Dissolved air flotation process (DAF process) is an efficient and fast method for separating solid particles from water and wastewater.

How it works:

Part of the treated wastewater is circulated into the dissolved air tank. In the state of pressurized air, the air is supersaturated and dissolved, and then mixed with the raw water added with flocculant at the inlet of the air flotation tank. Due to the pressure reduction, the supersaturated air is released. Tiny air bubbles are formed, which quickly attach to the suspended matter, lifting it to the surface of the flotation tank. This forms a sludge floating layer that is easy to remove, and the heavier solid matter settles at the bottom of the tank and is also removed.

Some DAF unit designs utilize parallel plate packing material (e.g. lamellas) to provide more separation surface and therefore to enhance the separation efficiency of the unit.

Scope of application:

It is suitable for purifying sewage with high chroma, low dissolved oxygen and many organic impurities. It is especially effective for sewage purification with low water temperature and unsuitable gravity sedimentation. This process is suitable for industrial wastewater treatment and production water treatment after printing and dyeing, electroplating, tanning, papermaking, chemical industry, textile, meat processing, oil refining, canned food, etc. It is also suitable for the separation of biological mud film and water in biological treatment. .

Process features:

1. Under pressurized conditions, the solubility of air is large, and the number of air bubbles used for air flotation is large, which can ensure the air flotation effect;

2. The dissolved gas is suddenly decompressed and released, and the generated bubbles are not only fine, uniform in particle size, high in density, but also float stable and have little disturbance to the liquid, so it is especially suitable for solid-liquid separation of loose flocs and fine particles;

3. The technological process and equipment are relatively simple, which is easy to manage and maintain; especially the partial reflux type, the treatment effect is remarkable and stable, and the energy consumption can be greatly saved.