The effect of bioclogging on the hydraulic conductivity of saturated porous media at different recharge water temperatures

Bioclogging in porous media is common and affects many engineering projects. The temperature of recharge water could significantly affect the process of bioclogging, thus impacting the hydraulic conductivity of porous media. In this study, a series of laboratory percolation experiments was conducted to understand the effects of recharge water temperature. The results of these experiments showed that bioclogging evolved in phases, and the gradual reduction (attenuation) of hydraulic conductivity caused by bioclogging could be described by an inverse logistic model. Analysis of microbial growth suggested that the bioclogging phases were strongly correlated with microbial growth stages. Both the clogging rate and degree of clogging through the seepage column decreased with distance from the inlet. Within the range of 10–25 ℃, the degree of clogging decreased with the increasing recharge water temperature; however, the degree of clogging increased with recharge water temperature within the range of 25–35 ℃. The relative hydraulic conductivity values decreased by 86.9% at a recharge water temperature of 10 ℃, 76.0% at 15 ℃, 65.1% at 20 ℃, 44.9% at 25 ℃, 82.5% at 30 ℃ and 98.7% at 35 ℃. Investigation by scanning electron microscopy found that the microorganism micromorphology differed at different recharge water temperatures, which made a significant difference in terms of clogging degree. A comprehensive model that describes hydraulic conductivity attenuation with varying recharge water temperature has been developed.