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

项目摘要 该项目解决了一个共同的挑战，即修复被污染的地下水， 氯化挥发性有机化合物（CVOCs）和1，4-二氧六环。CVOC包括氯化溶剂，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1，4-二氧六环是已知的或潜在的人类致癌物， 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， 确立了习然而，CVOC和1，4-二氧六环的混合物的生物修复尚不可行，因为至少 以下三个障碍：1）1，4-二氧杂环己烷在环境相关浓度下的低生物降解性， 2)1，4-二氧六环代谢需要有氧条件，但大多数CVOCs需要厌氧条件 CVOCs对1，4-二氧六环生物降解的抑制作用。该项目提出以下建议 联合修复方法来应对这些挑战：首先，创新的大环材料方法 选择性吸附CVOCs，促进脱氯生物膜在材料表面生长， 厌氧生物降解CVOCs。CVOCs处理后，另一类创新的大环材料 作为1，4-二氧六环的有效和选择性吸附剂，维持由高效培养物组成的生物膜， 需氧代谢1，4-二氧六环。大环分子，其包含重复的环状低聚物， 独特的几何结构和内部化学，仅与选定的客体分子形成特定的主体-客体复合物 (i.e., 1，4-二氧杂环己烷或CVOC）。一个高效的1，4-二氧杂环己烷代谢文化（以前建立）是非常重要的。 与文献中报告的所有其他浓度相比，在环境相关的低浓度下更有效。到 了解新型吸附剂如何增强生物修复的机制，并证明 为确定建议的修复方法的可行性，研究人员将进行以下工作： 新型大环材料的计算研究、合成与表征。两种吸附剂，一种 选择性和可逆地吸附CVOCs和另一个选择性吸附1，4-二氧六环将优化， 用于生物修复研究。2)1，4-二氧六环高效代谢菌的机理研究。 将分离混合培养物中对1，4-二氧六环具有高亲和力的关键微生物， 研究其降解中间体、途径和动力学。3)阐明下列因素之间的相互作用： 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 将执行，他们将与数学建模，结合两者的现象相结合， 生物膜中的吸附和生物降解。4)CVOCs生物修复的概念验证柱研究， 1，4-二氧六环混合物。将进行两项长期柱研究：1，4-二氧六环的异位处理和 CVOCs和1，4-二氧六环混合物的串联原位生物修复。绩效目标将是最高 CVOCs的污染物水平和1，4-二氧六环的健康建议水平（0.35微克/升）。

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).