Dual-Biofilm Reactive Barrier for Treatment of Chlorinated Benzenes at Anaerobic-

描述（由申请人提供）：拟议项目包括机制研究，以评估生物地球化学相互作用，影响生物利用度的氯苯（CB）污染的地下水和沉积物的原位修复过程中使用双生物膜屏障的方法。双生物膜屏障创新性地结合了厌氧脱卤菌群和好氧氧化菌，接种在颗粒活性炭（GAC）上，以实现高氯化苯完全转化为二氧化碳，否则通常会在高氯化苯还原脱氯后形成一氯苯和苯时停止。这一拟议项目的总体目标是进一步推动这一创新技术的科学和技术进步，并通过就地处理污染物和减少其向地表水或作为潜在饮用水源的地下羽流的质量通量，证明其在保护生态和人类健康方面的有效性。实验室和现场测试将使用一个超级基金网站，密集的非水相液体（DNAPL）CB污染存在于湿地沉积物和地下水，并已进行初步研究的污染物分布和降解过程。这种生物屏障技术作为该超级基金场地和其他危险废物场地的长期补救措施的有效性取决于几个因素，包括生物地球化学相互作用和与生物膜的动力学、其他生物屏障成分、底层沉积物和流入的地下水。这些因素将通过旨在解决五个具体目标的研究进行调查：（i）通过在冲击负荷条件下进行微观实验并采用电子显微镜和表面光谱表征表面，确定活性炭上好氧和厌氧生物膜的稳定性和有效性;（ii）研究未接种的活性炭和场地基质之间的相互作用（沉积物和水）在批量实验中通过利用水相形态和表面表征方法评估污染物吸附/解吸动力学;（iii）在重复的上流柱实验中研究CB的生物降解过程和速率，该实验将未接种的GAC与仅接种有厌氧培养物以及接种有需氧培养物和厌氧培养物的GAC进行比较，以评估双生物膜在处理CB中的有效性;（iv）评估不同电子受体和其他生物地球化学条件对上流柱实验中氯苯降解速率的影响，以建立优化屏障效率和性能的条件;（v）通过实地测试，评估双层生物膜屏障的实地表现，以确定生物膜屏障在多个在实际水文和地球化学动力学和环境条件下，

DESCRIPTION (provided by applicant): The proposed project comprises mechanistic research to assess the biogeochemical interactions that affect bioavailability of chlorinated benzenes (CBs) during in situ remediation of CB-contaminated groundwater and sediments using a dual-biofilm barrier approach. The dual-biofilm barrier innovatively combines both an anaerobic dehalogenating consortia and aerobic oxidizing bacteria, seeded on granular activated carbon (GAC), to achieve complete transformation of higher chlorinated benzenes to carbon dioxide, which otherwise commonly stalls at formation of monochlorobenzene and benzene upon reductive dechlorination of higher chlorinated benzenes. The overall goals of this proposed project are to further the scientific and technical advancement of this innovative technology and to demonstrate its effectiveness in protecting ecological and human health by treating contaminants in situ and reducing their mass flux to surface water or in subsurface plumes that are potential drinking water sources. Laboratory and field tests will be conducted using a Superfund site where dense non-aqueous phase liquid (DNAPL) CB contamination is present in wetland sediments and groundwater, and preliminary studies have been performed on the contaminant distribution and degradation processes. The effectiveness of this biobarrier technology to serve as a long-term remedy at this Superfund site and other hazardous waste sites depends on several factors, including biogeochemical interactions and dynamics with the biofilm, other biobarrier components, the underlying sediment, and the inflowing groundwater. These factors will be investigated through studies designed to address five specific aims: (i) determine the stability and effectiveness of aerobic and anaerobic biofilms on GAC through microcosm experiments under shock loading conditions and employing electron microscopy and surface spectroscopy to characterize the surfaces; (ii) examine the interactions between unseeded GAC and the site matrix (sediment and water) in batch experiments to assess contaminant sorption / desorption kinetics by utilizing aqueous phase speciation and surface characterization methods; (iii) investigate biodegradation processes and rates of CBs in replicate upflow column experiments that compare unseeded GAC to GAC seeded with only an anaerobic culture and both the aerobic and anaerobic cultures to assess the dual-biofilm effectiveness in treating CBs; (iv) assess the impacts of different electron acceptors and other biogeochemical conditions on degradation rates of CBs in upflow column experiments to establish conditions that optimize barrier efficiency and performance; (v) evaluate on-site performance of the dual-biofilm barrier through field tests to determine biofilm effectiveness and sustainability over a multi-year period under realistic hydrologic and biogeochemical dynamics and environmental conditions.