Pyrolysis residues of three particle sizes of sewage sludge produced using bed fluidized at 500? were subjected to TCLP and DTPA leaching test to assess the release and bioavailability of heavy metals in pyrolysis residues. Results showed that the smallest particle of sewage sludge produced the highest pyrolysis residue. Most functional characteristics of the pyrolysis residues were similar to those of sewage sludge itself, and some specific functional groups formed after fast pyrolysis. All heavy metals in original sewage sludge were kept in pyrolysis residue except As, and the contents of heavy metals were significantly concentrated in pyrolysis residues. Pyrolysis residues obtained from larger particles of sewage sludge would cause excessive level of specific heavy metals. The pyrolysis residues significantly suppressed heavy metals leaching. However, fast pyrolysis changed the patterns of leaching heavy metal contents in the three particle sizes of sewage sludge pyrolysis residues. Zinc, Cu and As in the pyrolysis residues of the larger particles of sewage sludge were easier to be leached to the environment; while their bioavailability was highest in the pyrolysis residue of biggest particle in sewage sludge for Cu, and in pyrolysis residue of the finest particle in sewage sludge for Zn and As.

Characteristics of Zn, Cu, and As in fast pyrolysis residues of different particle size of sewage sludge

248th National Meeting (2014)

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