The water contains excessive iron and manganese and is not suitable for domestic drinking or industrial production. This kind of water quality mostly occurs in underground water sources. What methods should be used to remove iron and manganese from water?

The process for removing iron from water consists of three parts: aeration, oxidation reaction and filtration. "Water"pHThe value has a significant impact on the oxidation reaction rate of divalent iron, and aeration and oxygenation are used to remove part of itCO2,pHIt can be raised to7.0The above can achieve a good oxidation reaction of divalent iron and flocculation sedimentation of trivalent iron, and then remove them through filtration. However, water often contains a small amount of dissolved silicic acid, and thus the waterSiO(OH)3-Ions strongly adsorb onto the surface of the trivalent iron hydroxide colloid, making it difficult for the trivalent iron hydroxide to alternately coagulate, which leads to penetration of the filter layer and affects the iron removal effect. Therefore, the contact oxidation method is widely adopted for iron removal. This method involves water being aerated and oxygenated, and then iron is removed through adsorption and contact oxidation on the filter material. Gradually, an iron filter membrane with catalytic activity is formed on the surface of the filter material. The iron active filter membrane further plays a role in iron removal. Contact oxidation for iron removal takes advantage of the catalytic effect of iron-based active filter membranes, which significantly accelerates the oxidation rate of divalent iron and more effectively removes iron from water.

To remove manganese from water, the contact oxidation process for manganese removal is widely adopted. The water containing manganese is aerated and then filtered through a filter layer. The hydroxides of high-valent manganese gradually adsorb onto the surface of the filter material, forming a manganese-based filter membrane. With the addition of oil contact catalytic effect, the oxidation rate is greatly accelerated, and the divalent manganese in the water is also adsorbed and removed.

However, iron and manganese often coexist in water. Since the REDOX potential of iron is lower than that of manganese, divalent iron acts as a reducing agent for high-valent manganese, thus greatly hindering the oxidation of divalent manganese. Only when divalent iron is basically non-existent in water can it be oxidized. Therefore, when iron and manganese coexist in water, iron should be removed first, followed by manganese. When the iron and manganese content in water is relatively high, two-stage filtration treatment should be adopted. This is what needs to be noted when removing iron and manganese from water.