| 英文摘要 |
The scope of this project includes: 1) Establishing and updating of the emission inventory; 2) Monitoring for the stationary emission and the ambient environment; 3) Investigating the contribution of mercury emission in the Kaohsiung metropolis; 4) Investigating the speciation changes of mercury in sintering plants and coal-fired cogeneration boilers and emission reduction strategies.
The total dioxin emission quantity in Taiwan is estimated to be 32.9~129 g I-TEQ/year in 2012 with an average of 51.4 g I-TEQ/year. As for the heavy metal emissions in 2012, the total lead emission is 15.9 metric tons/year, cadmium emission is 0.880 metric tons/year, mercury emission is 1.85 metric tons/year, and arsenic emission is 4.20 metric tons/year. The changes are small over the years.
The emission of dioxins is primarily from manufacturing of vinyl chloride, cement, asphalt mixing, oil boilers, and small wood-burning boilers. Statistics shows that the emission from small wood-burning boilers has exceeded the emission standards. Since the toxicity equivalence coefficients for some substances in the I-TEF are lower the WHO2005-TEF, conversion from WHO2005-TEF to I-TEF has reduce the equivalent toxicity by 96%. PCBs only accounts for 2~17% of toxicity equivalence, with an average of 7%.
The monitoring of heavy metal emission shows that asphalt mixing with reclaimed asphalt pavement can produce high concentration of heavy metals. Manufacture of semiconductors and optoelectronics were believed as major sources for selenium emission. However, our monitoring data showed that the emission from optoelectronic manufacturers were high, whereas the emission from semiconductor manufacturers were under detection limits. Indicating that, even though, the manufacturing of semiconductors and optoelectronics uses the same materials, the composition of pollutant is different. Our monitoring data also showed that the pollutant control devices have successfully reduced the emission of mercury. The actual detected of mercury emission coefficient is much lower than the U.S. coefficient.
In addition to the existing monitoring stations, 3 mobile source monitoring stations were set up this year to monitor the ambient dioxins. The monitored concentration was close to last year’s, reaching the five-year low point. Concentrations of dioxins were high at Shuimei, Ganglien, and Quanxing monitoring stations due to the surrounding major emission sources.
The monitoring of ambient heavy metal showed that the average concentrations of lead, cadmium, nickel and selenium didn’t rise comparing to last year. However, the concentration of mercury was higher in Kaohsiung area due to multiple major emission sources.
This year studies were done on the fate and transport of mercury in steel
sintering plants and coal-fired cogeneration boilers. In sintering plants, 8% of total mercury was in the fly ass collected by the ESP, 11% was in the sinter, and 81% was emitted to the atmosphere through stacks in the form of Hg(II). FGD were installed after the SCR control devices to reduce the emission of mercury. In coal-fired cogeneration plants, 95% of total mercury was removed. The mercury released from the stack are mostly in the form of elemental mercury and mercury(II), indicating that bag houses have good removal rate for mercury attached on particulate matters.
The amount of mercury emitted from the Kaohsiung area accounts for majority of mercury emitted in the entire country. Modeling showed that the Linhai industrial zone and the crematorium were major hot spots. The crematorium is working as batch operation; therefore, the operation of the control devices is difficult. Linhai Industrial Zone consists of several electric arc furnaces and the China Steel Corporation; all of them are major emission sources. The continuous monitoring system installed in the Tang Eng Iron Work factory shows that the average concentration of elemental mercury is 5.27 ng/m3, consistent with past monitoring results. The mercury(II) also comes from the direction of sintering plant, which is consistent with the findings from the fate and transport study.
The “Steelmaking and Casting Furnace Particulate Pollutants Control and Emission Standards” was promulgated on November 19th, 2013, hoping to reduce the emission of particulate matters and heavy metal from the steelmaking and casting furnaces. Currently, stationary source Dioxin Emission Standards have been taking effect. We have supervised the 30 of 95 inspection assignments out last year. 14% of all emission sources were inspected. 11 inspections had failed to meet the emission standards, the number is similar to past years.
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