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.
