MTM Iron / Manganese

Clack MTM® is used for reducing iron, manganese and hydrogen sulfide from water supplies.

Clack MTM® is a granular manganese dioxide filtering media used for reducing iron, manganese and hydrogen sulfide from drinking water. Its active surface coating oxidizes and precipitates soluble iron and manganese. Hydrogen sulfide is oxidized to sulfur. The precipitates are filtered out in the granular bed and removed by backwashing.

MTM® consists of a light weight granular core with a coating of manganese dioxide. MTM® is an example of contact oxidation where the media itself provides the oxidizing potential. This allows for a much broader range of operation than many other iron removal medias. A pH level as low as 6.2 can be treated. Dissolved oxygen is not essential. The media’s light weight reduces backwash water requirements.

MTM® requires either continuous or intermittent regeneration 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 buffer to reduce any excess potassium permanganate concentration and prevent it from entering the service lines. Continous feed regeneration using Cl2, KMnO4 or both is required for all systems that are larger than 3 cubic feet.

For intermittent regeneration use of a regenerating solution of 1½ to 2 ounces (dry weight) of potassium permanganate per cubic foot is usually sufficient. Upon start-up a new bed should be backwashed and caution taken to insure that the lightweight media is not backwashed to drain. A new bed should be regenerated the evening of installation. Operating the filter after its oxidizing capacity is exhausted will reduce its service life and may cause staining.

Untreated water should periodically be monitored for raw water parameters. Treated water should periodically be monitored for manganese and if present iron and hydrogen sulfide. When using intermittent regeneration take treated water samples shortly before a regeneration and immediately after a regeneration to monitor how the filter system is functioning. Elevated treated water manganese concentrations before regeneration may mean that the filter media is being destroyed or bed reduction capacity has been exceeded. Take corrective actions as necessary.

Low pH, lack of chlorine oxidant or lack of permanganate oxidant are the most likely conditions leading to media destruction.

Addition of other chemicals to influent or backwash water which contacts MTM® media may inhibit iron, manganese or hydrogen sulfide removal or may break down or coat MTM® media. Before adding any chemical to the influent or backwash water, other than chlorine or potassium permanganate, the chemical’s compatibility with MTM® should be thoroughly tested.