The
elemental distribution and physicochemical properties of residual
productsnamely, char, tar, and produced gasobtained
during the pyrolysis of anaerobically treated dried sewage sludge
was investigated and compared with those of raw sludge. Experimental
investigations were performed in a laboratory fixed-bed reactor and
revealed the migration fate of heavy metals (Cd, Co, Cr, Cu, Ni, Pb,
Ti, and Zn), alkaline earth metals and alkali metals (Ba, Be, Ca,
K, Mg, and Na), intermediate metals (Fe, Mn, Al, and Si), and nonmetals
(P, S, Cl, C, H, and N) in pyrolysis products. Primary attention was
focused on heavy metal migration. The highest heavy metal recoveries
were found for Cd > Co > Cr > Cu from sewage sludge into
the gas-phase, with 68.17% of the Cd eliminated. This study also showed
that high-temperature pyrolysis technology is an effective and promising
thermochemical treatment for sewage sludge to reduce its volume.