Manganese Dioxide (MnO?) as a Filter Media for Iron Removal

Manganese dioxide (MnO?) is another highly effective medium for removing iron from water. It is commonly used in granular form or as a coating on other filter media, and is particularly known for its ability to oxidize dissolved iron (Fe2?) into insoluble iron (Fe3?), which can then be filtered out. Here's an indepth look at how manganese dioxide works for iron removal:

How Manganese Dioxide Works

Manganese dioxide acts as a catalyst to oxidize ferrous iron (Fe2?) into ferric iron (Fe3?), a process that makes the iron particles insoluble, allowing them to be trapped in the filter bed.

Oxidation Process: The MnO? particles are not consumed during the oxidation process but rather act as a catalyst. When water containing dissolved iron flows through manganese dioxide, the MnO? facilitates the oxidation of Fe2? (ferrous) to Fe3? (ferric), which precipitates out of solution.

?

Iron Removal: The ferric iron (Fe3?) is no longer soluble and forms particulate matter (iron hydroxides), which can then be filtered out using the filter media.

Advantages of Manganese Dioxide for Iron Removal

High Efficiency: Manganese dioxide is highly effective in oxidizing dissolved iron at relatively low concentrations, often requiring no additional chemicals like chlorine or potassium permanganate.

Long lasting: It can be used for extended periods without significant degradation, which makes it ideal for long term use.

No Regeneration Needed: Unlike some other media like manganese greensand, manganese dioxide does not require chemical regeneration. Once it has oxidized iron, it continues to act as a catalyst for future oxidation cycles.

Works in a Wide pH Range: Manganese dioxide is effective at a wide range of pH levels (from acidic to neutral), making it suitable for various water sources, including mildly acidic water.

?

Forms of Manganese Dioxide for Iron Removal

1. Granular Manganese Dioxide: This is a bulk, granular form of MnO? that can be used directly in filtration systems. It is often used in the same way as Birm or Katalox Light.

Application: Ideal for low to moderate iron concentrations in water. Granular manganese dioxide can also be used in combination with an air injection system for optimal performance.

2. Coated Media: Some filter media, such as sand or other granular materials, are coated with manganese dioxide. These filters are marketed under names like "Pyrolox" (a trademarked version), and offer the same oxidation and filtration benefits of manganese dioxide while being more durable.

Application: These types of media are effective in removing both iron and manganese, and they can last a long time with minimal maintenance.

?

Common Uses

Residential Filtration: Manganese dioxide is often used in home water treatment systems to remove iron from well water or municipal water supplies with low to moderate iron content.

Industrial Water Treatment: It is also used in industrial applications where large volumes of water need to be treated for iron contamination.

Water Softening Systems: Manganese dioxide is sometimes used in conjunction with other filtration media, such as Birm, to treat hard water and remove iron and manganese simultaneously.

??

Advantages and Disadvantages of Manganese Dioxide

Advantages:

No Chemical Regeneration: Unlike manganese greensand, manganese dioxide does not need to be periodically regenerated with potassium permanganate, reducing maintenance costs.

Durability: Manganese dioxide is a very durable media that can last for many years without significant loss of efficacy.

Versatile: It works across a broad pH range (69) and can be used to treat both iron and manganese simultaneously, making it an excellent all around media.

?

Disadvantages:

Initial Cost: Manganese dioxide based filter media may have a higher upfront cost , but this is often offset by the long lifespan and low maintenance needs.

Pre oxidation Required in Some Cases: In certain situations, especially where iron concentrations are very high, additional pre oxidation (such as air injection or chlorine) may be needed to ensure effective removal.

Requires Backwashing: Like most iron removal filters, manganese dioxide media needs to be periodically backwashed to remove the accumulated iron particles.

?

Considerations for Using Manganese Dioxide

1. Water pH: While manganese dioxide works well in slightly acidic to neutral pH water (pH 69), very acidic water (pH < 6) may require pH adjustment to optimize the oxidation of iron.

2. Iron Concentration: Manganese dioxide works best when the iron concentration is not excessively high (usually up to around 10 ppm). For very high levels of iron, pre oxidation using air injection or chlorine might be needed.

3. Pre Treatment: For iron concentrations exceeding 510 mg/L, it is often recommended to use air injection or a similar pretreatment system. This helps ensure that the iron is oxidized before it passes through the manganese dioxide media.

4. Maintenance: While manganese dioxide does not require chemical regeneration, it still requires backwashing to remove the iron that has been precipitated out during filtration. The frequency of backwashing depends on the flow rate and the concentration of iron in the water.

??

Summary of Manganese Dioxide (MnO?) for Iron Removal

Best for: Removing ferrous (dissolved) iron from water.

Advantages: High efficiency, long lifespan, no chemical regeneration, works across a wide pH range.

Disadvantages: Potential need for pre oxidation for very high iron levels, requires backwashing.

Application: Ideal for residential and industrial iron removal, often used in granular form or as a coating on other media (e.g., Pyrolox).

?

Manganese dioxide is a highly effective and durable media for iron removal from water. It provides longterm performance with minimal maintenance, making it a costeffective choice in the long run. It is particularly suitable for applications where iron concentrations are moderate, and it works best when combined with a preoxidation step or air injection system for optimal results.

Starke is a premier supplier of high-quality filter media for various water treatment applications, including iron removal. For reliable and efficient filtration solutions, contact Starke Filter Media to order your filter media and discuss your specific needs.

Contact: [email protected]