Implementation and performance monitoring of the treatment system to remove arsenic from dam water in a full-scale urban water treatment plant

Nowadays, health and environmental problems caused by elevated arsenic concentration in water sources have become a major concern for researchers and environmental experts. Therefore, it is necessary to study processes that significantly reduce the arsenic content in aqueous solutions, which is of great interest to environmental experts. This work aimed to evaluate the effect of the pre-oxidation/coagulation process with commercially available coagulants (FeCl 3 , Al 2 (SO 4 ) 3 ·18H 2 O, and PACl) on the efficiency of arsenic removal (with initial concentration of 73 ± 2.5 μg/L) from Talvar Dam entering the Sheikhi Jan Hamadan water treatment plant. This was demonstrated on a laboratory and operational scale at the water treatment plant under different scenarios (pre-oxidant agents, type of coagulant, solution pH, and different coagulant dosages). It should be noted that, as part of an emergency project, the possibility of arsenic removal at the Sheikhi Jan water treatment plant, which receives Talvar Dam water at a flow rate of 1800 L/s, was investigated. The priority of the researchers and city officials in the present study was to use the potential of the water treatment plant and the existing equipment so that they could remove arsenic quickly and without additional costs. This study was conducted in three stages: laboratory scale, implementation of the process in the water treatment plant, and monitoring of the treatment plant's performance, which continues to this day. The results of this project showed that the pre-oxidation/coagulation process can effectively reduce the concentration of arsenic at the inlet of the treatment plant from to less than national and international recommended values. • Arsenic concentrations above the permissible limit were detected in the Talvar Dam. • Improved removal of arsenic in the pre-oxidation/coagulation process. • FeCl 3 was an effective coagulant in a wide pH range for arsenic removal. • A combined process for arsenic removal was fully implemented in emergency conditions. • The arsenic concentration as a result of the process reached less than the 10 μg/L.