Batch Electrocoagulation Process for the Removal of High Colloidal Clay from Open-Cast Coal Mine Water using Al and Fe Electrodes

Abstract Open-cast coal mining, which involves massive excavation and stockpiling of overburden, has the potential to affect surface water quality. In addition to the potential generation of acid mine drainage owing to the presence of sulfide minerals, mining operations also have the potential to produce water with high total suspended solids (TSS) concentrations. This can occur owing to the presence of clay materials, especially colloidal clays, which prevent solid particles from settling naturally. This study aims to develop an alternative electrocoagulation technology that can be used to remove colloidal clay from mine water. Monopolar batch electrocoagulation was performed at a laboratory scale using aluminum and iron electrodes with variations in the current (0.5, 1, and 2 A) and contact time (15, 30, and 45 min). The results showed that aluminum electrode electrocoagulation, with a current of 2 A and a contact time of 15 min, had a TSS removal efficiency of 99.58%, with concentrations decreasing from 5,400 to 22.84 mg/L. Iron electrode electrocoagulation achieved the highest efficiency with a current of 2 A and a contact time of 30 min. The TSS removal efficiency reached 98.78% while the concentration dropped to 65.66 mg/L. This study is the initial stage to develop electrocoagulation technology. This technology may become an essential alternative for treating mine water with colloidal clay in the future.