## 4 Conclusions and Future Perspectives  
Recently undertaken studies [40, 43, 44, 45] have demonstrated that PFCs, particularly PFOA and PFOS, are susceptible to degradation by certain microbial species. The metabolism mechanism of PFOA and PFOS follows a peculiar path relative to the degradation of fluorotelomer alcohols and organohalogens. The available literature [40, 43, 44, 45] suggests that certain microbial species (i.e., _Acidimicrobium_ sp. strain A6, _Pseudomonas parafulva_ strain YAB1, _Pseudomonas picoglossicidia_ 2.4-D, and _Pseudomonas aeruginosa_ strain HJ4), which can develop antiporters to protect themselves from the toxic fluoride ions, can biodegrade PFOA and PFOS. Despite the novel developments on PFOA and PFOS degradation by microbial species, further investigation needs to be carried out aimed at optimising PFOA and PFOS microbial degradation. Based on the reported literature, it is apparent that certain bacteria can use PFOA and PFOS as carbon sources; however, high concentrations of the aforementioned compounds can hinder the microbial growth rate, thus compromising the treatment efficiency. Such observations warrant further investigation aimed at optimizing the microbial growth rate under high PFOA and PFOS concentration levels. Moreover, further investigation needs to be performed on the co-substrate dose for different microbial species in enhancing microbial growth rate. The available literature suggests that there is lack of cellular benefits from PFC biodegradation; hence, microbial species require a co-substrate to facilitate their growth for effective PFC removal.  
Moreover, the current study has demonstrated that it is apparent that phytoremediation of PFOA and PFOS is one of the promising sustainable green technologies which can be utilized in eradicating PFCs in water bodies. Further investigation needs to be conducted on the biotransformation of PFOA and PFOS in plant tissues. Currently, there is very little information reported on the degradation of PFOA and PFOS in plant tissues. In conclusion, the reported PFOA and PFOS removal by microbial species and phytoremediation is associated with a high retention time, which makes it difficult for PFOA and PFOS remediation in receiving water bodies. Genetically engineered microbes need to be considered in order to eradicate the occurrence of PFCs in water bodies.  
Conceptualization, S.M.K., B.F.B. and S.R.; investigation, S.M.K.; resources, B.F.B. and S.R.; writing--original draft preparation, S.M.K.; writing--review and editing, S.M.K., B.F.B. and S.R.; supervision, B.F.B. and S.R.; project administration, B.F.B. and S.R.; funding acquisition, B.F.B. and S.R. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the South African National Research Foundation under the Research Development for Y-Rated Researchers, grant number 137765.  
Not applicable.  
The authors wish to express their appreciation to the Green Engineering Research Group at the Durban University of Technology and the Environmental Pollution and Remediation Research Group at the Mangosouthu University of Technology for proving all necessary resources to make this study a success. [PERSON]'s work is supported by the Durban University of Technology scholarship scheme.  
The authors declare no conflict of interest.