Natural water contains iron represented by minerals, and organic compounds, as well as colloidal and suspended finely-dispersed impurities. The state of iron in water greatly depends on the water source and the corresponding environment of iron compounds. Such sources are divided into two types: surface sources and underground sources. Various methods of disposal are applied based on the iron state in water.
Groundwater essentially includes dissolved iron represented by ferrum dihydrocarbonate. Thus, water obtained from an underground source is crystal clear but of a metal off-odor. When oxygen reaches the water, iron oxidizes and transforms into the insoluble form of iron hydroxide, conducting brown-colored water coloration and gradual brown-colored sedimentation.
Most techniques of water purification from iron compounds (except for the ion exchange technique) are based on various ways of iron compounds filtering.
Iron dissolved from underground sources should be transformed into insoluble before filtration. For this process, water is supplemented by an oxidizing agent as a reagent (potassium permanganate, sodium hypochlorite, ozone, etc.), or one of two aeration types is applied: pressure and non-pressure ones. For pressure aeration, compression and ejector admit air into the pipeline where water flows. For non-pressure aeration, water is sprayed into a container, while oxygen contained in the air enters the water droplets. After oxidation, the iron transforms into insoluble and can be separated by a granular filter - quartz sand as usual. Granulated loadings with catalytic properties are sometimes used to speed up iron oxidation. Such properties are encountered in manganese oxide grains or other filter loadings with manganese oxide-coated surfaces. These types of loadings speed up the iron oxidation thereby enabling efficient removal of iron under high filtration rates.
Filtration is also used for the deferrization of water from surface sources. Since iron impurities in surface sources exist as organic compounds and colloidal states, the main goal of filtration lies in water treatment by oxidizing reagents and impurities coarsening by coagulants and flocculants. Such processes are standard for surface-source water treatment before filtration. Thus, the deferrization of water from the surface sources is performed with the clarification process in parallel.
One more water deferrization method is the ion exchange process, which enables removing dissolved iron from water in an inorganic state. This method is used for underground source water, so it’s important to avoid entering air oxygen before the ion exchange filter into the water stream. If iron is oxidized before the ion exchange unit, its loading loses its properties due to damage to the structure of the ion exchange resin.
Water deferrization depends on most specifications, so deferrization methods like filtering loadings and treatment reagents are customized and should be selected under underground water composition analysis.
Manganese compound removal methods usually coincide with deferrization methods, differing only by higher pH values used for the oxidation of manganese compounds. Hence, water demanganization goes with its alkalescence.
Litech Aqua's product line includes domestic-purpose and industrial-purpose deferrization and demanganization systems. Both can differ with various automation levels based on customer expectations.
The selection of the filter and its performance depends on many specifications and indicators (water implementation area, average daily water consumption, required pressure, operating pressure, water temperature, etc.).
Our experts will do their best to assist you with a selection of a proper water filtration system upon your request.