A filtration method that includes a cleaning step using a chemical agent, wherein provided is the filtration method with excellent chemical resistance performance. The filtration method pertaining to the present invention comprises a filtration step in which a liquid to be filtered is filtered by being passed through a porous membrane formed of a resin, and a cleaning step in which the membrane interior of the porous membrane is cleaned after the filtration step, wherein a porous membrane for which the area ratio of a resin part having an area of 1 μm.sup.2 or less included in a cross section of the membrane interior is at least 70% of the total area of the entire resin part included in the cross section, and said cleaning step includes a step in which an aqueous solution of at least 1% sodium hydroxide is passed through the porous membrane.

A device for filtering liquids, including a filtration module and an ultrasound emission module, where the ultrasound emission module is fixed distant from the filtration module using a fixing means, and the ultrasound emission module is equipped coaxially along its axis with a weight or is equipped perpendicular to its axis with at least one weight, the filtration module and the ultrasound module equipped with its at least one weight going into resonance via the fixing means when the ultrasound emission module emits ultrasound.

A device for filtering liquids, including a filtration module and an ultrasound emission module, where the ultrasound emission module is fixed distant from the filtration module using a fixing means, and the ultrasound emission module is equipped coaxially along its axis with a weight or is equipped perpendicular to its axis with at least one weight, the filtration module and the ultrasound module equipped with its at least one weight going into resonance via the fixing means when the ultrasound emission module emits ultrasound.

A cleaning solution for accelerated cleaning of a membrane having an enzyme and an agent having a pH that is compatible with the enzyme. The cleaning solution may additionally include one or both of a binding agent and a surfactant. Once the cleaning solution has been included in a solution that is used to contact the membrane for a defined period of time, one or both of a binding agent and a reducing agent may be added to the solution that has contacted the membrane. Optionally, one or both of increasing a pH of the solution and increasing a temperature of the solution may be used to reduce an activity of the enzyme.

A cleaning solution for accelerated cleaning of a membrane having an enzyme and an agent having a pH that is compatible with the enzyme. The cleaning solution may additionally include one or both of a binding agent and a surfactant. Once the cleaning solution has been included in a solution that is used to contact the membrane for a defined period of time, one or both of a binding agent and a reducing agent may be added to the solution that has contacted the membrane. Optionally, one or both of increasing a pH of the solution and increasing a temperature of the solution may be used to reduce an activity of the enzyme.

An ion suppressor includes ion exchange membranes between a pair of electrodes. Regeneration liquid channels are provided in the spaces between the electrodes and the ion exchange membranes, and an eluent channel is provided between the ion exchange membranes. In the space between the electrode and the eluent channel, an element that increases the resistance in the voltage application direction is disposed. For example, ion permeable membranes are disposed in contact with the ion exchange membrane, thereby increasing the resistance in the voltage application direction.

An ion suppressor includes ion exchange membranes between a pair of electrodes. Regeneration liquid channels are provided in the spaces between the electrodes and the ion exchange membranes, and an eluent channel is provided between the ion exchange membranes. In the space between the electrode and the eluent channel, an element that increases the resistance in the voltage application direction is disposed. For example, ion permeable membranes are disposed in contact with the ion exchange membrane, thereby increasing the resistance in the voltage application direction.

An aerator device and a filter system including the same are provided. The aerator device includes: a housing having an inner cavity defined therein, the housing including at least one sidewall and an upper surface connected to the at least one sidewall; a first partition formed within the inner cavity and extending from an upper end to a lower end to define a first cavity and a second cavity; and a second partition formed within the inner cavity between the first partition and a first sidewall of the at least one sidewall and extending from an upper end to a lower end to define a first chamber and a second chamber of the second cavity, and the housing includes an inlet opening communicating with the first cavity and an outlet opening communicating with the second chamber, and the second chamber gradually narrows towards the upper surface of the housing.

An aerator device and a filter system including the same are provided. The aerator device includes: a housing having an inner cavity defined therein, the housing including at least one sidewall and an upper surface connected to the at least one sidewall; a first partition formed within the inner cavity and extending from an upper end to a lower end to define a first cavity and a second cavity; and a second partition formed within the inner cavity between the first partition and a first sidewall of the at least one sidewall and extending from an upper end to a lower end to define a first chamber and a second chamber of the second cavity, and the housing includes an inlet opening communicating with the first cavity and an outlet opening communicating with the second chamber, and the second chamber gradually narrows towards the upper surface of the housing.

A system for treating a tetraalkylammonium hydroxide-containing liquid having a high-pressure type reverse osmosis membrane device concentrating a liquid to be treated containing tetraalkylammonium hydroxide at a concentration side, and a line for supplying the concentrated liquid to be treated by the reverse osmosis membrane device to an evaporator further concentrating the concentrated liquid to be treated.