Bromine in waste incineration partitioning and influence on metal volatilisation

INTENTION, GOAL, SCOPE, BACKGROUND: The halogen bromine is far less abundant than chlorine, but it can be found at high concentrations in special materials like flame retarded plastics. The fate and effects of Br in waste incineration are not well understood. It may have similar implications like Cl for the volatilisation of heavy metals and the formation of low volatile organic compounds. Due to its lower oxidation potential, there is a risk of formation of elementary Br2 in the offgas. OBJECTIVE: Co-combustion tests of different types of Br containing plastic waste materials (up to 22%) and MSW in the TAMARA pilot plant for waste incineration were conducted to investigate the Br partitioning and the influence of Br on metal volatilisation. METHODS: The Br inventory of the fuel mix was elevated to approx. 1 wt-%. All input and output mass flows of the furnace have been sampled and the partitioning of Cl, Br, S, and a number of heavy metals, has been calculated on the basis of closed mass balances. RESULTS AND DISCUSSION: Organically-bound Br was typically released to more than 90% into the raw gas. Elementary Br2 was detected at high Br levels. Its presence was always analysed when all SO2 in the raw gas was oxidised to SO3. Br enhances the volatilisation of metals like K, Zn, Cd, Sn, Sb, and Pb out of the fuel bed principally in the same way as Cl. The tests gave strong indication that the promoting influence of the halogens on metal volatilisation is more pronounced than that of the fuel bed temperature. The volatilised metals are condensated on the fly ashes and are discharged along with the filter ashes. CONCLUSIONS: As long as a surplus of SO2 is present in the raw gas no Br2 is formed. Although the halogen induced transfer out of the fuel bed causes high concentrations of volatile metals in the filter ashes, a recovery is not economically feasible for the time being. The volatilisation gives no rise to metal emission problems as long as efficient dedusting is achieved. RECOMMENDATION AND OUTLOOK: If there is a risk of Br2 formation, in wet scrubbing a reducing agent has to be added to the neutral scrubber for efficient abatement. Filter ashes should be disposed of in a way that enables access for recovery in the future. The exact volatilisation characteristics of the various metals have to be studied in future using specifically tailored experiments.     

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玉溪市目前每年产生医疗危险废弃物2317.7t，建成集中垃圾焚烧厂后，每年可处理医疗危险废物1500t，其中的病原菌及各种微生物可全部杀死，废物减量90.3%以上，酚减少90.5％，做到残渣无害化。     

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城市生活垃圾的物理成份随时间和地点的不同有很大的差别，经以热为手段（焚烧和热解）的垃圾处理带来很大困难，尤其是城市生活垃圾中轻质组份的品质和数量是影响其处理质量的关键因素，分析了连续几年北京市城市生活垃圾的组成成份以及变化趋势。     

萃取／硝化／石墨炉原子吸收法测定海水中的三丁基锡

建立了萃取／硝化／石墨炉原子吸收法分析海水中三丁基锡的方法，筛选了最佳的萃取条件、基改剂及石墨炉参数。本方法检出限为０１６μｇ／Ｌ；相对标准偏差最高不超过４％；回收率为９４％～１０５％。     

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