Turcotte Patrice, Smyth Shirley Anne, Gagné François, Gagnon Christian
Water Science & Technology, Environment & Climate Change Canada, 105 Rue McGill, Montréal, QC H2Y 2E7, Canada.
Science & Risk Assessment, Environment & Climate Change Canada, 867 Lakeshore Rd, Burlington, ON L7S 1A1, Canada.
Toxics. 2022 May 17;10(5):254. doi: 10.3390/toxics10050254.
The use of lanthanides is increasing in our society, whether in communication technologies, transportation, electronics or medical imaging. Some lanthanides enter urban wastewater and flow through municipal wastewater treatment plants (WWTPs). However, little is known about the effectiveness of treatment processes to remove these elements and the concentrations released in effluents to receiving waters. The main objective of this study was to investigate the fate of lanthanides in various wastewater treatment processes. A secondary objective was to better understand the fate of medical gadolinium (Gd) complexes; anthropogenic inputs were differentiated from geological sources using an approach based on concentration normalization with respect to chondrite Post-Archean Australian Shale (PAAS). The hypothesis was that most lanthanides, especially of geological origin, are associated with the particulate phase and could be efficiently removed by WWTPs. To monitor these elements in different WWTPs, various urban influents and effluents from simple aerated lagoons to advanced treatments were sampled in Canada. The results showed that the rates of lanthanide removal by treatment processes decrease with their atomic number; from 95% for cerium (Ce) to 70% for lutetium (Lu), except for Gd, which was minimally removed. The normalization approach permitted the determination of the origin of Gd in these wastewaters, i.e., medical application versus the geological background. By distinguishing the geogenic Gd fraction from the anthropogenic one, the removal efficiency was evaluated according to the origin of the Gd; nearly 90% for geogenic Gd and a rate varying from 15% to 50% in the case of anthropogenic Gd. The processes using alum as the flocculating agent had the highest removal efficiency from wastewater.
镧系元素在我们的社会中的应用日益增加，无论是在通信技术、交通运输、电子领域还是医学成像方面。一些镧系元素进入城市废水，并流经城市污水处理厂（WWTPs）。然而，对于去除这些元素的处理工艺的有效性以及排放到受纳水体中的废水中这些元素的浓度，人们了解甚少。本研究的主要目的是调查镧系元素在各种废水处理工艺中的去向。次要目的是更好地了解医用钆（Gd）配合物的去向；利用基于相对于球粒陨石后太古代澳大利亚页岩（PAAS）进行浓度归一化的方法，将人为输入与地质来源区分开来。假设是大多数镧系元素，尤其是地质来源的镧系元素，与颗粒相相关，并且可以被污水处理厂有效去除。为了监测不同污水处理厂中的这些元素，在加拿大采集了从简单曝气塘到深度处理的各种城市进水和出水样本。结果表明，处理工艺对镧系元素的去除率随其原子序数降低；铈（Ce）的去除率为95%，镥（Lu）为70%，但钆除外，其去除率极低。归一化方法能够确定这些废水中钆的来源，即医疗应用来源与地质背景来源。通过区分地质来源的钆部分和人为来源的钆部分，根据钆的来源评估去除效率；地质来源的钆去除率接近90%，人为来源的钆去除率在15%至50%之间变化。使用明矾作为絮凝剂的工艺对废水的去除效率最高。
