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

项目摘要 该项目解决了修复被污染的地下水的一个共同挑战 氯化挥发性有机化合物(CVOCs)和1，4-二恶烷。氯代有机化合物包括氯化溶剂，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1，4-二恶烷是已知或潜在的人类致癌物质，并在物质优先列表(SPL)上 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 已经成立了。然而，CVOCs和1，4-二恶烷混合物的生物修复目前还不可行，因为至少 以下三个障碍：1)环境相关浓度的1，4-二恶烷的生物降解性低， 2)对1，4-二恶烷代谢的需氧条件，但对大多数CVOCs的厌氧条件 3)CVOCs对1，4-二恶烷生物降解的抑制作用。该项目提出了以下建议 应对这些挑战的综合补救办法：第一，创新的大循环物质办法 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CVOCs。继CVOCs处理后，另一种创新的大环材料 作为一种有效和选择性的1，4-二恶烷吸附剂，生物膜由高效的培养物组成 需氧代谢1，4-二恶烷。大环分子，包括具有以下特征的重复环低聚物 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客体络合物 (即1，4-二恶烷或CVOCs)。一种高效的1，4-二恶烷代谢培养物(以前建立) 与文献中报道的所有其他药物相比，在低浓度、与环境相关的情况下更有效。至 了解新型吸附剂如何增强生物修复的机理，并展示 为了验证所提出的补救方法的可行性，研究人员将开展以下工作：1) 新型大环材料的计算研究、合成和表征。两种吸附剂，一种是 选择性和可逆地吸附CVOCs，另一种选择性地吸附1，4-二恶烷将被优化为 在生物修复研究中的应用。2)高效代谢1，4-二氧六环培养的机理研究。 将分离出混合培养物中对1，4-二恶烷具有高亲和力的关键微生物，并 研究了它们的降解中间体、途径和动力学。3)阐明相互作用 污染物、微生物培养和新型吸着剂。为了实现这一点，完全混流实验 将被执行，它们将与数学建模相结合，该数学模型结合了两者的现象 生物膜中的吸附和生物降解。4)CVOCs和CVOCs生物修复的概念验证柱研究 1，4-二恶烷混合物。将进行两项长期的柱研究：1，4-二恶烷的异地处理和In CVOCs与1，4-二恶烷串联的原位生物修复绩效目标将达到最高 有机氯化合物的污染物水平和1，4-二恶烷的健康建议水平(0.35ug/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).