How is virgin greensand regenerated?

Virgin greensand is a type of filtration media used to remove iron and manganese from water supplies. The regeneration process is essential to restore its effectiveness after it has been exhausted. Soaking in a chlorine solution effectively removes the metal ions that have accumulated on the greensand during its filtration process. Chlorine acts as a strong oxidizing agent, which helps to regenerate the greensand by reverse-oxidizing the trapped iron and manganese, thereby reactivating its filtering capabilities.

The other methods listed are not effective for this specific regeneration process. For example, boiling in water does not provide the necessary chemical reaction to remove the contaminants. Exposure to sunlight or chemical oxidation with ozone are not typical processes used for regenerating greensand as they do not target the buildup of iron and manganese effectively. Therefore, soaking in a chlorine solution is the correct method for regenerating virgin greensand.