DIOXIN LEVELS IN THE EMISSIONS FROM MUNICIPAL WASTE INCINERATORS IN TAIWAN

In this study, characteristics of dioxins emission from existing moder n MWIs were evaluated via simultaneous sampling of flue gas and variou s types of fly ashes. Preliminary results showed that PCDDs congeners distributions were quite similar in flue gas and various types of ashe s of both MWIs. PCDFs/PCDDs ratio in cyclone ash was lower than that i n combustor ash or fabric filter ash excluding economizer ash of MWI-A . Similarly, PCDFs/PCDDs ratio in ESP ash was lower than that in boile r ash. PCDFs concentration was about 1.5 to 4.3 times higher than PCDD s concentration in flue gas of both MWIs. The mass balance factors of MWI-A (0.9 similar to 1.02) were clearly lower than that of MWI-B (7.7 1 similar to 15.63), indicating that de novo synthesis occurred under the operating conditions of ESP. In other words, MWIs equipped with ES P were less efficient in controlling PCDD/Fs emissions than that equip ped with fabric filters. (C) 1998 Elsevier Science Ltd. All rights res erved.