Removal of chlorinated organic compounds from ground water by AOP in a bubble column photochemical reactor

氯化挥发性有机化合物（CVOC），如三氯乙烯（TCE）和四氯乙烯（PCE），已被广泛用作金属和干洗的工业溶剂。许多土壤和地下水供应由于地下储存罐泄漏和处置不当而受到污染。高级氧化技术（Advanced Oxidation Process，AOPs）是一种高效的处理难降解有机物的方法，它是利用紫外光与臭氧、H_2O_2等氧化剂相结合，产生极强的氧化剂-OH自由基。然而，AOPs的效率在自由基清除剂的存在下降低，例如通常在地下水中发现的碳酸盐、腐殖物质和硝酸盐。本研究设计了一种新型的AOP反应器，通过减少OH自由基清除剂和UV吸收剂的用量，提高了UV/H_2O_2工艺的处理效率。这是通过构建紫外鼓泡塔反应器（UV-BCR），其中污染气体（空气汽提或土壤蒸汽提取后）可以被吸收到清除剂自由的环境中，在那里它可以进行氧化。然后，根据化学工程和光化学原理，结合数学模型，对UV-BCR的性能进行了分析和预测。

Chlorinated Volatile Organic Compounds(CVOCs), such as trichloroethylene(TCE) and tetrachloroethylene(PCE) have been widely used as industrial solvents for degreasing metals and for dry cleaning. Many soils and groundwater supplies have become contaminated as a result of leaking underground storage tanks and improper disposal practices. In the treatment of the refractory and non-biodegradable compounds the so-called Advanced Oxidation Processes(AOPs) are effective, because of the production of the extremely powerful oxidants -OH radicals, with the use of UV light in a combination win oxidants such as ozone and/or H_2O_2. The efficiency of AOPs is however reduced in the presence of radical scavengers, such as carbonates, humic material and nitrates usually found in groundwater. The AOPs for on-site destruction and detoxification of CVOC-contaminated groundwater has been needed.In this study, we designed the novel type AOP reactor that could improve the efficiency of the UV/H_2O_2 process due to the reduction of OH radical scavengers and UV absorbers. This was achieved by constructing the UV-bubble column reactor(UV-BCR) in which the polluted gas (after air stripping or soil vapor extraction) could be absorbed into the scavenger free environment where it can undergo the oxidation. Later, the performance of the UV-BCR was analyzed and predicted based on the chemical engineering and photochemical principles coupled with the mathematical modeling.