노천소각 모의연소를 통한 다이옥신류 및 PAHs의 Profile 특성과 배출량 산정에 관한 연구

Abstract

Emission of PCDD/DFs, dioxin-like PCBs(DLPCBs) and PAHs result from unintended combustion processes, most typically waste combustion. Uncontrolled combustion, such as open-burning of domestic, agricultural, and construction/demolition waste may produce emission of this compounds. However, few assessment of PCDD/DFs emissions are available from these non-point sources and guideline about emission and activity factors provided by UNEP is not accurately accorded to specific condition of each local case. In this study, an enquete was done about waste treatment method with 716 farmhouses and 112 construction sites to get fundamental data for open-burning system and evaluating activities. And the results of enquete showed that 2,270 tons of domestic waste, 1,649,528 tons of agricultural residue, and 656 tons of construction wood was open-burnt. After enquete, a flux chamber for simulating an open-burning was set by the size of 3.5m×2.5m×2.2m, and flue gas from flux chamber was estimated for researching characters of gas and contained dioxin-like compounds and PAHs. Also the emission factor and the emission amount of flue gas and incineration residue was presented. Flue gas was real-timely estimated to brought a result that average CO concentration was 403 ~ 1,605 ppm, CO₂ was 0.9 ~ 2.9%, and NOx was 3.6 ~ 24.5 ppm. The ratio of O₂/CO₂(%) was 3.6 ~ 4.8(%) for domestic waste, 7.3 ~ 12.4(%) and 2.2 ~ 3.4(%) for agricultural residue and construction wood, therefore the ratio of O₂/CO₂(%) from construction wood burning was variable. The concentration of PCDD/DFs in flue gas was 0.07 ~ 0.126 WHO-TEQ/Nm³ in case of domestic waste, 0.077 ~ 0.178 WHO-TEQ/Nm³ in agricultural residue and 0.224 ~ 0.274 WHO-TEQ/Nm³ in construction wood. And emission factor was 7.3, 8.9, 10.9 ㎍ WHO-TEQ/ton for each case, which was much lower than noticed factor in UNEP. Emission amount was estimated by multiplying emission factor by activity, the total amount emitted from open-burning into air was 0.017 g WHO-TEQ/yr for domestic waste, 14.86 g WHO-TEQ/yr for agricultural residue and 0.008 g WHO-TEQ/yr for construction wood. In this category of open burning, amount of agricultural residue burning occupied almost 99.8%, so open-burning of domestic waste and construction wood was not a major source. Analysis of homologue profile shows that PCDFs contribute more than PCDDs to total concentration, and the most contributory isomer to total dioxin amount was 2,3,4,7,8-PeCDF. DLPCBs were scarcely generated. PAHs were estimated to 137.8 ㎍/Nm³ for domestic waste, 288.7 ㎍/Nm³ for agricultural residue and 145.8 ㎍/Nm³ for construction wood. And emission factor was 7.5, 10.9 and 20.8 ㎎/㎏ respectively, which shows a lower tendency prepared to previous studies. Preparing the emission amount from open burning to that from other industries, emission amount from open burning accounts for 1.4% of total amount, and emission from industries excluding waste incineration facilities accounts for 8.9%, which takes the 3rd place after ferrous industry and non-ferrous metal industry. This is the first study in Korea about UPOPs including dioxins produced in open burning, and further researches are needed to control emissions of dioxins and dioxin-like compounds systematically considering these results.