State of the Art Review on the Geochemical, Microbial and Environmental Aspects of Passive Acid Mine Drainage Treatment Techniques

Acid Mine Drainage (AMD) mainly occurs as a result of the natural oxidation of Iron-sulfide minerals contained at operating or closed/decommissioned mine sites, which is one of the most significant environmental challenges faced by the mining industry people worldwide. AMD adversely affects the surrounding land use and water quality due to its typical low pH, elevated concentration of metals, reactive sulfide content, and high acidity. This study presents a state-of-the-art review of the Geochemical, Microbial, and Environmental aspects of AMD generation, collection, and cost-effective options for its treatment (source control to minimize acid generation, implementation of mitigation control, and treatment). This paper also provides an overview of Constructed wetlands (CWs) and phyto remediation options that could provide efficient passive low-cast viable treatment options with a higher percentage of sulfide reduction, removal of other metals, and alleviation of extreme acidic conditions for the developing, operating as well as closed/decommissioned mines. Thus, indigenous aquatic macrophytes and microbial communities that immobilize, bio-leach, or accumulate a small number of metals in constructed wetlands treatment could effectively contribute to the remediation of acidic metal-contaminated runoff waters from mines and mine waste processing/disposal areas. Thus, indigenous aquatic macrophytes and microbial communities based on an integrated constructed wetlands bioremediation approach may successfully lead to a cleaner, greener environment.