AWWA ACE58104

Assessment on the feasibility of bromate reduction by zero-valent iron (Fe0) has been carried out in this study. The effects of iron types, iron surface concentrations, mixing rates, pH, and concentrations of dissolved oxygen (DO), natural organic matter (NOM), nitrate and nitrite were investigated with batch tests. The observed rate constant (kobs) and the surface-area-normalized rate constants (kSA) were obtained from pseudo-first-order kinetics. The data revealed that irons from different manufacturers demonstrated significant variations in bromate reduction. Monotonic increases in the kobs were observed with increases in the iron surface concentration and the mixing rate. The kobs were also found to increase with a decrease in pH, especially when solution pH decreased from 6 to 5.5. The effects of DO, NOM, nitrate and nitrite on bromate reduction were insignificant, presumably due to the excessive Fe0 concentrations. Preferential reduction of bromate might also contribute to the effective bromate removal when nitrate or nitrite was present. Under the experimental conditions, soluble iron (Fe2+/Fe3+) at concentrations of sub to a few mg/L (up to 6 mg/L) were observed only in the beginning of all test runs. These findings indicate that chemical reduction by Fe0 can be a very effective alternative when bromate removal is required. Includes 24 references, tables, figures.