Abstract: A hollow fiber porous membrane includes polyethersulfone or polysulfone. The hollow fiber porous membrane has an inner diameter from 300 to 600 ?m, a thickness from 70 to 200 ?m, a molecular weight cut-off of 10000 or lower, and a plurality of pores having a pore diameter from 0.1 to 0.5 ?m throughout an outer surface; and a swelling rate of less than 5% as defined below: Swelling Rate (%): for 20 or more of the hollow fiber porous membranes, after a membrane thickness in a cross section of each one of the hollow fiber porous membranes in the width direction is measured at randomly selected 10 or more locations, an average membrane thickness is calculated based on 200 or more locations in total, and the swelling rate is calculated by a formula below: Swelling Rate (%)=(location numbers where the membrane thickness as measured exceeded 1.3 times the average membrane thickness)/(membrane thickness measurement numbers)×100.

Abstract: The present invention provides an aeration device made up of a rectangular elastic porous body, a support base supporting the elastic porous body from below and having an orifice for pressurized air, and a securing component which secures the elastic porous body to the support base integrally, wherein the support base contains a supporting portion supporting the elastic porous body from below and an attaching portion connected to the supporting portion and attaching the supporting portion to a pressurized air distribution pipe, the rectangular elastic porous body having a box shape having an opening portion, and the supporting portion being disposed in an elastic porous body. In addition, the present invention provides an aeration system made up of two or more of the above described aeration devices installed on a pressurized air distribution pipe, wherein each aeration device is disposed contacting mutually with no space between them.

Abstract: Provided a method for treating hardly-decomposable-substance-containing water, in which hardly decomposable substances such as dioxins, contained in contaminated water (treatment raw water) are concentrated and rendered harmless by providing the steps of (B) adding an adsorbent to water containing a hardly decomposable substance (treatment raw water) to cause the hardly decomposable substance to be adsorbed on the adsorbent (adsorption treatment step), (C) separating a permeated liquid through a filter membrane to concentrate the adsorbent adsorbing the hardly decomposable substance (membrane filtering treatment step), and (D) chemically decomposing the hardly decomposable substance adsorbed on the concentrated adsorbent with a peroxide without any operation of desorption from the adsorbent (chemical decomposition step), and the method can be applied to water containing a reducing substance such as bisulfate that neutralize free chlorine and can render the hardly decomposable substances harmless efficiently a