What is Dissolved Air Pump Flotation Technology

Solid Liquid Separator August 14, 2025 Dissolved Air Flotation

Dissolved air pump flotation technology is a new type of flotation technology developed in recent years. This technology overcomes the disadvantages of conventional DAF systems, such as the need for multiple auxiliary devices, high energy consumption, and the production of large bubbles in vortex flotation systems. At the same time, it offers the advantage of low energy consumption.

A dissolved air pump uses a vortex pump or a gas–liquid multiphase pump. Its working principle is that air and water enter the pump casing together through the pump inlet, where the high-speed rotating impeller repeatedly shears the incoming air into microbubbles. Under the high-pressure conditions inside the pump, these microbubbles rapidly dissolve into the water, forming dissolved air water, which is then sent to the flotation tank to complete the flotation process. The bubbles produced by the dissolved air pump generally range from 20 to 40 μm in diameter, with a maximum air dissolution rate of up to 100% and a maximum air content in the dissolved water of up to 30%. The pump maintains stable performance even when flow and air volume fluctuate, providing excellent operational conditions for pump adjustment and flotation process control.

A dissolved air pump flotation unit consists of several parts, including a flocculation chamber, contact chamber, separation chamber, scum scraper, dissolved air pump, and release pipe. The basic principle is as follows:
First, the dissolved air pump draws treated water as the return flow, generating dissolved air water (rich in a large number of fine bubbles). The dissolved air water is released via the release pipe into the water in the contact chamber. The fine bubbles rise slowly and adhere to impurity particles, forming aggregates with a density lower than that of water. These aggregates float to the water surface to form scum, which then slowly moves forward with the water flow into the separation chamber, where the scum is removed by the scraper. The clarified water is discharged via an overflow regulator, thus completing the flotation process.

Among the mature and widely applied systems, the EDUR-type high-efficiency flotation unit is a notable example. The EDUR system combines the advantages of vortex flotation (efficient bubble shearing) and dissolved air flotation (stable air dissolution). The complete system mainly consists of a dissolved air system, flotation unit, scum scraper, control system, and auxiliary equipment.