Heavy metal pollution level and potential ecological risk assessment of sludge landfill

Abstract

The level of heavy metals of the sludge in the landfills has attracted the environmental researchers due to their non-biodegradability, persistence, toxicity and biomagnification. Heavy metals contamination and ecological risk assessment in the sludge landfills were assessed. In this work, the enrichment factor (EF) and geo-accumulation index were used to analyze heavy metal pollution degree in the sludge landfills. Meanwhile, the potential ecological risk index was used to assess heavy metals potential ecological risk in the sludge landfills. Results indicated that heavy metal concentrations order was Cr > Cd > Ni > Zn > As>Cu = Pb > Hg. Cr, Cd and Ni coefficient variation were 57%, 53% and 38%, respectively, which indicated that Cr, Cd and Ni content have a large range variation. EF and geo-accumulation index analyze heavy metal pollution degree in the sludge landfills. Results demonstrated that Hg, Cd, Cu and Zn obtained a high pollution degree. However, Cr, Ni, As and Pb have a low pollution in the sludge landfills. Potential ecological risk index indicated that Hg obtained the highest pollution degree, which demonstrated that the potential ecological risk level is the highest value (Eri ≥ 3500, RI ≥ 4163). Whereas, other heavy metals have a low pollution degree in the sludge landfills. Therefore, Hg, Cd and Cu content of sludge should be strictly restricted in agricultural use. Meanwhile, it should be strictly restricted Hg, Cd and Cu content of wastewater discharge, and reduced heavy metal content of sludge.