Iron removal is the second most common water treatment and purification task after water softening. It is characteristic of Hungary that the stratified waters in the soil contain a significant amount of iron wich at higher concentration gives the water an unpleasant metallic taste. Waterworks and all facilities that are required to have drinking water quality must comply the drinking water quality regulation (you can about this in the information menu). This does not mean that w eget iron-free water or have to produce it. However there are technologies and applications where almost complete iron removal is required, regardless of the regulation.
Many times, iron removal may seem like and easy water purification and filtration task (it is usually true as well), but not every time.
There are several parameters to consider when selecting an iron remover device:
dissolved iron content of water (mg/l), amount of water to be treated (m3/h), other ingridients in water (magnese), dissolved oxygen content, water pH, is there chlorine in the water?
This water treatment and wate purification task can be performed in several ways. There are also old and new, more modern technologies for iron removal, such as:
this is the most common method, in 80-90% cases we use catalytic filter material for industrial iron removal. This catalytic charge converts water dissolved iron and manganese ions into water insoluble compounds so they can be easily filtered out of water. There is a charge that is regeneration-free and wich needs regeneration. It is important to know that regeneration does not mean backwashing, as it is necessary for all of them, but the preservation of the active surface of the filter insert. There are charges that do they job until they are exhausted, then they need to be replaced, and there are also charges that need to be kept active by chemical regeneration. This can be intermittent or continuous regeneration using a chemical additive added to the water. In this case, care must be taken that if a charge without regeneration is used, water must have an adequate amount of oxygen and the pH of the water must be adequate. If a regenerative iron remover device is used, care must be taken not to overdose the chemical, as this will appear in our treated water, or adding a small amount,the iron removal will not be effective.
in this case, the dissolved iron content is oxidized to iron flakes not by oxygen but by the oxidizing ability of the chemicals. This chemical may be based on active hydrogen or chlorin, or we can use a combination of these. In this case, care must be taken not to overdose the chemicals because it will appear in the treated water or if there is no ingredient in the water wich it cannot be used. And for low amount of dosing, oxidation will simply not be effective enough, so dissolved iron may remain in the water.
in this case, the oxygen content of the air is used to oxidize the dissolved iron to iron flakes (iron hydroxide) and then these flakes are filtered through a multimedia gravel filter. In these cases care must be taken that oxidation requires a relatively long reaction time and if the air added tot he water is not properly filtered through a special filter, the water may become contaminated. Furthermore, it may not be sure that the water can pick up enough air for oxidation compared tot he iron content of the water.
This is a more modern version of the method above. Ozone works in the same way as oxygen in the air, only the oxidation process is much more effective and faster. In this case, is imprtant to know that ozone oxidation can alsoproduce toxic substances (if bromine is in the water, bromate). This technology is mainly used for complex water treatment tasks such as arsenic removal, but also for excellent disinfection, or above (50-100m3) capacity, where it alredy pays of.
Whatever iron remover technology is used, many factors need to be considered in relation to the composition of the water, we also need consider, there is operating staff for the equipment, how much free space we have for the equipment, and finally how much money is available for realization and what is the operating cost that will still acceptable for economical production.