Department of Civil Engineering, Technical University of Denmark, Lyngby 2800, Denmark.
Department of Civil Engineering, Technical University of Denmark, Lyngby 2800, Denmark.
Waste Manag. 2018 Jan;71:215-223. doi: 10.1016/j.wasman.2017.09.035. Epub 2017 Oct 12.
Electrodialytic process offers a range of possibilities to waste management by electrodialytic separation (EDS) of heavy metals, depending on how the process is designed. Using three EDS cell setups (two two-compartment and one three-compartment) and their combinations, the extraction of Cr from municipal solid waste incineration fly ash by changing pH and redox conditions was investigated in the present work. The experiments were designed into single, two and three steps, based on the number of setups (by changing EDS cells) or effective setups (by shifting working electrode pairs) used. Prior to EDS the ash studied went through pretreatments such as water-washing and dry-sieving with a 50 µm sieve. The results showed that Cr was strongly bound in the ash, and the major fraction remained bound after the different treatments. Two/three-step treatment, which obtained the maximum Cr extraction rate of 27.5%, is an improvement on the single-step that extracted maximum 3.1%. The highest extraction was obtained due to the combined extraction of Cr(III) under low pH (accompanied with high redox) conditions and Cr(VI) under high pH (low redox) conditions subsequently. The Cr leaching from the treated ashes with acidic pH was lower than from those with alkaline pH; after the three-step treatment, Cr leaching was much lower from the coarse fraction (> 50 µm), as compared to the fine (≤ 50 µm) or the unsieved ash. As for the coarse fraction, two/three-step treatment reduced the leaching of Cr compared to the single-step in the same pH range (either acidic or alkaline).
电渗析过程提供了一系列的可能性来进行废物管理，通过电渗析分离（EDS）重金属，具体取决于过程的设计。在本工作中，使用三种 EDS 电池组（两个两室和一个三室）及其组合，通过改变 pH 值和氧化还原条件，研究了从城市固体废物焚烧飞灰中提取 Cr 的方法。实验设计为单步、两步和三步，基于使用的电池组数量（通过改变 EDS 电池）或有效电池组数量（通过移动工作电极对）。在 EDS 之前，对所研究的灰分进行了预处理，如水洗和用 50μm 筛网进行干筛分。结果表明，Cr 在灰分中结合牢固，经过不同处理后，主要部分仍保持结合状态。两步/三步处理获得了 27.5%的最大 Cr 提取率，优于仅提取 3.1%的单步处理。由于在低 pH（伴随高氧化还原）条件下和随后在高 pH（低氧化还原）条件下联合提取 Cr(III)和 Cr(VI)，因此获得了最高的提取率。用酸性 pH 处理的灰分中的 Cr 浸出率低于碱性 pH 处理的灰分；经过三步处理后，与细粒（≤50μm）或未筛分的灰分相比，粗粒（>50μm）的 Cr 浸出率要低得多。对于粗粒部分，两步/三步处理与相同 pH 范围内（酸性或碱性）的单步处理相比，降低了 Cr 的浸出率。
