The liners are the principal components of solid waste landfills which have the main role in controlling the spread of pollution through the landfills. The high cost of artificial materials and their un-usability in large projects for preventing leaks is a major concern that has led to more attention to natural liner materials with low permeability and effective adsorption and stabilization condition. Clay minerals have a high capacity to adsorb heavy metals due to their high specific adsorption levels and bonding sites with numerous negative charges. Along with absorption properties, Clay soils should have suitable hydraulic and geotechnical properties as landfill liners. Therefore, this study aimed to evaluate the efficiency of 5 types of soil (vermiculite Clay, sepiolite Clay, silty soil, silt+Clay mixtures as 90% silt and 10% Clay) as Clay liner. The chemical, physical and mechanical properties of the study soils were evaluated to address the quality of soils as a landfill liner. The results showed that in terms of environmental quality (pollutant adsorption), soils containing sepiolite Clay had a better adsorption capacity to adsorb cations rather than vermiculite Clay soils. From a physical and mechanical point of view, soils containing sepiolite Clay compared to vermiculite Clay soil revealed a variety of landfill liner characteristics in terms of strength, permeability, and plasticity properties, respectively. Based on the technical and economic perspective, the silt and sepiolite mixtures supply good features which may justify their potential use as a liner material in solid waste landfills.

Nanocomposite of Clay-carbon nanotubes (CNTs) is prepared by using carboxyl-modified multiwalled carbon nanotubes and amino-functionalized organophilic montmorillonite (Clay). The nanocomposite is characterized by scanning electron microscopy to evaluate the morphology. The findings show uniform dispersion of CNTs.

This research work demonstrates the feasibility of accelerating bioremediation of a Clay soil by supplementing with (NH4)2SO4, KH2PO4, sucrose (as an inducer for growth) and tween 80. The soil contained 7% residual gasoil. The bioremediation was stimulated by moisture adjustment to 10%, and inoculating with hydrocarbon degrading microorganisms. (NH4)2SO4 and KH2PO4 were added to the soil to obtain soil samples with C: N: P ratios of 100: 1. 4: 1. 4, 100: 6. 4: 1. 9, 100: 11. 4: 2. 4, and 100: 21. 4: 3. 4. The C: N: P of 100: 11. 4: 2. 4 resulted in more than 78% gasoil removal for duration of two months. Tween 80, in the range of 0-20mL/ (kg soil), was added to the soil samples with C: N: P ratio of 100: 1. 4: 1. 4. More than 84% removal was achieved when 10 mL/kg tween 80 was added to the soil. Sucrose, in the range of 0-20 g/(kg soil), was added to the soil samples with the C: N: P ratio of 100: 1. 4: 1. 4. For the sucrose level of 20 g/(kg soil), 79% removal was obtained in two months. Additional experiment was also conducted at two porosity levels of 54% and 22%. The removal percentage in the soil with high porosity was almost twice as compared to soil with low porosity.