What Is a DAF System?
The Dissolved Air Flotation (DAF) system is a highly efficient solid-liquid separation technology widely used in industrial wastewater treatment.
It works by generating a large number of microbubbles (10–30 μm) that attach to suspended solids, oil, and grease. These particles become lighter than water and float to the surface, where they are removed by a skimming system.
DAF is especially suitable for:
- Removing SS (Suspended Solids)
- Reducing COD / BOD
- Separating oil & grease
- Improving downstream filtration efficiency
How the DAF System Works
Working Process Overview
| Step | Process Description |
| 1 | Wastewater enters the DAF tank after pre-treatment |
| 2 | Part of treated water is recycled and pressurized with air |
| 3 | Air dissolves into water in a pressure tank (air saturation) |
| 4 | Sudden pressure release generates microbubbles |
| 5 | Microbubbles attach to suspended particles |
| 6 | Floated sludge rises to surface and is scraped off |
| 7 | Clean water flows out from the bottom |
Performance Benefits
- Microbubble size: 10–30 μm → strong adhesion capability
- High removal efficiency: up to 95%+ for SS and oil
- Compact design: saves installation space
- Stable operation: continuous and reliable performance
- Low maintenance: simple mechanical structure
- Flexible adjustment: sludge level and skimming speed adjustable
Typical Application Fields
DAF systems are widely used across multiple industries:
- Plastic recycling washing lines (removal of oil, labels, fines)
- Petrochemical wastewater
- Food processing & slaughterhouse wastewater
- Textile & dyeing industry
- Paper mills
- Pharmaceutical wastewater
- Landfill leachate treatment
- Water reuse & polishing treatment
Why DAF Is Important in Plastic Recycling
In plastic recycling plants (PET, PP, PE washing lines), wastewater often contains:
- Fine plastic particles
- Labels & paper fibers
- Oil and organic residues
The DAF system effectively:
- Removes floating contaminants
- Reduces sludge load in later stages
- Improves water reuse efficiency
- Helps meet environmental discharge standards
Conclusion
The Dissolved Air Flotation (DAF) system is a key solution for modern wastewater treatment, especially in plastic recycling operations. With its high efficiency, compact structure, and reliable performance, it significantly improves water quality and reduces environmental impact.
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