Phytoremediation of heavy metals in mine drainage by tropical aquatic plants

Abstract

Acid mine drainage (AMD) is a major environmental problem associated with mining activities. There are several methods to remediate these mine drainage by neutralizing and removing metals from solutions. Those mechanisms can be mainly divided into active or passive systems, which this study describes the utilization of aquatic plants abundant in tropical conditions, in line with the passive remediation technique known as phytoremediation. The plants were selected based on the survivability in the tropical conditions and efficiency of extracting metals. Eichhorniacrassipes(Water Hyacinth) was the most survivable plant, and was deployed to absorb Fe, Cu and Cd from solutions reflecting the generic characteristics of mine drainage. The drainage solutions were created, with increasing concentrations of each ion starting from the permissible threshold values in accordance to the World Health Organization (WHO) guidelines. The results reflect that the efficiency of phytoremediation process with Water Hyacinth was optimum when the solutions were neutral (pH ~ 7) and deteriorating under acidic conditions (i.e. pH<7).