To suppress the amount of conversion into sludge in aerobic treatment and make treated water possible to be discharged to sewerage system by treating wastewater containing organic solid matter such as garbage wastewater in an aerobic digestion tank, separating sludge in the aerobic digestion tank in a sedimentation tank, and then carrying out aerobic treatment fro separated wastewater.
Solid matter contained in organic solid-containing wastewater is decomposed by function of aerobic microorganism in an aerobic digestion tank 11 and the treated water 112 is transported to a contact aeration tank 13 by an air lift pump 14. Separated wastewater 111 treated in the sedimentation tank 12 and containing soluble organic matter is transported to a contact aeration tank 13 through a wastewater pipe 2. On the other hand, the sludge separated in the sedimentation tank 12 is transported to the contact aeration tank 13 while being stirred by an aeration apparatus 121 in the aerobic digestion tank 11. The treated water 113 of the contact aeration tank 13 overflows and is released out of the tank 13 at the time when the separated wastewater 111 and the treated water 112 flows into the tank 13.
YAMANE TOSHIO
FURUMURA HIDEMA
KOSHIMIZU SATORU
TAISEI CORP