| 摘要 |
PROBLEM TO BE SOLVED: To easily perform the concentration control of treated liquid after coagulant mixing treatment and also to reduce the area of a membrane to be used to lower costs by providing a process in which coagulated flocs in the coagulant mixing treated liquid are floated and separated. SOLUTION: Into treated liquid which is already subjected to coagulation mixing treatment in a coagulant mixing tank 1, a coagulant aid is injected from a coagulant aid dissolving tank 6. In this way, the growth of the diameter of coagulated flocs is promoted. And the treated liquid which is already subjected to flocculation mixing treatment in the coagulant mixing tank 1 is not directly introduced into a coagulation membrane circulating tank 16 but is introduced into a super cell 9 once and is made into a clear state in which the coagulated flocs are not contained and is introduced into the coagulation membrane circulating tank 16. As a result, the concentration control of the treated liquid which is already subjected to coagulant mixing treatment can be easily performed and the sludge concentration after separated by pressurized floating separation can be made to be about 2%, rendering good handling in a sludge treating process. And since the sludge concentration in the coagulation membrane circulating liquid is markedly decreased, permeated flow velocity is increased to allow a reduction in the area of a membrane to be used. |
