| 摘要 |
PURPOSE:To control the injection of chlorine in proper quantities, by calculating a chlorine injection ratio Sn by a first operation means and subsequently calculating a chlorine injection ratio Sn' injected actually by a second operation means. CONSTITUTION:Raw water and return waste water are introduced into a water arrival well 1 respectively separately and mixed to be made to flow down to a mixing basin through a flowmeter 2. Not only chlorine but also a flocculant or a neutralizing agent are injected in water on the way of the flowing-down from the water arrival well to the mixing well to be mixed in the mixing basin 3. A first operation means 7 uses feedback correction quantity to calculate a chlorine injection ratio objective value Sn synchronous to control and a second operation means 9 uses a flow amount, a measured flow amount, the concn. of the residual chlorine of the mixing basin and a chlorine injection ratio objective value Sn as input values to correct the chlorine injection ratio objective value Sn to calculate Sn'. By this method, drinking water having sanitary and stable quality is obtained.
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