Fuente: Sustainability - Revista científica (MDPI) Sustainability, Vol. 18, Pages 5599: Long-Term Assessment of Heavy Metal Removal Efficiency and Ecological Risk of Permeable Brick Pavement Systems with Modified Cushion Fillers
Sustainability doi: 10.3390/su18115599
Authors:
Yuanhao Li
Xiaoran Zhang
Ziyang Zhang
Hongrui Chen

As a widely used sponge facility, the permeable pavement system (PPS) frequently exhibited a decline in pollutant removal after long-term operation. However, the long-term impacts of different cushion fillers on pollutant removal and ecological risk remain unclear. This study modified a conventional sand-based PPS (S1) by replacing the cushion layer with five materials: construction waste bricks (S2), coal gangue (S3), activated carbon (S4), carbon nanotubes (S5), and graphene (S6). A 5-year laboratory experiment evaluated the removal efficiency, fraction distribution, and ecological risk of heavy metals (HMs: Mn, Pb, Zn, Cu, Cd, Ni) from rainfall. The key findings demonstrated significant variations among fillers. S2 showed the poorest performance with a removal efficiency of 83.26% ± 13.02 across all HMs, whereas carbonaceous-modified systems (S4–S6) exhibited high removal efficiencies, exceeding 97.00% ± 1.89. Residual and Fe/Mn oxide states were predominant among the HMs, exceeding 43.69%, indicating enhanced metal immobilization. The ecological risks of carbon nanotubes and graphene were the highest, with risk indices of 1123.02 and 1129.63, respectively. These findings demonstrated that carbonaceous fillers achieved superior HM sequestration, leading to an overall reduction in ecological risk in the effluent of PPS after long-term operation. Overall, this study provided new perspectives on elucidating long-term removal efficiency and the ecological risk mitigation of PPS, and supported future application of carbonaceous fillers in sustainable PPS design and construction.