Arsenite and Arsenate Removal from Contaminated Groundwater by Nanoscale Iron–Manganese Binary Oxides: Column Studies

Fixed-bed sorption process can be very effective at removing arsenic from contaminated groundwater. In this study, a continuous operation was demonstrated for the removal of both arsenite [As(III)] and arsenate [As(V)] from aqueous media in a column packed with nanoscale iron–manganese binary oxides (NIM). Treatment performance of the sorbent was quantified by upflow column experiments at different flow rates and bed depth. Bed depth service time model was used for the prediction of column service time, and the predicted values were compared with experimental values. A study of competing ions showed that silicate caused the greatest decrease in the As removal rate relative to phosphate and sulfate. Column regeneration studies were carried out for three sorption–desorption cycles using 0.1 M NaOH as the eluent, the NIM bed saturated with arsenic could be efficiently regenerated and reused. We found that NIM could be used for different types of real groundwater. This column study revealed that NIM was an efficient medium for As(III) and As(V) removal in groundwater.