Methods to reduce iron and manganese levels at the drinking water source
Besides hardness, iron is also an important cause of problems in the drinking water system. The danger doesn’t lie within the iron itself but in the unpleasant side-effects of its presence. Iron excess gives rise to discoloration of the water, scaling, pipe or nipple blockings, metal taste, promotion of biofilm etc. This affects animal health and can therefore indirectly increase antibiotic use. Manganese excess often comes along with iron excess and causes similar problems. Luckily there are several techniques to remove iron and manganese at the drinking water source:
De-ironing: This is an automatic technique that consists of two steps. 1) By aerating, the soluble iron (Fe2+) precipitates and becomes insoluble (Fe3+). These iron particles are then filtered out with a (sand) filter. Different variants of this technique are available, e.g., with an underground installation. The functioning of the system should be monitored regularly.
Ion exchange: a cation exchanger removes iron and manganese as well as calcium and magnesium from the water by exchanging them for sodium. This happens in column with a resin medium. Removing calcium and magnesium softens the water. This is an automatic technique but periodically, the resin medium needs to be regenerated.
Sedimentation basin: only works for moderate iron/manganese excess. The water flows slowly through an open basin. By periodically aerating the basin, iron and manganese precipitate and sink to the bottom, just as other suspended particles. This results in clear water.
Zeolite filter: zeolite is a rock that can be used as ion exchanger (same principle as above) or as filter. In the latter case, three steps are performed (filtration, regeneration, washing) to remove iron and manganese.