Detergents components such as linear alkylbenzene sulfonate (LAS) typically go down the drain after use and flow into municipal sewage treatment plants or domestic septic systems. In developing areas of the world, disposal is often directly into major sources of water such as rivers, streams or the oceans.
There have been many studies conducted over the years throughout Europe and the United States to determine exactly what happens to LAS during sewage treatment. The biological breakdown, or biodegradation, of LAS, actually starts in the raw sewage before it reaches and is processed by individual treatment plants. The treated water is then returned to natural water sources where LAS water and sediment levels have been proven to be minimal. These small concentrations of LAS pose no risk to the organisms present and will continue to biodegrade until it has mineralized into materials (carbon dioxide, water and sulfate salts) that are harmless to the environment.
Biodegradation is the natural process in which a substance is broken down or converted to simpler compounds in the environment. This process is carried out by microscopic organisms, such as bacteria, which are present in sewage treatment plants and septic tanks. These organisms use organic substances, such as LAS, as food and as an energy source.
In the case of LAS, organisms in the environment rapidly biodegrade LAS until it is completely broken down or mineralized into the simplest possible materials–carbon dioxide (CO2), water (H20) and sulfate salts (Na2SO4). These materials are harmless to the environment.
Surfactants are the active cleaning ingredients in laundry detergents and other cleaning products. Surfactants such as LAS in laundry detergents separate dirt and oily stains from the soiled clothing. In dishwashing detergents, surfactants such as LAS are effective in removing food and grease from dirty dishes.