Water iron removal filters

The purpose of water filters is to collect divalent iron, hydrogen sulfide, manganese, and mechanical impurities dissolved in water. This is done using the principle of aeration. Compressed air is fed into the water supply line upstream of the filtration system and mixed with ferrous water using a static mixer. The mixture of water and air enters an oxidation tank, where divalent iron undergoes an oxidation reaction and is converted into trivalent iron, forming iron hydroxide compounds (rust) (Fe2 → Fe3). The latter are retained together with other mechanical impurities when the water is filtered through a special filter containing granular rock fill. The filter fill is renewed (washed) at a selected time when water consumption is at its lowest. During backwashing, the filter media is flushed with a reverse water flow and all insoluble particles and trivalent iron hydroxide compounds collected in the filter are removed to the drain. Iron removal filters also have the property of reducing the amount of manganese and hydrogen sulfide in the water.

Iron in water and the process of water deironing

Rusty, orange-colored water running from the tap usually indicates that it contains high levels of iron. Iron in water can be almost invisible or in the form of tiny particles. However, even a small amount of iron can leave rust stains on sinks, household appliances, and other surfaces that have come into contact with water once the water has dried.

The formation of rust in water can change the taste of water and other water-based beverages. Using iron-rich water for cooking can change the color of food and cause it to taste unusual, and washing clothes with such water can leave stains on them. In addition, iron accumulating in pipes can cause plumbing problems over time.

Iron is an important nutrient for our body. Red blood cells and muscle cells contain about 70% of the body’s total iron, which is necessary for transporting oxygen in the blood and muscle tissue. However, most people get 95% of the iron their bodies need from food. According to the World Health Organization (WHO), the amount of iron that enters the human body naturally through water consumption does not exceed 10%.

However, the WHO does not provide recommended intake levels for iron obtained from water and food based on health factors, and the total daily intake of iron allowed by the WHO is 0.8 mg/kg of human body weight. Based on this data, the amount of iron that is not harmful to human health is 2 mg/l. Iron is not considered a pollutant that has a harmful effect on human health, but when the concentration of iron in water exceeds 0.3 mg/l, it can undoubtedly have a negative impact on water quality and cause domestic problems.

Causes of iron in water

Iron is one of the most abundant resources on Earth, making up 5% of the Earth’s crust. Iron deposits are found in many rocks. Some of the iron in these deposits is usually dissolved by rain as it passes through the rocks, and some of it is carried further as it passes through rocks and soil. Eventually, rainwater becomes groundwater or enters freshwater sources, where it can become part of the water we consume. Water filters designed to remove bacteria and other harmful contaminants are not always able to filter out iron.

Iron in water and its negative effects

• Metal taste and smell. Water reaching households with high iron concentrations acquires a metallic taste and smell. After washing with such water, a metallic smell may remain in the bathroom.
• Discolored water. If the water contains high levels of iron, it may appear brownish-red or orange in color.
• Appearance of stains. High iron concentrations in water can cause reddish-brown stains on various surfaces that come into contact with water, including laundry, dishes, and household appliances.
• Changes in the appearance and taste of food. Coffee, tea, vegetables, and other foods prepared with iron-rich water may turn black and have a metallic taste.
• Iron deposits in pipes. Iron deposits can build up in pipes. This can cause pipes to become clogged over time and disrupt water flow. This can cause additional household problems and require plumbing repairs.
• Dry and irritated skin. Iron in the water we use can dry out the skin. When washing with iron-rich water and using soap or other washing products, soap residue may remain on the skin because soap and iron do not mix well. All of this can cause dry skin and itching.
• Sediment and cloudy water. If there is iron in the water, it may be cloudy and contain sediment. This is because oxidized iron, unable to dissolve completely in water, eventually settles.

Water deironing process

When the iron concentration in water is high, many of the problems mentioned above arise. These can be avoided by using water deironing filters. Since each case is unique, it is recommended to first conduct a thorough water analysis to determine whether substances such as iron, manganese, hydrogen sulfide, and other mechanical impurities exceed the standards.

To date, the water deferrization process is one of the most complex, as it requires the simultaneous elimination of more than one problem. Therefore, complex water treatment solutions are needed to achieve the desired result.

During the water deferrization process, water filters collect divalent iron, manganese, hydrogen sulfide, and other mechanical impurities that may be present in the water. This is usually done using the principle of aeration, where iron compounds are aerated, i.e., iron is oxidized by air. During this process, soluble divalent iron compounds are converted into poorly soluble trivalent iron hydroxide, which is ultimately removed by filtration.

However, complex measures are often required, where not only iron is removed from the water, but also the amount of hydrogen sulfide and manganese in the water is reduced, the water is softened, and other particles in it are retained. Therefore, the specific measures to be taken before starting the water deironing process are determined after conducting water tests.