北京市安定生活垃圾填埋场VOCs恶臭物质及其臭气强度

挥发性有机物(VOCs)是填埋场重要的恶臭源之一.为了深入了解造成填埋场恶臭的VOCs及其臭气强度情况,在2014年7—8月采用固相微萃取(SPME)-气相色谱(GC)-质谱(MS)联用法测定了北京市安定生活垃圾卫生填埋场内各代表性地点的VOCs.共确认了48种化合物,包括烷烃、烯烃、芳香烃、环烷烃、萜类、酯类、醛酮类、卤代烃、醇类及含硫化合物和含氮化合物.烷烃的种类最多,达到13种,其次是芳香烃,为9种.以内标法和外标法相结合测定了其中35种物质的含量,发现浓度在0.05~40 mg·m~(-3)之间.在厂区入口和作业面浓度最高的VOC是2,2,4,6,6-五甲基庚烷,在沼气干管是甲苯.从实际经验和臭气强度出发,建立了一种恶臭物质筛选方法,即首先以检出频次和各地点浓度比值筛选出可能的恶臭物质,然后由臭气强度确定最终的恶臭物质.筛选结果表明,填埋场内的恶臭VOCs是对伞花烃、对二甲苯、乙苯、甲苯和邻二甲苯,其中对伞花烃和对二甲苯对恶臭贡献尤为显著.这些恶臭VOCs浓度之间呈现出显著的相关关系,表明这些物质均来源于填埋场内生活垃圾的降解过程.

Odorous volatile organic compounds and their odor intensities in Anding waste sanitary landfill in Beijing

Emissions of volatile organic compounds (VOCs) from landfills can cause odorous nuisances to their adjacent populations and contribute significantly to atmospheric pollution. To identify compounds responsible for odors in VOCs from landfills, air samples and landfill gas samples in Anding waste sanitary landfill, Beijing, were collected during July and August, 2014 and analyzed by solid phase microextraction-gas chromatography-mass spectra. A total of 48 compounds were identified, including alkanes, alkenes, aromatics, cyclanes, terpenes, esters, aldehydes, ketones, halogenated compounds, alcohols, sulfur compounds and nitrogen compounds. Alkanes were the most abundant VOCs with 13 species detected, followed by 9 aromatics. 35 compounds were quantitatively determined and their concentration levels were 0.05~40 mg·m^-3. 2,2,4,6,6-pentamethylheptane was the dominant compound both at the landfill entrance and the operational area, while toluene was dominant in the main landfill gas pipeline. Based on odor similarity and odor intensity over the landfill, an efficient procedure to identify odorous VOCs was presented. Potential odorous VOC were determined according to their frequencies and concentration ratios at different areas. The odorous compounds were confirmed by an index of odor intensity within potential odorous VOC. p-cymene, p-xylene, ethylbenzene, toluene and o-xylene were the odorous VOCs in Anding landfill, and the odor intensities of p-cymene and p-xylene were especially high. A significant relationship between concentrations of odorous VOCs was found, which indicated that these compounds were originated exclusively from the municipal solid waste.