Impact of food waste fraction in municipal solid waste on sorption of heavy metals

Abstract

The presence of organic materials plays an important role in the fate of heavy metals that are co-disposed together with municipal solid wastes. As a part of an on-going research project, which aims to find out the most effective attenuation mechanism of heavy metal removal in landfills, sorption batch experiments were performed to assess the sorption behaviour of iron, copper, nickel and zinc on synthetic solid wastes containing 76% (W1) and 45% (W2) food waste percentages and waste-to-solution ratios ranging from 1:4 to 1:16. The analysis of sorption data suggested that the data fit a Freundlich equilibrium isotherm. The time required for reaching equilibrium conditions varied for each metal investigated, but all generally reached equilibrium conditions within 7 h. For both solid waste compositions, metal sorption increased with increase in waste-to-solution ratio, with the order of metal removal percentages consistently found to be Zn > Ni > Cu > Fe. The results also show that a large fraction of the heavy metals could be attenuated by sorption on the solid waste. The removal percentages for Zn and Ni were slightly higher for W2, whereas the removal percentages for Fe and Cu were approximately equal for both waste types. Overall, this study demonstrates that sorption is a viable process that can mitigate the potential adverse impacts of landfill leachate.