Purification of runoff pollution using porous asphalt concrete incorporating zeolite powder

Purification of urban runoff is of great significance for reducing the pollution of receiving water bodies and protecting the urban water environment. Zeolite powder is added to porous asphalt mixture in this study to improve the purification effect. The influence of zeolite powder on the road performance was evaluated to determine its optimal content. The effects of air void content, suspended solid (SS) concentration, heavy metal concentration, and rainfall intensity on the purification effect were studied and the purification durability was also analyzed. The experimental results show that the addition of zeolite powder has no obvious impact on road performance of porous concrete and can increase the removal rates of SS, chemical oxygen demand (COD), Zn2+, and Pb2+ by 6.4%, 25.2%, 20.6%, and 23.5%. The removal rates of SS, COD, Zn2+, and Pb2+ increase with the increase in SS concentration while the removal rate of heavy metals decreased with the increase in heavy metal concentration. Large air void content and rainfall intensity result in a decrease in the adsorption and purification effect. The removal rate shows a rapid decline since the sixth year, especially for SS, indicating that maintenance should be conducted at this time.