TECHNICAL INFORMATION
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TECHNICAL INFORMATION
DAF
HELIFLOT™: Innovation of Dissolved Air Flotation
- 1. Overview of the general Dissolved Air Flotation (DAF):
- DAF is a water treatment technology that purifies water by removing suspended matter through the use of fine bubbles from dissolved air.
Advantages and disadvantages of DAF compare to Sedimentation
| Advantages | Disadvantages |
|---|---|
|
• High speed treatment • Produces thick sludge • Shorter flocculation detention time • Shorter start-up lead time • Compact facilities required • Omissible for recovered sludge thickener |
• Requires more complex facilities • Consumes more electrical power • Unsuitable for highly silt-laden water |
- 2. Introduction of HELIFLOT™
- HELIFLOT™ is a cylindrical DAF unit that runs with helical flows, developed by Aquosys.
- Raw water and fine bubbles are fed into the flotation tank (①) by an inflow pipe connected to the tangent (②).
- Suspended materials form flocs with fine bubbles, creating a helical flow with the water to move upwards (⑥) and gather around the center of the water surface (⑧). The flocs are discharged out of the flotation tank through a scum outflow pipe (④).
- The treated water then creates another helical flow to move downward (⑦) inside of the helical flow moving upwards.
They are then discharged continuously out of a treated water outflow pipe (③). - The water level of the flotation tank is controlled with a flow control valve (⑨) suitable for scum control.
- Silt or something dense moves to an outer position on the flotation tank by centrifugal force. It settles down to the conical bottom and then evacuates to the outside periodically (⑤).
- 3. A suspended material removal process by the HELIFLOT™
- Simple and high efficiency
- 4. Applicable wide range of contaminated water treatment
- From very low concentrations of algae water to high concentrations of settled sludge:
Algae Water Treatment
Sludge Concentration
- 5. Comparison with HELIFLOT™ to the conventional DAF
| Conventional DAF | HELIFLOT™ |
|---|---|
|
• More complex facilities required: – Scum skimmer, subnatant remover and (settling lamella plates) needed. • Weak on load fluctuation • Unsuitable for treating high silt-laden water. • Compact facilities required: – Detention time(min): Floating: 10 ~ 20. Conglomeration: 14 ~ 20. • Chemical consumption(ppm): – Organics: 5 ~ 10 – Inorganics: 10 ~ 30 (normally both chemical required) • Consumes more electric power: (1,000 ~ 1,200 kWh/5Ⅹ10³㎥·d) |
• Simplified facilities: – No scum skimmer, subnatant remover or settling lamella plates needed. • Stable on wide range of load fluctuation (even low flow rate or high solid content) • Capable for treating high silt-laden water. • More compact facilities required – Detention time(min): Floating : 8 ~ 10. Conglomeration : 4 ~ 8. • Chemical consumption(ppm): – Organics: 0.5 ~ 2 – Inorganics: 2 ~ 10 (available only one chemical used) • Consumes less electric power: (900 ~ 1,000 kWh/5Ⅹ10³㎥·d) |
- 6. Applications of HELIFLOT™:
- Tap water treatment (for pre-treatment, particularly for microalgae and cyanobacteria removal in replacement of a flocculation and sedimentation process).
- Sewage and wastewater treatment (for pre-treatment or sludge thickening).
- Industrial processes (for recovery of valuable effluences).
Scum on HELIFLOT
Removed scum
- 7. Standard Specifications
| HLF 250 | HLF 500 | HLF 1000 | HLF 5000 | HLF 10000 | |
|---|---|---|---|---|---|
| Treatment rate (㎥/day) | 250 | 500 | 1000 | 5000 | 10000 |
| Flotation tank volume (㎥) | 2.2 | 4.2 | 8.2 | 40 | 77 |
| Conglomeration tank volume (㎥) | 2.2 | 4.2 | 8.2 | 40 | 77 |
| Ground required (㎡) | 10 | 15 | 25 | 70 | 100 |
* Depending on the suspended solids in the water, the size of the conglomeration tank may be reduced or omitted.
- 8. Examples of the HELIFLOT™:
2,400㎥ /day
16,000㎥ /day