## 3 Results and Discussion
### Reduction Rate of TSS  
TSS are solid in a water body which includes a wide variety of materials, such as silt, decaying plants, animal matters, and other solid wastes [26]. Figure 2 shows the reduction rate of TSS using 50 g of _C. asiatica, I. aquatic, S. molesta, P. striatotes_, and _E. crassipes_ plotted against the days of treatment. It was found that _P. striatotes_ reduced TSS the most, with up to 98% reduction rate and a total of 43.3 mg/L of TSS by the 14 th day of treatment.  
[PERSON] et al. [27] stated that the charges in the root systems of aquatic plants or macrophytes improve their ability to trap and attract particles, such as TSS, in a medium. Hence, the reduction of TSS by plants primarily depends on the plants' root systems, and plants with fibrous roots can accumulate more TSS than those with taproots. In the present study, 98% of the TSS was reduced by _P. striatotes_, which has fibrous and long roots [27]. This result is also supported by the previous  
Figure 2: Reduction rate of TSS using five plant species after 14 days of phytoremediation.  
studies, which showed that _P. stratiotes_ was able to increase water clarity by trapping suspended solids in the roots [28]. It is believed that this species is also able to remove heavy metals magnificently. Based on the index of bio-concentrating factors, _P. stratiotes_ have been reported by [PERSON] et al. to be hyperconcentrated in the roots area for heavy metals like Cr, Cu, Fe, Mn, Ni, Zn and Pb [29]. According to [PERSON] et al. [25], 77.3% of Cr and 91.29% of Cu were removed during one month of treatment.  
Moreover, in _E. crassipes_, _C. asiatica_, _I. aquatica_, and _S. molesta_ tanks, the TSS concentration levels were reduced to 96%, 90%, 73%, and 89.3%, respectively. _I. aquatica_ possesses taproots; hence, it trapped the lowest amount of TSS among the five species. _E. crassipes_ has fibrous roots, which explains why the concentration of TSS on the last day of treatment was significantly reduced. However, _C. asiatica_ does not possess fibrous roots but effectively reduced TSS because it can be physically and biologically removed through filtration and sedimentation. TSS are trapped and accumulated when passing through the plant roots and eventually sink to the bottom by gravitational force or metabolized by microorganism [23]. The sedimentation process also helps to reduce TSS concentration by 60% in the control tank after 14 days, however, there was an increased TSS concentration for four days due to some disturbance to the tank on day 1 of experiment.  
The graph plot of TSS reduction in Figure 2 shows that TSS consistently decreased with the help of phytoremediation agents and the reduction was very inconsistent without the aid of any plants. The plots of _P. stratiotes_ and _E. crassipes_ showed the most significant decreasing patterns, followed by those of _C. asiatica_, _S. molesta_ and _I. aquatica_. However, starting from day 10, the concentration of TSS by most species tested in this experiment started to slowly decrease or stayed constant, possibly because it had already reached the maximum removal concentration.  
A one-way ANOVA was conducted and showed a significant value (\(p<0.05\)) for the reduction rate of TSS, from the first day of treatment until the end, by all five species. However, a statistical independent t-test showed no significant value (\(p<0.05\)) between the five plants, since the difference between the highest and lowest TSS concentrations removed was only 9.6 mg/L. This proves that all five species practically have almost the same potential to reduce TSS.