1 Arsenic Removal from Groundwater using Ferric

Arsenic is a carcinogenic metalloid that is currently regulated in drinking water. The levels of arsenic in finished water in an existing water treatment plant are exceeding the current regulation of 10 µg/L. One of the available technologies for arsenic removal from groundwater is adsorption onto coagulated flocs and in this field, ferric chloride is the most commonly used coagulant for arsenic removal. This research work was conducted to explore a suitable conventional treatment technology for arsenic removal from given groundwater in order to reduce the filtrate arsenic concentration to less than 10 µg/L. Bench scale jar test experiments and pilot-scale investigations were carried out to evaluate and improve the coagulation/flocculation process for arsenic removal using ferric chloride. Model water that represented the water from the existing water treatment plant was used to investigate the effects of different conditions of pH, coagulant doses, arsenic speciation, initial arsenic concentration, temperature, and flocculation conditions on the arsenic removal efficiency by coagulation/flocculation process. Based on these bench scale experiments, a direct filtration technique to separate the formed flocs was considered as the most suitable floc separation system to be applied after coagulation/flocculation process. A direct filtration pilot plant was operated to evaluate the efficiency of arsenic removal