The principle of manganese sand filter media in removing harmful substances such as iron and manganese in water is mainly based on its oxidation catalytic effect. The main component of manganese sand filter media is manganese dioxide (MnO₂). When water containing iron and manganese passes through the manganese sand filter layer, MnO₂ will undergo redox reactions with divalent iron (Fe²⁺) and divalent manganese (Mn²⁺) in the water, oxidizing them into trivalent iron (Fe³⁺) and tetravalent manganese (MnO₂) or high-valent manganese oxides.
Specifically, MnO₂ in manganese sand filter media acts as an oxidant, which can oxidize divalent iron and divalent manganese in water into high-valent metal ions. These high-valent metal ions then combine with hydroxide ions (OH⁻) in water to form hydroxide precipitates, which are intercepted by manganese sand filter media and discharged from the system during the backwashing process, thereby achieving the purpose of removing harmful substances such as iron and manganese in water.
In addition, a layer of catalytic "active filter membrane" will form on the surface of the manganese sand filter material, which can further accelerate the oxidation reaction of iron and manganese in the water and improve the efficiency of iron and manganese removal. This oxide film not only enhances the adsorption capacity and interception efficiency of the filter material, but also helps to protect the manganese sand particles inside from erosion.
