Environmental application of basic oxygen furnace slag for the removal of heavy metals from leachates

Industrial waste is a major environmental concern nowadays, stimulating the thorough study of the minimization and recycling of solid wastes and of the containment and treatment of liquid contaminants. Basic oxygen furnace (BOF) slag, a solid waste from the steel industry, has been found to be effective in the removal of heavy metals. However, this has not been applied so far in low permeability barriers, such as those used as bottom liners in landfills. This work studies the performance of BOF slag in both containment and treatment technologies for toxic leachates. Flow models are developed to assess the transport of metal ions through a permeable reactive barrier and a composite clay barrier. Reactive transport through the slag barrier and adsorption in the clay barrier are coupled for different conditions to find the residence time, the barrier life span and the optimum operative conditions. The results show that the use of BOF slag increases the breakthrough time of the contaminants, enabling improve design of low and high conductivity reactive barriers, and expands the life cycle of the material.