DMI 65 Iron Removal Water Filtration Media

DMI-65 filter media is an extremely powerful catalytic water filtration media that has been designed for the removal of iron and manganese from various feed water sources, without the requirement of potassium permanganate or chemical regeneration. DMI 65 water filter media has a unique micro-porous structure that effectively removes dissolved iron to near undetectable levels as low as 0.001 ppm and manganese to 0.001 ppm.  DMI-65 Iron removal filter media serves as an oxidation catalyst with immediate oxidation and filtration of insoluble precipitates derived from this oxidation reaction.

DMI-65 filter media also has the capability to remove Arsenic, Aluminium and other heavy metals along with Hydrogen Sulfide under certain conditions.

Physical Properties

Colour Brown to Black
Bulk Density 91.0 lbs/ft3 1.46 gr/m3 1.46 tonne/m
Specific Gravity 2.69
Effective Size 0.3 – 0.6mm
Uniformity Coefficient 1.4
Mesh Size 20 – 40
Annual Attrition 1% – 5%

Operating Conditions

pH Range 5.8 – 8.6
Maximum Water Temperature 113o F (45o  C)
Minimum Bed Depth 24 Inches (600mm)
Freeboard 40% minimum
Service Flow Rate 5 – 30 m3/m2 per hr
Backwash Flow Rate 25 – 40 m3/m2 per hr
Backwash Expansion 20% – 50%

DMI 65 Filter Media Feed Water Parameters for 10 Years Continuous Use   

pH: 8 – 8.
Turbidity : <2 NTU
Iron (Fe) : < 15ppm
Manganese (Mn): < 3ppm
Calcium (CaCo3): <250ppm
Sodium Chloride (NaCl): <1000ppm
TDS Total Dissolved Solids: <2000ppm
Ammonia (NH3): <1ppm
Silica(SiO2): <70ppm

DMI-65 Iron Removal Filter Media Certification

Certified and Tested Under the Industry Standards: NSF / ANSI 61 by the Water Quality Association of USA Gold Seal Program for Safety and Health effects for Drinking Water Equipment
Authorized by the Drinking Water Inspectorate safe to use according to: Regulation 31(4)(a) of the water supply (Water Quality) regulations 2010 for UK, England and Wales

Packaging Details

DMI-65 Advanced Oxidation Catalytic Water Filtration Media

Bag Weight Net: 21kg (46.30lb)
Bag Volume Net: 14.38L (0.5ft3)
Bulk Density: 1.46 gl/cm3 (91lb/ft3)
Specific Gravity (SG): 2.69gr/cm3
Porosity: 45.8%
Mesh 20:40
Pallets of 48 x DMI-65 (21kg) available = Net Weight 1008kg
Pallets of 56 x DMI-65 (21kg) available = Net Weight 1176kg
Whole 1 metric tonne (2,205 lbs / 24ft3) bulk bag Available

DMI 65 Operation

For beginning the process of oxidising the iron and manganese ions in a water solution, ensuring that the oxidative layer on the dmi65 granules is not compromised the media is designed to operate in the presence of chlorine or other oxidants such as ozone. During this process the oxidant removes electrons and is consumed in the process, operators need to ensure that there is a 0.1 – 0.3 ppm free chlorine residual in the untreated water.

Chlorine, dosed as sodium hypochlorite (NaOCl) or bleach (12.5% NaOCl), is the best oxidant as it is relatively cost effective, easily available throughout the world and it works. Alternative oxidants such as hydrogen peroxide (H2O2), chlorine oxide (ClO2) or ozone can also be used as long as a residual can be monitored and maintained. Another benefit of using chlorine is that it keeps the filter media and downstream equipment free from bacterial or slime growth. DMI-65’s manganese oxide catalytic surface needs to remain clean so that the ions in the water can come in contact with it.  At the same time, the chlorine is a source of oxygen more reactive than molecular oxygen.

DMI-65 filter media needs be activated before being placed into its first service function.  The activation of DMI65 requires a larger dosage of chlorine than used during standard operation but only has to be performed one time during the initial system start-up.  The chlorine dosage rate is 10 fluid ounces of 12.5% chlorine per cubic foot (ft3) of the DMI-65 filter media. Activation only requires a soak of several hours but an overnight soak would be better.

Once the DMI 65 Media has been activated, the filter vessel must be backwashed to get rid of excess Chlorine and fine particles and dust from the dry media. Manganese oxide is one of the constituents used in the manufacturing of DMI 65, an extended rinse is required at start up to remove any trace free manganese oxide residual left over from the manufacturing process. When the Mn levels in the backwash water reaches values of 0.05 to 0.15 ppm and the free chlorine residual is set, the iron removal filter is ready to start working.

DMI 65 Filter Media replacement due to the decreased physical filtration properties of the Media due to physical abrasion will occur before complete degradation of the catalytic layer takes place.  Under normal operating conditions media life is estimated at 5 – 10 years.

Iron (Fe) precipitation and removal using DMI 65

Iron (Fe) is the fourth most common element found in the earth’s crust and exists in a wide range of oxidation states from -2 to 6 although the most common states are ferrous ( 2) and ferric ( 3).

