Attenuation Characteristics of Laterite-Fly Ash-Bentonite Mix as Liner

The liners play an important role in controlling migration of contaminant present in the leachate in waste containment system such as landfills. Compacted clay liners are widely used because of their low permeability and large attenuation capacity. Nowadays the lack of availability of natural clay with satisfactory engineering properties resulted to look for an alternative material for liner. Commercial clay such as bentonite is commonly used for liner material. Fly ash is an industrial waste produced from thermal power plant, and disposal of this material is a serious problem. The present study is carried out to evaluate the capability of laterite-fly ash-bentonite liner to attenuate contaminant in municipal solid waste leachate. Laterite soil for the present study is collected from NIT Calicut campus. A series of laboratory tests were conducted to investigate the combined effect of fly ash and bentonite added at different percentage of lateritic soil as landfill liner. Suitable laterite-fly ash-bentonite mixes satisfying liner criteria were identified, and batch adsorption tests are performed on this mixes with hexavalent chromium as model contaminant. 78% removal efficiency was achieved for laterite soil mixed with 30% fly ash and 5% bentonite.