Abstract: The present invention provides a gas-permeable hollow fiber membrane having an inner diameter of 50 to 500 &mgr;m, which is preferably a composite hollow fiber membrane having a three-layer structure consisting of a nonporous layer having porous layers disposed on both sides thereof. This membrane can be used to remove dissolved gases present in an ink.

Abstract: The invention concerns a gas diffuser constructed and arranged to disperse gas into a aeration vessel of a water treatment assembly from a blower. The gas diffuser includes main pipes, branch pipes extending between the main pipes and containing gas discharge ports, wherein the branch pipes have a smaller cross-sectional area than the cross-sectional area of the main pipes. The gas discharge ports are further sized, constructed and arranged to reduce the possibility or likelihood of sludge from blocking the ports or entering the branch pipes. This object is achieved either by placement of the ports on the bottom sides of the branch pipes or, alternatively, by construction of the ports to include conduit members, themselves having an arrangement of openings or coverings to prevent or reduce the likelihood of sludge from blocking the ports or entering the branch pipes.

Abstract: A method for cleaning separating membranes uses a uniquely formulated detergent. The detergent includes a percarbonate-containing, material, existing in the condition in which hydrogen peroxide is adducted in carbonate and is desirably an alkali metal salt. The percarbonate decomposes the organisms deposited on the membrane surfaces while being environmentally desirable. The detergent preferably also includes at least one bivalent iron salt, which improves the cleaning capability of the percarbonate via the so-called Fenton's reaction in which hydrogen peroxide adducted in the percarbonate reacts with the iron ions to form OH— radicals which have a very high oxidative reactivity. The detergent may also contain other oxidizers, a surfactant, a chelating agent, an acid and a pH regulator. The detergent is dissolved in water prior to use.

Abstract: A membrane separator assembly for separating solids from water includes opposing enclosure wall structures, a membrane module unit, and a gas diffuser disposed below the membrane module unit. The membrane module unit includes a plurality of membrane modules respectively having at least one separating membrane extending between at least two membrane fixing members. At least one of the membrane fixing members has a main passage which is in fluid communication with a membrane passageway. The membrane passageway is accessible to water via permeation through the separating membranes and is inaccessible to solids which are impermeable relative to the separating membranes. The membrane separator assembly is preferably used with a detergent containing percarbonate, preferably sodium percarbonate. The assembly also includes a gas diffuser with two opposing main pipes and branch pipes extending therebetween to avoid undesired pressure differentials when cleaning the assembly.

Abstract: The described method is for the preparation of a carbonate spring by supplying carbon dioxide to a carbon dioxide dissolver and dissolving the carbon dioxide in raw water and includes of measuring the pH of the formed carbonate spring, calculating the carbon dioxide concentration data of the formed carbonate spring from the measured pH value and the alkalinity of the raw water, and controlling the feed rate of the carbon dioxide supplied to the carbon dioxide dissolver so as to make the carbon dioxide concentration data equal to a preset target carbon dioxide concentration value. According to this method, a carbonate spring having a desired concentration can be easily prepared by using an inexpensive pH measuring device.