Abstract: A water treatment system includes a water treatment facility which has a coagulation treatment unit injecting a coagulant into water to be treated including oil components and performing coagulation treatment and a monitoring control device which has an oil water separating unit introducing a part of the supernatant water after the coagulation treatment by the coagulation treatment unit and separating the oil components and a deposition tank depositing soluble components dissolved in the supernatant water after separating the oil water. The monitoring control device has a control unit which controls an injection rate of the coagulant, on the basis of at least a deposition amount of the soluble components by the deposition tank.

Abstract: In a water treatment system, fouling is made earlier detectable, considering additionally the effect of spacers arranged between its separating membrane layers. A water treatment system 1 includes a pre-treating unit for pre-treating a raw water; a desalting unit having a separating membrane unit for separating substance to be separated from the raw water pre-treated in the pre-treating unit, using a separating membrane; and a monitoring unit between the pre-treating unit and the desalting unit. The monitoring unit has a monitor device fitted to a bypass pipe and configured to have a closed vessel having at least one transparent or semitransparent surface, and an image-pickup device which makes the raw water flowing in this vessel visible through the transparent or semitransparent surface. In the vessel, separating membrane layers which the separating membrane unit has, and a fouling-generating member are arranged to be put onto each other.