TU Wien, Institute for Water Quality and Resource Management, Karlsplatz 13/226, 1040 Vienna, Austria.
Bundesanstalt für Materialforschung und prüfung (BAM), engl. Federal Institute for Materials Research and Testing, Division Thermochemical Residues Treatment and Resource Recovery, Unter den Eichen 87, 12205 Berlin, Germany.
Waste Manag. 2018 Mar;73:381-391. doi: 10.1016/j.wasman.2017.12.020. Epub 2017 Dec 20.
An environmentally friendly and cost efficient way for the management of municipal solid waste incineration (MSWI) fly ash represents its thermal co-treatment together with combustible waste. However, the safe introduction and storage of MSWI fly ash in the waste bunker is challenging and associated with severe problems (e.g. dust emissions, generation of undefined lumps and heat in case of moistened MSWI fly ash). Therefore, the aim of this study is to investigate the suitability of pelletisation as a pretreatment of MSWI fly ash. In particular, MSWI fly ash was characterised after sampling, pelletisation and thermal treatment and the transfer of constituents to secondary fly ash and flue gas was investigated. For this purpose, MSWI fly ash pellets with a water content of about 0.15 kg/kg and a diameter of about 8 mm have been produced by disc pelletiser and treated in an electrically heated pilot-scale rotary kiln at different temperatures, ranging from 450 °C to 1050 °C. The total contents of selected elements in the MSWI fly ash before and after thermal treatment and in the generated secondary fly ash have been analysed in order to understand the fate of each element. Furthermore, leachable contents of selected elements and total content of persistent organic pollutants of the thermally treated MSWI fly ash were determined. Due to the low total content of Hg (0.7 mg/kg) and the low leachate content of Pb (<0.36 mg/kg), even at the lowest treatment temperature of 450 °C, thermally treated MSWI fly ash pellets can be classified as non-hazardous waste. However, temperatures of at least 650 °C are necessary to decrease the toxic equivalency of PCDD/F and DL-PCB. The removal of toxic heavy metals like Cd and Pb is significantly improved at temperatures of 850 °C, 950 °C or even 1050 °C. The observed metal removal led to relatively high contents of e.g. Cu (up to 11,000 mg/kg), Pb (up to 91,000 mg/kg) and Zn (up to 21,000 mg/kg) in the secondary fly ash. This metal enriched secondary fly ash might represent a potential raw material for metal recovery (e.g. via acidic leaching). Due to the high content of total dissolved solids observed in the leachate of thermally treated MSWI fly ash pellets, a wet extraction procedure is suggested to enable its safe disposal at non-hazardous waste landfills.
一种用于管理城市固体废物焚烧（MSWI）飞灰的环保且经济高效的方法是将其与可燃废物一起进行热共处理。然而，在废物仓中安全地引入和储存 MSWI 飞灰是具有挑战性的，并且会伴随着严重的问题（例如，灰尘排放，在潮湿的 MSWI 飞灰的情况下产生未定义的块状物和热量）。因此，本研究的目的是研究颗粒化作为 MSWI 飞灰预处理的适用性。特别是，在采样、造粒和热处理后对 MSWI 飞灰进行了表征，并研究了成分向二次飞灰和烟道气中的转移。为此，通过圆盘造粒机生产了水含量约为 0.15kg/kg、直径约为 8mm 的 MSWI 飞灰球，并在不同温度（450°C 至 1050°C）下在电加热的小型旋转窑中进行了处理。为了了解每个元素的命运，分析了热处理前后以及生成的二次飞灰中 MSWI 飞灰中选定元素的总含量。此外，还测定了热处理后的 MSWI 飞灰中选定元素的可浸出含量和持久性有机污染物的总量。由于 Hg（0.7mg/kg）的总含量低，Pb 的浸出含量低（<0.36mg/kg），即使在最低的处理温度 450°C 下，热处理后的 MSWI 飞灰球也可被归类为非危险废物。然而，为了降低 PCDD/F 和 DL-PCB 的毒性等效物，至少需要 650°C 的温度。在 850°C、950°C 甚至 1050°C 的温度下，有毒重金属如 Cd 和 Pb 的去除率显著提高。观察到的金属去除导致二次飞灰中例如 Cu（高达 11,000mg/kg）、Pb（高达 91,000mg/kg）和 Zn（高达 21,000mg/kg）的含量相对较高。这种富含金属的二次飞灰可能代表了一种潜在的金属回收原料（例如通过酸性浸出）。由于在热处理后的 MSWI 飞灰球的浸出液中观察到高含量的总溶解固体，建议采用湿法提取程序，以便将其安全地处置在非危险废物填埋场中。
