Promoting microbial clogging through enhanced soil particle surface properties for improved seepage resistance in sandy soils

Microbial clogging, as an environmentally friendly solution to leakage, utilizes microorganisms to form biofilm structures in soil, significantly reducing the pore size and permeability of the bio-soil. To enhance its efficiency, this study introduced a coupling-grafting modification to improve soil surface properties and microbial compatibility. The optimal modification conditions were determined, and microbial adhesion and anti-seepage performance were evaluated through bio-soil column tests. Surface property changes were further analyzed to clarify interaction mechanisms between the modified soil and microorganisms. The coupling modifier was prepared using a deionized water–ethanol system. Compared with unmodified soil, microbial attachment increased significantly, and the hydraulic conductivity of the modified bio-soil decreased by nearly one order of magnitude with a faster reduction rate. The modified soil exhibited greater roughness and hydrophobicity with a lower negative surface charge, promoting microbial clogging. Optimal conditions were 90 °C, 6% modifier concentration, and 3 h treatment. These results demonstrate that coupling-grafted modification effectively enhances microbial clogging efficiency, providing an eco-friendly seepage control strategy for sandy soils.