Christianne Ridge A, Sedlak David L
Department of Civil and Environmental Engineering, 609 Davis Hall, University of California, Berkeley, CA 94720, USA.
Water Res. 2004 Feb;38(4):921-32. doi: 10.1016/j.watres.2003.10.004.
The presence of the synthetic chelating agent ethylenediaminetetraacetic acid (EDTA) in municipal wastewater has a significant impact on the efficacy of wastewater treatment plants because pollutant metal-EDTA complexes are difficult to remove. To understand the potential of FeCl3 addition during primary treatment to improve metal removal, laboratory experiments and a full-scale study were conducted. Results of laboratory experiments designed to simulate primary and secondary wastewater treatment indicate that a portion of pollutant metal-EDTA species can be converted into FeEDTA- by addition of FeCl3 during simulated primary treatment. Addition of FeCl3 also resulted in improved metal removal by adsorption. The combination of these two processes improved removal of Cu and Zn by 20% during simulated primary treatment. During full-scale treatment, a slight increase in the concentration of FeEDTA- in secondary effluent was observed when FeCl3 was added during primary treatment. However, FeCl3 addition had no observable effect on metal concentrations in the wastewater effluent. The most noticeable change in EDTA speciation at full scale occurred during primary treatment, where most of the pollutant metal-EDTA complexes were converted into FeEDTA-, irrespective of whether or not FeCl3 was added. The formation of FeEDTA- during primary treatment plays a potentially important role in metal removal and should be considered in future evaluations of wastewater treatment plant performance.
城市废水中合成螯合剂乙二胺四乙酸（EDTA）的存在对污水处理厂的效能有重大影响，因为污染物金属 - EDTA络合物难以去除。为了解在初级处理过程中添加FeCl₃以提高金属去除率的潜力，进行了实验室实验和全尺寸研究。旨在模拟初级和二级废水处理的实验室实验结果表明，在模拟初级处理过程中添加FeCl₃可以将一部分污染物金属 - EDTA物种转化为FeEDTA⁻。添加FeCl₃还通过吸附提高了金属去除率。在模拟初级处理过程中，这两个过程的结合使Cu和Zn的去除率提高了20%。在全尺寸处理过程中，当在初级处理中添加FeCl₃时，观察到二级出水中FeEDTA⁻的浓度略有增加。然而，添加FeCl₃对废水排放中的金属浓度没有明显影响。全尺寸处理中EDTA形态最明显的变化发生在初级处理过程中，无论是否添加FeCl₃，大部分污染物金属 - EDTA络合物都转化为FeEDTA⁻。初级处理过程中FeEDTA⁻的形成在金属去除中可能起着重要作用，应在未来对污水处理厂性能的评估中予以考虑。
