Implementing Heterogeneous Catalytic Dechlorination Technology for Remediating TCE-Contaminated Groundwater

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• 作者：Matthew G. Davie ; Hefa Cheng ; Gary D. Hopkins ; Carmen A. LeBron ; Martin Reinhard
• 刊名：Environmental Science & Technology
• 出版年：2008
• 出版时间：December 1, 2008
• 年：2008
• 卷：42
• 期：23
• 页码：8908-8915
• 全文大小：348K
• 年卷期：v.42,no.23(December 1, 2008)
• ISSN：1520-5851

文摘

To transition catalytic reductive dechlorination (CRD) into practice, it is necessary to demonstrate the effectiveness, robustness, and economic competitiveness of CRD-based treatment systems. A CRD system scaled up from previous laboratory studies was tested for remediating groundwater contaminated with 500−1200 μg L⁻¹ trichloroethylene (TCE) at Edwards Air Force Base (AFB), California. Groundwater was pumped from a treatment well at 2 gal min⁻¹, amended with hydrogen to 0.35 mg L⁻¹ and contacted for 2.3 min with 20 kg eggshell-coated Pd on alumina beads (2% Pd by wt) packed in a fixed-bed reactor, and then returned to the aquifer. Operation was continuous for 23 h followed a 1 h regeneration cycle. After regeneration, TCE removal was 99.8% for 4 to 9 h and then declined to 98.3% due to catalyst deactivation. The observed catalyst deactivation was tentatively attributed to formation of sulfidic compounds; modeling of catalyst deactivation kinetics suggests the presence of sulfidic species equivalent to 2−4 mg L⁻¹ hydrogen sulfide in the reactor water. Over the more than 100 day demonstration period, TCE concentrations in the treated groundwater were reduced by >99% to an average concentration of 4.1 μg L⁻¹. The results demonstrate CRD as a viable treatment alternative technically and economically competitive with activated carbon adsorption and other conventional physicochemical treatment technologies.