Combustion characteristics of tannery sludge and volatilization of heavy metals in combustion

Incineration is considered one of the most readily available techniques for sewage sludge disposal, including tannery sludge, which often contains significant amounts of volatile heavy metals. The combustion characteristics and kinetic analysis of tannery sludge were investigated using thermogravimetric analysis (TGA) at a heating rate of 30 °C/min in 50–950 °C. In addition to confirming that tannery sludge has a high content of volatile material and ash, it was further discovered that almost all the zinc (Zn) in tannery sludge is volatilized at 900 °C. The degree of volatilization for heavy metals at 900 °C followed the order of Zn>Cd>Cu>Mn>Pb>Cr. Moreover, the volatilization of these heavy metals increased with temperature. It is thus concluded that, to avoid heavy metal volatization during incineration disposal, 800 °C is a reasonable incineration temperature.