Saostusta

Saostusta is the process by which a dissolved substance forms a solid and separates from a solution. The solid that forms is called a precipitate (saostuma in Finnish). The term is used in chemistry, environmental engineering, geology and hydrology to describe both natural and engineered processes of solid formation and separation.

In chemistry, saostus occurs when a solute exceeds its solubility or when a chemical reaction creates an insoluble product. The resulting solid can be collected by filtration or allowed to settle from the liquid by gravity or centrifugation. Factors influencing saostus include temperature, pH, ionic strength, and the presence of complexing agents or competing ions.

In natural systems, saostus refers to the precipitation of minerals from aqueous solutions. Minerals such as calcite or gypsum can crystallize from groundwater or hydrothermal fluids, contributing to sedimentary deposits, caves’ formations, or evaporite beds. These processes often depend on changes in chemistry, temperature, pressure, or evaporation.

In water and wastewater treatment, saostus is a key step in solids removal. After coagulation and flocculation, suspended particles form larger aggregates that settle in clarifiers or sedimentation basins. The efficiency of saostus affects turbidity, contaminant removal, and overall treatment performance. Precipitation reactions are also used deliberately to remove dissolved contaminants by forming insoluble compounds, which are then separated from the water.

See also: precipitation (chemistry), sedimentation, coagulation, flocculation, precipitate, saostuma.