Desorption of PCDD/PCDF from municipal solid waste incinerator flyash under post-combustion plant conditions

摘要

The influence of temperature on the levels of PCDD and PCDF remaining in, and desorbed from, a municipal solid waste incinerator flyash was investigated by heating the ash to between 200 and 400℃ under a simulated flue gas for four days reaction time. Considerable desorption of PCDD/PCDF from the flyash was seen at 275℃ and above. Maximum desorption occurred at 350℃, with the equivalent of nearly eight times the total PCDD/PCDF concentration of the original flyash being lost to the vapour phase per unit mass of initial flyash. The I-TEQ value of the desorbed PCDD/PCDF was considerable, being over fourteen times that of the original flyash at 325℃. The results indicate that formation of PCDD/PCDF on flyash deposits in the post-combustion plant of incinerators can result in the release of significant amounts of PCDD/PCDF to the flue gas stream.