Suppression of Heavy Metals in Leachate by Co-disposal of Inorganic Waste and General Waste

To confirm the efficacy of stabilization of heavy metals by the co-disposal of the inorganic waste (designated waste) such as fly ash containing high concentrations of heavy metals and the general waste such as sewage sludge and garbage containing a large amount of organic compounds and sulfate-reducing bacteria, field surveys were made on landfill site of only designated wastes, and on landfill site of co-disposal of the general wastes and designated wastes. Next, a co-disposal model experiment was performed by using fly ash as the designated waste and sewage sludge as the general waste. As a result, the followings were clarified: 1) The concentrations of contaminant substances in leachate from the landfill site of co-disposal of the general wastes and the designated wastes were much lower than those in leachate from the landfill sites of only the designated waste. 2) The concentrations of sulfate-reducing bacteria in leachate from the landfill site of co-disposal of the general wastes and the designated wastes were higher than those in leachate from the landfill sites of only the designated waste. 3) Since sewage sludge, sewer sludge, bottom mud of the river, etc. are rich in the organic compounds and sulfate-reducing bacteria, the leaching of heavy metals to the leachate was suppressed by the co-disposal the sewage sludge and the fly ash.