## 5 Results and Discussion
### Wastewater Treatment
#### 5.2.3 Amount of Heavy Metals in Leaves, Stems, and Roots  
Figure 4 presents the amount of heavy metals according to the treatment period for the leaf, stem, and root sections. The average Al content accumulated by _I. aquatica_ was \(\sim\)1054 mg/kg per day, while the average Fe content was 972 mg/kg per day. The average contents of Al and Fe of _C. asiatica_ were less than those (\(\sim\)767 mg/kg per day and \(\sim\)47 mg/kg per day, respectively) of _I. aquatica_. _Ipomoea aquatic_  
Figure 4 shows the contents of Al in the leaf, stem, and root sections for day 2 to 10 of treatment by _I. aquatica_. Readings recorded for the leaf section were 973, 332, 261, 27, and \(-\)15 mg/kg. Overall, \(\sim\)1577 mg/kg of heavy metals was accumulated at 10 days of treatment, with an average of 157 mg/kg per day. The highest amount of heavy metals was recorded on the second day of treatment, which was \(\sim\)62%. On the final day of treatment, the percentage of heavy metals in leaves was the lowest, which was 0.01% of the total amount of heavy metals. The contents of heavy metals recorded for the stem section were 3055, 1157, 130, 88, and 18 mg/kg. In total, \(\sim\)4447 mg/kg of heavy metals was recorded for day 2 to 10 of treatment, with an average content of 448 mg/kg per day. The highest amount of heavy metals was recorded on the second day, which was \(\sim\)69% of the total amount of heavy metals, while the percentage of heavy metals was the lowest on the final day, which was 0.01%. The contents of heavy metals in the root section were 2859, 614, 556, 321, and 175 mg/kg. About 4524 mg/kg of heavy metals was recorded for 10 days of treatment, with an average amount of \(\sim\)452 mg/kg per day. The highest heavy metal content was recorded on the second day, which was \(\sim\)49%. On the final day of treatment, the percentage of heavy metals in leaves was the lowest, which was 0.08% of the total amount of heavy metals. Figure 4 also shows the contents of Fe in the leaf, stem, and root sections for day 2 to 10 of treatment. The contents of heavy metals accumulated in leaves were 113, 190, 499, \(-\)56, and 75 mg/kg. Overall, \(\sim\)821 mg/kg of heavy metals was accumulated at 10 days of treatment, with an average of 82 mg/kg per day. The highest content of heavy metals was recorded on the sixth day, which was \(\sim\)61% of the total amount of heavy metals, while the percentage of heavy metals was the lowest on the eighth day, which was 0.07%. The contents of the heavy metals accumulated in the stem section were 1606, 197, 55, \(-\)9, and \(-\)83 mg/kg. About 1767 mg/kg of heavy metals was recorded for 10 days of treatment, with an average amount of \(\sim\)177 mg/kg per day. The highest content of heavy metals was recorded on the second day, which was \(\sim\)91%. On the final day of treatment, the percentage of heavy metals in leaves was the lowest, which was 0.05% of the total amount of heavy metals. Readings recorded for the root section were 2198, 1089, 824, 621, and 352 mg/kg. Overall, \(\sim\)5084 mg/kg of heavy metals was accumulated at 10 days of treatment, with an average of 508 mg/kg per day. The highest content of heavy metals was recorded on the second day, which was \(\sim\)43%. On the final day of treatment, the percentage of heavy metals in leaves was the lowest, which was 0.07% of the total amount of heavy metals. (b) _Centella asiatica_  
Figure 4 shows the contents of Al in the leaf, stem, and root sections for day 2 to 10 of treatment by _C. asiatica_. Readings recorded for the leaf section were 3205, 690, 125, 111, and 72 mg/kg. In total, \(\sim\)4202 mg/kg of heavy metals was accumulated at 10 days of treatment, with an average of 420 mg/kg per day. The highest content of heavy metals was recorded on the second day, which was \(\sim\)76%. On day 10, the percentage of heavy metals in leaves was the lowest, which was 0.02% of the total amount of heavy metals. The contents of heavy metals recorded for the stem section were 2661, 1364, 303, 122, and 138 mg/kg.