CONTROL OF INJECTION AMOUNT OF SLAKED LIME IN TREATMENT OF FLUORINE-CONTAINING WASTE WATER AND FLUORINE COMPONENT REMOVING APPARATUS

PURPOSE:To set the injection amount of slaked lime to the necessary min. degree and to also stabilize the quality of treated water in the removal treatment of the fluorine component (fluorine ion) of fluorine-containing waste water. CONSTITUTION:The necessary concn. of calcium is calculated according to a predetermined calculation formula or multiplication coefficient on the basis of the fluorine concn. signal from a waste water fluorine concn. analyser 3 and the calcium concn. signal from a waste water calcium concn. analyser 4 is subtracted from the calculated value and the injection amount of slaked lime is operated by an operation circuit multiplying the inflow waste water flow rate signal from a waste water flow rate detector 1 to inject slaked lime into a reaction tank 5. From the polarity and magnitude of the deviation between an objective fluorine concn. value and the fluorine concn. measured value of treated water, the injection amount of slaked lime is controlled while a correction magnification coefficient is intermittently operated and corrected and the quality of treated water is stabilized.