Comparative Study of Separation of Heavy Metals from Leachate Using Activated Carbon and Fuel Ash

Abstract

Dumpsite leachate contains heavy metals, which eventually get discharged into natural water bodies inflicting heavy damage on the environment and human health. The separation of heavy metals, including Cr, Cu, Pb, Mn, and Zn from leachate is studied using two adsorbents, sludge-based powdered activated carbon (PAC) and pulverized fuel ash (PFA). The adsorption behaviors are analyzed in detail by applying different isotherm models using nonlinear regression methods. The best fit isotherm is determined based on the coefficient of determination (R2) and different optimality criteria. The effect of organic matter on the separation of heavy metals from leachate using PAC and PFA are examined. This study postulated the priority uptake of heavy metals by micropore encapsulation and complex formation by interparticle bridging in PAC and PFA, respectively. Furthermore, this study provides a promising way to utilize the sewage sludge and fuel ash as feasible adsorbents for the separation of heavy metals from dumpsite leachate. In addition, an effective immobilization technique was implemented and evaluated using the diffusivity coefficient (De) and leachability index (LX) for the safe disposal of used adsorbents.