## 2 Materials and Methods
### Pilot-Scale Multifiber Media Filtration Process Units  
In this study, a pilot-scale plant of radial multiplier (RMF) filtration was performed to control CSOs and was set up in a public wastewater treatment plant in Seoul, Republic of South Korea. A schematic of the RMF filtration process was performed under conditions of 480 m\({}^{3}\)/day and a linear velocity of 20 m/h (see Figure 1) as a natural flow. The whole pilot-scale treatment process consists of 3.0 m in length, 2.3 m in width, and 2.0 m in height.  
The radial multiplier media filtration process in this study involves a raw water tank, a pretreatment process, and a filtration tank. A mesh-type multilayer screen with mesh sizes of 8 mm, 5 mm, and 2 mm from the bottom of the tank was chosen to remove large particulates or debris as a pretreatment process. Fiber media filtration equipment with seven layers in radial formation and a filtration area of 1.00 m\({}^{2}\) was designed, and the filter area increases toward the outflows of the filtration process. From the inner to the  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sampling Time**} & \multicolumn{6}{c}{**Concentration of Pollutant in CSOs in Daegu**} \\ \cline{2-7}  & **BOD5** & **CODMn** & **SS** & **T-N** & **T-P** & **Remarks** \\  & **(mg/L)** & **(mg/L)** & **(mg/L)** & **(mg/L)** & **(mg/L)** & **Remarks** \\ \hline
15:10 & 39.9 & 25.9 & 31.0 & 16.4 & 1.27 & - \\
15:40 & 79.4 & 56.3 & 62.1 & 17.2 & 1.27 & - \\
16:00 & 141.2 & 72.5 & 120.5 & 18.2 & 1.35 & Overflow \\
16:15 & 145.5 & 71.2 & 159.5 & 21.6 & 2.62 & Overflow \\
16:30 & 175.8 & 75.4 & 232.5 & 19.5 & 2.11 & Overflow \\
16:45 & 206.4 & 86.4 & 330.4 & 23.5 & 3.11 & Overflow \\
17:00 & 210.7 & 85.1 & 305.4 & 22.3 & 3.05 & Overflow \\
17:15 & 161.2 & 59.4 & 290.2 & 18.8 & 1.66 & Overflow \\
17:30 & 168.5 & 60.2 & 160.4 & 16.9 & 1.61 & Overflow \\
18:00 & 60.9 & 43.1 & 85.2 & 15.2 & 1.24 & Overflow \\
18:30 & 51.2 & 45.2 & 49.5 & 13.4 & 1.23 & Overflow \\
19:00 & 45.0 & 34.2 & 45.5 & 13.5 & 1.23 & Overflow \\ \hline \hline \end{tabular}
\end{table}
Table 1: Water quality of CSOs in Daegu overflows.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Weather Condition**} & \multicolumn{6}{c}{**Public Sewer Treatment Facility in Testbed**} \\ \cline{2-7}  & **BOD5** & **TOC** & **SS** & **T-N** & **T-P** & **Remarks** \\  & **(mg/L)** & **(mg/L)** & **(mg/L)** & **(mg/L)** & **(mg/L)** & **-** \\ \hline Dry & Minimum & 74.0 & 51.1 & 42.0 & 27.6 & 2.78 & - \\ Weather & Average & 115.7 & 59.6 & 84.4 & 30.7 & 3.05 & - \\ Maximum & 156.6 & 68.1 & 126.0 & 37.8 & 3.73 & - \\ \hline Rainy & Minimum & 180.0 & 50.4 & 76.0 & 35.7 & 3.38 & - \\ Weather & Average & 224.7 & 60.9 & 130.6 & 38.0 & 3.63 & - \\ Maximum & 279.5 & 66.0 & 174.0 & 40.1 & 3.85 & - \\ \hline \hline \end{tabular}
\end{table}
Table 2: Water quality of raw wastewater associated with different weather conditions in testbed.  
outer of the fiber media filter, the inner fiber media filter is densely formed to remove large pollutants, and the outer fiber media filter treats fine residual pollutants. The RMF was to test for removal of SS, TOC, and BOD in different weather conditions.