Enhancing bioremediation of groundwater co-contaminated by chlorinated volatile organic compounds and 1,4-dioxane using novel macrocyclic materials

项目概要 该项目解决了修复受污染的地下水的常见挑战 氯化挥发性有机化合物 (CVOC) 和 1,4-二恶烷。 CVOC 包括氯化溶剂，例如 如三氯乙烯 (TCE) 和 1,1,1-三氯乙烷 (1,1,1-TCA) 及其降解产物。许多 CVOC 和 1,4-二恶烷是已知或潜在的人类致癌物，并在物质优先列表 (SPL) 中 超级基金网站。厌氧条件下的CVOCs生物修复（即还原脱氯）效果良好 成立。然而，CVOC 和 1,4-二恶烷混合物的生物修复尚不可行，因为至少 以下三个障碍：1) 1,4-二恶烷在环境相关浓度下的生物降解性较低， 2) 1,4-二恶烷代谢需要有氧条件，但大多数 CVOC 需要无氧条件 代谢，3) CVOC 抑制 1,4-二恶烷生物降解。本项目提出以下建议 应对这些挑战的综合修复方法：首先，创新的大循环材料方法 选择性吸附CVOCs，促进材料表面脱氯生物膜生长， 厌氧生物降解 CVOC。 CVOCs处理后的另一种创新大环材料 作为 1,4-二恶烷的有效选择性吸附剂，可维持由高效培养物组成的生物膜，以 有氧代谢 1,4-二恶烷。大环分子，由重复的环状低聚物组成 独特的几何形状和内部化学，仅与选定的客体分子形成特定的主客体复合物 （即 1,4-二恶烷或 CVOC）。高效的 1,4-二氧杂环己烷代谢培养物（之前已建立）对于 与文献中报道的所有其他浓度相比，在环境相关的低浓度下更有效。至 了解新型吸附剂如何增强生物修复的机制并证明 为了确定所提出的修复方法的可行性，研究人员将进行以下工作：1） 新型大环材料的计算研究、合成和表征。两种吸附剂，其中一种 选择性和可逆地吸附 CVOC，另一种选择性吸附 1,4-二恶烷将被优化 在生物修复研究中的应用。 2）高效1,4-二恶烷代谢培养物的机理研究。 混合培养物中对 1,4-二恶烷具有高亲和力的关键微生物将被分离并 研究了它们的降解中间体、途径和动力学。 3）阐明之间的相互作用 污染物、微生物培养物和新型吸附剂。为了实现这一点，完全混合流实验 将被执行，并且它们将与结合了两者现象的数学模型相结合 生物膜中的吸附和生物降解。 4) CVOC 生物修复的概念验证柱研究 1,4-二恶烷混合物。将进行两项长期柱研究：1,4-二恶烷的异位处理和 CVOCs 和 1,4-二恶烷混合物系列的原位生物修复。绩效目标将是最大化 CVOC 污染水平和 1,4-二恶烷健康建议水平 (0.35 µg/L)。

Project Summary The project addresses a common challenge in the remediation of groundwater contaminated with chlorinated volatile organic compounds (CVOCs) and 1,4-dioxane. CVOCs include chlorinated solvents, such as trichloroethylene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA), and their degradation products. Many CVOCs and 1,4-dioxane are known or potential human carcinogens and on the Substance Priority List (SPL) for Superfund sites. CVOCs bioremediation under anaerobic conditions (i.e. reductive dechlorination) is well established. However, bioremediation of mixtures of CVOCs and 1,4-dioxane is not yet feasible due to at least the following three obstacles: 1) low biodegradability of 1,4-dioxane at environmentally relevant concentrations, 2) requirement for aerobic conditions for 1,4-dioxane metabolism but anaerobic conditions for most CVOCs metabolism, and 3) inhibition of 1,4-dioxane biodegradation by CVOCs. This project proposes the following combined remediation approach to address these challenges: first, an innovative macrocyclic material approach to selectively adsorb CVOCs and promote the growth of dechlorinating biofilm on the material surface to anaerobically biodegrade CVOCs. After the CVOCs treatment, another type of innovative macrocyclic material as an effective and selective sorbent for 1,4-dioxane sustains biofilms consisting of a highly efficient culture to aerobically metabolize 1,4-dioxane. The macrocyclic molecules, which comprise repeating cyclic oligomers with unique geometry and internal chemistry, form specific host-guest complexes with only selected guest molecules (i.e., 1,4-dioxane or CVOCs). A highly efficient 1,4-dioxane-metabolizing culture (previously established) is much more effective at low, environmentally relevant concentrations compared to all others reported in literature. To understand the mechanisms of how the novel sorbents enhance bioremediation and to demonstrate the feasibility of the proposed remediation approach, the researchers will conduct the following work: 1) Computational study, synthesis, and characterization of novel macrocyclic materials. Two sorbents, one that selectively and reversibly adsorbs CVOCs and another that selectively adsorbs 1,4-dioxane will be optimized for use in the bioremediation studies. 2) Mechanistic study of the highly efficient 1,4-dioxane-metabolizing culture. Key microorganisms responsible for the high affinity to 1,4-dioxane in the mixed culture will be isolated and investigated for their degradation intermediates, pathways, and kinetics. 3) Elucidation of interactions among contaminants, microbial cultures, and the novel sorbents. To achieve this, completely mixed flow experiments will be performed, and they will be coupled with mathematical modeling that incorporates phenomena of both sorption and biodegradation in biofilms. 4) Proof-of-concept column studies for bioremediation of CVOCs and 1,4-dioxane mixtures. Two long-term column studies will be performed: ex situ treatment of 1,4-dioxane and in situ bioremediation of CVOCs and 1,4-dioxane mixture in series. Performance objectives will be Maximum Contaminant Levels for CVOCs and the Health Advisory Level for 1,4-dioxane (0.35 µg/L).