| 摘要 |
PURPOSE:To control the amt. of chemicals to be injected in accordance with the quality of water to be treated by controlling the injection of chemicals with different control objects when the inflow of water to be treated is larger than a set value or smaller than the set value. CONSTITUTION:When untreated water A flows into an influent water well 2, the inflow is measured by a flowmeter 1, the detected signal is outputted from an oscillator 1a and whether the inflow is larger than a set value FH or smaller is judged by an alarm setter 10. When the flow of untreated water A into the well 2 is smaller than the set value, the injection of an aq. soln. B contg. a flocculant is made constant by a functional arithmetic unit 12 until the turbidity of untreated water becomes a specified concn. and the injection is increased at a specified rate at more than the concn. When the flow of untreated water into the well 2 is larger than the set value, the aq. soln. B contg. a flocculant is injected at a specified rate by a functional arithmetic unit 11 until the inflow of untreated water becomes a specified value and the injection is made constant at more than the inflow.
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