Comparative evaluation of wastewater and bioventing system for the treatment of acid mine drainage contaminated soils

Abstract

The increasing rate of soil pollution poses a prolific threat to the sustenance of the ecosystem. Acid mine drainage (AMD) is an environmental problem that has contributed immensely to soil pedogenesis and contamination associated with mining activities. Physical, chemical, and thermal methods of soil treatment have some rooms for improvement to meet remediation purposes. Contrary to other methods, bioremediation is a cost-effective and a sustainable biological approach that utilizes microorganisms for the remediation of a contaminated environment and does not recontaminate or further degrade the soil after application. This study aims to comparatively evaluate the application of wastewater and bioventing system for the the treatment of AMD contaminated soils. A microcosm containing 1 kg of contaminated soil was amended with wastewaters of varying (biostimulation (BSTa)) while bioventing treatment (BVTa) consists of the injection of atmospheric air through the vadose zone into bioreactors and amended with wastewater effluents. The treatment was conducted at ambient condition for 28 days. The result of the treatment recorded 28–67% and 58–70% metal (Mn, Fe, Al, Cu and Zn) removal efficiencies with 51% and 34% sulfate removal efficiencies for BSTa and BVTa treatments, respectively. However, attempts to improve the sulfate removal efficiencies through the injection of atmospheric air were not effective. This study showed that wastewater and bioventing can be effectively applied as a potential alternative for the treatment of AMD contaminated soils.