This system uses manganese zeolite as both the oxidizing source and filter medium. Manganese zeolite is made from processed green sand zeolite by alternate treatments with manganese sulfide and KMn04, as follows:

NaZ + Mn⁺⁺ —————> MnZ + 2Na⁺

MnZ + KMn0₄ —————> Z.Mn0₂ + K⁺

NaZ is green sand zeolite and Z.Mn02 is manganese zeolite.

This process produces higher oxides of manganese in and on the granules of green sand. The resultant manganese zeolite is a black granular material.

Although the original green sand is a natural softening material, no softening of the water takes place during treatment with manganese zeolite. The bed oxidizes soluble iron or manganese to insoluble oxides and simultaneously filters them out of the water. The oxidation reaction is as follows:

Once the oxidizing capacity of the bed is exhausted, soluble iron and manganese breakthrough occurs. To prevent this leakage or breakthrough of iron or manganese into the water supply, the bed is batch-regenerated (to restore its oxidizing capacity) at predetermined intervals. The manganese zeolite bed is regenerated by treating it with a 0.5% solution of KMnO4 .

Besides regeneration, backwashing is carried out at intervals whenever accumulated deposits in the bed build up a pressure loss. Backwashing is best accomplished with treated filter water.

This manganese zeolite process can also be operated by dosing the continuously ahead of the filter bed. Instead of the bed being regenerated, the continuous feed of the permanganate oxidizes iron and manganese to an insoluble state before it reaches the manganese zeolite bed which acts as a buffer. It oxidizes any residual dissolved iron and manganese like the batch regenerated system if the permanganate dosage is slightly low and removes any excess unreacted permanganate when the dosage is high, by partial regeneration of the manganese zeolite bed.