Assessment of rainwater and greywater utilization potential on university campuses: The case study of Artvin Çoruh University

Within the scope of this study, the potential water quantities that could be obtained through rainwater harvesting and greywater reuse across all campuses of Artvin Coruh University were determined. The usability of these alternative water sources for the irrigation of campus green areas was evaluated, and an economic feasibility analysis of the systems was also conducted. In the study, the rainwater harvesting potential was calculated using the roof areas of all buildings and annual precipitation data; additionally, the amounts and characteristic properties of greywater generated based on user numbers were determined. The main findings showed that rainwater harvesting could provide a total of 22,854 m³ of water per year, with the highest harvest at Seyitler Campus (8,887 m³) and the lowest harvest at Ardanuç Campus (630 m³). Daily greywater production of 649 m³ was calculated university-wide, but analyses revealed that greywater was classified as "3rd class water" according to wastewater standards in terms of conductivity, sodium, chloride, and boron values; therefore, it was determined that the direct use of greywater for irrigation without treatment would not be appropriate. As a region receiving precipitation, approximately 117,000 m³ of water is required for 155,989 m² of green area during the five-month period planned for irrigation (May-September), and it was determined that when harvested rainwater and generated greywater are used together, the entire irrigation water need of Merkez, Hopa, Şavşat, and Arhavi campuses could be met, but it was found to be insufficient in Seyitler, Borçka, and especially Ardanuç campuses. As a result of economic analysis, it was calculated that the use of rainwater and greywater would provide annual total savings of 1.57 million TL; the shortest investment payback periods were found to be in Merkez, Seyitler, Borçka, and Hopa (15-16 years), while the longest period was determined to be in Ardanuç (146 years). In line with the obtained results, it is recommended that systems be established primarily in Borçka, Hopa, Merkez, and Seyitler campuses, which are economically advantageous; integration of biological treatment, filtration, disinfection, and reverse osmosis units to make greywater suitable for irrigation; and designing optimum volumes for hybrid tanks where rainwater and treated greywater will be stored together according to seasonal fluctuations. In conclusion, it has been shown that rainwater harvesting and greywater recovery are technically feasible at the scale of Artvin Coruh University and economically reasonable in certain campuses. Through the implementation of these systems, it will be possible to reduce potable water consumption, protect local water resources, and make significant contributions to the university's sustainability goals.