MTM Filter medium:
It is a granular manganese dioxide medium used for the reduction of iron, manganese and hydrogen sulfide in drinking water. Its active surface coating oxidizes and soluble iron and manganese precipitate. Hydrogen sulfide is oxidized to sulfur. The precipitates are filtered into the granular bed and removed by backwashing also called backwashing.
It is composed of a light weight granular core with a layer of manganese dioxide. It is an example of contact oxidation where the media itself offers the oxidant potential. This allows for a much wider variety of operation than many other means of iron removal. A level of h as low as 6.2 can be treated. Dissolved oxygen is not essential. The light weight of the media reduces backwash water requirements. MTM requires regeneration, either continuous or intermittent to maintain its oxidizing layer. For regeneration either continuous or intermittent to maintain its oxidizing capacity.
For continuous regeneration a solution of potassium permanganate (or chlorine then potassium permanganate) can be pre-fed to maintain capacity. In the latter case, the manganese dioxide coating acts as a catalyst to enhance the oxidation reaction and as a regulator to reduce any excess potassium permanganate concentration and prevent it from entering utility lines. Continuous feed regeneration using CI2, KMnO4, or both is required for all systems that are greater than 3 cubic feet.
For intermittent regeneration use a regeneration solution of 1 1/2 2 ounces (dry weight) of potassium permanganate per cubic foot is usually sufficient. After commissioning a new litter it should be backwashed and care taken to ensure that light weight media are not washed for drainage. A new bed must be regenerated by the afternoon of installation. Operating the filter after its oxidizing capacity is exhausted will reduce its life and may cause staining. The water not treated periodically must control the parameters of the raw water. The treated water should be monitored periodically for manganese and if iron and hydrogen sulfide are present.
When intermittent regeneration is used, samples of treated water should be taken shortly before a regeneration and immediately after a regeneration to check if the filter system is working. High manganese concentrations in treated water prior to regeneration may indicate that the filter media is being destroyed or that the reduction capacity of the bed has been exceeded.
Low pH, lack of chlorine oxidant, or lack of permanganate oxidant are the most likely conditions leading to destruction of the media. The addition of other chemicals to the influent or wash water that contacts the MTM media may inhibit iron, manganese, or hydrogen sulfide removal or may degrade.