Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, Canada.
Department of Civil, Geological and Mining Engineering, Polytechnique Montreal, Quebec, Canada.
Water Res. 2020 Sep 15;183:116098. doi: 10.1016/j.watres.2020.116098. Epub 2020 Jun 26.
We present the first study investigating optimized regeneration strategies for anionic ion exchange (IX) resins during the removal of persistent per- and poly-fluoroalkyl substances (PFAS, including GenX) from surface and treated wastewater effluents. IX regeneration studies are of critical importance from environmental perspectives. Specifically, the knowledge is essential for water utilities who presently operate IX (for PFAS removal) in a single use-and-dispose mode. In this study, legacy PFAS such as PFOA/PFOS were tested along with other harmful short-chained PFAS (PFBA/PFBS) and other toxic perfluorinated substitutes (GenX). Studies were performed on synthetic water (spiked with Suwannee River Natural Organic Matter (SRNOM), Fulvic Acid (SRFA) and Humic Acid (SRHA)), surface water, and wastewater effluents, and the regeneration was performed in batch stirred reactors. The resin service life with and without regeneration was investigated in the presence of background organic matter. In ultra-pure waters, all PFAS (C ∼10 μg/L, concentrations similar to that of natural waters) were effectively removed for >100,000 Bed Volume (BV) of operation. This was reduced to ∼23,500 BV in the presence of SRNOM (C = 5 mg C/L), 20,500 BV in SRFA and 8500 BV in SRHA, after which the saturated resins required regeneration. More importantly, all resin breakthrough (PFAS> 70 ng/L) corresponded to > 90% resin site saturation (in meqs), an essential information for optimizing IX loading. The competitive dissolved organic matter (DOM) fractions were estimated to be approximately 5-9% of the initial DOC, as estimated by the IAST-EBC model. Finally, it was identified that IX regeneration efficiency improved with increasing brine contact time but effectiveness plateaued for brine concentrations above 10% (W/V). Nonetheless, a regeneration with 10% NaCl solution with a contact time of 2 h was found to be optimal for IX operations in synthetic and natural waters. Therefore, this study provides key knowledge essential for the scientific community and the water industry on optimizing IX operational parameters for DOM and PFAS removal and would be highly valuable for systems which presently operate IX in a use-and-dispose mode.
我们首次研究了从地表和处理后的废水废水中去除持久性全氟和多氟烷基物质（PFAS，包括 GenX）过程中优化阴离子离子交换（IX）树脂的再生策略。从环境角度来看，IX 再生研究至关重要。具体来说，对于目前以单次使用和处置模式运行 IX（用于去除 PFAS）的水公司来说，这方面的知识是必不可少的。在这项研究中，我们测试了包括 PFOA/PFOS 在内的传统 PFAS，以及其他有害短链 PFAS（PFBA/PFBS）和其他有毒全氟代替代品（GenX）。研究在合成水中（用苏万尼河天然有机物 (SRNOM)、富里酸 (SRFA) 和腐殖酸 (SRHA) 进行了加标）、地表水和废水废水中进行，并在批式搅拌反应器中进行了再生。在存在背景有机物的情况下，研究了树脂在有/无再生条件下的使用寿命。在超纯水中，所有 PFAS（C∼10μg/L，浓度与天然水相似）在超过 100,000 个床体积（BV）的操作中均有效去除。而在存在 SRNOM（C=5mg C/L）时，这一数值降至约 23,500 BV，在存在 SRFA 时降至 20,500 BV，在存在 SRHA 时降至 8,500 BV，之后饱和树脂需要再生。更重要的是，所有树脂穿透（PFAS>70ng/L）都对应于树脂位饱和度（meqs）的>90%，这是优化 IX 加载的重要信息。通过 IAST-EBC 模型估计，竞争溶解有机物（DOM）分数约为初始 DOC 的 5-9%。最后，研究确定 IX 再生效率随盐水接触时间的增加而提高，但在盐水浓度高于 10%（W/V）时效果趋于平稳。尽管如此，在合成水和天然水中，发现用 10%NaCl 溶液接触 2 小时的再生方法对 IX 运行最为有效。因此，本研究为科学界和水工业提供了优化 DOM 和 PFAS 去除过程中 IX 操作参数的关键知识，对于目前以使用和处置模式运行 IX 的系统将具有很高的价值。
