摘要 |
A filtration method for filtering raw water to obtain permeate by performing a filtration operation using pressure as a driving force for membrane modules, wherein the filtration operation is performed in three modes: raw water side pressure filtration, permeate side negative pressure filtration, and composite filtration combining the raw water side pressure filtration and the permeate side negative pressure filtration, any one of raw water side water quality, membrane filtration flux and transmembrane pressure is measured, and any one of the three filtration modes is switched to another in response to a measured value thereof. |