| 摘要 |
PROBLEM TO BE SOLVED: To provide a pressure floatation device capable of maintaining the water level inside a floatation vessel within a specified range even when a rapid increase in flow rate of raw water is caused, and discharging highly concentrated scum having a stable concentration. SOLUTION: A raw water treatment process using this pressure floatation device comprises: allowing raw water and pressurized water to flow into a floatation vessel from an inflow pipe 2 through a feed well 3 to perform solid- liquid separation of the raw water, raking up floated scum within the floatation vessel with a scum rake 4 so as to allow the raked scum to fall into a sludge discharge box 5 for the scum to discharge the scrum; making treated water pass through a space between a baffle wall 8 and the bottom surface of a floatation vessel body 1 and then discharging the treated water through a treated water discharge pipe 6 to the outside of the device, and controlling a pump 7 placed in the treated water discharge pipe 6 so as to maintain the water level within the vessel body 1 detected by a water level gage 9, at a constant level by using an arithmetic unit 10.
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