Get to Know Dissolved Air Flotation and How It Works

In industrial operations, water quality can affect the smoothness of production processes and the efficiency of wastewater treatment. Therefore, choosing the right water treatment technology becomes an important factor for various industrial sectors.

Dissolved Air Flotation (DAF) is a widely used technology for separating suspended solids, oil, and grease from water. To understand how it works, what it’s used for, and its advantages, read the full explanation below.

What Is DAF in Manufacturing?

Dissolved Air Flotation (DAF) is a water treatment method that uses micro-sized air bubbles to separate suspended solids, oil, grease, and other contaminants from water.

This method is widely used in both wastewater and clean water treatment systems across various industries as part of the pretreatment stages.

Practically, DAF is generally used as a pretreatment step to reduce the contaminant load before the water enters the next treatment process.

How Dissolved Air Flotation Works

In its industrial application, the DAF process can be combined with coagulants and flocculants to help bind small particles into flocs that are easier to separate. In general, the way DAF works goes through the following stages:

1. Pre-Treatment and Coagulation-Flocculation

Wastewater can go through a pre-treatment process before entering the DAF unit. If needed, coagulants and flocculants are added to help combine small particles into larger flocs, making them easier to catch with air bubbles during the flotation process. Flocs themselves are clusters of particles that have come together, making them easier to separate from the water.

2. Air Dissolution  

Part of the water flow is circulated into a pressure tank. Inside the tank, air is dissolved into the water under high pressure, around 3–6 bar. The water now contains dissolved air and is directed back to the flotation unit.  

3. Pressure Release and Formation of Microbubbles  

Water with dissolved air is released through a pressure-reducing valve into the flotation tank. This pressure change causes the air to come out of the solution in the form of very tiny microbubbles.

4. Contaminant Flotation 

Microbubbles attach to flocs, oil, grease, and suspended solids in the wastewater. The combination of bubbles and contaminants becomes lighter, so it moves to the surface of the tank and forms a layer of floating material.

5. Separation of Material and Treated Water  

The contaminants that have floated to the surface will form a layer of float sludge or floating mud. This layer is removed using a skimmer, which is a mechanical tool designed to collect material floating on the surface of the tank.  

Meanwhile, the water that has been separated will go out through the bottom of the tank to move onto the next treatment stage or be adjusted according to the operational needs of the industrial wastewater treatment system.

Relevant Article: What Are the Water Quality Parameters? Check Out Here!

Advantages of Dissolved Air Flotation

Dissolved Air Flotation (DAF) has several advantages in supporting industrial water and wastewater treatment processes. Here are some of them:

• Effectively removes suspended solids: Dissolved Air Flotation (DAF) can separate suspended solids, oils, greases, and light particles that are hard to settle using conventional sedimentation methods.
• Capable of handling particles that are difficult to settle: Unlike sedimentation, which relies on gravity, DAF uses microbubbles to lift particles with densities close to water, such as oils, greases, algae, and biological flocs, making them easier to separate.
• The process is relatively fast: The flotation mechanism allows the separation process to take place in a shorter time compared to conventional settling methods. This can help improve operational efficiency, especially in industrial facilities with large processing capacities.  
• Needs a more compact installation space: DAF units generally have a more compact design compared to sedimentation tanks of similar capacity. This advantage makes it a suitable choice for industries with limited land space.
• Flexible for various operational needs: The DAF system can be adjusted to the characteristics of the wastewater as well as the water quality targets you want to achieve. Operation parameters, such as pressure, flow rate, and the use of coagulants and flocculants, can be optimized according to the needs of each industry.
• Helps reduce the load on further treatment processes: By separating most suspended solids, oils, and greases in the early stage, DAF can reduce the load on biological processes and the next treatment units. This can potentially improve the overall performance of industrial wastewater treatment systems.

Further Reading: Getting to Know Membrane Bioreactors in Wastewater Treatment

Uses of Dissolved Air Flotation

In industrial water and wastewater treatment, Dissolved Air Flotation (DAF) is used to separate certain contaminants through a flotation process. In general, some of its uses include:

• Reducing total suspended solids (TSS).
• Separating oils and greases (FOG).
• Lowering BOD and COD loads.
• Improving the efficiency of further treatment processes.
• Supporting industrial wastewater treatment in various sectors, such as mining and oil and gas industries.
• Recovering valuable oils and fats from wastewater in food production processes so they can be reused.

Differences Between Dissolved Air Flotation and Sedimentation

Although both are used in water and wastewater treatment, DAF and sedimentation have different working principles and characteristics. Here is what sets them apart:

Let's Treat Industrial Wastewater More Effectively with CDI  

Proper wastewater management is an important part of maintaining the sustainability of industrial operations. For that reason, a company needs support from water treatment facilities and services that can be adjusted to the needs and characteristics of the wastewater produced.

As an associated company of PT Chandra Daya Investasi Tbk (CDI), PT Krakatau Tirta Industri (KTI) provides integrated industrial water solutions, ranging from supplying clean water, treating demineralized water, to industrial wastewater treatment.

In the field of wastewater treatment, KTI, through its subsidiary, PT Krakatau Blue Water (KBW), which is a joint venture with Blue O&M Co Ltd., supports wastewater treatment using conventional and membrane technologies to reduce pollutant levels.

KTI also operates a Wastewater Recycling Plant (WRP) that allows treated water to be reused for certain needs, supporting water use efficiency in industrial operations, for example, in building cooling systems. 

Besides treatment facilities, KTI provides Operation & Maintenance (O&M) services to support the operation and maintenance of industrial wastewater treatment facilities. 

So, if you need industrial water solutions, including demineralized water treatment or wastewater treatment, trust your company's needs to CDI and KTI. 

To get more complete information or discuss your industrial water treatment needs, contact us to get solutions that suit your operational requirements.

With the spirit to be #YourGrowthPartner, CDI and KTI are ready to support reliable and sustainable industrial water management needs.

More to Explore: What Is Sea Water Reverse Osmosis? Understand How It Works!