Abstract: A process for treating contaminated fluid is disclosed. An apparatus for treatment of contaminated fluid comprises: an integral tank; an inlet for introducing a mixture of flocculent polymer and contaminated fluid; a mixer in the bottom of an innermost cylinder that has first stage aerating means; a rotary skimmer above the fluid level of the innermost cylinder and a second stage aeration cylinder that has second stage aerating means surrounding the innermost cylinder; a de-aeration baffle on the same plane as the rotary skimmer and extending around an outermost cylinder; fluid level control means between the second stage aeration cylinder and the outermost cylinder, directing fluid flow from the second stage aeration cylinder out of the tank; means for powering the mixer and the rotary skimmer; and an outlet permitting clear fluid to exit the tank and an outlet permitting waste effluent to exit the tank.