The present invention provides a fresh water generator operating method and a determination program that are employed in a method for cleaning a separation membrane module following membrane filtration, and that, while various cleaning steps such as reverse pressure cleaning, air cleaning, chemical solution cleaning are taking place after completion of the membrane filtration, determines cleaning troubles by calculating a temporal change in resistance increase rate on the basis of an increase in membrane differential pressure.

An object of the present invention is to provide a chemical liquid purification method by which a chemical liquid capable of inhibiting the occurrence of short in a semiconductor substrate manufactured by a photolithography process is obtained. Another object of the present invention is to provide a chemical liquid manufacturing method and a chemical liquid. The chemical liquid purification method of the present invention includes a purification step of filtering a liquid to be purified by using a filter, in which a filter satisfying a condition 1 or a condition 2 in the following test is used as the filter. Test: 1,500 ml of a test liquid formed of the organic solvent is brought into contact with the filter for 24 hours under a condition of 23° C., and a content of particles containing at least one kind of metal selected from the group consisting of Fe, Al, Cr, Ni, and Ti in the test liquid after the contact satisfies a predetermined condition.

The degassing device includes a degassing flow path, a vacuum chamber, a vacuum pump, an inlet flow path, an outlet flow path, a drain flow path, a downstream side switching unit, and a controller. The degassing flow path is made of a gas-permeable, liquid-impermeable tube, and is accommodated in the vacuum chamber. The inlet flow path is for introducing a mobile phase to the degassing flow path, and the outlet flow path is for causing a mobile phase which has passed through the degassing flow path to flow out. The drain flow path is provided separately from the outlet flow path and is configured to drain the mobile phase in the degassing flow path from the degassing flow path. The downstream side switching unit is configured to switch the downstream end of the degassing flow path so as to be connected to either the outlet flow path or the drain flow path. The controller controls the operation of the downstream side switching unit, and is configured to connect the downstream end of the degassing flow path to the drain flow path at a predetermined timing when feeding of the mobile phase by the liquid feeding pump is stopped to drain the mobile phase in the degassing flow path through the drain flow path.

A water treatment assembly comprising a spiral wound hyperfiltration membrane module connected to: i) a feed line adapted for connection to a source of pressurized feed water, ii) a permeate line adapted for connection to a dispenser of treated water and iii) a concentrate line adapted for connection with drain; wherein the assembly further includes a pressurizable reservoir with valves for selectively diverting flow of pressurized feed water along the feed line, through the reservoir and returning to the feed line prior to passing through the hyperfiltration membrane module.

A water treatment assembly comprising a spiral wound hyperfiltration membrane module connected to: i) a feed line adapted for connection to a source of pressurized feed water, ii) a permeate line adapted for connection to a dispenser of treated water and iii) a concentrate line adapted for connection with drain; wherein the assembly further includes a pressurizable reservoir with valves for selectively diverting flow of pressurized feed water along the feed line, through the reservoir and returning to the feed line prior to passing through the hyperfiltration membrane module.

The present application provides a water treatment method, a water treatment device, and a slime inhibitor for membranes that are capable of, in water treatment using a separation membrane and a reverse osmosis membrane in the subsequent stage, inhibiting the generation of a slime both in the separation membrane and in the reverse osmosis membrane by a simple method. The water treatment method includes adding an iodine-based oxidizer to water to be treated, subjecting the water to be treated obtained during the adding of the iodine-based oxidizer to filtration with the separation membrane, and causing filtrated water obtained during the filtration to be separated with the reverse osmosis membrane into permeated water and concentrated water.

The present application provides a water treatment method, a water treatment device, and a slime inhibitor for membranes that are capable of, in water treatment using a separation membrane and a reverse osmosis membrane in the subsequent stage, inhibiting the generation of a slime both in the separation membrane and in the reverse osmosis membrane by a simple method. The water treatment method includes adding an iodine-based oxidizer to water to be treated, subjecting the water to be treated obtained during the adding of the iodine-based oxidizer to filtration with the separation membrane, and causing filtrated water obtained during the filtration to be separated with the reverse osmosis membrane into permeated water and concentrated water.

A deposit monitoring device includes a non-permeated water line discharging non-permeated water where dissolved components and dispersed components are concentrated from water to be treated from a separation membrane device for obtaining permeated water by concentrating the dissolved components and dispersed components from water to be treated by a separation membrane; a first deposit detecting unit using part of the non-permeated water branched off as a detection liquid, and having a first separation membrane for detection in which the detection liquid is separated into permeated water for detection and non-permeated water for detection; a deposition condition altering device altering deposition conditions for deposits in the first separation membranes for detection; and first flow rate measuring devices for separated liquid detection that measure the flow rates of one or both of the permeated water for detection and the non-permeated water for detection separated by the first separation membrane for detection.

A deposit monitoring device includes a non-permeated water line discharging non-permeated water where dissolved components and dispersed components are concentrated from water to be treated from a separation membrane device for obtaining permeated water by concentrating the dissolved components and dispersed components from water to be treated by a separation membrane; a first deposit detecting unit using part of the non-permeated water branched off as a detection liquid, and having a first separation membrane for detection in which the detection liquid is separated into permeated water for detection and non-permeated water for detection; a deposition condition altering device altering deposition conditions for deposits in the first separation membranes for detection; and first flow rate measuring devices for separated liquid detection that measure the flow rates of one or both of the permeated water for detection and the non-permeated water for detection separated by the first separation membrane for detection.

Provided are a cleaning agent and a cleaning liquid that prevent a reduction in the rejection rate of an RO membrane which may occur when the RO membrane is cleaned and a method for cleaning an RO membrane with the cleaning liquid. The agent for cleaning an RO membrane includes a urea derivative. The urea derivative preferably includes urea (H.sub.2N—CO—NH.sub.2) and/or biuret (H.sub.2N—CO—NH—CO—NH.sub.2). The cleaning liquid is an aqueous solution produced by diluting the cleaning agent. The method for cleaning an RO membrane uses the cleaning liquid. Urea and biuret have a structure analogous to amide bonds included in aromatic polyamide RO membranes, and have a strong affinity for amide bond portions. Urea and biuret adsorb onto the amide bond portions, and prevent the amide bonds from being broken by the cleaning liquid.