Clack MTM is a granular manganese dioxide filtering media
used for reducing iron, manganese and hydrogen sulfide
from water. Its active surface coating oxidizes and precipitates
soluble iron and manganese. Hydrogen sulfide is oxidized
to a sulfur. The precipitates are filtered out in the granular
bed and removed by backwashing.
MTM consists of a lightweight granular core with a coating of
manganese dioxide. The coating provides an example of contact
filtration where the media itself provides the oxidizing
potential. This allows for a much broader range of operation
than many other iron removal media. A pH level as low as 6.2
can be treated. Dissolved oxygen is not essential. The
media’s lightweight reduces backwash water requirements.
When the oxidizing power of MTM is reduced, the bed has to
be regenerated with a weak solution of potassium permanganate
(KmnO4), thus restoring its oxidizing capacity. A
regenerating solution of 1-1/2 to 2 ounces (dry weight) of
potassium permanganate per cubic foot is sufficient for normal
regeneration. 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.
MTM requires either intermittent or continuous regeneration
to maintain its oxidizing capacity. 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
Capacity/Cu. Ft.:
Iron (Fe+2) alone 600 grains (10,000 ppm)
Manganese (Mn+2) alone 300 grains (5,000 ppm)
Hydrogen Sulfide (H2S) alone 175 grains (3,000 ppm)
Advantages:
Broad operating range for iron reduction
Lower pressure loss through the bed with highflock
holding capacity
Effective hydrogen sulfide, iron and manganese
reduction
Lightweight requires lower backwash rates and
reduces pumping requirements.
Chlorine can be beneficial in extending filter run times
Low attrition loss for long bed life
Lower shipping cost
Physical Properties:
Color: Dark brown
Bulk Density: 45 lbs./cu. ft.
Specific Gravity: 2.0 gm/cc
Effective Size: 0.43 mm
Uniformity Coefficient:
Conditions for Operation:
Water pH range: 6.2 – 8.5
Maximum water temp: 100°F/38°C
Bed Depth: 24-36 in.
Freeboard: 50% of bed depth (min.)
Service flow rate: 3 – 5 gpm/sq.ft., 8 – 10 gpm/sq.ft.
intermittent flow possible.
Backwash flow rate: 8 – 10 gpm per sq. ft.
Backwash expansion rate: 20 – 40% of bed depth (min.)
Regenerate dosage: 1-1/2 to 2 oz of KMnO4 by
weight per cu. ft.
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