Uptake of heavy metals in landfill leachate by vetiver grass

摘要

Many waste disposal sites in Thailand may be considered as sources of environmentalrnpollution because waste is still largely disposed of without effective and proper managementrncontrol. Landfill leachate usually contains high concentrations of heavy metals that are seriouslyrnharmful to the environment and human health. The study was conducted using vetiver for phyto-remedyingrnsoil contaminated with landfill leachate. Surat Thani ecotype vetiver plants planted inrnpots were watered with the landfill leachate at the strength levels of 0, 50, 70 and 100 %. Data onrngrowth and heavy metal uptake analyzed by the X-ray fluorescence technique were recorded. Thernresults indicated that the growth of vetiver was reduced as the landfill leachate strength increased.rnThe vetiver grass watered with the 100 % leachate could not survive at 80-85 days after planting.rnVetiver grass uptook more heavy metals as the strength of leachate increased and these heavyrnmetals were evenly distributed in shoot and root. Heavy metals derived from leachate remainedrnmore in soil as the leachate strength was higher and could be above the heavy metal standard valuernin soil and might toxicate plants. The results of a field trial at the landfill site also indicated thatrnvetiver technology could be useful for rehabilitating landfills and nearby areas. Practically, vetiverrnplants should be contour-planted on the side slopes of old landfills or at the leachate site. For youngrnlandfills, this green technology could be used with a limit of leachate strength. The shoot partrnshould be harvested periodically in order to remove the heavy metals from the contaminated soilrnand stimulate new growth for more uptake.