Iron & Manganese Removal Plants

Water

• Water with excessive iron and manganese can create brown stains on clothing and an odd flavor in drinks, including tea and coffee. When dissolved iron is left in standing water, oxygen in the air creates a rust stain in the water. Manganese can create a brownish-black color. Such stains may not be removable, even with bleach application. Many of these contaminant problems build up over time as water pipes, water heaters and other containers degrade and release particles into passing water.

Oxidation

• The first process most plants use to remove iron and manganese is oxidation, which is generally inexpensive and easy to accomplish. Chemical oxidants change the chemistry of these elements to an insoluble form. Ferrous iron, for example, is changed to ferric iron and then to iron hydroxide complex, which is insoluble. Treatment plants usually use oxidants such as chlorine, chlorine dioxide, ozone or potassium permanganate to create this chemical process. Manganese oxidation tends to take longer to treat than iron oxidation due to its slow reaction rate.

Filtering

• Once iron and manganese are in an insoluble form, they can be filtered from the water. Common filtering media used include manganese greensand, iron-man sand and macrolite. Greensand and iron-man sand are coated with manganese oxide, which catalyzes oxidation and subsequently removes iron and manganese. Macrolite filters, on the other hand, physically remove the contaminants by straining them through a textured ceramic surface.

Other Processes

• Some plants do not require a separate iron and manganese removal process. Those that use a lime-soda ash softening system create a high pH environment that oxidizes and eliminates these elements as it purifies other contaminants. Other treatment systems achieve removal when they implement coagulation, sedimentation, filtration or flocculation techniques.

  Other methods of removing iron and manganese include sequestration, which uses chemicals to counter the effects of contamination, and ion exchange, used only for removing small quantities of the elements.