小型生活垃圾热处理炉二恶英和重金属的排放特征

摘要

In order to know the emission levels of dioxins and heavy metals from small-scale thermal treatment furnaces for disposing rural domestic solid waste,three types of furnaces including incinerators,gasification-incineration furnace and gasifier located in mountainous rural area in Guangxi,Yunnan and Guangdong province were investigated.Results showed that the emission contents of dioxins in the flue gas from incinerator,gasification-incineration furnace and gasifier were 0.70～24.88,3.14～4.88,0.20～1.49ngI-TEQ/Nm3,respectively.Emission levels of dioxins from the flue gas were in the order of incinerator＞gasification-incineration furnace＞gasifier,whilst in an opposite order from the slag.Dioxins produced in gasifier mainly existed in the slag.However,for incinerator and gasification-incineration furnace,the formed dioxins were mainly distributed both in the slag and flue gas.The mass content distribution characteristics of dioxin congeners in the slag and flue gas from all the three types of furnaces were quite different,whilst the I-TEQ distribution characteristics were similar with the 2,3,4,7,8-PeCDF being the highest among all the dioxin congeners.The emission content of Pb in flue gas from the three types of furnaces was the highest.The contents of Pb,Cd,Cr and Hg in all flue gas sample,were far lower than the emission limit values of the Standard for Pollution Control of Municipal Solid Waste Incineration (GB 18485-2014) except for Cd from one of the incinerators.The toxic leaching concentrations of heavy metals in slag from the three types of furnaces were also lower than the standard limits for hazardous waste identification (GB 5085.3-2007).%为了解小型农村生活垃圾热处理炉二恶英和重金属的排放水平,对我国广西、云南、广东部分山区农村正在运行的3种小型生活垃圾热处理炉排放的二恶英和重金属进行采样调查.结果显示,小型生活垃圾焚烧炉、气化焚烧炉、气化炉烟气二恶英排放浓度分别为0.70～24.88、3.14～4.88、0.20～0.50ng I-TEQ/Nm3,平均排放水平为焚烧炉＞气化焚烧炉＞气化炉,而炉渣中二恶英浓度顺序正好相反.小型气化炉产生的二恶英主要存在于炉渣中,而焚烧炉和气化焚烧炉产生的二恶英主要存在炉渣和烟气中.3种不同炉型炉渣、烟气中二恶英同系物质量浓度分布特征不同,但是毒性当量浓度分布特征较相似,均以2,3,4,7,8-PeCDF所占比例最高.3种炉型烟气中Pb的排放浓度最高,除1个焚烧炉烟气中Cd排放浓度轻微超标,其余热处理炉烟气中Pb、Cd、Cr、Hg浓度均远低于生活垃圾焚烧污染物控制标准(GB 18485-2014).炉渣的毒性浸出浓度显示,3种炉型炉渣重金属浸出浓度均低于危险废物浸出毒性鉴别标准(GB5085.3-2007),不同炉型炉渣中重金属浸出特性存在一定差异性.