To provide a sewage treatment method for markedly reducing the production amount of excess sludge while enhancing the quality of treated water, and treatment equipment therefor.
The sewage treatment equipment includes an aeration tank 10 being a biological treatment tank for biologically treating sewage, a solid-liquid separator 11 for subjecting the sewage discharged from the aeration tank 10 to solid-liquid separation treatment to obtain treated water and return sludge, an alkali treatment tank 21 for treating a part of the return sludge with alkali at a pH 9-12.5, the biological solubilizing tank 22 connected to the alkali treatment tank 21 and biologically solubilizing the sludge discharged from the alkali treatment tank 21 under an anaerobic, oxygen-free or microaerophilic condition, and a sludge return means for returning the sludge, which is discharged from the biological solubilizing tank 22, to the aeration tank 10 being the biological treatment tank.
YAO YASUKO
YOMURA YOSHINORI
