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DISSOLVED AIR FLOTATION
WHAT IS IT?
A liquid solid separation process achieved by microscopic air bubbles attaching themselves to solids suspended in a liquid and causing these
solids to float to the surface.
WHY SHOULD YOU USE IT?
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A.
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Smaller space requirement
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Example:
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500 GPM = 20 to 25' dia D.A.F.
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500 GPM = 35' dia
Gravity Thickener
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B.
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D.A.F. recovered solids are four to eight times
thicken than gravity sedimentation
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C.
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Faster processing times
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D.
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Lower chemical costs due to effective removal
of smaller flocculating particles
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HOW DOES IT WORK?
A stream of treated water (recycle) is taken from the
D.A.F. unit and is pumped into an air dissolving tank. Air and water are then ULTRA MIXED™ under pressure by Hi-Tech's backpressure valve (Re-Injector™) and then is released at a point that allows it to mix thoroughly with the raw
waste stream entering the cell.
As the air comes out of solution millions of bubbles are attached to the material that is going to be floated to the surface, causing the solids to agglomerate and rise to the surface of
the tank in the form of a "float" blanket on top of the clear water.
This float blanket is then allowed to thicken and de-water prior to removal by a series of rotating surface skimmers.
Full Pressurization
The entire wastewater flow is injected with air and pressurized for dissolution of the air in the water. This flow then passes into the
flotation cell where pressure is relieved. A pump equalization line is used to return water to the pump in order to maintain flooded suction during periods of low flow.
Recycle and Partial Pressurization
Raw influent is introduced directly into the flotation cell. A portion (generally from 50% to 200% of raw flow) of the system effluent is
pressurized and recycled to the flotation cell where it is blended with the raw wastewater flow.
Air Dissolving System
The Hi-Tech pressurization system uses compressed air or gas that is forced into solution by a controlled air-water interface and mixing
components located inside an ASME code vessel.
The vessel is fitted with an automatic excess air release valve, sight glass, and pressure safety relief valve.
Backpressure Valve
The special combination valve/injector assembly is inserted into the raw flow feed line and releases the pressurized flow near the tank center,
just prior to entering the distribution well.
Float Removal System
All Hi-Tech flotation cells are fitted with a minimum of four skimmer arms to assure effective removal of the floating material. The surface
skimmers, center torque tube, and lower sludge scraper arms are all driven by one of Hi-Tech's top quality
drive units.
Air Control Panel
Each Hi-Tech flotation system comes equipped with an air control panel containing a pressure regulator with condensate trap, air regulating
rotometer, air control valves, check valve, and automatic solenoid shut-off valve.
All components are factory assembled in a corrosion resistant enclosure.
HOW EFFICIENT IS THE HI-TECH D.A.F. SYSTEM?
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80 to 90 %
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Capture of Suspended Solids Without Chemical Addition
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90 to 98 %
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Capture of Solids With Chemical Addition (Typically a
Polymer)
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3.5 to 5.5 %
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Float Thickness (Solids Concentration)
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85 to 90 %
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Air Dissolution Capability
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80 to 90 %
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Oil and Grease Removal
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50 to 80 %
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B.O.D. Reductions
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WHERE CAN YOU USE THE HI-TECH D.A.F. UNIT?
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Industry
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Anticipated Performance
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Food Processing
Canning
Prepared Foods
Snack Foods
Seafood
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85 to 95 % TSS Removal
85 to 95 % O&G Removal
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Oily Wastes
Railroads
Oil Refineries
Storm Water
Trucking
Aircraft Maintenance
Automotive
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85 to 95 % TSS Removal
90 to 99 % O&G Removal
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Food Providers
Chicken Processing
Hog Slaughtering
Cattle Slaughtering
Stockyards
Milk & Dairy
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85 to 97 % TSS Removal
95 to 99 % O&G Removal
80 to 85 % B.O.D. Removal
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