A Novel Combination of Anaerobic Bioleaching and Electrokinetics for Arsenic Removal from Mine Tailing Soil

Abstract

This study provides evidence that a hybrid method integrating anaerobic bioleaching and electrokinetics is superior to individual methods for arsenic (As) removal from mine tailing soil. Bioleaching was performed using static reactors in batch tests and flow conditions in column test, and each test was sequentially combined with electrokinetics. In the bioleaching, indigenous bacteria were stimulated by the injection of carbon sources into soil, leading to the mobilization of As with the concurrent release of Fe and Mn. Compared with the batch-type bioleaching process, the combined process showed enhanced removal efficiency in the equivalent time. Although the transport fluid bioleaching conditions were inadequate for As removal, despite long treatment duration, when followed by electrokinetics the combined process achieved 66.5% removal of As from the soil. The improvement of As removal after the combined process was not remarkable, compared with single electrokinetics, whereas a cost reduction of 26.4% was achieved by the reduced duration of electrokinetics. The As removal performance of electrokinetics was significantly dependent on the chemical species of As converted via microbial metal reduction in the anaerobic bioleaching. The synergistic effect of the combined process holds the promise of significant time and cost savings in As remediation.