GREEN SAND

anganese greensand is a purple-black filter media used for removal soluble iron, manganese and hydrogen sulfide from well water supplies through oxidation and filteration. It also has the capacity of removing radium and arsenic. It is processed from the mineral glauconite that is zeolite. Using iron exchange properties of this natural zeolite, a manganese dioxide coating is deposited on the surface of the glauconite grains. The manganese dioxide acts as a catalyst in the oxidation reduction reaction of iron and manganese. The media can be used in two methods of operations: continuous regeneration (CR) and intermittent regeneration (IR).
Soluble iron and manganese are oxidized and precipitated by contact with higher oxides of manganese on the greensand granules. The hydrogen sulfide is reduced by oxidation to an insoluble sulfur precipitate. Precipitates are then filtered and removed by backwashing. When the oxidizing capacity power of the Manganese Greensand bed is exhausted, the bed has to be regenerated with a weak potassium permanganate (KMnO4) solution thus restoring the oxidizing capacity of the bed. 1 ½ to 2 ounces of potassium permanganate, in solution, per cubic foot of Manganese Greensand is considered sufficient for normal regeneration. It is required to vigorously backwash and regenerate the bed when it is placed in service and before its oxidation capacity is totally exhausted. Operating the bed after oxidation capacity is exhausted will reduce its service life and may cause staining.

ADVANTAGES :

• Iron reduction over wide pH range
• Effective reduction of hydrogen sulfide in addition to iron and/or manganese
• No harmful effects from a chlorine feed
• Low attrition for long bed life