Subsurface transport of microorganism and its application to bioremediation of groundwater contaminated by halogenated organic compound

实验室柱试验证实，激活四氯乙烯(PCE)脱氯的微生物双发酵梭菌DPH-1的迁移特性可用流动-固定两区模型(TRM)很好地描述，该模型已被用于土壤中污染物的物理迁移模型。测定的TRM参数表明，对于广泛分布的受污染地下水，大浓度细菌注入地下难以修复。结合试验条件和在柱子中测试的土壤的特性，仔细评估了校准参数。提出了用于模拟细菌在生物强化中的迁移和降解的传输参数的实用估计值。在间歇试验中，菌株与四氯乙烯或三氯乙烯的卤代脂肪族化合物混合作为初始污染物时，生物反应符合一级动力学。以Michaelis-Menten方程为基础，三氯乙烯对PCE的脱氯反应可用Monod型函数来描述，而微生物的生长速率用Monod函数不能很好地描述。由此，提出了微生物生长速率与PCE和TCE浓度之间的关系式，并通过固定床反应器中PCE脱氯的数值模拟验证了该关系式的合理性。

Laboratory column tests confirmed that the transport characteristics of microorganism, Clostridium bifermentans DPH-1 activating tetrachloroethylene (PCE) dechlorination, was well described by a mobile-immobile two-region model (TRM), which has been used in physical transport model of aqueous pollutants through soils. Determined TRM parameters implied that bacterial injection into ground at large amount of concentration is difficult in a rehabilitation manner for widely dispersed contaminated groundwater. Calibrated parameters were carefully evaluated in conjunction with test conditions and features of the soils tested in column. Practical estimation were proposed in transport parameters to simulate bacteria transport and degradation of PCE in bio-augmentation. Biological reaction was identified as first-order kinetics from batch tests where the bacterium strain was mixed with halogenated aliphatic compounds of PCE or TCE (trichloroethylene) as initial pollutant. PCE dechlorination to cis-dichloroethylene (cDCE) via TCE was mathematically described by Monod type function based on Michaelis-Menten equation while the microbial growth rate was not well represented by Monod function. Thus, a relationship between the microbial growth rate and the concentration of PCE and TCE was newly proposed and its appropriateness was verified through a numerical simulation of PCE dechlorination in a fixed-bed reactor column.