Factors affecting bromate removal capacity of zerovalent iron packed columns

In a series of column experiments lasting for approximately 1500 pore volume, the effects of operational factors (flow rates, sand admixtures) and water quality factors (concentrations of DO, sulfate, phosphate and bicarbonate) on bromate removal capacity of zerovalent iron were investigated. The bromate removal capacity, obtained from migration of concentration profiles, was observed to decrease with increases in flow rate. In the case that 20 wt-% iron was replaced by sands, the bromate removal capacity increased, but, on the contrary, the bromate removal capacity inevitably decreased when the weight percentage was increased by two times. Dissolved oxygen played a minor role in decreasing the bromate removal capacity, this decreasing effect only prevailed near the proximal end of depassivating irons. The bromate removal capacity increased in the presence of 100 mg/L sulfate concentration but decreased when the sulfate concentration further increased. When comparing the effect on removal capacity for phosphate and sulfate, the inhibiting effect of phosphate on the bromate removal capacity was larger. Lastly, the removal capacity increased with increasing bicarbonate concentration, which may due to the formation of aqueous complexes.