# Photo-Transformation of Effluent Organic Matter by ZnO-Based Sunlight Irradiation
## 3 Results and Discussion
### DOC and Optical Parameters
#### 3.1.2 Photocatalytic Degradation of DOM, EfOM, and EfOM-Impacted  
The organic matter in the water samples was subjected to lab-scale photocatalysis experiments under simulated solar irradiation using ZnO as a photocatalyst. After 120 min of irradiation, photocatalysis led to a significant decrease in the fluorescence intensity and significant changes in the shape of the EEM contour plots (Figure 1). The broad, strong peaks at emission wavelengths above \(\sim\)350 nm, commonly referred to as humic-like peaks, were significantly lower. The UV/Vis absorbance show that the wastewater contains a greater amount of organic substances absorbing UV-B and UV-C range than the upstream sample, and those substances rapidly decreased with reaction time; \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameters** & **Sources of Variation** &
\begin{tabular}{c} **Sum of** \\ **Squares** \\ \end{tabular} & **Degree of Freedom** & **Mean Square** & **F** & **Significance** \\ \hline \multirow{3}{*}{DOC} & Between Groups & 7.069 & 4 & 1.767 & 992.871 & 0.000 \\  & Within Groups & 0.018 & 10 & 0.002 & & \\  & Total & 7.087 & 14 & & & \\ \hline \multirow{3}{*}{UV\({}_{254}\)} & Between Groups & 0.002 & 4 & 0.000 & 612.306 & 0.000 \\  & Within Groups & 0.000 & 10 & 0.000 & & \\  & Total & 0.002 & 14 & & & \\ \hline \multirow{3}{*}{SUVA\({}_{254}\)} & Between Groups & 0.017 & 4 & 0.004 & 26.324 & 0.000 \\  & Within Groups & 0.002 & 10 & 0.000 & & \\  & Total & 0.018 & 14 & & & \\ \hline \multirow{3}{*}{\(\epsilon_{250}\)} & Between Groups & 13.254 & 4 & 3.313 & 5.664 & 0.012 \\  & Within Groups & 5.850 & 10 & 0.585 & & \\  & Total & 19.104 & 14 & & & \\ \hline \multirow{3}{*}{S\({}_{275-259}\)} & Between Groups & 0.000 & 4 & 0.000 & 11.866 & 0.001 \\  & Within Groups & 0.000 & 10 & 0.000 & & \\  & Total & 0.000 & 14 & & & \\ \hline \multirow{3}{*}{S\({}_{350-400}\)} & Between Groups & 0.000 & 4 & 0.000 & 1.840 & 0.198 \\  & Within Groups & 0.000 & 10 & 0.000 & & \\  & Total & 0.000 & 14 & & & \\ \hline \multirow{3}{*}{S\({}_{\text{g}}\)} & Between Groups & 0.248 & 4 & 0.062 & 16.305 & 0.000 \\  & Within Groups & 0.038 & 10 & 0.004 & & \\  & Total & 0.286 & 14 & & & \\ \hline \multirow{3}{*}{E2/E3} & Between Groups & 2.980 & 4 & 0.745 & 1.266 & 0.346 \\  & Within Groups & 5.886 & 10 & 0.589 & & \\  & Total & 8.865 & 14 & & & \\ \hline \multirow{3}{*}{FI} & Between Groups & 0.303 & 4 & 0.076 & 47.810 & 0.000 \\  & Within Groups & 0.016 & 10 & 0.002 & & \\  & Total & 0.318 & 14 & & & \\ \hline \multirow{3}{*}{HIX} & Between Groups & 0.524 & 4 & 0.131 & 313.496 & 0.000 \\  & Within Groups & 0.004 & 10 & 0.000 & & \\  & Total & 0.528 & 14 & & & \\ \hline \multirow{3}{*}{BIX} & Between Groups & 0.011 & 4 & 0.003 & 10.298 & 0.001 \\  & Within Groups & 0.003 & 10 & 0.000 & & \\  & Total & 0.013 & 14 & & & \\ \hline \multirow{3}{*}{C\({}_{1}\)\({}_{\text{Fmax}}\)} & Between Groups & 0.638 & 4 & 0.159 & 174.686 & 0.000 \\  & Within Groups & 0.009 & 10 & 0.001 & & \\ \cline{1-1}  & Total & 0.647 & 14 & & & \\ \hline \multirow{3}{*}{C\({}_{2}\)\({}_{\text{Fmax}}\)} & Between Groups & 0.850 & 4 & 0.212 & 186.690 & 0.000 \\ \cline{1-1}  & Within Groups & 0.011 & 10 & 0.001 & & \\ \cline{1-1}  & Total & 0.861 & 14 & & & \\ \hline \multirow{3}{*}{C\({}_{3}\)\({}_{\text{Fmax}}\)} & Between Groups & 0.096 & 4 & 0.024 & 263.678 & 0.000 \\ \cline{1-1}  & Within Groups & 0.001 & 10 & 0.000 & & \\ \cline{1-1}  & Total & 0.097 & 14 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The results of one-way ANOVA for characteristic parameters of organic matters by varying the mixing ratios. however, after 120 min of irradiation, absorption was still observed, which suggested that complete mineralization could not be achieved under these experimental conditions (Figure S3).