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

描述(由申请人提供)：拟议的项目包括机械研究，以评估在使用双生物膜屏障方法就地修复受CB污染的地下水和沉积物期间，影响氯代苯(CBS)生物有效性的生物地球化学相互作用。双生物膜屏障创新性地结合了厌氧脱卤菌和好氧氧化菌，接种在颗粒活性碳(GAC)上，实现了高氯苯完全转化为二氧化碳，否则通常在高氯苯还原脱氯时形成一氯苯和苯。这一拟议项目的总体目标是促进这一创新技术的科学和技术进步，并通过就地处理污染物并减少其向地表水或潜在饮用水水源地下羽流中的质量通量，展示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Superfund的一个场地进行，在那里湿地沉积物和地下水中存在致密的非水相液体(DNAPL)CB污染，并已对污染物的分布和降解过程进行了初步研究。这种生物屏障技术在这个超级基金场地和其他危险废物场地作为长期补救措施的有效性取决于几个因素，包括与生物膜、其他生物屏障成分、底层沉积物和流入的地下水的生物地球化学相互作用和动态。这些因素将通过旨在解决五个具体目标的研究来研究：(I)通过冲击负荷条件下的微观实验并利用电子显微镜和表面光谱来表征表面，确定好氧生物膜和厌氧生物膜在GAC上的稳定性和有效性；(Ii)通过间歇实验考察未接种的GAC与现场基质(沉积物和水)之间的相互作用，以利用水相形态和表面表征方法评估污染物的吸附/解吸动力学；(Iii)在重复上流柱实验中研究CBS的生物降解过程和速率，比较未接种的GAC和只接种厌氧培养的GAC以及同时接种好氧和厌氧培养的GAC，以评估双生物膜处理CBS的效果；(Iv)在上流柱实验中评估不同的电子受体和其他生物地球化学条件对CBS降解速度的影响，以建立优化屏障效率和性能的条件；(V)通过现场测试来评估双生物膜屏障的现场性能，以确定在现实的水文和生物地球化学动力学和环境条件下的生物膜有效性和可持续性。

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.