Univrsity Of Tehran Press Water and Irrigation Management 2251-6298 14 4 2025 02 19 Examining the effect of treatment plant construction on Abbas Abad Mountainous River's quality and pollution Examining the effect of treatment plant construction on Abbas Abad Mountainous River's quality and pollution 863 875 98075 10.22059/jwim.2024.369706.1127 FA Atefe Noorali Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran. Safar Marofi Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran. Omid Babamiri Department of Water Science and Engineering, Faculty of Agriculture, Tabriz University, Tabriz, Iran. Journal Article 2023 12 16 The purpose of this research is to investigate the quality status of the Abbas-Abad Mountainous River in Hamedan and evaluate the impact of the implementation of the urban sewage treatment plant and agricultural effluents on its pollution process. In this regard, three scenarios include the existing conditions (reference scenario), the construction of a treatment plant by reducing the amount of biochemical and chemical oxygen (BOD and COD) at the level of class B₁ in accordance with the standard of the Environmental Protection Organization (the second scenario) and the construction of a treatment plant with an increase in the amount Dissolved Oxygen (DO) at the level of class B₁ (third scenario) was investigated and compared. For this purpose, the simulation of the river was done using the QUAL2Kw model and during the first scenario, taking into account the actual conditions of pollutant discharge for the period of May and August 1400, it was calibrated and validated. Then, by identifying six important point sources polluting the river, the second and third scenarios were implemented. The results of the reference scenario showed that with the increase of BOD and COD values of water, its DO value also decreases and the quality of the river is in a critical condition. Also, with the reduction of BOD and COD values at the standard level of class B₁, the value of DO in the third scenario will increase dramatically compared to other scenarios. Therefore, based on these results, the performance of the third scenario is better than the other scenarios, and the construction of the proposed treatment plants has a significant effect on improving the quality of the Abbas-Abad River. It is also suggested to prevent pollutants from entering the riverbed in order to improve the quality of rivers. The purpose of this research is to investigate the quality status of the Abbas-Abad Mountainous River in Hamedan and evaluate the impact of the implementation of the urban sewage treatment plant and agricultural effluents on its pollution process. In this regard, three scenarios include the existing conditions (reference scenario), the construction of a treatment plant by reducing the amount of biochemical and chemical oxygen (BOD and COD) at the level of class B₁ in accordance with the standard of the Environmental Protection Organization (the second scenario) and the construction of a treatment plant with an increase in the amount Dissolved Oxygen (DO) at the level of class B₁ (third scenario) was investigated and compared. For this purpose, the simulation of the river was done using the QUAL2Kw model and during the first scenario, taking into account the actual conditions of pollutant discharge for the period of May and August 1400, it was calibrated and validated. Then, by identifying six important point sources polluting the river, the second and third scenarios were implemented. The results of the reference scenario showed that with the increase of BOD and COD values of water, its DO value also decreases and the quality of the river is in a critical condition. Also, with the reduction of BOD and COD values at the standard level of class B₁, the value of DO in the third scenario will increase dramatically compared to other scenarios. Therefore, based on these results, the performance of the third scenario is better than the other scenarios, and the construction of the proposed treatment plants has a significant effect on improving the quality of the Abbas-Abad River. It is also suggested to prevent pollutants from entering the riverbed in order to improve the quality of rivers. https://jwim.ut.ac.ir/article_98075_e88cc90e723158965de89e7cd2534a52.pdf