| 摘要 |
PROBLEM TO BE SOLVED: To prevent the clogging of a membrane in a post-stage by installing a mechanism for adding a reducing agent between a membrane separator in a per-stage and a membrane separator in the post-stage. SOLUTION: An oxygen-containing gas supply line is connected to a nitrification/denitrification tank A, and a flocculation auxiliary 12 injection line is connected between the tank A and a membrane separator B in a pre- stage. A concentrated sludge 4 discharge line connected to the concentration side of the membrane separator B is branched, and one branch line is connected to the tank A and the other is connected to a solid-liquid separator D for separating sludge. Between the membrane separator B and a membrane separator E in a post-stage, reducing agent injection lines 20a, 20b, 20c are connected to three spots of a dephosphorization apparatus C and two spots in front of and behind it. In this way, labor to clean a membrane associated with the clogging of the membrane of the membrane separator E, expenditure for chemicals, and a load for replacing the membrane can be reduced. |
