Phytoremediation of mercury in wastewater from the mining industry

Abstract

Mining is an industry activity very important but pollutes the environment through exposure to its wastewater containing toxic heavy metals like mercury, which contaminates the water, soil, and the animal and plant wildlife. Therefore, there is a need to minimize or removal this heavy metal from the mine effluents. One eco-friendly and sustainable technology of toxic heavy metal removal is phytoremediation. The objective of this research is to evaluate the performance of the aquatic macrophyte water hyacinth (Eichhornia crassipes) in a constructed wetland with subsurface flow for phytoremediation of a real mining wastewater containing mercury. The study was done in two phases: i) transplant and acclimatization of the plants which lasted 24 days, and ii) phytoremediation of mining effluent about 7 months. The plants responded positively to environment. Moreover, mercury initial concentration for contaminated effluent was 0.325 mg/L. This value is high enough to exceed the permissible limit (0.002 mg/L) stipulated by Colombian legislation for discharge of meaning wastewater into surface water, however, the plants effectively removed up to ï¾ 71% of Hg from the contaminated water. Most of the mercury removal occurred during the first month. It was not possible further Hg reductions to drinking water standards (0.001 mg/L), however, considering the high removal efficiencies of Hg by these aquatic macrophytes, these plants can be recommended for fast removal of mercury in the initial stage of water body remediation.