PAH emissions from coal combustion and waste incineration

The characteristics of PAHs that are emitted by a municipal waste incinerator (MWI) and coal-fired power plant are examined via intensive sampling. Results of flue gas sampling reveal the potential for PAH formation within the selective catalytic reduction (SCR) system of a coal-fired power plant. In the large-scale MWI, the removal efficiency of PAHs achieved with the pilot-scaled catalytic filter (CF) exceeds that achieved by activated carbon injection with a bag filter (ACI + BF) owing to the effective destruction of gas-phase contaminants by a catalyst. A significantly lower PAH concentration (1640 ng/g) was measured in fly ash from a CF module than from an ACI + BF system (5650 ng/g). Replacing the ACI + BF system with CF technology would significantly reduce the discharge factor (including emission and fly ash) of PAHs from 251.6 to 77.8 mg/ton-waste. The emission factors of PAHs that are obtained using ACI + BF and the CF system in the MWI are 8.05 and 7.13 mg/ton, respectively. However, the emission factor of MWI is significantly higher than that of coal-fired power plant (1.56 mg/ton). From the perspective of total environmental management to reduce PAH emissions, replacing the original ACI + BF process with a CF system is expected to reduce environmental impact thereof.