Abstract
A significant amount of reddish brown sediment was found at the sluice gate of the neutralization treatment plant for Tamagawa hot spring acidic water. The reduction in the concentrations of As and Cr in the spring water was studied in relation to sediment formation. XRD analysis and FT-IR spectrometry revealed that the sediment mainly consisted of a poorly crystallized iron hydroxide phase, which is similar to the mineral schwertmannite. The concentrations of Fe, As and Cr in fresh spring water were 150, 2.8, and 0.093 mg·L-1, respectively, these concentrations respectively decreased to 55, 0.75, and 0.025 mg·L-1 after the neutralization treatment. On the other hand, the concentrations of these elements in the sediment were respectively determined to be 39, 1.7, and 0.020 wt.%. The above these results strongly suggested that As and Cr accumulate in the sediment during the neutralization treatment process.
