Abstract: In order to effectively solve the problem of iron and manganese overload in groundwater, this paper proposes a new method of removing iron and manganese by combining powdered activated carbon (PAC) and ozone, and explores the mechanism of the effect of PAC in treating iron and manganese in water by ozone oxidation. The effect of PAC and ozone on the treatment of Fe and Mn alone was firstly investigated; Then the effect of PAC and ozone on the treatment of Fe and Mn in combination was investigated, and the effect of different conditions (pH, temperature, PAC dosage, and oxidant concentration) on the removal of Fe and Mn in water was investigated; Finally, the mechanism of the effect of PAC on the treatment of Fe and Mn in ozone oxidation water was investigated. The results showed that PAC could enhance the oxidation of Fe and Mn by ozone under different conditions. Under the conditions of PAC dosage of 0.3 g/L, ozone mass concentration of 5 mg/L, pH of 7.0, and room temperature, the mass concentration of Fe and Mn mixed solution rapidly decreased from 0.5 mg/L to 0.1 mg/L within 5 min, which met the requirements of corresponding emission standards; With the increase of PAC dosage, the residual concentrations of Fe and Mn gradually decreased, which indicated that the reaction was highly dependent on the active sites on the surface of PAC, further confirming the effect of PAC on the removal of Fe and Mn from water. The characterization results such as scanning electron microscopy (SEM) and Mapping analysis showed that the reaction formed iron oxide and manganese oxide coatings on the surface of PAC, and these oxide coatings would further accelerate the removal of free iron and manganese from water.

Key words: iron removal, manganese removal, powdered activated charcoal, ozone, adsorption, oxidation