Introduction of Dissolved Air Flotation system

DAF machine, namely Dissolved Air Flotation system, is a highly efficient sewage treatment equipment, which is widely used in industrial wastewater treatment, urban sewage treatment and water purification.

1. Definition and working principle

DAF flotation device is a solid-liquid or liquid-liquid separation device used for sewage treatment. Its working principle is: a large number of microbubbles are generated by high-pressure reflux dissolved air water to reduce pressure. These microbubbles adhere to solid or liquid particles with a density close to water in the wastewater to form a floating body with a density less than water. Under the action of buoyancy, these floating bodies float to the water surface, thereby achieving solid-liquid or liquid-liquid separation.

2. Structural composition

DAF machine is mainly composed of the following parts:

Floating machine: It is the main body and core of sewage treatment. It usually adopts a square steel structure, which contains a releaser, an emptying pipe, a water outlet pipe, a sludge tank, a scraper and a transmission system. The releaser is placed in the center of the flotation machine and is a key component for producing microbubbles.

Dissolved air system: including dissolved air tanks, air storage tanks, air compressors, high-pressure pumps, etc. The function of this part of the system is to supersaturate the air and dissolve it in the water to form dissolved air water.

Agent tank: used to store and process the coagulants, flocculants and other agents required in the process.

3. Workflow

The workflow of the DAF machine is as follows:

Mixing and dissolving air: Part of the treated clean water (usually 20%-40% of the design index, usually 30%) is pressurized by the flotation circulation working pump into the dissolved air tank and mixed with air to dissolve the air into the water to form dissolved air water.

Microbubble generation: After the dissolved air water reaches a certain pressure in the dissolved air tank (usually 0.3-0.4MPa), it is suddenly decompressed and released by the releaser, and the air dissolved in the water is released in the form of tiny bubbles. The particle size of these bubbles is usually between 20-50μm.

Floatation separation: The dissolved air water containing microbubbles enters the flotation tank and mixes with the raw water with flocculants added. The microbubbles quickly attach to the suspended matter and lift it to the surface of the flotation tank to form a sludge floating layer that is easy to remove. At the same time, heavier solids settle at the bottom of the tank.

Sludge treatment: The scum on the top of the flotation tank is scraped off by a scraper and discharged into the sludge tank for subsequent treatment. The clean water at the bottom of the tank enters the flotation clean water tank through the clean water supply pipe. Except for part of it being used as reflux dissolved air water, it can be directly discharged to the outside or enter the next level of treatment equipment.

4. Application Scope

DAF machines are widely used in the following fields due to their advantages such as high efficiency, fast speed and small footprint:

Industrial wastewater treatment: wastewater treatment in industries such as electroplating, printing and dyeing, papermaking, chemical industry, textile, meat processing, oil refining, canned food, etc. DAF equipment can be used to remove pollutants such as suspended solids, grease, metal ions and organic matter in wastewater to meet environmental protection regulations

Urban sewage treatment: used to improve the water quality of urban sewage and remove impurities such as suspended solids, grease, heavy metal ions, etc. Through the DAF process, solid particles and impurities such as grease in urban sewage can be effectively separated, thereby improving the effluent quality and reducing pollution to natural water bodies

Water purification: used for water purification of natural water bodies such as rivers, lakes, etc. to improve water quality.

5. About Nihao Water's DAF equipment

Nihao DAF Machine performs well in removing suspended solids in sewage, with a total suspended solids (TSS) reduction of up to 97% and a chemical oxygen demand (COD) removal rate of up to 85%, which is of great significance for reducing water pollution and protecting the ecological environment.

Nihao Water's DAF equipment also has the ability to treat high-salinity water. This is especially important for companies in coastal areas or those that need to treat high-salinity industrial wastewater. If your factory is located near a port and needs to treat high-salinity industrial wastewater, you might as well try Nihao DAF Machine.