Permeable pavement is a low impact development technology for stormwater (SW) runoff control and pollutant removal. The strength of SW depends on land use of the catchment, e.g., semi-urban vs. industrial. The performance (in terms of pollutants removal) of permeable clay bricks (PCB) has not been adequately assessed for SW of varying strengths. For using the permeable clay bricks as a pavement surface layer, the present research investigates its pollutant removal capacity through SW infiltration using a laboratory setup. SW samples of two different strengths, i.e., high polluted stormwater (HPSW) and less polluted stormwater (LPSW), were tested for a pavement system consisting of the clay brick layer on top of a coarse gravel support layer. The tests were performed at a rainfall intensity of 12.5 mm/h (for a 10-year return period in Buraidah, Qassim) to evaluate the suitability of PCB for the arid and semi-arid regions. The experiments revealed that PCB became fully saturated and achieved a steady-state outflow condition after 10 min of rainfall. Irrespective of contamination level, the pollutant removal efficiency was found to be similar for both HPSW and LPSW. High TSS (>98%) and turbidity (>99%) removals were achieved for both strengths, while BOD5 (78.4%) and COD (76.1%) removals were moderate. Poor to moderate nutrient removal, 30.5% and 39.1% for total nitrogen (TN) and 34.7% and 31.3% for total phosphorus (TP), respectively for HPSW and LPSW, indicates an adsorptive removal of nutrients in the system. Heavy metal removal efficiency ranged from 6.7% to 94%, with higher removals archived for Fe, Mn, Se, and Pb. The study provides insights into the role of PCB as a surface layer in the permeable pavement for pollutant removal. The study also establishes the guidelines for the optimal permeable pavement design to deal with SW of varying contamination levels. Permeable clay bricks showed the potential to be used as a sustainable LID technology for arid regions.

The permeable pavement system (PPS) has effectively contributed to stormwater management as a low-impact development (LID) technology. The suitability of clay bricks, consolidated with waste materials, for sustainable PPS applications in urban infrastructure needs further attention. In this study, several series of permeable clay paving bricks samples were prepared by mixing different ratios and particle sizes of sawdust (SD) with clay soil and firing at 900 °C. The raw soil and SD samples were characterized through sieve analysis, X-ray Fluorescence (XRF), X-ray diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FTIR). The bricks were tested for their compressive strength, bulk density, apparent porosity, water adsorption, permeability coefficient, and stormwater treatment efficiency. The clay soil comprised 17.5% clay/silt with appropriate amounts of SiO2 (50.47%), Al2O3 (19.14%), and fluxing agents (15.34%) and was suitable for brick manufacturing. XRD and FTIR analysis revealed that the soil predominantly comprises quartz, dolomite calcite, feldspar, kaolinite, illite, and chlorites. The SD samples were enriched with amorphous and crystalline cellulose. The compressive strength of the bricks decreased, while the permeability of the bricks increased with an increasing percentage of SD. An optimal percentage of 10% SD achieved a 21.2 MPa compressive strength and a 0.0556 m/s permeability coefficient, meeting the ASTM specifications for PPS. The optimal size of SD, between 0.5 and 1.0 mm, achieved the desired compressive strength of the bricks. The permeable bricks effectively removed the total suspended solids (TSS), turbidity, and BOD5 from the stormwater, which complies with the guidelines for wastewater reuse applications.