4 mg/L) (Fig. 1), the concentration of which was determined by the
stoichiometry of oxidizing manganese and ferrous ions from the
raw water. The system was operated continuously for approximately
30 days, thus successfully preparing the ripening sand
coated with MeOx. After that, dosing with potassium permanganate
ceased. The reaction equations for the oxidation of manganese
and ferrous ions with potassium permanganate are as
follows [18].