With such a large amount, iron ores are found almost everywhere in our daily activities. In their natural state, they are most often found in the form of magnetite (Fe3O4), hematite (Fe2O3) and siderite (FeCO3). Iron ores are characterized by their solubility or insolubility in water.
In the ferrous state, i.e., Fe2, iron is soluble in water and is recognized as being bivalent. While in the ferric state, Fe3, iron is insoluble in water and is said to be trivalent.
Sources of Iron in Water
Most often, the sources of iron in water are natural. Generally caused by the erosion of rocks containing iron. For example, magnetite has a concentration of 72.4% metallic iron.
Obviously, iron can come from other sources such as human activities like drilling, mining, etc.
In Quebec, there is no legislation governing the amount of iron in drinking water. However, a concentration of 0.3 mg/L will affect the taste and color of the water. Moreover, the use of water with such a high concentration of iron can stain clothes or appliances.
It should be noted that in Quebec there are no regulations in place since the concentration of iron in water is generally harmless for human consumption. Despite this lack of regulation in Quebec, the World Health Organization (WHO) recommends an iron level below 0.3 mg/L.
How to Extract Iron From Water
Depending on the type of iron found in water, the simplest methods to extract it are the following. Starting with Fe3, which does not dissolve in water, it is sufficient to incorporate a filtration step. This physical barrier will capture impurities and decrease the concentration of ferric iron.
As for ferrous iron (Fe2), the extraction must be done in three steps. First, the water must pass through aeration/filtration tank, which allows for the removal of larger contaminants. Next, oxidizing filters must be installed. Finally, a chlorination stage to allow the precipitation of dissolved iron and then a final filtering barrier to remove the iron residues.