## 3 Results and Discussion
### Assessment of Echinodorus Subalatus Growth and Development  
_Echinodorus subalatus_ measured 20 cm when introduced into the wetlands, a height below the recommended ideal range of 25 to 60 cm for perennial plants of this species [44], since the plants used in this study were younger and therefore smaller. However, [PERSON] and [PERSON] [45] suggest that using younger individuals is preferable for wetland systems, as they tend to assimilate a greater number of contaminants during their growth phase. They also noted that at the senescence stage, the decomposition of macrophytes can release nutrients into the environment, potentially influencing the microbial dynamics. Higher nutrient release can reduce microbial diversity, negatively impacting wastewater treatment in constructed wetlands.  
During the operation of the system, desiccation of leaf edges was observed, although new small leaves emerged without fully developing, leading to limited plant decomposition. Symptoms such as chlorosis (yellowing) and leaf curling, which are early indicators of senescence, were noted. These symptoms can arise from nutrient imbalances or toxicity in greywater [46]. It is possible that greywater exerted a toxic effect on the plants, as similarly reported by [PERSON] and [PERSON] [47], who operated a small-scale, shallow vertical flow CW for dairy industry effluents (COD (3014.3 \(\pm\) 37.9) mg/L; pH (4.25 \(\pm\) 0.05)). They observed growth inhibition and subsequent death of _Pistia stratites_ (water lettuce), which was replaced by _Eichhornia crassipes_ (water hyacinth) due to its better adaptation. This suggests that the sensitivity of macrophtye species to specific environments can significantly influence the performance of the system, highlighting the importance of species selection. [PERSON] and [PERSON] [48] also operated a vertical subsurface flow CW and observed a partial loss of the planted macrophytes in their system, which was fed with domestic wastewater containing 464.2 mg BOD/L (789.14 mg COD/L). Over a period of 45 days, _Colocasia esculent_ experienced a 100% loss of the initially planted individuals (five replacements), _Typha_ sp. had a 33% loss (two replacements), and _Pemisetum purpneum_ experienced a 66% loss (three replacements). This decline in plant survival was attributed to the effects of the wastewater and the low temperatures (12 to 16 \({}^{\circ}\)C).  
In the present study, the average temperature in the laboratory where the wetland was installed was approximately 24 \({}^{\circ}\)C, which is higher than the temperatures reported by [PERSON] and [PERSON] [48]. Over the 49 days of operation with the vegetated system, there was no total loss of individuals. However, the average number of leaves per plant decreased from 10 to 4 by the end of the experiment, and no new leaves were observed to sprout. This suggests that _Echindoorus subalatus_ endured the imposed conditions relatively well, without requiring the replanting of new individuals in the system. Additionally, [PERSON] and [PERSON] [48] noted that the optimal age for macrophytes used in constructed wetlands should be between 60 and 90 days. In this study, _Echindoorus subalatus_ was planted at just 30 days old, which is below the recommended age. This may have contributed to the lack of a significant difference in the system's performance between the vegetated and non-vegetated phases. It is important to note that the _Echindoorus subalatus_ individuals did not exhibit any increase in height, remaining at 20 cm, the same as at the start of the experiment. This stagnation in growth suggests that the composition of the greywater, combined with the young age of the plants (30 days), may have restricted the optimal development of the macrophytes, thereby limiting the system's ability to achieve greater pollutant removal. Consequently, planting _Echindoorus subalatus_ at an age of 30 days or younger is not recommended, as it did not significantly enhance greywater treatment.