| 摘要 |
In a method of membrane separation of filtrating water to be treated (2) by a membrane module (3) in a biological treatment tank (1) and alternately carrying out nitrification and denitrification treatments in the biological treatment tank (1), during the nitrification treatment, an oxygen including gas as an aeration gas for aerating the membrane module (3) is introduced into the water to be treated (2) and during the denitrification treatment, introduction of the oxygen including gas is stopped and an inner tank gas in the biological treatment (1) is used to circulate as the aeration gas of the membrane module (3). In this case, aeration of the membrane module is carried out both in the nitrification and denitrification treatments. Therefore, even in the denitrification treatment, filtration of the water to be treated by the membrane module is made possible and when the water amount of the water to be treated which is to be treated in the nitrification and the denitrification treatments is intended to be maintained constant, compared with a case in which the filtration is carried out only in the nitrification treatment, an area of a membrane of the membrane module (3) is reduced. <IMAGE> |
