15 Filtration Examples - encyclopedia

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Filtering examples
Other techniques for separating mixtures

The filtration is a process of separation of a substance solid of a liquid in which it is in suspension, from a mechanical means called sieve, filter or sieve. This is a porous medium, which allows the passage of smaller molecules and ductile molecules of the water, but retains the larger particles of the solid.

Known filters are fabrics, plastic or metallic nets and different types of papers, and this method is perhaps one of the most widely used both industrially and daily to separate solids from a suspension or to rescue bulky objects from some liquid substance.

According to the size and nature of the mixture, can we talk about:

Filtration. As such, it is based on the separation of tiny solid particles (often invisible) in a colloidal suspension.
Casting. Separation of small solid but visible particles from the liquid, through a filter called a strainer.
Sifting. Separation of larger particles from a liquid or even from a medium from smaller solid particles, by using a sieve.

Filtering examples

Coffee preparation. The ground coffee is served directly into a strainer (made of cloth or paper) and boiling water is poured over it, which extracts the flavor and properties of the coffee, knowing that it "erases" it or the solid residue of the coffee powder. it will remain in the filter and will not enter the cup.
Pasta cooking. Pasta must be cooked in boiling water to hydrate and regain its characteristic elasticity and texture, but it is consumed outside of it, so it must be filtered, allowing the water to drain and the cooked pasta to remain in the strainer.
Juice straining. In the production of many juices, the fruit is blended into whole pieces with water, or the pulp is squeezed to obtain the juice. Whatever the case, it must then be strained to separate the solid fiber or pulp residues from the liquid itself.
Preparation of infusions. Many teas and infusions are made from fresh herb, deposited in strands in boiling water. Once the substances contained therein are released, they are strained to extract the solid strands and leave the liquid in the cup.
Air filters. In many closed environments or even in the air injection system of automobile engines, filters are used to retain airborne impurities, such as dust particles and other tiny solid elements, thus keeping the air entering the system as clean as possible. clean as possible. The same goes for the dryer filter, which collects lint and textile debris from the air.
Water filters. Often in homes a water filter is used to extract impurities from the water before using it for domestic use. These filters usually consist of porous stones that allow the passage of water but retain the tiny particles and substances that accompany it.
Oil filters. In combustion engines, oil filters are used to retain the carbon particles produced by the hot circulation of these lubricants, thus keeping the particles retained in the filter and the oil as clean as possible, extending the useful life of the machinery. .
Tinajeros or stone filters. Based on the passage of water from an upper to a lower container through a porous stone, they were water purification devices used in houses in colonial times. Today they are kept as decorative relics.
Sewer grates. The metal grates at the mouth of the sewers work as sieves to keep out large solid waste and avoid clogging the drainage ducts through which rainwater descends.
The cigarette filter. Made from acetylated cellulose, they fulfill the role of filtering the air with smoke from the burning of tobacco leaves, to prevent solid residues from combustion from entering the lungs together with the air.

Pool nets. Used for cleaning water, they retain insects, leaves and general waste in a solid state that are suspended in the water and allow the passage of liquid, thus serving as a cleaning tool.
Sifting the flour. Often the flour (solid) is passed through a sieve or strainer, not only to clean it of any residue or insects, but to aerate it and allow a greater fluffiness in the desserts and avoid the formation of lumps.
Cement sieving. In preparations for the construction sector, cement powder is usually sifted before mixing, to prevent the particles of the material from already adhering or granular and thus guaranteeing that the mixture is homogeneous.
Dialysis. In patients with kidney failure, a blood filtering task is necessary, which removes toxins and unnecessary waste from it: this is called dialysis and it is carried out through specialized machinery. The kidneys would become the natural blood filter.
Filter paper. Used in laboratories to separate water and easily dilutable substances such as sugar, salt or sand, it is a porous paper that retains even very small particles but allows water to pass through.