River bank filtration for sustainable water supply on Gorganroud River, Iran

River bank filtration (RBF) is one among the managed aquifer recharge methods which is inexpensive and sustainable means to improve the quality of surface waters undergoes natural treatment by subsurface flow through the aquifer medium. This study was carried out to investigate the feasibility of a RBF to improve water quality of Gorganroud River, Iran. For this purpose, 48 water samples were simultaneously collected from three water sources (river, production well, and groundwater) to analyze twenty-six water quality parameters. Hydrogeochemical results revealed that the production well together with river water had a similar origin whereas the groundwater was different. Furthermore, the water quality of production well is mainly controlled by the chemical quality of the Gorganroud River water together with microbial, chemical, and physical processes that occur during the RBF. Results showed that 12 out of 26 the water quality parameters (e.g., total coliforms, turbidity, color, salinity, ammonia, nitrite, nitrate, BOD, COD, iron, manganese, and pH) decreased in the production well. The average removal efficiency of total coliforms bacteria, turbidity, and color parameters was found to be about 98, 97.7, and 72%, respectively. Results of Tukey and Games-Howell tests indicated that there was no statistical difference between chemical composition of river water and the production well water (except ammonia, calcium, and magnesium). Results revealed that the natural attenuation of surface water using the RBF can effectively enhance the water quality index values of the extraction well. Therefore, the RBF system is an effective approach to treat Gorganroud River water that will expand the natural treatment options available to Iranian water utilities in Golestan Province.