Phytoremediation of acid mine wastewater using aquatic plants: a case study of a gold mine in Chanaka

Author

Manyinyire, Melissa

Title

Phytoremediation of acid mine wastewater using aquatic plants: a case study of a gold mine in Chanaka

Abstract

Acid mine wastewater contains high concentrations of heavy metals and has a low pH, making it harmful to aquatic life and human health. In Bindura, gold mining is a major contributor to such pollution. Conventional treatment methods are often expensive and ineffective, prompting interest in sustainable solutions like phytoremediation. This study investigates the potential of three aquatic plants, water hyacinth (Eichhornia crassipes), duckweed (Lemna minor) and salvinia (Salvinia molesta) to remediate acid mine wastewater. Water samples were collected from a gold mine in Chanaka, an area found in Bindura. Healthy specimens of each plant species were acclimatized and then exposed to the wastewater in 10 litre containers over a period of 28 days. Each treatment was replicated three times. Thereafter, weekly water samples were collected and analysed for pH, turbidity, heavy metals (Pb, Cd, Fe, Cu) and nutrients (nitrate and phosphate) using standard procedures, including atomic absorption spectroscopy for metal quantification. The results showed that all three aquatic plants contributed to improvements in water quality, but Eichhornia crassipes demonstrated the highest overall removal efficiency across all measured parameters. It raised the pH from 3.2 to 6.1 and reduced turbidity by 68%. Metal removal efficiencies for Eichhornia crassipes were Pb (84%), Cd (79%), Fe (88%) and Cu (81%) along with notable reductions in nitrate (65%) and phosphate (58%). Lemna minor and Salvinia molesta were less effective but still contributed significantly to pollutant removal. Although Eichhornia crassipes outperformed the other species, one-way ANOVA showed no statistically significant differences (p>0.05) in removal efficiencies among the plant species. The study concludes that aquatic macrophytes, particularly Eichhornia crassipes offer a low cost and environmentally friendly approach for improving the quality of acid mine wastewater. These findings support the adoption of phytoremediation as a sustainable alternative for managing water bodies impacted by mining activities.

Date

June 2025

Publisher

BUSE

Keywords

Aquatic Plants

Phytoremediation

Acid Mine Wastewater

Supervisor

Mr. Zingoni