What is the function of a greensand filter in water treatment?

A greensand filter plays a key role in water treatment by removing certain unwanted elements and impurities, especially hydrogen sulfide gas, which is characterized by a distinct rotten egg smell. This type of filter contains glauconite, a green mineral that acts as a medium for oxidizing and reducing hydrogen sulfide. When water passes through the greensand, the hydrogen sulfide is converted to a less odorous form, helping to improve the overall taste and safety of the drinking water.

The effectiveness of greensand filters in removing manganese and iron also contributes to the overall quality of water but does not directly correlate to softening water or bacterial filtration. Therefore, while these minerals are indeed addressed through greensand filtration, the primary focus remains on the removal of hydrogen sulfide gas. The other options, such as softening water or adding minerals, do not accurately represent the primary function of a greensand filter.