| 摘要 |
PURPOSE:To always perform optimum flocculating treatment in a purification plant wherein two and more lines of raw water different in quality are mixed fro water treatment with a common flocculating agent by correcting the rate of injection of the flocculating agent with weight factor thereof resulting from the mixing and automatically deciding the proper rate of injection of the flocculating agent. CONSTITUTION:Raw water A is introduced into a mixing tank 7 through a duct 3 provided with a flowmeter 1 and a turbidimeter 2 and raw water B is introduced thereinto through a duct 6 provided with a flowmeter 4 and a turbidimeter 5. The raw water mixed in the mixing tank 7 is passed through a duct 9 wherein a flocculating agent is injected with an injection installation 8 and introduced into a flocculating sedimentation basin 10, and the supernatant water in the basin 10 is filtered in a filter basin 11 and distributed to consumers as clear water. Rates Ca, Cb of injection of the flocculating agent for each raw water which are calculated with a first arithmetic circuit 13 and weight factor W of the rate of injection of the flocculating agent resulting from the mixing and the ratio R of flow rate which are calculated with a second arithmetic circuit 16 are sent to a third arithmetic circuit 17. The rate C of mixed injection is calculated with this circuit 17 and this value is output to the injection installation 8.
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