NOVELTY - The method comprises configuring a dissolved air flotation (DAF) unit (120) in a wastewater treatment system in fluid communication between a contact tank (110) and a biological treatment unit (130) to remove solids from a portion of a first mixed liquor output from the contact tank prior to the portion of the first mixed liquor entering the biological treatment unit and to recycle a portion of the solids to the contact tank. The recycle of the portion of the solids to the contact tank reduces an amount of biological oxygen demand to be treated in the biological treatment unit.    USE - The method is useful for facilitating increased operating efficiency of a wastewater treatment system (claimed).    ADVANTAGE - The method is capable of economically, rapidly, energy-efficiently and eco-friendly facilitating the increased operating efficiency of the wastewater treatment system.    DETAILED DESCRIPTION - The method comprises configuring a dissolved air flotation (DAF) unit (120) in a wastewater treatment system in fluid communication between a contact tank (110) and a biological treatment unit (130) to remove solids from a portion of a first mixed liquor output from the contact tank prior to the portion of the first mixed liquor entering the biological treatment unit and to recycle a portion of the solids to the contact tank. The recycle of the portion of the solids to the contact tank reduces an amount of biological oxygen demand to be treated in the biological treatment unit as compared to the wastewater treatment system operating in the absence of recycling the portion of the solids to the contact tank. Greater than 50% of the solids are recycled from the DAF unit to the contact tank. The method further comprises recycling the solids from the DAF unit to the contact tank in an amount sufficient to increase biogas production of an anaerobic digester of the wastewater treatment system having an inlet in fluid communication with an outlet of the DAF unit, where a second portion of the solids removed in the DAF unit is directed into the anaerobic digester, and recycling the solids from the DAF unit to the contact tank in an amount sufficient to reduce the energy consumption of the wastewater treatment system. INDEPENDENT CLAIMS are included for:    (1) a wastewater treatment system; and    (2) a method for treating wastewater.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a wastewater treatment system.    Wastewater source (105)    Contact tank (110)    DAF unit (120)    Biological treatment unit (130)    Clarifier. (140)