The presence of colloids and bacteria in groundwater affects contaminant migration either by facilitation or retardation. The co-transport of contaminant and colloidal particles had been simulated using various finite difference schemes which may suffer from the known and common numerical dispersion problem. In this study, a random walk particle tracking (RWPT) scheme is developed to simulate the co-transport of contaminants, colloids, and bacteria in porous media. Processes modeled include colloidal deposition to and release from solid matrix, bacterial attachment to and detachment from solid matrix, and contaminant sorption onto and desorption from mobile and immobile colloidal particles and bacterial cells as well as solid matrix. Also, the biological processes between contaminant and bacterial cells including bacterial growth, decay, and contaminant utilization are simulated. The developed model is verified against MT3D-MS for reactive contaminant transport with solid matrix, and reaction processes have been verified with solution of a developed analytical solution of mass balance equations. The biological processes are incorporated into the developed RWPT model which is verified against TVD finite difference model developed by (El-Kordy 2008). The results show good performance of RWPT technique in simulating contaminant transport in the presence of colloids and bacteria. The effects of various physical and biological parameters on contaminant transport are investigated. The results show that at least 50,000 particles are required to simulate each constituent mass in case of consideration of biological processes in contaminant transport simulation. On the other hand, 10,000 particles are found to be sufficient to simulate each constituent mass for case of contaminant transport undergoing physical and chemical processes only. The results indicate that contaminant utilization increases by increasing the ratio of initial concentrations of bacterial cells and contaminant, the ratio of the half-saturation constant to initial contaminant concentration, and the ratio of the maximum growth rate to the yield coefficient. It is also found from the results that higher contaminant utilization occurs at early time and decreases as time progresses.

地下水中胶体和细菌的存在通过促进或阻碍影响污染物迁移。污染物和胶体颗粒的共同传输已经使用各种有限差分方案进行了模拟，这些方案可能会受到已知和常见的数值分散问题的影响。在这项研究中，开发了一种随机游走粒子跟踪 (RWPT) 方案来模拟多孔介质中污染物、胶体和细菌的共同传输。模拟的过程包括胶体沉积到固体基质上和从固体基质上释放、细菌附着到固体基质上和从固体基质上脱离，以及污染物吸附到移动和固定胶体颗粒和细菌细胞以及固体基质上和从其解吸。此外，污染物和细菌细胞之间的生物过程，包括细菌生长、腐烂、和污染物利用进行模拟。开发的模型针对 MT3D-MS 进行了验证，用于固体基质的反应性污染物传输，并且反应过程已经通过质量平衡方程的开发解析解的解决方案进行了验证。生物过程被纳入开发的 RWPT 模型中，该模型通过 (El-Kordy 2008) 开发的 TVD 有限差分模型进行验证。结果表明 RWPT 技术在模拟胶体和细菌存在下的污染物迁移方面具有良好的性能。研究了各种物理和生物参数对污染物迁移的影响。结果表明，在污染物传输模拟中考虑生物过程的情况下，至少需要 50,000 个粒子来模拟每个组成质量。另一方面，10，发现 000 个粒子足以模拟仅在经过物理和化学过程的污染物传输情况下的每个组成质量。结果表明，污染物利用率随着细菌细胞与污染物初始浓度之比、半饱和常数与初始污染物浓度之比以及最大生长速率与产量系数之比的增加而增加。结果还发现，较高的污染物利用率发生在早期，随着时间的推移而降低。结果表明，污染物利用率随着细菌细胞与污染物初始浓度之比、半饱和常数与初始污染物浓度之比以及最大生长速率与产量系数之比的增加而增加。结果还发现，较高的污染物利用率发生在早期，随着时间的推移而降低。结果表明，污染物利用率随着细菌细胞与污染物初始浓度之比、半饱和常数与初始污染物浓度之比以及最大生长速率与产量系数之比的增加而增加。结果还发现，较高的污染物利用率发生在早期，随着时间的推移而降低。