Influence of Temperature on Characteristics of Particulate Matter and Ecological Risk Assessment of Heavy Metals during Sewage Sludge Pyrolysis

The formation process of Particulate Matter (PM) during sludge pyrolysis at different temperatures (300-700 degrees C) and the ecological risks of heavy metals were studied. The results showed that the particulate matter is mainly condensed on the quartz film in a carbon-based organic matter when the pyrolysis temperature was between 200-500 degrees C in a volatilization process. Inorganic particles was found in the particulate matter when the temperature was raised to 500-700 degrees C in a decomposition stage. Heavy metals were enriched in particulate matter with increase in pyrolysis temperature. When the temperature reached 700 degrees C, the concentration of Pb and Cd in the particulate matter significantly increased. The ecological risk assessment showed that heavy metals in the sewage sludge had considerable ecological toxicity. When the pyrolysis temperature reached 700 degrees C, the ecological toxicity of those heavy metals enriched in the particulate matter decreased considerably.

Automated summary

The study investigated the formation of Particulate Matter (PM) at different temperatures during sludge pyrolysis and the ecological risks associated with heavy metals. It was found that heavy metals were enriched in the particulate matter as the pyrolysis temperature increased, with a significant decrease in ecological toxicity at 700 degrees C.