Laboratory Study on Stormwater Runoff Treatment via Sand-Based Micron-scale Pore Pervious Paver

摘要

Stormwater runoff samples from a road in China were collected and analyzed for pH,TSS(total suspended solid),TDS(total dissolved solid),COD(chemical oxygen demand),TP(total phosphorus),TN(total nitrogen),Pb,Al,Zn,Fe,Cd,and Mn.Results showed that the pollutant concentrations from road runoff were relatively high.TSS and COD concentrations exceeded the Class B effluent requirement of the Chinese Standards of Pollutant Discharge from municipal WWTPs(wastewater treatment plants).COD,TP,and TN concentrations exceeded Class V of the Chinese Environmental Quality Standard for Surface Water.TSS,Zn,Fe,and Al concentrations exceeded the USEPA(U.S.Environmental Protection Agency)benchmark values.All these indicated proper runoff treatment to avoid negative impacts on the environment is needed.Metal partitioning analysis was conducted and it showed that Pb,Al,Zn,Fe,and Mn exist mostly in particulate forms in the runoff.Thus,gravitational settlement and filtration can still be cost-effective methods for removing most of these metals.Runoff samples were treated through two bench-scale laboratory set-ups,composed of micron-scale pore pervious paver systems and subsoil.The average removal rates of TSS,TP,and TN were 95.2%,81.8%,64.1%,and 64.4%,respectively.The removal rates of Pb,Al,Zn,Fe,and Cd also reached 50%-99.2%.The tested sand-based pervious paver has micron-scale pores with good filtration potential.The system can effectively reduce stormwater runoff pollution,thereby reducing the potential for groundwater pollution.In addition,residues and sediments collected from the surfaces of the pervious pavers were also tested.The metallic constituents in the residues and sediments were correlated to these in the runoff.Pb and Cr were low in the residues,but Zn exceeded the Class A limit of the Chinese Control Standard of Pollutants in Sludge for Agricultural Applications.Thus,proper disposal of the solid wastes generated from the pavers is also to be further investigated.