Yu Seungho, Semprini Lewis
Department of Civil, Construction, and Environmental Engineering, Oregon State University, Corvallis 97331, USA.
Water Res. 2002 Dec;36(20):4985-96. doi: 10.1016/s0043-1354(02)00222-1.
Microcosm studies were conducted to demonstrate the effectiveness of tetrabutoxysilane (TBOS) as a slow-release anaerobic substrate to promote reductive dehalogenation of trichloroethylene (TCE). The abiotic hydrolysis of TBOS and tetrakis(2-ethylbutoxy)silane (TKEBS), and the biotic transformations of the hydrolysis products from both were also investigated. Comparison of TCE reductive dehalogenation was performed with microbial communities stimulated from three different sites: Site 300 Lawrence Livermore National Laboratory (LLNL), CA, Point Mugu Naval Weapons Facility, CA, and the Evanite site in Corvallis, OR. Poisoned microcosms showed that 1 mol of TBOS slowly and abiotically hydrolyzes to 4 mol of 1-butanol, while the live microcosms showed the 1-butanol ferments to butyrate and/or acetate, producing H2. The hydrolysis of TBOS and TKEBS was abiotic and not enhanced by biotic processes under the anaerobic conditions of these tests. Hydrogen consumption was correlated with reductive dehalogenation, indicating it served as an electron donor for reductive dehalogenation. TBOS was found to be a slow-release anaerobic substrate to support long-term dechlorination of TCE to ethylene in Point Mugu microcosms, and in the LLNL microcosm bioaugmented with the Evanite culture. Electron mass balances showed most of the electron flow went into the creation of organic acids, especially acetate, and the production of methane. Electron efficiencies for reductive dechlorination were as high as 14% based on the electrons used for dechlorination to the total electrons associated with the mass of TBOS and TKEBS hydrolyzed. Rates of TBOS hydrolysis increased with greater TBOS concentrations as a light nonaqueous-phase liquids (LNAPL). These results indicate that TBOS has promise as an effective anaerobic substrate for remediating a wide range of CAH concentrations at different CAH contaminated sites.
开展了微观世界研究，以证明四丁氧基硅烷（TBOS）作为一种缓释厌氧底物促进三氯乙烯（TCE）还原脱卤的有效性。还研究了TBOS和四（2-乙基丁氧基）硅烷（TKEBS）的非生物水解以及两者水解产物的生物转化。利用从三个不同地点富集的微生物群落对TCE还原脱卤进行了比较：加利福尼亚州劳伦斯利弗莫尔国家实验室（LLNL）的300号场地、加利福尼亚州穆古角海军武器设施以及俄勒冈州科瓦利斯的埃瓦尼特场地。中毒微观世界实验表明，1摩尔TBOS缓慢地非生物水解为4摩尔1-丁醇，而活性微观世界实验表明，1-丁醇发酵生成丁酸盐和/或乙酸盐，并产生氢气。在这些测试的厌氧条件下，TBOS和TKEBS的水解是非生物性的，且不受生物过程增强。氢气消耗与还原脱卤相关，表明其作为还原脱卤的电子供体。在穆古角微观世界以及用埃瓦尼特培养物进行生物强化的LLNL微观世界中，发现TBOS是一种缓释厌氧底物，可支持TCE长期脱氯生成乙烯。电子质量平衡表明，大部分电子流用于生成有机酸，尤其是乙酸盐，以及甲烷的产生。基于用于脱氯的电子与水解的TBOS和TKEBS质量相关的总电子之比，还原脱氯的电子效率高达14%。作为轻质非水相液体（LNAPL），TBOS的水解速率随TBOS浓度的增加而提高。这些结果表明，TBOS有望作为一种有效的厌氧底物，用于修复不同CAH污染场地中广泛的CAH浓度。
