粒径和流速对大肠杆菌在饱和多孔介质中迁移的影响

采用室内柱迁移实验,研究了在不同离子强度下多孔介质粒径和孔隙水流速对大肠杆菌在饱和石英砂柱中沉积与释放行为的影响。结果表明,介质粒径和孔隙水流速均能影响大肠杆菌在石英砂中的迁移过程。介质粒径的减小可增强大肠杆菌在多孔介质中的筛滤效应,增加其沉积率和滞留率,减小水化学扰动引起的释放效应,流速的降低有利于提高大肠杆菌的沉积率和滞留率。离子强度的高低可改变粒径和流速对大肠杆菌迁移影响的大小,在较高离子强度条件下,减小介质粒径和孔隙水流速对提高大肠杆菌的沉积率和滞留率的作用增强。由于自然环境的复杂性,今后的研究应注重真实地下水环境中多因素对大肠杆菌迁移行为的复合影响,以便更加准确地掌握大肠杆菌在多孔介质中迁移的规律。

Effects of particle size and pore water velocity on transport of Escherichia coli in saturated porous media

The transport of pathogenic microbes in porous media is critical to groundwater quality. This study investigated the combined effects of particle size and pore water velocity on the deposition and release behavior of Escherichia coli(E. coli) in saturated quartz sands at different ionic strengths. Results showed that both particle size and pore water velocity affected the transport of E. coli in porous media. Decreasing particle size increased straining effect, deposition and thus retention rates of E. coli. Moreover, the enhanced straining effect resulted in lower releases of E. coli from the smaller particles. Reducing pore water velocity tended to increase deposition and retention rates of E. coli. At greater ionic strength, decreases in both particle size and pore water velocity further enhanced deposition and retention rates of E. coli. These results would improve our understanding of releases and transport of biocolloids under transient ionic strength.