Birm is a relatively inexpensive material which can be used for iron and manganese removal by catalytic oxidation. It requires a pH of 7 or more for iron removal and pH 8 for manganese removal. It is advised not to use Birm in combination with chlorination and the water should be free of oil and hydrogen sulphide. If the pH of the water is too low pH correction maybe required. Birm is a light, inexpensive media but often doesnt last quite as long as other natural media.
How does it work?
Water flows into the valve at the top, down through the media and then up through the riser tube in the middle of the vessel. As the water travels through the media the iron and manganese are oxidised bringing the metals out of solution and trapping them so only clean clear water flows out to service. These systems also act as sediment filters trapping any natural turbidity. As the media act as a catalyst they do not need to be topped up or replaced on a regular basis.
There are timer options that can be set to automatically self clean (backwash) and wash away any of the accumulated iron and manganese.
The Aquamandix, Filox and Birm filters require dissolved oxygen in the water to oxidise the metals. This normally is present naturally but can be added by aerator or as an air filtration option. Greensand and MTM contain a lower concentration of active catalyst so require frequent regenerations with oxidation chemicals like potassium permanganate.