A manganese greensand filter is regenerated using which chemical?

The regeneration of a manganese greensand filter is achieved through the use of potassium permanganate. Manganese greensand is a type of filtration medium that is coated with manganese dioxide, which is effective in removing iron and manganese from water. During the operation of the filter, these minerals are adsorbed onto the greensand, reducing its effectiveness over time.

To restore the filter's capacity to remove these contaminants, potassium permanganate is used to oxidize the adsorbed iron and manganese, converting them into forms that can be easily removed. This regeneration process restores the manganese dioxide coating on the greensand, allowing the filter to continue functioning efficiently. Thus, potassium permanganate serves as a regenerating agent that revitalizes the filter's ability to remove impurities from water, making it the correct choice for this question.