Dioxin-like PCBs released from waste incineration and their deposition flux.

To investigate the formation and decomposition behaviors of dioxin-like PCBs during incineration of municipal solid wastes in a recently constructed facility, the concentrations of dioxin-like PCBs were measured in municipal solid waste before incineration and in the incinerator emission gas and residues. Using these values, release/inflow ratios of dioxin-like PCB congeners (ratio of the amount released from the incinerator to the amount flowing into the incinerator through waste) were calculated. For PCB congeners 126, 169, and 189, these ratios were greater than 1. In contrast, ratios of the other dioxin-like congeners were much less than 1. To take into account atmospheric sources, the amounts of dioxin-like PCBs released via emissions from municipal solid waste incineration were compared with atmospheric depositions in the Kyoto City area. Most of the PCDD/F congeners and homologue groups were deposited in amounts similar to those found in emissions from the waste incinerator. Deposition of dioxin-like PCB congeners 81, 126, 169, and 189 were also found in amounts similar to those released via the waste incinerator emissions. However, depositions of congeners 105, 114, and 118 greatly exceeded the amounts released via waste incinerator emissions. In reviewing the congener profiles of industrial PCB products and emission gas, the following general trends were observed: (i) For congeners whose contents are high in industrial PCB products (e.g., 105 and 118), the amounts deposited were much higher than the amounts released with waste incineration emission gas. (ii) For congeners whose percentages were high in the waste incineration emission gas (e.g., 126 and 189), the amounts deposited were similar to the amounts released in the waste emission gas.