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Arsenic is of environmental concern because of its toxicity to plants, animals, and humans. Arsenic in drinking water has the greatest impact on the general population and human health. In natural waters arsenic can be found in inorganic forms as oxidized pentavalent arsenate (As(V)) or trivalent arsenite (As(III)), mostly as H 2 AsO 4 -, HAsO 4 2-, H 3 AsO 3 , and H 2 AsO 3 - [1]. As(V) predominates in surface waters, while groundwater may also contain relevant concentrations of As(III) that are more mobile and toxic than As(V) [2]. Elevated concentrations of arsenic in groundwaters of China are the result of biogeochemical processes [3] or anthropogenic activities such as agriculture (the extensive use of herbicides and insecticides) and irregular disposal of hazardous waste from heavy industry [4][5].Long-term exposure through drinking water to even low concentrations of arsenic (≤50 μg/l) can cause Pol. J. Environ. Stud. Vol. 26, No. 4 (2017), 1847-1854 The adsorption of arsenate (As(V)) and arsenite (As(III)) was conducted in a continuous fixed-bed column by using organic modified spent grains (OSGs). The column performances were evaluated by varying the influent flow rate (0.91, 1.36, and 2.72 ml/min) and arsenic ions initial concentration (1.0, 2.0, and 6.0 mg/l for As(V); 0.5, 1.0, and 3.0 mg/l for As(III)) in order to obtain experimental breakthrough curves. The maximum adsorption capacity was at 6.0 mg/l for As(V) and 3.0 mg/l for As(III) influent concentration and 1.36 ml/min flow rate. The Thomas model, Adams-Bohart model, and Yoon-Nelson kinetic models were used to analyze column performance. The value of rate constant for Thomas and Adams-Bohart models decreased with increase of influent concentration, but increased with increasing flow rate. The rate constant for the Yoon-Nelson model decreased with increases in both initial influent arsenic ions concentration and flow rate.

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