Abstract
Hybrid methods for arsenic removal from synthetic groundwater were investigated in this study. Batch study showed that As(III) removal was first-order at high Fe(0) shavings concentration and approached zero-order at low concentration. It was suggested that As(III) was removed by surface precipitation and adsorption processes. A single Fe(0) shavings column experiment was conducted for As(III) removal and the experimental data were evaluated by the Thomas and Yan adsorption models. As(III) removal capacity of Fe(0) shavings estimated by the Thomas model (11.3 mg/g) and Yan models (10.8 mg/g) were closed to the values calculated from the experimental data (10.3 mg/g). Two types of hybrid column filtration methods (Hybrid 1 and Hybrid 2) were conducted to evaluate the processes with regard to the applicability and remedial performance of As(III). Hybrid 1 was bacterial column (BC) filtration followed by Fe(0) shavings column filtration (MC), while Hybrid 2 was MC followed by BC. Results showed that As(III) was removed to less than 10 μg/l in Hybrid 1 but the effluent Fe concentration was higher (> 0.5 mg/l). By contrast, both As and Fe were removed to less than 10 μg/l and 0.3 mg/l, respectively in Hybrid 2. The MC columns data of Hybrid 1 and Hybrid 2 were examined by the Thomas and Yan models. As(III) removal capacity was increased in Hybrid 2 MC due to the presence of Fe(II) in the synthetic groundwater. Accordingly, it was suggested that the hybrid methods would be effective processes to remove As(III) from highly contaminated groundwater.
