Iron and/or Manganese Reduction
Signs of the problem – Brown staining from the presence of iron, black staining or deposits from the presence of manganese, the discolouration is often increased when the water is left to settle and oxygen causes the iron and manganese to precipitate from solution (noticeable in water tanks, toilet cisterns and drinking bowls/troughs). Metallic tasting water is a common sign of heavy metals in the water, often described as tasting like, blood or rusty nails. High levels of iron and manganese can cause health problems and foul pipe and appliances.
Solution. Install an iron/manganese reduction filter. The correct type of iron/manganese reduction unit will need to be specified based on the feed water quality, water flow rates and water demand. A backwashing/regenerating filter vessel would be used. There are two main approaches to iron and manganese reduction. Firstly, oxidisation by way of either a contact assembly (aerator system) before the iron/manganese reduction vessel or an air draw valve adapted to the electronic control valve. These medias require a pH of 7 for iron reduction and 8 for manganese reduction. The second approach is ion exchange / base exchange which regenerate on a brine solution (sodium chloride) and also softens the water. Ion exchange requires a clear water for reliable results and often the pH requirement isn’t as critical with much less water discharged to drain than an oxidising system. For high levels of iron and manganese a zeolite type media or mixed media ion exchange resin can be used. For low levels of iron or manganese often a standard base ion exchange resin can be used.
Commonly used iron/manganese reduction medias include Filox (the superior media to Pyrolox, which is heavier and requires a higher backwash flow rate), and BIRM for the oxidising technique. Crystal Right CR100 (pH above 6), Crystal Right CR200 (pH above 7), Ecomix or Low Fouling resin for ion exchange systems.
