What are the different processes used to remove iron from drinking water?

Posted by Doctorwater on March 3rd, 2020

Iron has a tendency to leach into water supplies from different rock and soil formations. In fact iron is at least 5% of the earth’s crust. Even relatively lower levels of iron content can cause a reddish discolouration which is the beginning of staining and scale processes. Moreover it can also lead to unpleasant odour and taste of water. Let us have a look at the processes which are used to remove different types of iron content from water.

In some places sequestering agents are used in iron removal plants with hand pump. In Odisha there are such types of iron removal plants which are playing an important role in water treatment. Such iron removal plants with hand pump in Odisha are not used without successful field testing. This process of iron removal is used by municipalities and industry to treat large quantities of water. Some iron removal systems use a filtration media to remove oxidised iron and chlorine residuals from water following the oxidation process. Sometimes very low level of iron content can provide favourable conditions for the growth of different types of iron bacteria. Such bacteria are capable of surviving in different types of conditions. The presence of iron bacteria in water results in a reddish colour and unpleasant odour. Growth of these organisms causes the formation of a jelly-like bio-mass which renders media and resin filtration ineffective in removing iron content from water. Moreover iron bacteria is most difficult to remove and control because of its organic nature. Therefore sodium hypochlorite is used to treat such water. Similarly multi-media filters are used to remove red water and clear water iron as softening resins are ineffective in removing these types of iron content. Iron is usually found in its oxidised insoluble form in nature. Small filters used to filter iron content may pack out in a short time which reduces flow and pressure. In such a scenario changing filters becomes expensive and it also takes a lot of time. Although multi-media filters are more expensive to procure, but the cost incurred in filtering a gallon of water is much less and it takes lesser time.

The different types of iron mentioned above are usually found in the supplies of drinking water. There are also other types of iron found in varying conditions which require some other types of special methods to be removed from water. However this article is an attempt to briefly discuss the more commonly found iron contents and the processes used to remove them.