THE EMISSION OF POLYCYCLIC AROMATIC-HYDROCARBONS FROM MUNICIPAL SOLID-WASTE INCINERATORS DURING THE COMBUSTION CYCLE

The emission of polycyclic aromatic hydrocarbons (PAHs) during start-u p, burning, and burn-out were determined for four municipal solid wast e MSW incinerators. During start-up conditions, PAH concentrations wer e shown to be high due to unstable combustion. A positive correlation was seen between PAH concentrations and the organic carbon content of the dust. This study was conducted to examine the emission behaviors o f PAHs according to furnace type and to measure emissions during the c ombustion cycle. The organic carbon in the dust, as well as PAH emissi ons, during three combustion periods were determined for four MSW inci nerators. PAHs were high during start-up because of incomplete combust ion at low temperature. In the fluidized-bed incinerator, PAHs were hi gh because combustion in the fluidized bed, was more unstable than in the step grate. A batch fluidized bed showed particularly higher conce ntrations compared to a continuous fluidized bed; owing to less stable combustion. Organic carbon in the dust was normally highest during st art-up and lowest during burning. Continuous incinerators with longer operation periods showed higher emission rates during burning. This pa rameter for the batch-type fluidized bed increased during start-up and burn-out.