Experimental study on the water purification performance of carbonated recycled aggregate pervious concrete

By carbonation treatment, the disadvantages of recycled aggregates (RAs), such as a high porosity, high crushing index and weak interface transition zone, can be improved to some extent. However, the purification performance of carbonated recycled aggregate pervious concrete (CRAPC) remains unknown. In this study, the purification performance of three types of pervious concrete prepared from natural aggregates (NAs), RAs and carbonated recycled aggregates (CRAs) was investigated. High-throughput sequencing of microorganisms was carried out as well. The results reveal that pervious concrete has a significant purification capacity, and the pervious concrete prepared by RAs and CRAs can further improve the ability to remove pollutants. Compared with natural aggregate pervious concrete (NAPC), recycled aggregate pervious concrete (RAPC) and CRAPC were more favourable for pollutant adsorption and microorganism growth due to their special pore structure. Furthermore, although the purification capacity of CRAPC was slightly inferior to that of RAPC, its mechanical properties and alkalinity were improved. In addition, the purification mechanism of pervious concrete mainly includes adsorption and microorganism degradation. The total COD removal amounts of NAPC, CRAPC and RAPC were 87.00 mg/L, 104.00 mg/L and 108.00 mg/L, respectively. The adsorption amounts were 10.00, 12.50, and 16.75 mg/L, and the microorganism degradation amounts were 77.00, 91.50 and 91.25 mg/L, respectively. Compared with adsorption, microorganism degradation plays a major role in total pollutant removal. Furthermore, a water purification model for pervious concrete is proposed.