# A Cyclic Graywater Treatment Model for Sustainable Wastewater Management Applied in a Small Scale
## 5 Conclusions  
Treated graywater, when processed through simple and natural methods, such as the cyclic treatment system, offers a promising sustainable solution for addressing water stress in agriculture. To explore the effects of cyclic-treated graywater on soil and plant physicochemical properties, a series of measurements and analyses were conducted on samples from experimental pots exposed to different treatment levels (T1, T2, and T3). The data were correlated with the graywater irrigation treatments (GWT1, GWT2, GWT3) and the cultivation status (cultivated vs. bare soil). Cyclic treatment of graywater demonstrated several benefits, including reductions in pH, biochemical indicators (COD, BOD), and pathogenic microorganisms, while EC increased. Notably, soil ECe also increased significantly at each treatment stage, signaling changes in salinity and alterations in the chemical composition of the soil solution. Irrigation with treated graywater led to a substantial reduction in soil pathogenic bacteria. Additionally, quinoa biomass was notably affected by the graywater treatments, with the control group exhibiting the highest fresh biomass compared to the plants irrigated with treated graywater. The graywater treatment further enhanced quinoa growth by significantly increasing the levels of minerals such as calcium and magnesium, with variations across different plant organs and treatment levels. Overall, this study demonstrates that graywater irrigation through the cyclic treatment system represents a viable approach for sustainable agricultural practices. This method offers an effective strategy for utilizing non-conventional water sources in agriculture, contributing to the mitigation of global water limitations, particularly in arid regions. By reserving high-quality freshwater for human consumption, it plays a crucial role in conserving limited water resources and reducing pressure on freshwater supplies. However, to scale this system for real-world applications, further research is necessary to evaluate long-term field trials in various agricultural settings and climatic conditions. Implementing this system on a larger scale will require careful consideration of site-specific factors, such as soil type, crop species, and local water availability. Economic feasibility also plays a critical role in scaling up, as the costs of installation, operation, and maintenance must be balanced with the benefits, including the potential reduction in reliance on potable water for irrigation. A thorough cost-benefit analysis would be essential to determine the long-term economic viability of widespread graywater use. Future studies should explore advanced treatment technologies, such as UV disinfection or advanced filtration systems, to enhance pathogen removal efficiency and minimize any health risks associated with graywater reuse. Furthermore, research should focus on the long-term impacts of graywater irrigation on soil health, particularly the effects on soil microbial communities, nutrient cycling, and sustainability of crop yields over multiple growing seasons. Investigating the integration of graywater treatment systems with existing agricultural practices, such as organic farming, would also be an important avenue for future research. Conceptualization, H.F. and M.H. ; methodology, H.F.; software, M.M. ; validation, H.F, N.B. and M.H. ; formal analysis, O.I. ; investigation, H.F.; writing--original draft preparation, H.F.; writing--review and editing, N.B. ; visualization, V.N. ; supervision, M.H. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. All data used is in the article are available upon request. The authors would like to express their gratitude to the technical staff of the Laboratory of Vaporization of Non-Conventional Water (LR VENC), INRGREF (Tunisia), for their unwavering technical support.