VOCs emission from landfills co-disposed of rural solid waste and sewage sludge: Identification, diffusion, and impact.

Volatile organic compounds (VOCs) emitted from landfills are significant contributors to air pollution, attracting considerable attention. In this study, we investigated VOCs emission from a landfill located in a dry, cold region of Northwest China, where residual sludge from a sewage plant was utilized as a cover material for waste. A total of 43 VOCs were detected, with concentrations ranging from 0.58 to 412.15 mg/m3 for each single VOC, predominantly comprising aromatic and oxygenated compounds. Elevated VOCs concentration was observed in both the covered area and work area, with aromatic (71 %) and chlorinated compounds (76 %) at the downwind site boundary primarily originating from the landfill. Seven priority control pollutants were identified using the fuzzy composite evaluation method. Their diffusion behavior was simulated using the Gaussian plume model, and their chronic toxicity and carcinogenic risks were assessed utilizing Environmental Protection Agency recommended techniques. Styrene, 1,2,3-trimethylbenzene, and toluene exhibited principal ozone generation potential, whereas toluene and benzene contributed most to secondary aerosol generation. VOCs pollution was more severe within 500 m in the downwind direction, posing chronic toxicity and carcinogenic risks within 430 m. It is recommended to cover the area that is not temporarily landfilled with air tightness materials, such as HDPE film, to prevent the dispersion of VOCs. This investigation provides insights for developing effective measures to mitigate health risks and secondary pollution.