Application of Mg–Al layered double hydroxide for treating acidic mine wastewater: a novel approach to sludge reduction

To reduce sludge volume, Mg–Al layered double hydroxide (LDH) was used to remove pollutants from mine wastewater. Mg–Al LDH can remove both cations and anions from mine wastewater via co-precipitation and anion exchange mechanisms, respectively. We herein investigated the difference in removal efficiencies between Mg–Al LDH and Ca(OH)2. Initial As and Fe concentrations of 8.4 and 308.6 mg/L led to final concentrations of 2 gave As and Fe concentrations of 0.1 and 2 treatment, As is removed by the co-precipitation of arsenate with the formation of ferric oxyhydroxide (FeO(OH)), while Fe is removed by co-precipitation of the formed Fe(OH)3. The sludge volume obtained using Mg–Al LDH was approximately ten times lower than that obtained when using Ca(OH)2.