Abstract: This invention provides an aerator comprising a jet stream generator for ejecting a gas and a liquid in a mixed state from a nozzle, and a tubular flow straightener for mixing the bubble-containing stream ejected from the nozzle with ambient water and discharging the resulting mixture from the discharge orifice thereof, characterized in that the flow straightener has a tubular form whose internal diameter is reduced from the inlet toward the discharge orifice through at least a part of its length.This aerator can produce a stream containing minute gas bubbles, even when a gas is supplied thereto in such a large amount as to give a gas-to-liquid volume ratio of 3/1.

Abstract: The present invention provides a hollow-fiber filter module comprising a straight tube, a bundle of hollow fibers having at least a part thereof disposed within the straight tube, a fastening member for bundling and fixing the open ends of the hollow fibers, and at least a branch tube having an end protruding to the outside of the straight tube, that surface of the fastening member which includes the open ends of the hollow fibers being attached to the branch tube in a fluid-tight manner, as well as a filtration method in which a plurality of such hollow-fiber filter modules are connected in series to form a filter module assembly and a fluid to be treated is filtered by utilizing one end of the connected straight tubes of the assembly as an inlet for the fluid to be treated, the other end thereof as an outlet for the fluid to be treated, and the branch tube of each module as an outlet for the filtered fluid.

Abstract: Flake- or sliver-like porous structures of a polymeric material heavily loaded with a finely divided inorganic substance are prepared by spurting a mixture of the polymeric and finely divided inorganic components in a solvent. The products have many fine, irregular voids. The thickness of walls forming such voids is 5.mu. or less. The products are especially useful for producing sheet-like structures therefrom by beating and/or refining them followed by general paper making procedures. The sheets, when calendered, have a high initial modulus and improved dimensional stability.

Abstract: An inorganic substance composition comprising at least 50% by weight of a finely divided inorganic substance and 2 to 50% by weight of a fiber forming organic polymeric material and having a specific surface area of more than 2 m.sup.2 /g is described. The composition is prepared by preparing a liquid suspension from the inorganic substance, the organic polymeric material and a solvent; heating the liquid suspension to at least 100.degree. C to dissolve the organic polymeric material in the solvent; and then extruding the heated liquid suspension at a pressure equal to or higher than the vapor pressure of the solvent through an orifice into a zone of a lower pressure to evaporate the solvent.