**5. Conclusions**

This study has shown that a pilot-scale system consisting of open lagoons (with or without aeration) and a constructed wetland with *Typha latifolia* L. treating raw swine wastewater has removed about 99% of the total suspended solids and COD, and from 80% to 95% of the total nitrogen in the effluent at both tested recirculation rates (4:1 and 10:1). Both the pH and the electrical conductivity (the indirect measure of wastewater salinity) were noticeably modified by the combined system, and reductions in the electrical conductivity (85–90%) were detected. The lagoon system alone showed low to moderate depuration performances ( −40% of TSS, −2% of COD, and −31% of TKN removed), but represented an effective pre-treatment of CW, particularly for the nitrogen removal.

This experience has also demonstrated the suitability to increase the effluent recirculation ratio up to a value of 10:1, when high nitrogen removal rates are expected, since the higher RR allowed the removal of about 20% more of nitrogen compounds compared to an RR of 4:1. In contrast, the organic matter removal was not affected by an increased RR, given the very high depuration efficiency detected at the lower RR.

The irrigation of the CWs with SW did not generally determine the phyto-toxic effects on *Typha latifolia* L., except at the start of the experiment and under the lower effluent recirculation ratio, when a peak in the soil nitrogen killed about 25% of plants.

Although this study was carried out on pilot plants and throughout a short monitoring period (two years), the relevant results provide a starting point for the use of V-SSF CWs as a depuration solution in highly polluting livestock wastewater (such as, SW). An upscale of this preliminary investigation is suggested to verify the depuration performance of the system by real-scale experiments. A more detailed analysis of the physico-chemical and microbiological processes acting in the CW system may help to identify the most effective mechanisms for removing the polluting compounds of SW. Moreover, the incidence of each process that determines a mass loss (e.g., volatilization, denitrification, nitrogen plant uptake, and hydraulic losses) on water, soil, and plants of each sub-component of the experimental system should be quantified adopting a mass balance approach in future research.

**Author Contributions:** Conceptualization, G.B., D.A.Z. and S.M.Z.; methodology, N.B., G.B., P.D., A.F. and D.A.Z.; validation, G.B., D.A.Z. and S.M.Z.; formal analysis, G.B., P.D., A.F., D.A.Z. and S.M.Z.; data curation, N.B., G.B., P.D., A.F. and D.A.Z.; writing—original draft preparation, P.D. and D.A.Z.; writing—review and editing, G.B., P.D., D.A.Z. and S.M.Z.; supervision, G.B., D.A.Z. and S.M.Z.; project administration, S.M.Z.; funding acquisition, S.M.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Project "PRIN—Programmi di Ricerca di Interesse Nazionale" (2015), by the Italian Ministry of Education, University and Research (M.I.U.R., Principal Investigator Attilio Toscano).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** We cordially thank the "Società Agricola Biondo dei F.lli Biondo & C." firm (Cardeto, Reggio Calabria, Italy) for hosting the experimental device and providing the manpower for its management.

**Conflicts of Interest:** The authors declare no conflict of interest.
