Infiltration Effects of Polyacrylamide Adsorption on Porous Media

Synthetic organic polymers are typically used in water treatment to coagulate colloids and enhance the performance of sedimentation and filtration processes. This research investigates polyacrylamide (PAM) application for use in unlined conveyance channels to decrease water infiltration rates. Column studies were conducted with well-sorted sand to determine the infiltration effects of PAM dosage and to evaluate possible seepage reduction mechanisms. Results showed hydraulic conductivity reduction increases with increased PAM concentration, with a maximum hydraulic conductivity reduction of 95% at a 150 ppm PAM dose. In addition, results indicated that a polymer adsorption mechanism was responsible for the hydraulic conductivity reduction. With adsorption, the polymer most likely interacted with the porous media, creating a coating layer around the sand particles. Long term column tests showed that with adsorption, hydraulic conductivity returned to background values once polymer application ceased. An adsorption isotherm test confirmed that PAM was capable of adsorbing to the media. Isotherm data was described using the Freundlich equation with n = 0.56 and a distribution coefficient (K_d) of 7.7 L/mg.