Search Results (3)

This study proposes the technology of “runoff storage and seepage utilization” for achieving purification of road rainfall–runoff and presents a multi-level series purification system (PBT-GR) comprising porous asphalt pavement (PAP), a bioretention system (BS), a storage tank (T) and a hydroponic green roof (GR). The operation parameters of each component unit were optimized and the contribution of each unit to pollution was analyzed. The results showed that under typical simulated rainfall, the suspended solids (SS), total nitrogen (TN), total phosphorus (TP), Pb, Zn and Cu removal rates by filtration and interception of porous pavement were 62.26 ± 3.19%, 16.29 ± 1.74%, 29.27 ± 1.37%, 37.61 ± 2.58%, 35.57 ± 4.64% and 31.17 ± 3.27%, respectively. The average concentrations of SS, TN, TP, Pb, Zn and Cu in the effluent of the PBT-GR system were 14.70 ± 2.21 mg/L, 1.52 ± 0.24 mg/L, 0.14 ± 0.04 mg/L, 0.09 ± 0.04 mg/L, 0.11 ± 0.03 mg/L and 0.04 ± 0.01mg/L, respectively, which met the water quality standards recommended in the Chinese guidelines and showed a high adaptability to pollution load. The contents of pesticide residues and heavy metals in cultivated vegetables met the national standards. The period required to recoup the investment in the system was approximately 3 years, indicating its good economic feasibility. The present study can provide a valuable reference of the construction of an efficient, low consumption and sustainable urban stormwater treatment system and can contribute to the improvement in the quality of the urban water environment. Full article

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. Full article

Porous asphalt pavement (PAP) with a high drainage capacity was modified with powdered activated carbon (PAC) addition to produce permeable reactive pavement (PRP), which may exhibit the potential to reduce environmental non-point source (NPS) pollution. The experimental design mixtures used to produce and test the PRP incorporated with PAC (named PRP-PACs) were conducted as follows: first, the PACs were initially tested to determine their feasibility as an additive in PAP; second, different amounts of PAC were added during the preparation of PAP to produce PRP-PAC, and the unregulated and regulated physical characteristics for the mechanical performance of PRP-PACs were examined to ensure that they meet the regulatory specifications. Third, the aqueous contaminants, namely benzene, toluene, ethyl-benzene, and xylene (BTEX), column adsorption tests were preliminarily conducted to demonstrate their adsorption capacities compared to traditional PAP. The compositions of 0.8% and 1.5% PAC (by wt.) (PRP-PAC08 and PRP-PAC15) met all the regulated specifications. As compared to PAP, PRP-PAC08 exhibited higher BTEX adsorption capacities than PAP, which were 47%, 49%, 29% and 2%. PRP-PAC08 showed both superior physical properties and adsorption performance than PAP and may be recommended as an engineering application that reduces the potential for NPS contamination of air, soil, groundwater, and surface water. Full article