| 摘要 |
PURPOSE:To make it possible to calculate easily the amount of SS generated by the neutralization of raw water by calculating the amount of an insoluble material generated by chemical reaction between alkali and drained water based on the amount of consumed alkali, in a device for generating the insoluble material by adding alkali to drained water containing metal ion. CONSTITUTION:A raw water tank 1, a preliminary neutralization tank 2, a neutralization tank 3, a flocculation tank 4, a sedimentation tank 5 and a reaction tank 6 are installed, and an insoluble material is generated by adding alkali to drained water containing a metal ion, and this insoluble material is separated as sludge from treated water. In addition, the alkali is added to a part of the separated sludge, and a mixed product thus obtained is added to the drained water to obtain a high sludge concentrate which can be highly dehydrated. In this case, the concentration of SS is calculated by a control device 10 using an SS coefficient based on a required amount of alkali for adjusting the pH value of raw water to a specified level. In addition, a return rate is calculated based on the concentration of SS, the concentration of returned sludge, the flow of returned sludge and the flow of raw water, and the discharge amount of a sludge return pump P4 is controlled so that the return rate shows a specified value. |
