The DAF unit generates a large number of fine bubbles through dissolved air release; the bubbles attach to suspended particles, oil, and colloidal flocs and rise with them to the water surface to form scum, which is continuously discharged by the skimming device, for efficient separation of oily wastewater and light suspended solids.
Separation Principle
- The air dissolving tank dissolves air in water under pressure, and the release device reduces pressure to form fine bubbles.
- After the bubbles attach to hydrophobic particles, oil droplets, and flocs, the combined density is lower than that of water, and they float to the liquid surface by buoyancy.
- Scum is continuously removed by the skimmer, and clear water flows out from the bottom or middle collection pipe, enabling continuous operation.
Product Features
- It provides targeted separation of light suspended solids and emulsified oil that are close to water density and difficult to settle naturally.
- Short retention time and high surface loading; at the same treatment capacity, the footprint is usually smaller than that of sedimentation processes.
- When combined with coagulation/flocculation units, it can significantly improve the removal efficiency of emulsified oil and colloids.
- Compact structure, fast response during startup and shutdown, suitable for conditions with large fluctuations in water quality and flow rate.
Application Industries
- Pretreatment of oily wastewater in petrochemical, refining, and machining industries.
- Removal of grease and suspended solids from slaughterhouse, food processing, and restaurant wastewater.
- Decolorization of dyeing/printing and papermaking wastewater, and recovery of fibers and fillers.
- Pretreatment of municipal and industrial wastewater and sludge thickening.
Specifications and Models
| Parameter | Unit | Typical value |
|---|---|---|
| Treatment Capacity | m³/h | 5–500 (typical; multiple stages in parallel possible) |
| Dissolved Air Pressure | MPa | 0.3–0.5 (typical) |
| Surface Loading | m³/(m²·h) | 5–12 (typical) |
| Bubble Diameter | μm | 20–50 (typical) |
| Effluent Suspended Solids | mg/L | ≤ 30 (typical; depends on influent) |
| Material | — | Anti-corrosion carbon steel / stainless steel 304, 316L |
The data in the table are common ranges for similar equipment and are for selection reference only; specific specifications, models, materials, connections, and control methods must be confirmed during the selection stage based on water quality, treatment scale, and site conditions.