A Statistical Comparison of Mathematical Models for Heavy Metal Leaching Phenomena from Solidified Landfill Waste Mortar

Abstract

Abstract In this research, landfill solid waste was solidified as cement-waste matrix to protect the environment from excessive intrusive contaminants like Fe, Cu and Ni and minimize the waste load. Within this context, ingredients of cement-waste mortar were characterized to determine their physical properties. Long-term feasibility study was conducted to examine the metal contents stabilization by employing the standard mass transfer-leaching test. The cumulative leaching concentration of Fe, Cu and Ni were found to be 1.29 mg/l, 0.18 mg/l and 0.63 mg/l respectively up to 180 days static leaching test period that satisfied the surface water quality standard. Mechanical strength test was also conducted to characterize the solidification technique. Five well-established non-linear mathematical Models were conducted to evaluate the mechanisms of Fe, Cu and Ni migration. Goodness of fit statistical parameter analysis and visual examination indicated that polynomial equation Model is better for explaining the experimentally generated data. Moreover, parameter of polynomial equation was extended from five to nine for examining the best calibration profile to the observations. In context of slope-intercept and visual observation analysis resulted that polynomial equation based Model bearing five parameters with 0.5 power interval of each parameter describes the leaching phenomena quite similar with the experimental observations whereas goodness of fit parameters and information criterion shows reverse. It was found that the studied immobilized landfill waste mortar have acceptable mechanical performance that confirms to be used as construction material.