Decontamination performance and cleaning characteristics of three common used paved permeable bricks

To investigate the effectiveness of different permeable bricks on the pollutants from urban rainfall runoff, three common used bricks (ceramic brick, cement brick, and steel slag brick) were selected and applied to study their decontamination performance. The influencing factors such as rainfall intensity and contaminant concentrations were investigated. Then the ultrapure water was used to wash the permeable brick to research the pollution status and cleaning characteristics by monitoring the water quality of the rinsing water. Suspended solids (SS), chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), total phosphorus (TP), and heavy metals (Cu, Zn, Pb, and Cd) in the influent and effluent were measured. The results showed the following: (I) The upper layer of the brick may play a more critical role in purification process; the uniform and dense pore distribution of ceramic permeable brick was instrumental in the retention of particulates. (II) Contaminant concentration and rainfall intensity had a great influence on pollutants with lower removal rate and had little effect on pollutants with higher removal rate. (III) Non-sintered bricks containing a certain amount of cement increased the pH after filtration. (IV) The removal performance of permeable brick for dissolved pollutants such as COD, NH₄-N, and TN was inferior to that for SS, TP, and heavy metals since the discrepancy in removal mechanism of pollutants. The study could offer a new perspective for the decontamination research of pervious bricks.