Study on the preparation optimization and characteristics of modified media for coal-mine wastewater treatment with high iron and high manganese concentration

Nowadays, the coal-mine wastewater contained high concentration of iron ion and manganese ion was treated by filter process, in which manganese sand, as a kind of common filter media, was extensively applied, but its disadvantage is long set-up period for manganese ion removal. In this paper, for many advantages of hydrated manganese dioxide, such as high surface areas, abundant surface hydroxyl and strong absorption capacity, MnCl₂ and KMnO₄ solution were selected as modified agents for lava media in order to make its surface form the layer of hydrated manganese dioxide, thus it can enhance manganese ion removal efficiency and shorten set-up period. This paper firstly investigated the optimization of preparation parameters, namely 4times of soaking and oxidizing by modified agents and 1hour soaking-time were considered as optimal preparation parameters. Secondly, the pollutants removal efficiencies were compared among the modified lava media, lava media, modified manganese sand and manganese sand, results showed that modified lava media had high-efficiency and durable Mn²⁺ removal. Finally, the experiment of backwashing and generation for modified lava media showed that backwashing can recover the removal capacity for total iron and turbidity, and only generation can recover the removal capacity for Mn²⁺. The specific generation method was that the saturated media was submerged in 1mol/L NaNO₃ solution for 15min.