Patent ID: 8784658
Filing Date: 2014-07-22
Classification: C02F,Y02W

Abstract:
1. A process for treating wastewater comprising: a. a contact step, wherein wastewater contacts bacteria retained on a support surface and the dissolved oxygen concentration of the wastewater is maintained at 1.0 mg/l or less, wherein the wastewater is maintained at the dissolved oxygen concentration by control of the supply of the oxygen to the wastewater; b. an aeration step, wherein gas is passed through wastewater that has passed through the contact step and the dissolved oxygen concentration of the wastewater is reduced as the wastewater passes through the aeration step; c. a sedimentation step, wherein wastewater that has passed through the aeration step is substantially separated into treated water and sludge; and d. a sludge recycling step, wherein sludge from the sedimentation step is continuously passed to the contact step.