Drinking water can have various deficiencies: increased iron content, heavy metals, organic impurities, residual chlorination products. Water may also have excessive hardness or too high alkalinity. To eliminate the harmful effects of these features, water purification is applied.
It represents a number of systems aimed at maximizing purification of water entering our homes, country houses or food production lines. When water purification is required, several types of filters and systems are used, such as:
- Mechanical filters are the simplest filtering devices. They mechanically retain particles, solids suspended in water or located on its surface. In any purifying system, a mechanical filter is a device used at the initial stage.
- Ion exchange filters retain unwanted water impurities in the form of ions. There are anion-exchange and cation-exchange filter materials. The latter are designed to remove metals, including heavy metals.
- Sorption filters are designed to eliminate dissolved gases and a variety of organic impurities. The material most commonly used in this method is the activated carbon.
- Reverse Osmosis water treatment systems.
As a rule, a whole range of filtration systems is used as a complex solution for water treatment to improve purification efficiency.
Water treatment: the process and the result
Both man-made and natural impurities in the form of iron, manganese, hydrogen sulfide, and many other chemical elements and compounds may be present in tap water and artesian well water. When their concentration in water is exceeded, the use of such water is unsafe.
That is why we use water purification, which allows us to remove harmful impurities, and, if necessary, increase hardness, eliminate turbidity and odor, and improve the taste of water. To select a water treatment system, it is required to conduct a detailed water analysis. Based on the information about the source of water, we determine specific features of the purification system to be used. There are several principles of water treatment, for example:
The aggregate-free water treatment plant implies the following work pattern: first, water enters a coarse filter, where sand, rust and other mechanical impurities are removed from water. In the aeration column, the liquid is saturated with atmospheric oxygen; dissolved gases, including hydrogen sulfide, are removed from it; and dissolved iron and manganese are oxidized. Then the water enters an automatic filter that purifies it from iron hydroxide. Water purification is performed in the automatic filter softener to reduce the salt content in water with excessive hardness.
An ion-exchange resin can act as a filter element. At the end, a fine filter with pressed activated carbon performs fine water purification, adjusts its taste, color and odor. Water disinfection is carried out in an ultraviolet sterilizer. Now water is ready for use. The key advantages of such water treatment system are its low operating costs and suitability for solving various household and industrial problems.
Water treatment systems
Modern drinking water treatment systems are divided into several groups:
- mechanical filters;
- cabinettype filters;
- balloontype filters;
- osmotic filters;
- household small-sized devices that are placed under the sink.
Mechanical drinking water purification systems relieve it from suspended particles and are suitable as pre-treatment. A mechanical filter is rarely used alone, as, most likely, water purified with such filter will not meet the sanitary standards. The cabinet type filter is a monolith casing that operates at all stages of water purification - from water softening to improving its organoleptic characteristics.
The most popular drinking water treatment systems for cottage houses are of balloon type. If water contains impurities that cannot be removed by a selective method, it is advisable to use the reverse osmosis system.
Additional information on water treatment
Bicarbonates in water are acid salts of carbonic acid soluble in water. The presence of bicarbonate ions and elements of hardness — calcium and magnesium — causes temporary water hardness (hardness which is eliminated by boiling.)
Water iodination is a method of conditioning water using iodine-containing compounds or a solution of molecular iodine.
Water mineralization is a quantitative indicator of substances contained in water. Mineral substances dissolved in water are found in the form of dissociated (decomposed) salts, most often these are chlorides, sulfates and bicarbonates. Thus, the total mineralization of water is the sum of positively charged ions (cations) and negatively charged ions (anions).
Fluoridation of water is the process of adding fluorine-containing compounds to water in order to adjust the fluoride ion content to the health criteria. Due to fluoridation, the incidence rate of dental caries is reduced; the fluoridation process must be carefully monitored.
Remineralization of water is a correction of water composition subjected to complete or partial desalination in the process of water treatment (including using reverse osmosis systems) in order to enhance the taste properties of water and to improve its physiological value. This process can be carried out within the water treatment technology for water production.
Increasing water hardness is a special case of increasing the overall salinity of drinking water, i.e. increasing the concentration of calcium and magnesium ions up to a physiologically adequate level.