Induced Gas Flotation (IGF) units are sometimes used when the injection of air is not recommended e.g. when the risk of potentially hydrocarbon-rich environment could increase the risk of explosion in presence of oxygen. In such conditions natural gas is used instead of air.

Dissolved air flotation (DAF) is the technique for removal of oil and suspended matter achieved by dissolving air in water or wastewater under pressure and then releasing air at atmospheric pressure in a flotation tank or basin. A portion of the clarified effluent water leaving the DAF tank is pumped into a pressure vessel (air drum) into which compressed air is also introduced. This results in saturating the pressurized effluent water with air. The air-saturated water stream is recycled to the front of the float tank and flows through a pressure reducing valve which results in air being released in the form of tiny bubbles. The bubbles adhere to suspended matter and make it float to the surface from where it is then removed by a skimmer.