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The use of volcanic soil as mineral landfill liner - III. Heavy metals retention capacityChemical Engineering Department, University of La Frontera, P.O. Box 54-D, Temuco, Chile, rnavia{at}ufro.cl
Chemical Engineering Department, University of La Frontera, P.O. Box 54-D, Temuco, Chile
Chemical Engineering Department, University of La Frontera, P.O. Box 54-D, Temuco, Chile
Department of Sustainable Waste Management & Technology, University of Leoben, Peter Tunner Strasse 15, 8700 Leoben, Austria The volcanic soil of Southern Chile was tested for its heavy metal retention capacity. The maximum uptakes for CrO4 2- (CrVI), Cu2+, Zn2+ and Pb2+ were determined to be 2.74, 5.32, 5.86 and 7.44 mg g-1, respectively. At a slightly alkaline pH value (7.5), it seems that a precipitation-adsorption process was responsible for the Cu2+ and Zn2+ uptake onto volcanic soil. All the determined values are of the same order of magnitude as natural zeolites heavy metals adsorption capacities. In addition, the heavy metals diffusion model through a 1 m volcanic soil mineral liner shows breakthrough times of 21.6, 10.2 and 8.9 years, for Pb2+, Zn2+ and Cu2+, respectively, confirming the trend obtained in the adsorption isotherms. The natural volcanic soil of Southern Chile is an interesting material for possible use as landfill mineral basal sealing. It has an appropriate sealing potential (average K f value of 5.85 x 10-9 m s-1) and a heavy metals retention capacity comparable with natural zeolites. About two-thirds of the agricultural land in Chile (approximately 0.4 million km2) is derived from volcanic ash, suggesting an important soil volume for future landfill projects, that could be obtained in sufficient quantities from urban building activities.
Key Words: Allophane volcanic soil heavy metals retention capacity landfill liner wmr 823-9
Waste Management & Research, Vol. 23, No. 3,
260-269 (2005) |
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