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）脱氯的微生物双歧梭菌（Clostridium bifermentans DPH-1）的输运特性可以用移动-不移动双区模型（TRM）很好地描述，该模型已被用于水体污染物在土壤中的物理输运模型。确定的TRM参数表明，对于广泛分布的污染地下水，细菌以大浓度注入地下是难以修复的。校准参数仔细评估结合测试条件和特征的土壤测试柱。为模拟生物强化过程中PCE的细菌迁移和降解，提出了可行的迁移参数估计方法。将该菌株与PCE或TCE（三氯乙烯）的卤化脂肪族化合物混合作为初始污染物进行批量试验，确定生物反应为一级动力学。PCE经TCE脱氯制顺式二氯乙烯（cDCE）的过程可以用基于Michaelis-Menten方程的Monod型函数进行数学描述，而微生物生长速率不能很好地用Monod函数表示。因此，提出了微生物生长速率与PCE和TCE浓度之间的关系，并通过固定床反应器柱中PCE脱氯的数值模拟验证了其适用性。

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.