## 3 Results and Discussion
### Taguchi Analysis
#### 3.2.1 Analysis of Variance (ANOVA) for SN Ratios  
The ANOVA for the treatments SN ratios were studied to evaluate the significant influence of design parameters on quality characteristics of the treatment [35]. ANOVA estimates the total variability of the SN ratios, by calculating the sum of the squared deviations of the total mean SN ratio. The % contribution of each design parameter is the ratio of the sum of squared deviation of the individual parameter to the total sum of squared deviation given in (21).  
Tables 7 and 8 present the ANOVA model summary and analysis of SN ratios obtained for each treatment. The model summary comprised of the S and R\({}^{2}\) value. The lower the S value and the higher the  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**FeSO\({}_{4}\)**} & \multicolumn{4}{c}{**Fe(0)**} \\ \hline \multirow{2}{*}{**Level**} & **Reaction** & \multirow{2}{*}{**MPs**} & \multirow{2}{*}{\(\mathbf{H_{2}O_{2}\text{:}FeSO_{4}}\) **(Fe(II))**} & **Initial** & **Reaction** & \multirow{2}{*}{**MPs**} & \multirow{2}{*}{**H\({}_{2}\)O\({}_{2}\):Fe(0)**} & **Initial** \\  & & & **(Fe(II))** & & & **pH** & & **Time** & & **pH** \\ \hline
1 & 4.68 & 7.46 & 5.62 & 5.78 & 2.62 & 2.13 & 2.81 & 6.96 \\
2 & 3.00 & 3.76 & 4.70 & 2.48 & 2.08 & 2.83 & 3.09 & \(-\)0.77 \\
3 & 3.31 & 2.15 & 3.02 & - & 3.28 & 3.77 & 4.19 & - \\
4 & 5.52 & 3.14 & 3.17 & - & 4.39 & 3.65 & 2.28 & - \\ \hline Delta & 2.52 & 5.31 & 2.59 & 3.30 & 2.31 & 1.64 & 1.91 & 7.73 \\ \hline Rank & 4 & 1 & 3 & 2 & 2 & 4 & 3 & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Response for the mean SN ratio; condition: Smaller is better.  
Figure 3: Main effect plot for the signal-to-noise ratio for FeSO\({}_{4}\) treatment (top) and Fe(0) treatment (bottom). Units: Reaction time (min); DOC (mg/L); H\({}_{2}\)O\({}_{2}\):FeSO\({}_{4}\), H\({}_{2}\)O\({}_{2}\):Fe(0) (molar ratio).  
\(\text{R}^{2}\), the more reliable the model is considered to interpret the information. The FeSO\({}_{4}\) treatment design parameters influence on determining the significant effect on overall response can be considered at 66.4% \(\pm\) 3.8 reliability. The Fe(0) model developed was more significantly reliable giving 98.8% \(\pm\) 0.8 regression.  
The ANOVA analysis of % contribution is in line with the delta statistics obtained from the mean SN ratio response. As said earlier, Fe treatment outcomes are hugely affected by initial pH and 88.9% of the response can be altered with an initial pH difference. Even though other control factors had around 3-4 % contribution but, _F_-value \(>\)4 provides evidence of their significant contributions. Since the FeSO\({}_{4}\) treatment was around 66% reliable, a low _F_-value was not considered in interpreting the relative significant contribution for each factor. Though, like delta statistics, the initial DOC had a maximum contribution in determining the quality of the treatment process (FeSO\({}_{4}\)). Likewise, the initial pH also had around 20% contributions in determining treatment efficiency. The results were further studied for Pearson's correlation to attain a significant result.  
\(\%\) Contribution = (SS\({}_{\text{f}}\)/SS\({}_{\text{T}}\)) \(\times\) 100