Florida Drinking Water Operator "B" Practice Test

What accelerates the oxidation of iron by aeration?

1. An increase in water temperature

2. An increase in pH

3. An increase in dissolved oxygen

4. Reducing the flow of air

The correct answer is: An increase in dissolved oxygen

The acceleration of the oxidation of iron by aeration is significantly influenced by the presence of dissolved oxygen in water. When dissolved oxygen levels are increased, the oxidation process occurs more rapidly because oxygen is a key reactant in the oxidation of ferrous iron (Fe²⁺) to ferric iron (Fe³⁺). This reaction is critical in water treatment processes, particularly in the removal of iron from drinking water. Iron in its ferrous state is soluble in water; however, when oxidized to its ferric state, it precipitates out of solution, allowing for easier removal through sedimentation or filtration. Thus, increased levels of dissolved oxygen lead to a faster rate of oxidation, enhancing the effectiveness of iron removal methods employed in water treatment facilities. Other factors like temperature and pH can influence the rate of reaction, but increased dissolved oxygen is the most direct factor in accelerating the oxidation process in this context.