Optimization of operation condition of water treatment system based on the in-situ observation of the reaction of arsenic, iron and manganese

在该项目的第一年，主要目标是开发在生物过滤器的固液界面处获得XAFS光谱的程序，其中溶解的Mn（II）氧化成Mn（III）或Mn（IV），并且锰氧化物发生积累。这是通过在空的塑料柱上钻一个窗口（装有聚酰亚胺膜），用适应Mn去除的生物过滤器填充柱，并应用快速XAFS测量技术来实现的。锰氧化的原位测量是可能的，当含有4毫克/升的Mn（II）的水进料到柱。同样，尝试观察当处理含有Fe（II）和As（III）的原水时，在生物过滤器的固-液界面处As（III）（亚砷酸盐）的去除。自制的柱可以抵抗由于铁氢氧化物在过滤器上积累而引起的压力增加，当向生物过滤器中进料含有8 mg/L或40 mg/L Fe和4 mg/L As的水时，使用该柱来获得As K边光谱。结果表明，As（3）以As（3）的形式吸附在生物铁氧化物上，并逐渐氧化为As（5）。

During the first year of the project, the principal goal was the development of the procedure to obtain XAFS spectrum at the solid - liquid interface of the biological filter where oxidation of dissolved Mn(II) to Mn(III) or Mn(IV), and accumulation of the manganese oxides are taking place. This was achieved by boring a window (fitted with polyimide film) on the empty plastic column, packing the column with biological filter acclimated for Mn removal, and applying the quick XAFS measurement technique. In-situ measurement of manganese oxidation was possible when water containing 4 mg/L of Mn(II) was fed to the column. Likewise, an attempt was made to observe the removal of As(III) (arsenite,) at the solid - liquid interface of the biological filter when raw water containing Fe(II) and As(III) was treated. A house-made column that can resist the pressure build- up due to accumulation of iron hydroxides on the filter was used to obtain As K-edge spectra when water containing 8 mg/L or 40 mg/L of Fe and 4 mg/L of As was fed to the biological filter. The results suggested that As(3) was sorbed on the biologically formed iron oxides as As(3), and was gradually oxidized to As(5).