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