Impact of Heavy Metals on Consolidation Properties of Bentonite

Abstract

AbstractBentonite is frequently used as a liner material at the waste disposal site because of its high swelling ability, high contaminant adsorption capacity and low hydraulic conductivity. It acts as a barrier material by preventing and minimising the ingress of pollutant to contaminate the ground water resource. Metals present in the landfill leachates may shrink the thickness of the diffuse double layer (DDL) of bentonite, which in turn reduce its effectiveness as a liner material. Therefore, it is very essential to investigate the behaviour of bentonite in the existence of the different pollutant present in the leachate. Consolidation is one of the important behavior of bentonite, which is required to be investigated for settlement analysis of landfill liner. This study was performed to investigate the influence of copper (Cu2+) and zinc (Zn2+) solutions of various concentrations, on the consolidation behaviour of bentonite. Various consolidation parameters, such as compression index (Cc), coefficient of consolidation (cv), volume change (mv), time requires for the completion of 90% of consolidation (t90), were studied in the presence of heavy metals of concentration of 0, 500 and 1000 mg/L. The results indicated that with the increase in concentration of heavy metals the Cc, mv, and t90 of the bentonite decreases; whereas, cv increases. The study concluded that the presence of the heavy metals in the lechate increases the rate of consolidation of the compacted bentonite. The outcomes of this investigation may provide a general suggestion for evaluating the liner performance in the presence of different kinds of pollutants present in the lechate. KeywordsBentoniteConsolidation characteristicsHeavy metalLandfill linerLeachate