# A Cyclic Graywater Treatment Model for Sustainable Wastewater Management Applied in a Small Scale
## 4 Discussion
Other studies have highlighted the efficiency of sand filtration and granulated blast furnace slag, achieving substantial reductions in both total and fecal coliforms, which significantly lowers health risks associated with graywater reuse [40]. Furthermore, staircase wetlands have shown impressive removal rates of 90-99% for total coliforms, while also contributing to improved soil microbial health, offering a dual benefit of graywater treatment and enhanced soil quality [41]. The influence of graywater irrigation on soil properties was assessed through a comparative analysis of soils irrigated with raw graywater and those irrigated with treated graywater. The results showed a significant increase in soil salinity (measured as EC of the extract, ECe) at all treatment levels, with a direct correlation to the increased EC of the treated graywater. This finding is consistent with previous studies, which have reported that graywater reuse tends to elevate soil salinity [42]. Research suggests that treated graywater can promote plant growth without causing significant changes in soil salinity, thereby maintaining a stable ionic balance [43]. Despite slight variations in pH, the increase in salinity poses a challenge for long-term soil health and agricultural productivity. Monitoring and managing soil salinity are, therefore, crucial for sustainable graywater irrigation. The non-significant reduction in vegetative growth parameters (e.g., stem diameter, plant height, root length, fresh and dry weight) in quinoa irrigated with treated graywater suggests that increased salinity may have negatively impacted plant development. This observation is consistent with previous studies highlighting the adverse effects of salinity on plant growth [44]. In a similar context, [PERSON]. [45] found that elevated salinity levels in irrigation water led to a noticeable reduction in plant height as well as in both fresh and dry weight across all three quinoa varieties studied. These findings emphasize the detrimental effects of salinity stress on quinoa's growth performance. Although quinoa is recognized for its salinity tolerance [46; 47]. [PERSON]. [45] reported that despite the negative impact of salinity on growth parameters, quinoa yield remained unaffected by the increasing the EC of the irrigation water. This suggests that quinoa may possess a unique resilience to salinity, allowing it to sustain yield even under elevated salinity conditions. However, the observed decline in growth parameters in the present study suggests that excessive salinity could still limit quinoa's overall performance. Further research is needed to evaluate the long-term effects of graywater irrigation on quinoa yield and quality. The analysis of the mineral composition in quinoa irrigated with cyclically treated graywater reveals significant patterns of ion accumulation within its tissues. Notably, quinoa demonstrates a strong capacity to accumulate ions, which has been previously documented [48]. The preferential accumulation of Na+, Ca2+, and N in the roots suggests that quinoa may employ these tissues as reservoirs for essential macronutrients, potentially as a mechanism to minimize their toxic effects on other plant tissues. The accumulation of P and Mg2+ in the seeds reflects the plant's strategy of channeling these nutrients into reproductive structures, which is consistent with their role in energy transfer, DNA synthesis, and cellular metabolism during seed development. The observed pattern of K+ accumulation, with initial concentration in the leaves followed by the roots, aligns with the typical physiological processes of potassium transport and storage in plants. Potassium is crucial for enzymatic activity and osmoregulation, particularly under saline conditions, and its movement into the roots may help mitigate the effects of salinity stress by maintaining cellular homeostasis.