Rapid sand filter
Overview
Water purification
Water purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...
and is commonly used in municipal drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
facilities as part of a multiple-stage treatment system. Rapid sand filters were first used in the United States in 1896 and were widely used in large municipal water systems by the 1920s, because they require smaller land areas compared to slow sand filter
Slow sand filter
Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically 1 to 2 metres deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water...
s.
Rapid sand filters use relatively coarse sand and other granular media to remove particles and impurities that have been trapped in a floc
Floc
Floc can refer to either:* FLOC is the abbreviation for the Farm Labor Organizing Committee, a labor unionor* Floc is flake of precipitate that comes out of solution during the process of flocculation...
through the use of flocculation
Flocculation
Flocculation, in the field of chemistry, is a process wherein colloids come out of suspension in the form of floc or flakes by the addition of a clarifying agent. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually...
chemicals--typically salts of aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
or iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
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Unanswered Questions
