The gas dissolved in water by dissolved air flotation can escape from the water when the water surface pressure drops.

There are two ways:

① Make the space on the air flotation tank a vacuum state, and the water under normal pressure will release micro-bubbles after flowing into the tank, which is called vacuum dissolved air method;

②The air is dissolved into the water under pressure to reach saturation, and the dissolved air flow will release microbubbles when it enters the air flotation tank under reduced pressure, which is called the pressurized dissolved air method. The latter is more commonly used. The pressurized dissolved air water can be all or part of the water to be treated, or it can be the return water from the effluent of the air flotation tank. The percentage of the return water to the treated water is called the reflux ratio. It is an important factor affecting the efficiency of air flotation and must be determined by experiments. . The equipment of the pressurized dissolved air method includes a pressurized pump, a dissolved gas tank, and an air compressor. The dissolved gas tank is a pressure-bearing steel cylinder with a deflector or packing inside. The effluent of the dissolved gas tank enters the air flotation tank through a pressure reducing valve or a release device. 

https://www.khnwatertreatment.com/