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原位修复cb污染的地下水和沉积物过程中影响氯化苯（CBs）生物可利用性的生物地球化学相互作用。双生物膜屏障创新地结合了厌氧脱盐菌群和好氧氧化菌，将其种植在颗粒活性炭（GAC）上，以实现高氯化苯向二氧化碳的完全转化，否则高氯化苯的还原脱氯通常会在形成一氯苯和苯时停滞不前。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流入地表水或潜在饮用水源的地下羽流的质量，证明其在保护生态和人类健康方面的有效性。实验室和现场试验将在一个超级基金场址进行，那里的湿地沉积物和地下水中存在致密非水相液体（DNAPL）氯化碳污染，并对污染物的分布和降解过程进行了初步研究。这种生物屏障技术能否作为超级基金场地和其他危险废物场地的长期补救措施，取决于几个因素，包括生物地球化学与生物膜、其他生物屏障成分、底层沉积物和流入地下水的相互作用和动力学。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)通过冲击载荷条件下的微观实验，并使用电子显微镜和表面光谱学来表征表面特征，确定GAC上有氧和厌氧生物膜的稳定性和有效性；（ii）在批量实验中检验未播种GAC与场地基质（沉积物和水）之间的相互作用，利用水相形态形成和表面表征方法评估污染物的吸附/解吸动力学；（iii）在重复的上流式柱实验中研究生物降解过程和CBs的速率，将未播种的GAC与只进行厌氧培养的GAC进行比较，并同时进行好氧和厌氧培养，以评估双生物膜处理CBs的有效性；（iv）在上流式色谱柱实验中评估不同电子受体和其他生物地球化学条件对CBs降解率的影响，以建立优化屏障效率和性能的条件；㈤通过实地试验评估双生物膜屏障的现场性能，以确定生物膜在实际水文和生物地球化学动态及环境条件下多年的有效性和可持续性。

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.