## 5 Results and Discussion
### Wastewater Treatment
#### 5.2.4 Translocation Factor of Heavy Metals
A graph of the heavy-metal concentration (mg/L) over treatment days revealed that the regression (R2) value is positive and close to R2 of 1: R2 for Al is 0.7607, and R2 for Fe is 0.8239 for _I. aquatica_, and R2 for Al is 0.8182 and R2 for Fe is 0.8862 for C. asiatica. This result indicated that the heavy-metal concentration exhibits a good relationship for reflecting the decrease in the heavy-metal concentration over the treatment day. If the regression was similar to R2 = 1, it verified the relationship between the variables and vice versa, if R2 \(<\) 1. In addition, the TF of roots to stems was calculated to determine the location of heavy metal accumulation as an alternative for the accumulation of heavy metals from roots to leaves. Table 3 summarizes the TF of aluminum and iron, reflecting the ability of _I. aquatica_ to extract heavy metals from roots to stems. The results indicated that TF \(<\) 1 for _I. aquatica_, indicating that most of the heavy metals are still accumulated in the roots. For Al accumulation, the highest TF was observed on the second day of treatment, which was 1.89, while the lowest TF was observed on the final day, which was 0.10. For Fe accumulation, the highest TF was observed on the second day of treatment, which was 0.73, and the lowest TF was observed on the eighth day, which was 0.01. Table 3 also shows the TF of aluminum and iron, reflecting the ability of _C. asiatica_ to extract heavy metals from roots to stems. Results indicated that TF \(>\) 1 for Al accumulation, and the highest TF is observed on the sixth day of treatment, which is 133. The lowest TF was obtained on the final day, which was 0.31. For Fe accumulation, TF \(<\) 1, and it is negative, indicating that most of the heavy metals are not accumulated in the roots due to the amount of heavy metals in the roots was negative. Results obtained for the TF of heavy metals via their accumulation in leaves and stems by _I. aquatica_ revealed that a significant TF variation is observed for the stem section compared to the leaf section. For Al accumulation, _I. aquatica_ exhibited significant TF of heavy metals from roots to leaves (R/L) and from roots to stems (R/S), while for _C. asiatica_, a significant value was obtained for the amount of Fe in leaves and stems. No significant value for Al accumulation was observed, even though TF for stems (TF = 132) and leaves (TF = 54) was different. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multicolumn{8}{c}{**Translocation Factor/Day (TF)**} \\ \hline  & \multicolumn{6}{c}{_Ipomoea aquatica_} \\ \hline Day & 2 & 4 & 6 & 8 & 10 & MIN \\ Aluminum & 1.07 & 1.89 & 0.23 & 0.27 & 0.10 & 0.71 \\ Iron & 0.73 & 0.18 & 0.07 & \(-\)0.01 & \(-\)0.23 & 0.15 \\ \hline \multicolumn{8}{c}{_Centella asiatica_} \\ \hline Day & 2 & 4 & 6 & 8 & 10 & MIN \\ Aluminum & 1.78 & 6.48 & 133.20 & (0.36) & (0.31) & 28.16 \\ Iron & (1.25) & (1.46) & (0.12) & (0.13) & (0.37) & (0.67) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Translocation factor for _Ipomoea aquatica_ and _Centella asiatica_ from root to stem (R/S).