The emission characteristics and influencing factors of volatile organic compounds in sludge drying exhaust gases

This study investigates the release characteristics and influencing factors of volatile organic compounds (VOCs) in sludge drying exhaust gases from two urban sewage treatment plants and one sludge treatment plant in Zhengzhou, Henan Province. Through on-site sampling and dynamic simulation experiments, 99 VOC components were analyzed. Results show that aromatic hydrocarbons (28.2%–31.8%), particularly benzene-related compounds, dominate in sewage plants, while volatile oxygenated organic compounds (OVOCs) (22.9%–36.1%) are more prominent in sludge plants. Peak VOC concentrations of 780, 1220, and 1720 μg/m³ were observed 7−10 minutes after aeration, stabilizing thereafter. Higher drying temperatures and aeration intensities increase VOC release, with composting fermentation producing the highest emissions. These findings provide insights into selecting drying methods and exhaust gas treatment strategies for effective air pollution control.