Evaluation of Partitioning Electron Donors for Enhanced Bioremediation of Chlorinated Solvent Source Zones

分区电子供体对氯化溶剂源区强化生物修复的评价

• 批准号: 1215837
• 负责人: Natalie Capiro
• 金额: $ 34.44万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1215837&HistoricalAwards=false
• 关键词: Evaluation; Partitioning; Electron; Donors; Enhanced

Evaluation of Partitioning Electron Donors for Enhanced Bioremediation of Chlorinated Solvent Source ZonesNatalie L. Cápiro and Kurt D. Pennell (Tufts University; Medford, MA)Recent studies have demonstrated that microorganisms are capable of biodegradation within close proximity to chlorinated solvent source zones. This biological activity can enhance (accelerate) aqueous dissolution (removal) of chlorinated solvents, and has the potential to provide more effective source zone treatment, thereby reducing potential exposure and remediation costs. However, the performance of bioremediation, and more specifically, biologically-enhanced dissolution, faces two challenges; sustained release of electron donor (food source) and delivery of electron donor to the intended target. To overcome these limitations, a potential alternative are partitioning electron donors (PEDs), organic compounds (e.g., n-butyl acetate) that are relatively water soluble, but also partition into (directly mix with) chlorinated solvents. When a PED is delivered to the subsurface contaminant source zone, it preferentially partitions into the organic separate phase chlorinated solvent, and then slowly dissolves back into the passing groundwater along with the contaminant. This strategy of electron donor delivery is intended to promote the growth of chlorinated solvent degrading bacteria in close proximity to the contaminant source zone, while minimizing consumption of electron donor in microbial processes not associated with chlorinated solvent bioremediation (e.g., methane production). The specific objectives of this research are designed to assess the physical, chemical and biological processes that govern PED delivery, mass transfer, and consumption to support sustained microbial biodegradation in chlorinated solvent source zones. A combination of laboratory-scale experiments and mathematical modeling will be conducted using trichloroethene (TCE) as a representative contaminant. The research program is structured around four tasks that will: (1) evaluate and select PEDs for detailed study based on abiotic and biotic batch reactor studies, (2) quantify PED delivery and release, and rates of bioenhanced dissolution and degradation in columns containing residual TCE in comparison to current electron donor delivery approaches, (3) measure the spatial distribution and temporal evolution of PED delivery/release, TCE dissolution and degradation, and microbial communities in heterogeneous aquifer cells to assess the potential for improved bioremediation under more realistic conditions, and (4) implement mathematical models to obtain mass transfer and utilization rate parameters from experimental data, and predict responses to alternative PED delivery strategies and subsurface aquifer conditions to support potential scale up to field-application. The U.S. EPA estimates that more than $209 billion dollars (in constant 2004 dollars) will be needed over the next 30 years to mitigate hazards at 235,000 to 355,000 chlorinated solvent contaminated sites, impacting nearly 30% of U.S. drinking water supplies. Additionally, these cost estimates do not include many sites susceptible to vapor intrusion, which is now recognized as a key exposure pathway in urban areas. The knowledge gained from the testing and validation of this novel remediation technique will provide a sustainable approach to reduce chlorinated solvent source zone longevity and remediation costs through an improved understanding of enhanced biological treatment. Integration of experimental studies with mathematical modeling will yield guidelines and rate parameters necessary for practitioners and researchers to assess PED performance for a range of potential remediation scenarios. Furthermore, the project will incorporate educational initiatives into the research and instructional activities of the investigators, with the goal of extending the impact of acquired knowledge beyond the traditional framework of journal publications and conference presentations. This goal will be achieved through the following initiatives: (a) the inclusion of undergraduate students conducting laboratory research, and (b) recruitment of female and underrepresented minority science and engineering undergraduate and graduate students, (c) dissemination of instructional tools to regulatory agencies and impacted communities.

评价分配电子供体以加强氯化溶剂区的生物修复Natalie L.CáPiro和Kurt D.Pennell(塔夫茨大学；马萨诸塞州梅德福德)最近的研究表明，微生物能够在靠近氯化溶剂区的地方进行生物降解。这种生物活性可以增强(加速)氯化溶剂在水中的溶解(去除)，并有可能提供更有效的来源区域处理，从而降低潜在的暴露和修复成本。然而，生物修复的效果，更具体地说，生物促进的溶解，面临着两个挑战：电子供体(食物来源)的持续释放和电子供体向预定目标的传递。为了克服这些限制，一个潜在的替代方案是分配电子给体(PED)，即相对水溶性的有机化合物(例如乙酸丁酯)，但也可以分配到(直接与)氯化溶剂中。当PED被输送到地下污染源区域时，它优先分配到有机分离相氯化溶剂中，然后随着污染物慢慢溶解回经过的地下水中。这种提供电子给体的策略旨在促进氯化溶剂降解菌在污染源区域附近的生长，同时最大限度地减少与氯化溶剂生物修复(例如甲烷生产)无关的微生物过程中电子给体的消耗。这项研究的具体目标旨在评估控制PED传递、传质和消费的物理、化学和生物过程，以支持氯化溶剂源区的持续微生物生物降解。将使用三氯乙烯(TCE)作为代表性污染物，进行实验室规模的实验和数学建模相结合。该研究计划围绕四项任务构建：(1)基于非生物和生物间歇反应装置的研究，评估和选择PED用于详细研究；(2)与当前的电子供体输送方法相比，量化PED的输送和释放以及在含有残留TCE的柱中的生物增强溶解和降解速率；(3)测量PED输送/释放、TCE溶解和降解以及非均质含水层细胞中微生物群落的空间分布和时间演变，以评估在更现实的条件下改进生物修复的可能性；以及(4)实施数学模型以从实验数据获得质量传递和利用率参数，并预测对替代PED输送策略和地下含水层条件的反应，以支持潜在的扩大到现场应用的规模。美国环保署估计，未来30年将需要超过2,090亿美元(按2004年不变美元计算)，以减轻23.5万至35.5万个氯化溶剂污染场地的危害，影响近30%的美国饮用水供应。此外，这些成本估算不包括许多易受蒸汽入侵的地点，这现在被认为是城市地区的关键接触途径。通过测试和验证这一新的修复技术所获得的知识将提供一种可持续的方法，通过更好地了解强化生物处理来减少氯化溶剂源区的寿命和修复成本。将实验研究与数学建模相结合，将为从业者和研究人员提供必要的指南和评级参数，以评估一系列潜在补救方案的PED性能。此外，该项目将把教育举措纳入调查人员的研究和教学活动，目的是将所获得的知识的影响扩大到期刊出版物和会议发言的传统框架之外。将通过以下举措实现这一目标：(A)吸纳从事实验室研究的本科生；(B)招募女性和人数偏少的少数民族理工科本科生和研究生；(C)向监管机构和受影响社区传播教学工具。