| 摘要 |
PURPOSE:To improve transmitting rate of precision filter membrane in the process of treating waste water containing phosphoric acid and iron (II) ion by adding alkali to the waste water and separating a sludge with precision filtering membrane. CONSTITUTION:A part of concentrated liquid from an MF membrane separating device 6 is circulated to the circulating tank 3 which is controlled to pH5-8. By maintaining the circulating tank 3 to pH5-8, phosphoric acid efficiently by removed, which gives high filtering efficiency. Iron (II) ion is oxidized into iron (III) ion by oxygen in air introduced to the circulating tank 3 with the concentrated liquid, so that no iron ion is dissolved in a pH5-8 range. Thus, the transmitting rate of the membrane is improved and the obtd. sludge has higher concn. and dehydrating property. |
