Interaction of Treated Sanitary Landfill Leachate with Soil1
- K. Y. Chan,
- B. G. Davey and
- H. R. Geering2
Treated leachate (pH 10, ionic strength ∼0.1M) collected from sanitary landfill was passed through a Yellow earth covering material (pH 4.2) in leaching columns, to simulate the field practice of land disposal of leachate. No reduction in the level of chemical oxygen demand of the leachate occurred as a consequence of passage through the soil. On the other hand, the cations in the leachate were retained by the soil in the order Mg > Ca > K > Na. Enhanced adsorption of magnesium and calcium started to occur about pH 6, coinciding with the most rapid rate of increase of pH in the effluent from the column. After addition of 108 cm of leachate, equivalent to the amount sprayed on the landfill in the field over 8 mo, total storage of cations in the soil was 9.24 meq 100 g−1, of which 88% was Ca and Mg. About half of the Ca and Mg cations was stored in exchangeable form and only Na and K were entirely exchangeable. None of the experimental conditions caused precipitation of Ca or Mg, so it was likely that they were specifically adsorbed on the soil clay. The soil sprayed with the same amount of treated leachate in the field had pH 10 and retained twice the amount of Ca and Mg stored in the laboratory column. This difference could have resulted from the longer residence time that the leachate was in contact with the soil in the field.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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