Department of Civil, Environmental and Construction Engineering, Texas Tech University, Lubbock, Texas 79409, United States.
Regional Centre of Advance Technologies and Material, Palacky University, Olomouc, Czech Republic.
Environ Sci Technol. 2021 Apr 20;55(8):4851-4861. doi: 10.1021/acs.est.0c07702. Epub 2021 Mar 31.
Sulfur amendment of zerovalent iron (ZVI) materials has been shown to improve the reactivity and selectivity of ZVI toward a select group of organohalide contaminants in groundwater, most notably trichloroethene (TCE). In previous studies, chemical or mechanochemical sulfidation methods were used; however, the potential of using sulfate-reducing bacteria (SRB) to enable sulfur amendment has not been closely examined. In this study, lab-synthesized nanoscale ZVI (nZVI) and Peerless iron particles (ZVI) were treated in a sulfate-reducing monoculture () and an enrichment culture derived from freshwater sediments (AMR-1) prior to reactivity assessments with TCE as the model contaminant. ZVI conditioned in both cultures exhibited higher dechlorination efficiencies compared to unamended ZVIs. Remarkably, nZVI and ZVI exposed to AMR-1 attained similar TCE dechlorination rates as their counterparts receiving chemical sulfidation (i.e., S-nZVI) using previously reported method. Product distribution data show that, in the SRB-ZVI system, abiotic dechlorination is the dominant TCE reduction pathway. In addition to dissolved sulfide, biogenic or synthesized FeS particles can enhance nZVI reactivity even as nZVI and FeS were not in direct contact, implying that SRB may influence the reactivity of ZVI via multiple mechanisms in different remediation situations. A shift in Archaea abundance in AMR-1 with nZVI amendment was observed but not with ZVI. Overall, the synergy exhibited in the SRB-ZVI system may offer a valuable remediation strategy to overcome limitations of standalone biological or abiotic dechlorination approaches for chlorinated solvent abatement.
硫改性零价铁（ZVI）材料已被证明可以提高 ZVI 对地下水选择的有机卤代污染物，尤其是三氯乙烯（TCE）的反应性和选择性。在以前的研究中，使用了化学或机械化学硫化方法；然而，利用硫酸盐还原菌（SRB）来实现硫改性的潜力尚未得到密切研究。在这项研究中，实验室合成的纳米级 ZVI（nZVI）和 Peerless 铁颗粒（ZVI）在硫酸盐还原单培养物（）和源自淡水沉积物的富集培养物（AMR-1）中进行处理，然后用 TCE 作为模型污染物进行反应性评估。在两种培养物中处理的 ZVI 表现出比未经改性的 ZVI 更高的脱氯效率。值得注意的是，暴露于 AMR-1 的 nZVI 和 ZVI 达到了与使用先前报道的方法用化学硫化（即 S-nZVI）处理的对应物相似的 TCE 脱氯速率。产物分布数据表明，在 SRB-ZVI 系统中，非生物脱氯是 TCE 还原的主要途径。除了溶解的硫化物之外，生物或合成的 FeS 颗粒即使在 nZVI 和 FeS 没有直接接触的情况下也可以增强 nZVI 的反应性，这意味着 SRB 可以通过不同的修复情况下的多种机制来影响 ZVI 的反应性。在用 nZVI 进行 AMR-1 中的古菌丰度发生了变化，但用 ZVI 则没有。总的来说，SRB-ZVI 系统中表现出的协同作用可能为克服单独的生物或非生物脱氯方法在氯化溶剂去除方面的局限性提供了一种有价值的修复策略。
