Exploring the Potential Utilization of Vetiver in Treating Acid Mine Drainage (AMD)

摘要

Acid mine drainage (AMD) released from mining industry usually has a low Ph and contains high levels of heavy metals, which significantly impacts on the water quality and ecosystems of southern China. Constructed wetlands have been considered effective, low cost and a practical approach for the cleanup of different wastewaters including AMD. A microcosm test was conducted to assess the tolerance of different wet land species to AMD and purification capacity of wetlands. The plant species trialed included: Vetiveria zizanioides (VZ) ,Phragmites australis (PA), Cyperus alternifolius (CA),Panicum repens (PR), Gynura crepidiodes (GC),Alocasia macrorrhiza (AM) and Chrysopogon aciculatus (CHR).Chemical analysis indicated that AMD collected from Lechang lead/zinc mine tailings contained high concentrations of Zn, Mn,Pb,Cd,Cu and SO_4~(2-),and was also extremely acid. The 75-day experiment indicated Cyperus alternifolius had the highest but Gynura crepidiodes had the lowest tolerance index to AMD among the six plants tested. V. zizanioides also had a high tolerance to the AMD. The capacity of the microcosm (wetland) in adjusting Ph and removing SO_4~(2-) ,Cu, Cd, Pb, Zn and Mn only lasted for 35 days, which may be due to the high acidity of AMD. Further experiments should be conducted before using wetlands in treating AMD in practice, especially the acidity of AMD should be reduced before it discharged into the wetland.