Influence of permeable pavement design and hydraulic management on runoff treatment capacity: Addition of adsorbent drinking water treatment sludge and water reuse potential

Permeable pavements offer multifunctional benefits for sustainable urban water management, yet their design and operation must be optimised to maximise treatment performance and enable water reuse. This study investigates how the design and hydraulic management of permeable interlocking concrete pavements (PICP) influence pollutant removal performance, and presents, for the first time, an assessment of drinking water treatment sludge (DWTS) as an adsorbent material to enhance phosphorus retention. The analysis of a PICP system designed for runoff infiltration reveals a higher contaminant removal capacity (90% TN, 97% TP, 96% COD and 99.97% TSS) compared to a PICP system configured primarily for water storage and reuse (59% TN, 81% TP, 87% COD and 99% TSS). These results demonstrate that pollutant removal is strongly governed by both the pavement design and its operational mode. The use of DWTS led to a slightly significant improvement of 1% in phosphorus removal efficiency. Beyond treatment, PICP structures functioning as water treatment and storage units demonstrated compliance with European and Spanish reuse standards (EU 2020/741 and UNE-EN 16941-1) for specific urban applications, reducing reliance on potable water and supporting circular water strategies. Overall, combining design optimisation, reactive media, and controlled operation, positions permeable pavements as a key solution for climate-resilient cities.