Effects of Colloid Release on Permeability of Water-Bearing Media in Different pH Medium

A column experiment was conducted to investigate the release of colloids in water-saturated porous media, and the mechanism for the permeability of the water-bearing media changed by release of colloids are discussed. The research results showed that the accumulative amount of colloid particles release in effluent from water-bearing media increased with increasing pH. The accumulative amount of colloid particles in effluent with pore volumes showed a curve of "S" type. Colloid release was restrained under strong acidic condition, while was favorable under the neutral and alkaline conditions, and the critical pH of colloid release was 7. The release of colloids had great influence on the permeability of the water-bearing media, and the permeability of water-bearing media decreased by 98.2 % in the process of the experiment. The migration and interception of the released colloids resulted in the permeability loss of the porous media.