Department of Chemical Engineering, University of Vigo, 36310 Vigo, Spain.
J Hazard Mater. 2010 Apr 15;176(1-3):1073-8. doi: 10.1016/j.jhazmat.2009.11.150. Epub 2009 Dec 3.
Sewage sludge contains several potentially hazardous compounds such as heavy metals, PCBs, PAHs, etc. However, elements with high agricultural value (P, K or Ca) are also present. During the last years, the fluidized bed sludge combustor (FBSC) is considered an effective and novel alternative to treat sewage sludge. By its use, the high amount of sludge is reduced to a small quantity of ash and thermal destruction of toxic organic constituents is obtained. Conversely, heavy metals are retained in the ash. In this work the possibility for electrodialytic metal removal for sewage sludge ash from FBSC was studied. A detailed characterization of the sewage sludge ash was done initially, determining that, with the exception of Cd, the other heavy metals (Cr, Cu, Pb, Ni and Zn) were under the limiting levels of Danish legislation for the use of sewage sludge as fertilizer. After 14 days of electrodialytic treatment, the Cd concentration was reduced to values below the limiting concentration. In all experiments the concentrations of other metals were under limiting values of the Danish legislation. It can be concluded that the electrodialytic treatment is an adequate alternative to reduce the Cd concentration in FBSC ash prior to use as fertilizer.
污水污泥含有几种潜在危险化合物，如重金属、多氯联苯、多环芳烃等。然而，也存在具有高农业价值的元素（P、K 或 Ca）。在过去的几年中，流化床污泥燃烧器（FBSC）被认为是处理污水污泥的一种有效和新颖的替代方法。通过使用该方法，可以将大量的污泥减少到少量的灰烬，并获得有毒有机成分的热破坏。相反，重金属则保留在灰烬中。在这项工作中，研究了从 FBSC 中用电渗析法去除污水污泥灰分中金属的可能性。首先对污水污泥灰分进行了详细的特性描述，结果表明，除 Cd 外，其他重金属（Cr、Cu、Pb、Ni 和 Zn）的含量均低于丹麦将污水污泥用作肥料的法规所规定的限量。经过 14 天的电渗析处理，Cd 的浓度降低到限量以下。在所有实验中，其他金属的浓度均低于丹麦法规的限量值。可以得出结论，电渗析处理是在将 FBSC 灰分用作肥料之前降低 Cd 浓度的一种合适的替代方法。
