The most common water quality problem is water hardness, which is the sum of magnesium ions Mg2 + and calcium Ca2 + dissolved in water. Often, water from a water supply system or artesian wells has increased hardness. Therefore, a water softening installation is quite often used, let’s consider this issue in more detail.
Harm of hard water
Ions of magnesium and calcium are not particularly harmful to living organisms, however, water with a high content of these elements is not suitable for food and for use in household needs.
The use of hard water entails an increased consumption of powder and soap for washing (by 60%), slow cooking of vegetables and meat.
When using such water as drinking water, gastric motility decreases, and disorders of the digestive system are observed. In addition, it has a bitter taste. To combat hard water, water softeners of various modifications are used.
At home, water with a high level of calcium and magnesium salts negatively affects the quality of food — a sedimentary mass appears during storage. Also, water leads to blockage of water metering and heating systems, boilers, increased power consumption (by 20%), the formation of scale on the walls of kettles and pots, limescale deposits in irons, dishwashers and washing machines, which results in damage to devices.
Hard water impairs the quality of dishwashing and washing — fabrics become harder and more fragile, detergents do not rinse out of them, white fabrics acquire a yellow tint, colored ones begin to darken, and worse, they have an unpleasant odor, and the dishes become covered with white spots.
Hard water affects the appearance of hair and skin. When salts come into contact with soap or shampoo, insoluble compounds are formed that are deposited on the skin and hair.
Disadvantages of too soft water
Water softening — the extraction of hard salts of magnesium and calcium from its composition — reduces the harm from its harmful effects in a hard form. For this, special water softeners are used — ion exchange filters.
Water softening, which is based on the principle of ion exchange, is the passage of a liquid through a container filled with a synthetic resin (cation) enriched with sodium ions. Thanks to the cottonized resin, the magnesium and calcium ions present in the water are replaced by sodium ions. The ion exchange process converts calcium bicarbonate into baking soda.
However, it is not recommended to soften the water too much, as too soft water is also undesirable. Drinking water is considered normal when its hardness is 0.1-0.2 mg / liter. Along with water, a sufficient amount of calcium must enter the human body to ensure its normal functioning. With insufficient water hardness, discomfort begins to be felt, for example, it seems that it is impossible to wash off the soap from your hands.
In addition, too softened water increases the total concentration of salts. There is an increased content of soda, which is harmful to the gastrointestinal tract. The acidic component of gastric juice and soda enter into the reaction, which leads to a neutralization process, and this is fraught with the formation of carbon dioxide in the stomach and indigestion.
The soda formed during water softening has a bad effect on household appliances: under its influence, rubber gaskets and hoses are destroyed. To find the «golden mean» in the preparation and filtration of water, it is necessary to use special water filters.
Water softening filters
Softener filters are special devices whose task is to reduce the hardness of the water. Modern filtering devices allow you to quickly achieve the required water characteristics: a solution speed of 20-40 m / h ensures water softening, even if its initial hardness ranged from 5-10 to 0.05-0.1 mg / l.
Automatic softeners are becoming increasingly popular in the water treatment equipment market today. As a rule, regardless of the manufacturer, such water filters can have a similar configuration. This means that the unit consists of a high-pressure housing made of polyethylene and coated on the outside with a special compound with fiberglass reinforcement components, a valve that controls it, and a brine tank in which the regeneration solution is prepared and stored.
The water entering the softener passes through the bed (cation), which is a high quality ion exchange resin. As a result of this process, the chemical composition of the salts changes (due to the replacement of magnesium and calcium ions with sodium ions, which are saturated with the cation).
When the absorption capacity of the resin drops to a certain limit, the control valve automatically initiates a regeneration cycle, the frequency of which depends on the amount of water that can pass through the filter until it is completely depleted.
The frequency is calculated based on the results of water analysis, plant performance, resin characteristics, etc.
A special flow meter is built into the valve, which gives a signal to start regeneration. An aqueous solution of highly purified table salt supplied to the softener restores the properties of the ion-exchange resin due to the reverse replacement of the magnesium and calcium ions accumulated in the resin with sodium ions. When flushing, the accumulated dirt from the softener is flushed into the drain.
The regeneration cycle time depends on the volume of the cation, and can reach 2 hours. It is not recommended to take water during the regeneration process, as the water at the outlet will be of inadequate quality.
Modern ion exchange resins make it possible to operate softeners at high water flow rates. Depending on the quality of the water, the service life of the resins reaches 6-8 years. A wide variety of resins allows filters for water softening, in addition to basic tasks, to perform minor ones, for example, purifying water from iron, manganese and organic matter.
Depending on the mode of operation, automatic filters for softening are of periodic action, providing an alternation of filtration and regeneration processes, and continuous action, providing round-the-clock production of purified water without interruptions for regeneration.
According to their design features, softeners are of the cabinet type, when a container with a filler is located in the inner space of the body, which is simultaneously used as a brine tank. There are also softeners in which the brine tank is located separately from the cylinder.
In addition, membrane filters are widely used to soften water. Post-treatment systems for small production use cartridge-type softeners. Cartridges are produced in standard sizes, but they have a small resource, which can be called their disadvantage.