Claims
- 1. A method of biologically treating an organic waste water, comprising the steps of:biologically treating the organic waste water in a biological treatment device; solid-liquid separating the waste water treated in the biological treatment device into a treated water and a sludge by a solid-liquid separation device; returning a portion of the sludge separated by the solid-liquid separation device to the biological treatment device; concentrating at least a portion of a residual sludge by a concentration device; and solubilizing the concentrated sludge by thermophilic bacteria in a solubilizing tank.
- 2. The method of claim 1 wherein at least a portion of the treated liquid solubilized by the solubilizing tank is returned to the biological treatment device.
- 3. A method of biologically treating an organic waste water comprising the steps of:biologically treating the organic waste water in a biological treatment device; solid-liquid separating the waste water treated in the biological treatment device into treated liquid and a sludge by a solid-liquid separation device; concentrating the sludge separated by the solid-liquid separation device in a concentration device; returning a portion of the sludge to the biological treatment device; and solubilizing at least a portion of a residual sludge by thermophilic bacteria in a solubilizing tank.
- 4. The method of claim 3 wherein at least a portion of the treated liquid solubilized by the solubilizing tank is returned to the biological treatment device.
- 5. A method of biologically treating an organic waste water comprising the steps of:biologically treating the organic waste water in a biological treatment device having a membrane separation device provided in a tank; concentrating at least a portion of the sludge in the biological treatment device by a concentration device; and solubilizing the concentrated sludge by thermophilic bacteria in a solubilizing tank.
- 6. The method of claim 5 wherein at least a portion of the treated liquid solubilized by the solubilizing tank is returned to the biological treatment device.
- 7. The method of claim 1 wherein the sludge is concentrated to have a water content of 99% or less by the concentration device.
Priority Claims (2)
Number |
Date |
Country |
Kind |
9-351217 |
Dec 1997 |
JP |
|
10-235238 |
Aug 1998 |
JP |
|
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of application Ser. No. 09/173,224, filed Oct. 15, 1998, now U.S. Pat. No. 6,224,769.