Solubility, hydrogeochemical impact, and health assessment of toxic metals in municipal wastes of two differently populated cities

• Critical characterization of municipal solid wastes from two cities of India
• Risk assessment showed high non-cancer risk of Cu contamination.
• Probable metal precipitation/dissolution is predicted through Visual MINTEQ.
• Metal fractionation showed potential eco-toxicity.

Paradigm change in the demographic distribution in the Indian subcontinent has positioned urban services, including solid waste disposal, under immense pressure. The present study was an attempt to understand the fate of different metals from municipal solid waste (MSW) in the land disposal environment. Accordingly, the characteristics and ecotoxicity potential of MSW of two cities of the region namely, Guwahati and Tezpur were determined. Concentration of bioavailable metals was lower in Tezpur MSW (TMSW) as compared to Guwahati MSW (GMSW). Significant occurrence of various functional groups (O–H, CO, C–C etc.) in the MSW samples indicated predominance of aromatic hydrocarbons. Human risk assessment reveals high possibility of metal contamination from the GMSW. Saturation indices of water solubility data modeled in Visual MINTEQ predict that Calcite (CaCO3) and Zn based minerals could potentially precipitate from both MSWs. Visual MINTEQ is a useful geochemical data analysis tool that computes the mass distribution between the dissolved, adsorbed, and various solid phases of different elements. Furthermore, the mobility dynamics of various fractions of toxic metals or potentially toxic elements (PTEs) such as Fe, Cr, Cu, Ni, Pb, and Zn, revealed that most of these elements were bound to organic and residual fractions.