Absorption and Diffusion Potential of Waste Wood Ash-Treated Lateritic Soil

Lateritic soil treated with up 10% waste wood ash (WWA) and compacted with British standard heavy (BSH) energy (relative compaction = 100%) was evaluated for its absorption and diffusion capacity for selected cations and anions commonly found in landfill leachate. Addition of WWA increased the pH of the medium which immobilized most of the metal ions within the stabilized soil and reduced the availability of ions for desorption thereby making the lateritic soil-WWA mixture more potent to attenuate the concentration of the cations. Generally with increase in WWA content retardation factor reduced while tortuosity increased. For the adsorption and diffusion characteristics, the values of apparent diffusion coefficient, D* decreased with higher WWA content for monovalent cations while it increased for the divalent cation considered; however, it decreased for the anions considered. The tortuosity factor, tau(a) also behaved in a similar pattern for all the treated specimens tested. The study showed that lateritic soil treated with 4 % WWA will reduce the detrimental effect of municipal solid waste (MSW) leachate in groundwater via adsorption to the soil matrix and prevent its conductivity through soil by diffusion.