Development of Permeable Reactive Barrier System Utilizing Locally Available Geo- and Bio-Waste

Abstract

Open dumping is the common method for final waste disposal used in many developing countries. Various kinds of heavy metals are often detected in landfill leachate and groundwater surrounded at open dumpsites in Sri Lanka. Thus leachate and groundwater treatment facilities are strongly recommended in order to prevent contamination of natural ecosystems. Permeable Reactive Barrier (PRB) systems might be an effective method to treat contaminated water at open dumpsites, which required low initial cost, maintenance cost and technical support.. Therefore, the objectives of this study were to characterize the heavy metal adsorption and permeability performances of low-cost filling materials (soil, char, brick, and their mixed samples) locally found in Sri Lanka. Adsorption isotherms studies were conducted for Pb and Cd and results showed that the maximum adsorption capacity and removal percentage of Pb were higher than those for Cd. Maximum adsorption capacity and removal percentage of brick were relatively low for both Pb and Cd, thus the mixed samples with brick also showed lesser adsorption capacities. However, the removal percentage reached 90 for all mixed samples especially for Pb,. The mixed material with brick showed the highest hydraulic conductivity and satisfied with the targeted value (10~3 cm/s ) under approximately 75% degree of compaction. Therefore, the mixture of brick is highly important to maintain required permeability of PRB filling materials.