## 4 Conclusions  
This study contributes to addressing the new EU directives on nutrient recovery and water preparation for reuse (Directive (EU) 2024/3019), with the added value of using real wastewater, an aspect often overlooked in many studies. The dual-P recovery system was validated, and it was concluded that the effectiveness of this low-cost adsorbent was significantly enhanced when applied to the treated stream following chemical precipitation.  
The lab-scale experimental design showed, with 95% confidence, that both the operating parameters, bed height, and flow rate significantly affect the fraction of saturated bed and adsorption time. The optimal conditions for maximizing _FSB_ and minimizing \(\Delta t_{\text{ads}}\) were found to be \(h\) = 30 cm and \(Q\) = 5 mL/min. Tests with different initial P concentrations (1, 10, and 40 mg P/L) showed that adsorption with CES700 is not feasible for streams with concentrations above 10 mg P/L, such as those after centrifugation, confirming previous batch study results [14]. Approximately 86% of the bed remained unused at 40 mg P/L. Unlike the findings from batch experiments [14], the presence of SO\({}_{4}\)\({}^{2-}\) ions in the effluent did not affect P removal under dynamic conditions with a bed height of 30 cm and a flow rate of 5 mL/min.  
The scale-up experiments demonstrated the strong performance of the adsorbent, with the _FSB_ increasing from 0.425 to 0.764 and the adsorption capacity improving from 70.9 to 84.1 mg P/kg under optimal lab-scale conditions. The unused fraction of the bed was reduced to only 40% of its height after scaling up. Additionally, the process consistently maintained effluent P concentrations below 0.5 and 0.7 mg P/L, thus meeting the discharge limits set by the Urban Wastewater Treatment Directive--Directive (EU) 2024/3019 for over 400 min of continuous operation.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15126761/s1](https://www.mdpi.com/article/10.3390/app15126761/s1)]([https://www.mdpi.com/article/10.3390/app15126761/s1](https://www.mdpi.com/article/10.3390/app15126761/s1)), Figure S1: Bohart-Adams, Thomas, and Yoon-Nelson fitting for the design of experiments developed; Table S1: Characterization of wastewater sample and methods used; Table S2: Parameters of the models compared to the logistic equation parameters.  
Conceptualization, A.F.S., L.M.G.-F. and M.J.Q.; methodology, A.F.S., L.M.G.-F. and M.J.Q.; investigation, A.F.S.; writing--original draft preparation, A.F.S.; writing--review and editing, P.A., L.M.G.-F. and M.J.Q.; supervision, P.A., L.M.G.-F. and M.J.Q. All authors have read and agreed to the published version of this manuscript.  
[PERSON] acknowledges the Fundacao para a Ciencia e Tecnologia (FCT) for the Ph.D. Grant (2020.08213.BD). [PERSON], [PERSON], and [PERSON] the financial support to CERES ([[https://doi.org/10.54499/UIDB/00102/2020](https://doi.org/10.54499/UIDB/00102/2020)]([https://doi.org/10.54499/UIDB/00102/2020](https://doi.org/10.54499/UIDB/00102/2020)) and [[https://doi.org/10.54499/UIDP/00102/2020](https://doi.org/10.54499/UIDP/00102/2020)]([https://doi.org/10.54499/UIDP/00102/2020](https://doi.org/10.54499/UIDP/00102/2020))), financed by FCT through national funds. [PERSON] acknowledges the support of LEAF--Linking Landscape, Environment, Agriculture and Food Research Centre (Ref. UIDB/04129/2020 and UIDP/04129/2020) and the Associate Laboratory TERRA).  
Not applicable.  
The original contributions presented in this study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author(s).  
The authors declare no conflicts of interest.