Uptake of Heavy Metals in Landfill Leachate by Vetiver Grass

Abstract

Many waste disposal sites in Thailand are sources of environmental pollution because waste is still largely disposed of at these places without effective and proper management control. Landfill leachate usually contains high concentrations of heavy metals that are seriously harmful to the environment and human health. The study was conducted using vetiver for phyto-remedying soil contaminated with landfill leachate. Surat Thani ecotype vetiver plants planted in pots were treated with landfill leachate at the strength of 0, 50, 70 and 100 %. Data on growth and heavy metal uptake analyzed by X-ray fluorescence technique were recorded. The results indicated that the growth of vetiver was reduced as the landfill leachate strength increased. The vetiver grass treated with 100 % leachate could not survive at 80-85 days after planting. Vetiver grass uptook more heavy metals as the strength of leachate increased and these heavy metals were evenly distributed in shoot and root. Heavy metals derived from leachate
remained more in soil as the leachate strength was higher and could reach the toxic level for plants. The results of a field trial at the landfill site also indicated that vetiver technology could be useful for rehabilitating landfills and nearby areas. Practically, vetiver plants should be contour-planted on the side slopes of old landfills or at the leachate site. For young landfills, this green technology could be used with a limited leachate strength. The shoot part should be harvested periodically in order to remove the heavy metals from the contaminated soil and stimulate new growth for more uptake.