Continuous treatment of abandoned mine wastewater containing As and Fe using Mg–Al layered double hydroxides with flocculation

In this study, we conducted a continuous wastewater treatment of an abandoned mine site in Japan to remove As and Fe using Mg–Al layered double hydroxides followed by flocculation and with Ca(OH)2 for comparison. The combination of flocculant ACCOFLOC®A-110 obtained low As and Fe residual concentration, suspended solids, and sludge volume and improved treatment performance by solely layered double hydroxides. Results of continuous wastewater treatment showed that post-treated water conformed with the Japanese Uniform National Effluent Standards for pH, concentration of As, Fe, and suspended solids amount. Compared with treatment using Ca(OH)2, treatment using layered double hydroxides was able to reduce the volume of hydrous sludge with a lower water content and also showed a possibility to reduce transportation cost of sludge based on cost calculation.