Risk of physical clogging induced by low-density suspended particles during managed aquifer recharge with reclaimed water: Evidences from laboratory experiments and numerical modeling

Abstract

How to reduce the risk of physical clogging is the most significant challenge during managed aquifer recharge (MAR). The prediction of occurrence and development of physical clogging has received increasing attention. In this study, chlorinated secondary wastewater (SW) was recharged into a laboratory column filled with quartz sands. The results showed that the continuous injection of reclaimed water caused a significant reduction in hydraulic conductivity by about 86% in porous media, during the 50-h injection process. The reduction was attributed to physical clogging resulting from the deposition of suspended particles with a flocculent and reticular structure, significantly increasing the surface area and the effective volume of the particle deposits. A numerical model was established based on the mass balance equations for liquid and suspended particles, coupling the particle transport-deposition model and the expressions describing the relationships between the porosity, hydraulic conductivity (K), and the concentration of deposited particles; the model was used to obtain a quantitative description of the temporal and spatial distribution of physical clogging. The bulk factor and the attachment and detachment coefficients were calibrated simultaneously. The model results provided an improved understanding of the influence degree of the three parameters on the physical clogging process. The sensitivity analysis results showed that the bulk factor had the largest sensitivity among the three parameters. In addition, a significant correlation was observed between the simulated data and the experimental data (R2 > 0.90, p < 0.01). The proposed numerical model provides a meaningful guidance tool for assessing and predicting the risk of physical clogging induced by low-density floc particles during artificial recharge with reclaimed water at a large-scale site.