Mineralogical and chemical changes in mineral liners in contact with landfill leachate

Abstract

The mineralogical and chemical integrity of mineral liners for domestic waste landfill sites was investigated using a series of batch reactor experiments. A synthetic acetogenic leachate was developed based on the composition of domestic waste leachates. The interactions between the synthetic leachate and mudrocks used by Shanks and McEwan Ltd. to line land fill sites located in the United Kingdom are described. The results of the laboratory experiments are contrasted against those obtained from samples of a 15-year-old mineral liner from a landfill site located near Stewartby, Bedfordshire. The interactions between a concentrated, ionic solution, such as a leachate, and mineral liners include ion-exchange, particle size reduction, mineral dissolution and clay-mineral disorder ing and collapse. Bentonites and high-swelling clays are more susceptible to mineral transformations than mixed assem blage mudrocks and low-swelling clays. Understanding the interactions between leachate and mudrocks will assist the prediction of the long term performance and integrity of nat ural lining materials.