School of Environmental Science & Engineering, Tianjin University, Tianjin 300072, China.
Water Res. 2013 Oct 15;47(16):5977-85. doi: 10.1016/j.watres.2013.06.028. Epub 2013 Jun 26.
In this paper, an anaerobic two-layer permeable reactive biobarrier system consisting of an oxygen-capturing layer followed by a biodegradation layer was designed firstly for evaluating the remediation effectiveness of nitrate-contaminated groundwater. The first layer filling with granular oxygen-capturing materials is used to capture dissolved oxygen (DO) in groundwater in order to create an anaerobic condition for the microbial denitrification. Furthermore, it can also provide nutrition, such as carbon and phosphorus, for the normal metabolism of immobilized denitrifying bacteria filled in the second layer. The second layer using granular activated carbon as microbial carrier is able to biodegrade nitrate entering the barrier system. Batch experiments were conducted to identify the effect of DO on microbial denitrification, oxygen-capturing performance of zero valent iron (ZVI) powder and the characteristics of the prepared oxygen-capturing materials used to stimulate growth of denitrifying bacteria. A laboratory-scale experiment using two continuous upflow stainless-steel columns was then performed to evaluate the feasibility of this designed system. The first column was filled with granular oxygen-capturing materials prepared by ZVI powder, sodium citrate as well as other inorganic salts, etc. The second column was filled with activated carbon immobilizing denitrifying microbial consortium. Simulated nitrate-contaminated groundwater (40 mg NO3-N/L, pH 7.0) with 6 mg/L of DO content was pumped into this system at a flow rate of 235 mL/d. Samples from the second column were analyzed for nitrate and its major degradation byproduct. Results showed that nitrate could be removed more than 94%, and its metabolic intermediate, nitrite, could also be biodegraded further in this passive system. Further study is necessary in order to evaluate performance of its field application.
本文首次设计了一种由吸氧层和生物降解层组成的厌氧双层可渗透反应生物屏障系统，用于评估受硝酸盐污染地下水的修复效果。第一层填充颗粒状吸氧材料，用于捕获地下水中的溶解氧（DO），为微生物反硝化创造厌氧条件。此外，它还可以为填充在第二层中的固定化反硝化细菌的正常新陈代谢提供营养，如碳和磷。第二层使用颗粒状活性炭作为微生物载体，能够生物降解进入屏障系统的硝酸盐。进行了批处理实验，以确定 DO 对微生物反硝化作用、零价铁（ZVI）粉末的吸氧性能以及用于刺激反硝化细菌生长的制备吸氧材料的特性的影响。然后进行了使用两个连续上流不锈钢柱的实验室规模实验，以评估该设计系统的可行性。第一根柱子填充了由 ZVI 粉末、柠檬酸钠和其他无机盐等制备的颗粒状吸氧材料。第二根柱子填充了固定化反硝化微生物菌剂的活性炭。以 235 mL/d 的流速将含有 6 mg/L DO 的模拟硝酸盐污染地下水（40 mg NO3-N/L，pH 值 7.0）泵入该系统。对第二根柱子的样品进行硝酸盐及其主要降解中间产物的分析。结果表明，该被动系统可去除超过 94%的硝酸盐，其代谢中间产物亚硝酸盐也可进一步生物降解。需要进一步研究以评估其现场应用性能。
