( micrite ) or chert (see also → mudstone ).
Others
Silt is a clay slurry having a high content of organic impurities, inter alia, in battings produced. If an organic-rich sludge is deposited in oxygen-poor or oxygen-free water, it may form. a. Hydrogen sulfide. One then speaks of digested sludge ( sapropel ). A mixture of superheated water vapor and fine-grain volcanic material "bubbles" in a mud pot . Volcanic ash deposited on mountain slopes , softened by heavy rain, can go down in the form of a mudslide ( lahar ).
See also
Web links
Individual evidence
- ↑ Duden | Feces | Spelling, meaning, definition, synonyms, origin. Accessed January 31, 2018 .