## 4 Conclusions  
In this study, a radial-type fiber media filtration process was developed to control CSO treatments for urban areas in different weather conditions. The physicochemical properties of the media were characterized in order to obtain an average water contact angle of 116.8\({}^{\circ}\) and a negatively charged value of \(-\)28.84 at pH 7. The removal efficiencies of SS, TOC, and BOD\({}_{5}\) in dry weather are 87.4%, 42.8%, and 48.5%, respectively, while they are 89.6% for SS, 45.3% for TOC, and 58.4% for BOD\({}_{5}\) in rainy weather. In addition, the RMF process has rejected 20 \(\upmu\)m of particulate and organic matter due to its size exclusion, large negative charge, and hydrophobicity adsorption. Due to the high concentration of organic pollutants in CSOs from urban areas, organic pollutants can be easily adsorbed onto the surface of the highly hydrophobic fiber media filter. Chemical backwashing was then applied to control the organic pollutants on the surface of the fiber media filter.  
NaClO soaking can oxidize the most particulates, colloids, and organics and overcome the problems involved in removing pollutants deposited on the surface of fiber media filters. Compared with the initial head loss of the radial-type multimedia filtration process, the optimal head loss recovery after 2000 mg/L of NaClO soaking was 96.2%. Removal efficiencies of 88.5%, 59.4%, and 42.3% were realized for TSS, TOC, and BOD\({}_{5}\), respectively. Therefore, chemical soaking with a concentration of 2000 mg/L for the NaClO solution can be selected as the optimal condition in actual CSO treatments involving fiber media filter applications. We expect that the accumulation of field data on CSO treatment using fiber media-based filtration will efficiently contribute to the development of operational guidelines for such treatment processes and their operations. Furthermore, the RMF process is a physical treatment process that comprises seven fiber media filters and easily treats insoluble matter such as SS; however, RMF hardly treats dissolved pollutants or fine pollutants such as soluble BOD and micropollutants in CSOs (e.g., pharmaceuticals  
Figure 7: Scanning electron microscopy (SEM) images of the **(a)** virgin fiber media filter and fiber media filter after **(b)** 20 h of operation, **(c)** physical backwashing, **(d)** chemical soaking with 500 mg/L of NaClO, **(e)** chemical soaking with 1000 mg/L of NaClO, and **(f)** chemical soaking with 2000 mg/L of NaClO.  
and microplastics) that need more advanced treatment technology. The process can be improved by incorporating an advanced water treatment process as a post-treatment for CSO, such as ozonation, granular activated carbon, and membrane technology. Such a development of the RMF process should be necessary for future research to protect the river bodies by satisfying the next-generation river quality standards.  
Conceptualization, H.K. ([PERSON]), I.S. and S.L.; Methodology, H.K. ([PERSON]); Software, H.K. ([PERSON]); Validation, H.K. ([PERSON]); Investigation, H.K. ([PERSON]), I.S. and D.L.; Resources, H.K. ([PERSON]) and D.L.; Data curation, H.K. ([PERSON]) and I.S.; Writing-original draft preparation, H.K. ([PERSON]); Writing-review and editing, H.K. ([PERSON]) and T.-M.H.; Visualization, H.K. ([PERSON]); Supervision, H.K. ([PERSON]) and B.H.; Project administration, H.K. ([PERSON]) All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Korea Environment Industry and Technology Institute (KEITI) through Prospective Green Technology Innovation Project, funded by the Korea Ministry of Environment (MOE) (2020003160012).  
Written informed consent has been obtained from the patient to publish this paper.  
Not Applicable.  
The authors declare no conflict of interest.