Ferrous or Iron salts are readily soluble. Before the ferrous iron, a dissolved solid commonly found as ferrous bicarbonate, can be removed by filtration it must be oxidized, become ferric hydroxide and in neutral pH waters precipitate out in the media bed.  The catalytic surface of DMI-65 contains manganese oxide or exposes manganese and oxygen sites for adsorption of [Fe] ions that are in the water.  The reaction of ferrous bicarbonate and NaOCl is almost instantaneous and the ferrous bicarbonate oxidizes (gives up an OH-) to become the insoluble ferric hydroxide which is then removed through filtration in the catalytic surface of the media.

Manganese, Mn precipitation and removal using DMI 65

DMI-65 is a catalytic material specifically tailored to the oxidation and removal of manganese.  The catalytic surface contains manganese oxide for brining into proximity of covalent bonding manganese and oxygen atoms from water.  However, oxidation and removal of manganese (Mn) is vastly different from that of Fe.  A major difference is caused by the solubility of manganese oxy-hydroxide, MnO(OH)2.

Manganese does not precipitate as oxy-hydroxide but as oxide, MnO2 and higher valence oxides. Presence and concentration of hydroxide anions does not help much in the precipitation and removal of manganese.  Manganese hydroxide will be attracted with the manganese end to the oxygen in catalytic lattice surface.  An Oxygen molecule has to be available in the proximity for facilitating oxidation through the oxygen from lattice and swapping to the lattice with molecular oxygen.  Conditions for this to happen are statistically less probable and reaction is of much slower rate than the oxidation of Fe via hydroxide.

Key DMI-65 operating conditions

Treatment processes have to be conducted in such manner so that the catalytic surface of the material is kept clean and available to ion from water to contact.
Water with a large amount of suspended solids has to be clarified before passing it through the catalytic filter with DMI-65. Acceptable levels of suspended solids depends on their nature.  A larger amount of mineral suspended solids than organic suspended solids could be handled.
Bacteria could grow and deposit slime on DMI-65. Thus disinfectant and oxidation conditions have to be maintained.
Water containing clays and large organic molecules may result in deposition of such material on the surface of DMI 65 and blinding of the catalytic surface. Treatment for removal of such contaminant before the catalytic filter is needed.
Polymer flocculent could also stick to the DMI-65 and blind catalytic surface.
Hard, unstable groundwater could cause scale deposition in the catalytic filter and blind the material in a solid mono bloc. In such case the DMI-65 material in the bed is lost and would have to be replaced. Treatment for stabilizing the water to prevent scale formation in the catalytic filter has to be carried out.
Both low acidic pH and anoxic conditions could cause dissolution of manganese from catalytic layer of DMI-65 and loss of its capacity. Excessively high pH means excessive concentration of hydroxyl ions (corrosive to metals) and could also cause dissolution of manganese from the catalytic layer.
Do not use demineralized water, distilled water or water known to be strongly corrosive to metals for initial soaking and activation of DMI-65.

DMI 65 Filter Media History

Back in the day water treatment was done with naturally occurring zeolites like glauconitic greensand were used to soften and remove iron and manganese from boiler make-up and process waters. As the demand for high quality water increased due to higher pressure type boilers, the water purification industry mostly moved away from traditional products used for water softening to the new developments in synthetic ion-exchange resins.

However, in the case of iron and manganese removal from water this move was a slower process and resulting in the use of greensand filtration media and still continues until this day. Greensand was and is often used as a pre-treatment step before an ion-exchange system since the iron in a feed water fouls the cation softener resin. Other processes include aeration and oxidation filtration with standard multi-media filters or activated glass filter media.

There are and have been other Fe (Iron) & Mn (Manganese) removal products and processes developed since greensand was introduced the use of greensand continued even though there were several issues that made it a less than ideal water filter media.  Greensand required periodic regeneration with potassium permanganate, it could not be used in waters with a lower pH (<6.2), it had a low operating temperature (27’C), and had a tendency to soften through time resulting in pressure drop complications at higher flow rates. Also, the supply of greensand would become restricted due to environmental concerns with the processing facilities along the East Coast of the United States.

Due to the issues associated with greensand as a water filter media, during the 1970s water purification and water purification companies began to research in “an alternative” to replace the greensand water filter media. In response to the demand for a better heavy metals removal water filter media, scientists and researchers in Japan began to look for ways to impregnate oxidizing agents to different types of materials.  It was concluded that a commercially produced iron and manganese filtration media could be made with higher strength, have better physical properties and be more susceptible to improvements or modifications than any naturally occurring water filter media.

Half a century of further research and development of the Japanese Infusion Technology has resulted in the uniquely Australian manufactured product, DMI-65 a granular catalytic media used to boost the advanced reduction/oxidation (redox) processes in water. The media is part of a wide family of products deriving its physical and chemical action from the interaction of its metal oxide surface with the water molecules and ions in a system. DMI 65 Iron and Manganese Removal Filter Media is a revolutionary due to proprietary infusion technology that penetrates the micro pours substrate of the matrix material, allowing for a larger catalytic contact surface area and of a tight particle size distribution. DMI-65 has low level of fines, a tolerance to wider pH range and chemically infused catalytic surface that won’t be consumed or diminished under normal operating conditions. Service life of 5 – 10 years with continuous use.