Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

The presence of iron in water is most commonly treated by which method?

1. Filtration

2. Aeration

3. Chlorination

4. Reverse osmosis

The correct answer is: Aeration

The presence of iron in water is primarily treated by the process of aeration. This method works effectively because it involves introducing air into the water, which promotes the oxidation of dissolved ferrous iron (Fe2+) into ferric iron (Fe3+), an insoluble form. Once oxidized, the ferric iron can then be effectively removed through subsequent filtration. Aeration is advantageous in treating iron because it not only helps in oxidizing the iron but also reduces any associated taste and odor issues related to iron and other dissolved substances. Additionally, since aeration relies on natural processes, it is often more cost-effective compared to more complex treatment methods. Filtration is a necessary step following aeration to remove the precipitated iron particles, but it is the aeration process that primarily facilitates the transformation of iron into a form that can be filtered out. Methods like chlorination or reverse osmosis are not as commonly employed for iron removal; chlorination is primarily used for disinfection purposes, while reverse osmosis is typically reserved for the removal of a wide range of contaminants, making it less efficient for specific removal of iron.