Deciphering the Synergistic Influence of Bacterial Proliferation and EPS Secretion on Soil Water Dynamics

Bio-clogging is critical to the efficiency of soil aquifer treatment. Herein, utilized a percolation recharge device to investigate dynamic changes in biofilm and the corresponding response changes of three typical hydraulic properties of media within the percolation column. The results revealed that the biofilm exhibited a five-stage growth morphology: bacterial stage, colony stage, biofilm with filamentous EPS stage, biofilm with mesh EPS stage, and dense biofilm stage. The hydraulic conductivity exhibited nonuniform decay across five stages: initial fluctuation period, swiftly declining period, accelerated declining period, gently decreasing period, and equilibrium stabilizing period. Both bacteria and EPS contribute to the attenuation of the infiltration properties. Due to its hydrophilic nature, EPS played a more prominent role in storing and dispersing water. As such, significant changes in water holding capacity and material transport mechanism occurred at EPS secretion onset. From 0-18h, bacterial colonisation enhanced water-holding capacity somewhat, whereas the hydraulic dispersion coefficient gradually rose. After 18 hours, a substantial amount of extracellular polymers were produced, considerably enhanced water-holding capacity and altered medium migration from convection to dispersion.