## 4 Conclusions  
In this work, NaOH-activated with LaCl\({}_{3}\)-impregnated synthetic modified zeolite porous microspheres (MZP-PM) were designed, aiming at increasing N and P retention efficiency by exchanging with sodium for NH\({}_{4}\)+-N and surface complexion for TP. Two laboratory-scale PAP systems were developed by comparing limestone bedding and zeolite incorporated into MZP-PM as a filter column under a typical rainfall. The following conclusions were made by the experimental results.  
(1) Batch adsorption data from solutions of nutrients mixtures onto the two PAP system bedding layers and the MZP-PM fitted the Langmuir model with adsorption capacities in the following order: MZP-PM > zeolite > limestone for NH\({}_{4}\)+-N and MZP-PM > limestone > zeolite for TP.  
(2) Augmentation of ammonium and phosphate elimination from stormwater runoff was effectively achieved in the PAP system with an MZP-PM column of adsorbent as a post-treatment. During the rainfall events, the study demonstrated by the zeolite or limestone-based PAP system didn't remove NH\({}_{4}\)+-N and TP in stormwater that passed through this system completely and the concentrations of nutrients in effluent couldn't meet the standard quality of surface water. While a post-treatment with a filter column containing MZP-PM (<5% of zeolite weight) was added to the zeolite-based PAP system, 72.9-92.6% of the nutrients were eliminated. The combined treatment was satisfactory and effluent met the standards criteria of surface water.  
(3) Speciation pathway and XPS, FTIR analysis established that ammonium removal was mainly ascribed to exchanging with sodium in the adsorbent, and phosphate adsorption.  
Figure 9: XPS analysis of MZP-PM before or after adsorption. (**a**) XPS survey scan of MZP-PM before and after adsorption; (**b**) La 3d5/2 spectra and (**c**) Na 1s spectra before and after adsorption.  
tion mainly followed the surface complexion mechanism, the surface hydroxyl groups played the key role.  
Conceptualization, H.L. and Z.J.; methodology, H.L.; software, B.H.; validation, W.Z.; formal analysis, W.Z.; investigation, H.L.; resources, Z.J.; data curation, W.Z.; writing--original draft preparation, H.L.; writing--review and editing, Z.J.; visualization, B.H. and W.Z.; supervision, Z.J.; project administration, Z.J.; funding acquisition, Z.J. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Science and Technology Support Program (2015 BAL02B04); the Technology Project of China Housing and Urban Rural Development Ministry (2015-K7-012); a Project Funded by the National First-class Disciplines (PNFD), and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).  
Not applicable.  
The datasets used during the current study are available from the corresponding author on reasonable request.  
The authors would like to thank [PERSON] and [PERSON] for their assistance in the laboratory experiment.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.