Unveiling the Potential: Selecting Optimal Materials for Physical Pools in a Pavement-Runoff-Integrated Treatment System

Pavement runoff contains complex pollutants that can lead to environmental pollution and health risks. A pavement-runoff-integrated treatment system has been recognized as an effective way to deal with pavement runoff pollution. However, there is little support for selecting appropriate materials for physical pools due to a lack of understanding of the selective filtration and physical adsorption characteristics. In this study, gravel and activated carbon were chosen as the substrate materials for physical filtration and adsorption pools, and their corresponding purification characteristics were investigated using an indoor scaled down model. The results showed that the removal rate of all pollutants was related to the size of the gravel used. This was mainly due to the increased gravel particle size and voids, which resulted in a higher water velocity, shorter hydraulic retention time, and inadequate filtration. Compared with coconut shell granular activated carbon (GAC) and coal column activated carbon (EAC), analytically pure granular activated carbon (ARAC) showed a better removal rate for petroleum and heavy metals. This is mainly because ARAC has a larger specific surface area, higher pore volume, and wider pore size distribution, resulting in a remarkable adsorption capacity for pollutants. Overall, the combination of 0.3 mm gravel and ARAC was found to be the most suitable for use as filtration and adsorption materials for physical pools. These findings offer a gravel- and ARAC-based pavement-runoff-integrated treatment system, which has excellent potential to enhance the removal of pollutants from pavement runoff.