Iron & Manganese Removal from Groundwater
Removing iron and/or manganese from water supplies can be accomplished by a variety of means, depending on the amount of material to be removed, whether both iron and manganese are present, and whether there are constraints on the use of chemicals.
Iron and manganese in groundwater supplies are typically present as dissolved substances. As the water is exposed to atmosphere, some of the iron and manganese are oxidized and become suspended solids. Simple exposure to atmosphere, however, is not generally sufficient to achieve effective removal.
The most frequent approach to removal is by means of oxidation.
Oxidation can be accomplished by:
- injecting an oxidizing agent into the water (such as sodium hypochlorite and/or potassium permanganate) or
- aerating the water, followed by detention in a holding tank.
Once oxidation has occurred, the particles of iron and manganese can be removed via mechanical filtration.
Mechanical filtration can be accomplished with or without the use of “activated” media. Activated media is comprised of:
- manganese greensand (a naturally occurring granular substance) or
- silica sand that has been impregnated or coated with manganese dioxide.
As water passes through the media, further oxidation occurs, thus optimizing the removal of iron and manganese.
In order to maintain the active properties of these media, an oxidizing agent is needed (typically sodium hypochlorite and/or potassium permanganate). These agents also cause oxidation of the substances to begin before they enter a filter.
In instances where iron and/or manganese concentrations are high, removal may require aeration, detention, and chemical injection followed by filtration using activated media as described above.
If chemicals cannot be used, oxidation can be achieved in most cases via aeration, followed by detention in a holding tank, and finally filtration using a dual-media filter bed. The larger particles of iron and manganese will settle out in the holding tank, while the smaller particles will be removed by the dual-media filter.
Everfilt manufactures iron and manganese removal systems for flows from small to very large. For a specific treatment process tailored to your water quality and treated water requirements, consult an Everfilt Application’s Engineer.