Method and apparatus for treating developer-containing waste water at multiple biological treatment stages

摘要

Developer-containing waste water is subjected to a multi-stage biological treatment. A waste water treatment apparatus for carrying out a two-stage biological treatment has an adjustment tank for receiving raw waste water and for preliminarily adjusting water quality of the waste water. First and second contact aeration tanks are used to biologically treat the waste water. First and second settling tanks are connected to the first and second contact aeration tanks for separating by sedimentation sludge from the waste water. Specifically, the first settling tank is connected to the second contact aeration tank. Sludge separated from the waste water is returned from the first and second settling tanks to first and second mixing tanks, respectively, and mixed with Bacillus Subtilis Kubota (BSK) and excess household sludge. The mixture is aerated and then transferred to the first and second contact aeration tanks, respectively. The aerated mixture in the first mixing tank is also transferred to the adjustment tank in accordance with the water quality of the raw waste water.