Removal of Nitrogen and Phosphorus in Synthetic Stormwater Runoff by a Porous Asphalt Pavement System with Modified Zeolite Powder Porous Microsphere as a Filter Column

Abstract

Porous asphalt pavement (PAP) system is a widely used treatment measure in sustainable stormwater management and groundwater recharge, but their variable performance in nitrogen (N) and phosphorus (P) removal requires further reinforcement prior to widespread uptake. Two laboratory-scale PAP systems were developed by comparing limestone bedding and zeolite incorporated into modified zeolite powder porous microsphere (MZP-PM) as a filter column under a typical rainfall. The PAP system of zeolite bedding incorporated into MZP-PM (a weight less than 5% of zeolite) removed 74.5% to 90.6% of ammonium (NH4+-N) and 72.9% to 92.4% of total phosphate (TP) from the influent, as compared with 25.7% to 62.7% of NH4+-N and 32.6% to 56.4% of TP by that of the limestone as bed material. This improvement was presumably due to MZP-PM’s high adsorption capacity and surface complexation. The formation of ≡(La)(OH)PO2 was verified to be the dominant pathway for selective phosphate adsorption by MZP-PM and ion-exchange was proved to be the main removal process for ammonium. This study provides promising results for improving N and P removal by modifying a porous asphalt pavement system to include an MZP-PM adsorbent column as a post-treatment.

Keywords

• nutrients removal
• porous asphalt pavement system
• modified zeolite powder porous microspheres
• ion exchange
• Nemerow pollution index