Combined sedimentation and pressure floatation wastewater treatment tank

A combined sedimentation and pressure floatation wastewater treatment apparatus, comprising:

• a tank body containing wastewater;
• a sedimentation treatment device including a plurality of inclined walls and operated to remove relatively heavier sludge from the wastewater by means of sedimentation treatment, with the sedimentation treatment device arranged at a lower portion of the tank body;
• a pressure floatation treatment device operated to remove relatively lighter sludge from the wastewater by pressure floatation treatment, with the pressure floatation treatment device arranged at an upper portion of the tank body above the inclined walls;
• and
• means for alternately flowing the wastewater from the lower portion to the upper portion of the tank body to be initially treated by the sedimentation treatment device and the initially-treated wastewater to be further treated by the pressure floatation treatment device above the inclined walls and reversely flowing the wastewater from the upper portion to the lower portion of the tank body to be initially treated by the pressure floatation treatment device and the initially-treated wastewater to be further treated by the sedimentation treatment device below the pressure floatation treatment device.