Flotation clarifier removes suspended solids as well as fats, oils, greases, and heavy metals. This system uses a two chamber chemical mixing zone, where each chamber has five minutes of mixing time and its own variable speed mixer. It is provided with an elongated settling tank having an inlet at one end, an outlet at the opposite end, a generator producing air saturated liquid released near the inlet end of the tank to float lighter sludge to the top of the tank. The recirculating effluent is pumped to a mixing device that is to be saturated with air. The air saturated effluent is discharged back into the inlet end of the tank. A pressurized tank for air saturated effluent receives the admixed air and effluent from the mixing device into the bottom. The air from the top of the tank is compressed by a liquid ring compressor to charge the mixing device. The dissolved air flotation takes place at the inlet end of the tank and the floating froth or scum is pushed into the top of the collector trough extending across the inlet end of the tank.