Granular iron-impregnated attapulgite adsorbents (Fe-ATP) were developed for effective removal of arsenic from groundwater. Fe-ATP with an iron content of 15% and calcinated at temperature of 200 degrees C showed the best adsorption performance for both arsenite and arsenate. The adsorption data of arsenite onto Fe-ATP fitted both Langmuir and Freundlich isotherms well, while Langmuir described the adsorption of arsenate onto Fe-ATP better than Freundlich isotherm. Both arsenite and arsenate adsorption onto Fe-ATP followed pseudo-second-order kinetics model. The removal efficiency of arsenite by Fe-ATP was insensitive to pH in a wide pH range of 3-11, however, Fe-ATP exhibited better removal performance for arsenate in the pH < 7 conditions. Co-existing anions did not evidently inhibit arsenic removal by Fe-ATP. In column tests using lab-prepared arsenic containing water as influent, about 4900, 1500 and 550 (1320, 520 and 260) bed volumes (BVs) of water with 200 mu g/L arsenite (arsenate) were treated before breakthrough (10 mu g/L, WHO standard) was reached under flowing rates of 200, 600 and 1000 mL/h, respectively. While the influent contaminant concentration was 303 mu g/L from real groundwater and the flowing rate was 200 mL/h, breakthrough BVs at the WHO provisional guideline value of 10 mu g/L were 1300.