PAHs and heavy metals in the surrounding soil of a cement plant Co-Processing hazardous waste

Abstract

The Chinese government is encouraging domestic cement producers to move from traditional coal power sources to the co-processing of waste as the primary energy source for the industry. In this study, 32 samples collected from the soil surrounding a cement plant in Beijing were analyzed for the presence of 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and 12 heavy metals. Ten samples were selected for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) analysis. The pollution distribution patterns, sources, and potential risks to human health and the environment were investigated and evaluated. The highest concentrations of PCDD/Fs occurred 1200 m downwind from the cement plant. The levels of ∑16 PAHs ranged from 130.6 to 1134.3 μg kg^-1 in the sampled soils. Source identification analysis suggested that the cement plant was the most likely source of PAH contamination. The concentrations of most of the heavy metals detected in the sampled soils were close to background levels, except for the levels of cadmium (Cd) and mercury (Hg), which were, on average, two times and six times higher than background values, respectively. The co-incineration of sludge, coal, and hazardous waste in the cement plant is a major contributing cause for the high levels of Hg in the surrounding soil. Risk assessment models, both the incremental lifetime cancer risks (ILCRs) for PAHs and the potential ecological risk index (RI) for heavy metals, indicate potential risks to the population and the environment surrounding the cement plant.

Keywords: Cement plant; Environmental risk assessment; Hazardous waste; Heavy metals; Polycyclic aromatic hydrocarbons; Soil.