High Solids Dissolved Air Flotation System and Methods

A method of treating wastewater comprising:

• directing the wastewater into an aeration unit and aerating the wastewater with oxygen to form an aerated mixed liquor;
• directing the aerated mixed liquor into a contact tank and mixing the aerated mixed liquor with an activated sludge to form an activated mixed liquor;
• directing the activated mixed liquor into a dissolved air flotation unit and separating the activated mixed liquor to form a floated biosolids and an effluent;
• selectively directing a first portion of the floated biosolids into the aeration unit and a second portion of the floated biosolids into the contact tank;
• and
• directing the effluent into a biological treatment unit and biologically treating the effluent to form a biologically treated mixed liquor.

A method of retrofitting a wastewater treatment system comprising a contact tank, a dissolved air flotation unit, and a biological treatment unit, the method comprising:

• providing an aeration unit having a first inlet fluidly connectable to a source of wastewater to be treated, a second inlet fluidly connectable to a source of oxygen, a third inlet, and an outlet, the aeration unit configured to aerate the wastewater with the oxygen to form an aerated mixed liquor;
• fluidly connecting the outlet of the aeration unit to an inlet of the contact tank;
• and
• fluidly connecting the third inlet to a floated solids outlet of the dissolved air flotation unit.