## 4 Conclusions  
In conclusion, the use of microalgal systems as a polishing treatment for UWW seems to be successful. This study demonstrated that the growth of both C. _vulgaris_ and AMS in UWW promotes the removal of conventional pollutants such as PO\({}_{4}\)-P and the reduction of _E. coli_ and other coliforms' abundance. However, when comparing specific parameters of both microalgal systems, the use of AMS seems to be more promising due to the high (i) growth rate (\(\mu_{\rm max}\) of 0.687 \(\pm\) 0.065 d\({}^{-1}\)), and biomass productivity (9.0 \(\pm\) 0.3) \(\times\) 10\({}^{4}\), (ii) removal rate of PO\({}_{4}\)-P (c.a. 92%), (iii) reduction of _int1_ (0.5 log) and _bla_TEM (0.6 log) genes' abundance after 9 d, and (iv) reduction of _int1_ (1 log), _su1_ (0.5 log), and _bla_TEM (2.5 log) genes' abundance and their prevalence in treated water stored for 5 d. For future work, it should be interesting to identify the microalgal and bacterial species in the AMS system. Moreover, monitoring the AMS species and wastewater composition, namely in terms of nitrogen and phosphorus, would be helpful in understanding the dynamics of this system. As discussed throughout the present work, abiotic factors such as light intensity have a main role in both microalgal growth and the reduction of pathogens' proliferation, namely in conjugation with pH. Hence, studies considering the light intensity and pH ranges would be helpful in optimizing the potential of AMS. Moreover, due to the scarcity of information related to the microalgal mechanisms involved in ARGs reduction of abundance and prevalence in real wastewater, future studies should focus on these events. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13074266/s1](https://www.mdpi.com/article/10.3390/app13074266/s1)]([https://www.mdpi.com/article/10.3390/app13074266/s1](https://www.mdpi.com/article/10.3390/app13074266/s1)), Figure S1. Pearson correlation of all analyzed variables obtained for each PBRs: (A) CV (_Chlorella vulgaris_ + UWW); (B) positive control, C+ positive control (_C. vulgaris_ + autoclaved UWW); and (C) negative control, C\(-\) (raw UWW). Variables: pH; HA: humic acid concentration; COD: chemical oxygen demand concentration; MCC: microalgal cell concentration; PO\({}_{4}\)-P: Phosphate-phosphorus concentration; OFC: other faecal coliforms except _Escherichia. coli_ concentration; Ec: _E. coli_ concentration; TH: Total heterotrophs concentration. White squares correspond to non-determined values. Conceptualization, H.M.A., J.C.M.P. and O.C.N. ; methodology, H.M.A. and O.C.N. ; investigation: H.M.A., J.F.S. and E.M.S. ; resources, J.C.M.P. and O.C.N. ; data curation, H.M.A., J.F.S. and E.M.S. ; writing--original draft preparation, H.M.A. and J.F.S. ; writing--review and editing, J.C.M.P., O.C.N. and E.M.S. ; supervision, J.C.M.P. and O.C.N. ; project administration, J.C.M.P. and O.C.N. ; funding acquisition, J.C.M.P. and O.C.N. All authors have read and agreed to the published version of the manuscript. Figure 9: Abundance of the \(\blacksquare\)16S rRNA, \(\blacksquare\)_int1_and the antibiotic resistance genes \(\blacksquare\)_su1_ and \(\blacksquare\)_bla_TEM (**A**) and their relative abundance (prevalence) (**B**) in the C\(-\) (raw UWW) PBR over time and after 5 d of water storage (ST5d). Results (average \(\pm\) standard deviation) of abundance are expressed in gene log (gene copy number 100 mL\({}^{-1}\)) and genes’ relative abundance is normalized according to 165 rRNA. Bars of the same gene with the same letter are not statistically different (two-way ANOVA followed by Tukey post hoc test \(p\) < 0.05). **Funding:** This work was financially supported by: (i) LA/P/0045/2020 (ALiCE) and UIDB/00511/2020- UIDP/00511/2020 (LEPABE) funded by national funds through FCT/MCTES (PIDDAC); (ii) Project PhotoBioValue (ref.