| 摘要 |
PURPOSE:To regulate hydrogen ion concentration between the upper and lower limits by detecting inflection point of electric conductivity of a waste water to be treated, which is neutralized by a secondary pH control material after a primary pH control material containing acid, base or salt is added, and by settling upper and lower limits of hydrogen ion concentration. CONSTITUTION:A specific volume of a treated water W treated to satisfy the water quality standard is fed into the tank 1. When the treated water reaches to the specific volume, electric conductivity of the treated water W is measured and after the primary pH control material P1 in the base tank 11 is added into the tank 1 by controlling the solenoid valve 2, electric conductivity is measured. Furthermore, the secondary pH control material in the acid tank 12 is added by controlling the solenoid valve 3 and electric conductivity is measured. Next, increasing rate of initial electric conductivity is calculated based on the difference between electro conductivity after the base is added and after the acid is added. After that, the acid is added little by little to calculate increasing rate of electric conductivity and lst inflection point and 2nd inflection point, at which increasing rate changes, is detected. |
