**4. Conclusions**

The FTWs augmented with bacteria is proven efficient among all the phytoremediation techniques. Hydrocarbons degrading bacterial strains and the *Cyperus laevigatus* L plant improved the diesel oil remediation in FTWs. This study investigates and justifies a way to remediate the diesel oil pollution in water. *Cyperus laevigatus* L plant can be the appropriate choice in FTWs for phytoremediation of diesel oil contaminated water. The performance and effectiveness of the developed FTWs were proven by successful reduction in hydrocarbons, COD, BOD, and TOC of diesel oil contaminated water. Though the experiment was completed in FTWs consisting of a microcosm set up, it displayed an effective bacterial association together with wetland plants. The study highlights a very supportable application of FTWs for conceivable removal of hydrocarbons from contaminated wastewater. This study further offers the prospects of evaluating the effectiveness of FTWs and is a promising option in the wastewater treatment at pilot and field scale levels. Furthermore, FTWs technology involves natural ways of treating wastewater and minimum energy is required for its operational cost. Application of this FTWs technology in developing countries like Pakistan is more feasible and cost effective in contrast to expensive technologies used for wastewater treatment worldwide.

**Author Contributions:** Conceptualization, M.F., S.A., S.R.A., M.A. (Muhammad Afzal), M.A. (Muhammad Arslan), E.F.A.A., M.N.A. and P.A.; Data curation, M.F., G.S. and M.A. (Muhammad Afzal); Formal analysis, M.F., G.S., S.R.A., T.Y., A.H. (Afzal Hussain) and M.A. (Muhammad Afzal); Funding acquisition, M.A. (Muhammad Afzal), A.H. (Abeer Hashem), E.F.A.A. and P.A.; Investigation, S.A., S.R.A., M.A. (Muhammad Arslan), M.N.A. and P.A.; Methodology, M.F., T.Y., A.H. (Abeer Hashem), A.H. (Afzal Hussain) and P.A.; Project administration, S.A., T.Y. and E.F.A.A.; Resources, M.A. (Muhammad Afzal), M.A. (Muhammad Arslan), A.H.(Abeer Hashem), E.F.A.A., M.N.A. and P.A.; Software, G.S. and A.H. (Afzal Hussain); Supervision, S.A., T.Y. and M.A. (Muhammad Afzal); Validation, G.S.; Visualization, M.N.A.; Writing—original draft, M.F.; Writing—review & editing, S.A., S.R.A., M.A. (Muhammad Afzal) and M.A. (Muhammad Arslan). All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Higher Education Commission, Pakistan (grant number 20-3854/R&D/HEC/14). The authors would like to extend their sincere appreciation to the Researchers Supporting Project Number (RSP-2019/116), King Saud University, Riyadh, Saudi Arabia.

**Acknowledgments:** This research was supported by the Higher Education Commission, Pakistan (grant number 20-3854/R&D/HEC/14). The authors would like to extend their sincere appreciation to the Researchers Supporting Project Number (RSP-2019/116), King Saud University, Riyadh, Saudi Arabia.

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