PURPOSE: To prevent the increase in stickiness, by mixing fresh water with sludge in an amount 2W10 times that of excessive sludge before or immediately after flowing sludge into a sludge aeration tank.
CONSTITUTION: Org. waste water is supplied to an aeration tank 2 and air is blown in the aeration tank 2 by a blower B and an air diffuser 2a to purify activated sludge. Excessive sludge is supplied to a sludge aeration tank 8 from a flow line 7 and fresh water is mixed in excessive sludge immediately before or immediately after flowed in the sludge aeration tank 8 from a flow line 9 in an amount 2W10 times that of excessive sludge. Air is blown in the sludge aeration tank 8 by a blower B and an air diffuser 8a to reduce the amount of excessive sludge. The excessive sludge subjected to amount reduction treatment is supplied to a sedimentation tank 10 and supernatant water is sent to a flocculative sedimentation tank 4 through a flow line 11.
KAWAKAMI MASAKI
FUJII YOSHIHARU
ISHIDA KOJI
