Chen Wan, Kirkelund Gunvor M, Jensen Pernille E, Ottosen Lisbeth M
Department of Civil Engineering, Technical University of Denmark, Denmark.
Department of Civil Engineering, Technical University of Denmark, Denmark.
Waste Manag. 2017 Oct;68:240-251. doi: 10.1016/j.wasman.2017.07.011. Epub 2017 Jul 27.
To reduce heavy metal leaching and stabilize municipal solid waste incineration (MSWI) fly ash, different methods and combination of methods were tested: water washing, electrodialytic separation and thermal treatment at 1000°C. A comparison of heavy metal concentration and leaching levels of As, Cr, Pb and Zn for the different untreated and treated ashes was made. The results showed that minimizing leaching to meet the limiting values of the all the studied heavy metals can be obtained at the same time by combining water washing, electrodialytic separation and thermal treatment. The ash subjected to this combination had lower Cr than the ash solely subjected to thermal treatment or subjected to water washing prior to thermal treatment. The electrodialytic separation (EDS) of the washed ash lowered pH from alkaline to acidic, which resulted in elevated leaching of Cd and Zn, while the Cr leaching was reduced. Up to 58.6% of Zn and 5.5% of Pb were extracted by EDS compared to less than 0.6% extraction by water washing. During thermal treatment of the EDS treated ash, the ash was re-alkalized. Due to solidification and possibly evaporation, most heavy elements left in the thermally treated ash were stabilized and immobilized. However, leaching of As and/or Cr was still problematic and did not meet the limit value for the thermally treated ash being recycled in construction work. The removal of Ca and decomposition of Ca oxides and minerals during EDS was linked to the leaching patterns of As and Cr after thermal treatment.
为减少重金属浸出并稳定城市固体废物焚烧（MSWI）飞灰，对不同方法及方法组合进行了测试：水洗、电渗析分离以及在1000°C下进行热处理。对不同未处理和处理后飞灰中砷、铬、铅和锌的重金属浓度及浸出水平进行了比较。结果表明，通过将水洗、电渗析分离和热处理相结合，能够同时实现将浸出量降至最低以满足所有研究重金属的限值。经过这种组合处理的飞灰中铬的含量低于仅进行热处理或在热处理前进行水洗的飞灰。水洗后飞灰的电渗析分离（EDS）使pH值从碱性降至酸性，这导致镉和锌的浸出量增加，而铬的浸出量减少。与水洗提取率低于0.6%相比，EDS提取了高达58.6%的锌和5.5%的铅。在对经EDS处理的飞灰进行热处理期间，飞灰重新碱化。由于固化以及可能的蒸发，留在热处理飞灰中的大多数重金属元素得以稳定和固定。然而，砷和/或铬的浸出仍然存在问题，并且不符合热处理飞灰用于建筑工程回收利用的限值。在EDS过程中钙的去除以及钙氧化物和矿物质的分解与热处理后砷和铬的浸出模式有关。
