Study on heavy metals in particulate matter of municipal sewage sludge pyrolysis

In this study, sewage sludge from a waste water treatment plant in Shenzhen was used for pyrolysis to investigate the characteristics of generated particulate matter (PM) and the change of 8heavy metals. The results showed that the PM production rate peaked twice at 400~600℃ and at the first 30minutes holding at 1000℃, respectively. The thermal volatility of the 8heavy metals was as follows: Cd>Zn>As>Pb>Mn>Ni>Cu>Cr. And the enrichment capacities of the 8heavy metals in the PM followed the order: Pb>As>Mn>Zn>Cd>Ni>Cr>Cu. The volumetric heavy metals concentration generally showed an increase trend with the pyrolysis process. However, Zn and Cd decreased after peaking at the stage of temperature rising (before 1000℃). The research suggests that the heavy metals enriched during sludge pyrolysis and the generated PM exceeds the standard value. Therefore, the exhaust PM removal device is necessary. © 2018, Editorial Board of China Environmental Science. All right reserved.