Assessment of the impact of the Ahvaz comprehensive sewage plan on the water quality of the Karun River using the QUAL2Kw model.

Document Type : Research Paper

Authors

1 PhD Student, Department of Water Engineering and Sciences, Imam Khomeini International University of Qazvin.

2 associate professor, water eng. group, Imam Khomeini International University، Qazvin

Abstract

Despite its significant importance, the Karun River is under serious threat from pollution caused by urban and industrial wastewater. Given the river's critical role in supplying drinking water, supporting agriculture, and facilitating industrial activities, maintaining its water quality is of vital importance. This study investigates the impact of the Ahvaz comprehensive sewage plan on the water quality of the Karun River using qualitative modeling. In this research, the QUAL2Kw model was employed to simulate water quality changes along a 28-kilometer stretch of the river. After validating the model, various wastewater management scenarios were examined, including the current situation, the operation of the eastern treatment plant, the expansion of the western treatment plant, full implementation of the Ahvaz comprehensive sewage plan, and drainage control measures. The results showed that the full implementation of the Ahvaz comprehensive sewage plan significantly improves water quality by reducing pollutants such as BOD, ammonium, organic and inorganic phosphorus. For instance, BOD concentration decreased from 6.1 to 2.6 mg/L, organic nitrogen concentration from 425 to 234 µg/L, organic phosphorus concentration from 135 to 35 µg/L, inorganic phosphorus concentration from 251 to 0.23 µg/L, and dissolved oxygen concentration increased from 5.55 to 6.79 mg/L. Additionally, controlling agricultural drainage also had a positive effect by reducing nitrate concentrations, EC, and enhancing overall water quality. This study demonstrates that proper and comprehensive wastewater management, especially in densely populated urban areas, can significantly improve river water quality.

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