عدد المساهمات : 3514
تاريخ التسجيل : 15/09/2009
العمر : 49
الموقع : مصر
|موضوع: DAF Dissolved Air Flotation Systems/ وحدة التطويف بالهواء المذاب الأربعاء فبراير 22, 2012 8:59 am|| |
Dissolved Air Flotation Systems
TECHNOLAB EL-BAHAA GROUP
The DAF Series Dissolved Air Flotation systems are designed to
remove petroleum products, FOG, TSS, BOD, COD and other
contaminants in a wide variety of industries & applications.
Flotation systems are an extremely versatile
design allowing high loads of a very wide variety
of contaminants to be removed from your
DAF is considered to be the best,
most cost-effective device for separating FOG
The DAF process consists of super saturation of
effluent discharge water with air.
water stream is then redirected and mixed with
the wastestream prior to entering the inlet.
As pressure is removed from the saturated
stream millions of microscopic bubbles form and
attach themselves to the contaminants in the
wastestream, thereby changing their bouyancy
and floating them to the water surface where
they can be skimmed from the water.
Our unique, compact, small footprinted
“Dinky DAF” design is offered for small flows
and tight spaces.
Chemical pretreatment can be
provided where required for all DAFs.
Our DAF systems can be used for removal of
oils, fuels, emulsfied products, FOG, BOD,
suspended solids, COD, vegetable matter,
vegetable oils, animal processing waste, river
water for drinking or plant use, bilge water,
pretreatment prior to bio-reactor systems and
many many other types of applications.
DAF is a hardy piece of equipment and can
accommodate many wastes.
♦ A36 or 304 or 316 SS construction
♦ Adjustable water weir
♦ Integral float reservoir
♦ Influent diffuser
♦ Effluent chamber
♦ Recycle saturation system
♦ NPT/flanged fittings
♦ Surface drag skimmer
♦ V-hopper Bottom, sludge auger
♦ Lifting lugs
♦ Nema 4 controls
♦ Groundwater remediation
♦ Tank truck tank wash
♦ Refinery wastestream
♦ Biodiesel process water
♦ Drinking water pretreatment
♦ Pet food plant process water
♦ Beef, fish, foul, pork processing
♦ Rendering plant wastewater
♦ Food processing plant water
♦ Algae removal
♦ Industrial process water
♦ Bilge water treatment
♦ Bakery wastewater
♦ Military wash racks
♦ Steel mills
The DAF systems can be provided with
many options to create a complete, custom
system design to fit your application and
Customization of the tank is offered to
further tailor the design to your needs.
Chemical pretreatment typically increases
pretreatment systems to coagulate
flocculate, precipitate, oxidize, break
emulsions and/or adjust pH before or after
DAF Options Descriptions
Influent Feed System Air operated, diaphragm
pump with air controls or progressive cavity pump, sump
level switches & Nema 4 control panel, base mounted,
115/230/460V power offered. Electric diaphragm pumps
Effluent Pumpout Centrifugal pump with level
switches & Nema 4 control panel, base mounted,
115/230/460V power offered.
OS Effluent chamber must be
expanded to accommodate pumpout or provision of an
external pumpout tank.
Sludge Pumpout System Air operated, diaphragm
pump with air controls & Nema 4 control panel, auto on/off
timer, base mounted, 115V/1ph/60Hz power req'd.
Progressive cavity pump system also available. 1 - 100
Float Pumpout System Air operated, diaphragm
pump with air controls, level switches & Nema 4 control
panel, base mounted, 115V/1ph/60Hz power req'd.
gear or progressive cavity pump systems available. 1 - 100
GPM (larger if required)
Sludge Auger Dinky DAF V-hopper can be provided
with a sludge auger.
System consists of stainless steel
shafts with coated steel screw auger(s) driven by a slow
speed gear motor drive assembly.
The auger extends the
full length of the solids hopper and conveys solids to the
A Nema 4 on/off control box is provided,
power required: 230 or 460V/3ph/60Hz.
Cover DAF tank can be provided with a vapor retaining
Freeze Protection Immersion heaters mounted
through tank wall. Each heater has an independent
thermocouple well, 0-100 deg.
F thermostat and Nema 1
(or optional Nema 4) housing. 230/460V/3ph/60Hz power
Oil Sight Glass Two automatic, brass valves with
tempered sight glass and protection rods mounted in oil
If glass is broken check ball stops outflow from
External Sight / Level Glass An externally
mounted clear PVC sight tube is provided with multi-point
level switch for indication or pump control of oil or water.
Elevation Stand Epoxy coated steel stand or legs to
elevate tank to desired level.
Standard deck height is 30".
Full platforms & walkways with ladders or stairways can be
designed where required or desired.
Alternate Tank Construction Standard carbon
steel construction can be changed to 304 or 316 stainless
External Storage/Feed Tanks A wide variety of
tank volumes can be supplied for your water, product and
sludge holding needs.
Flat bottom and cone bottom
designs constructed in polyethylene, fiberglass, steel &
stainless steel can be provided.
Effluent Filter Systems Solids filter systems can be
provided to remove filterable solids from the separator
AQAM Filter Systems AQAM (Alkyl Quaternary
Ammonium Montmorillonite) filter systems can be provided
to remove trace hydrocarbons, sheens, DNAPLs, slightly
soluble chlorinated hydrocarbons and high molecular
weight organics from the separator effluent.
AQAM can also be used to protect and
increase GAC lifespan.
Carbon Filtration Systems (GAC) GAC carbon
filters can be provided to remove contaminants after the
Emulsion Cracking Systems Emulsion cracking
systems can be provided to remove oil-in-water emulsions
prior to the separator.
pH Adjustment Systems pH adjustment systems
can be provided to maintain pH levels prior to or after the
Chemical Pretreatment Systems Chemical
pretreatment system can be provided to coagulate,
flocculate, precipitate, oxidize, break emulsions and/or
adjust pH before or after the DAF
System Containerization DAF systems with any
options can be installed in a 20 or 40’ shipping container(s)
to simplify system provision and field implementation.
System would include the complete mounting, piping and
wiring of the system in one or more container as required
by the project.
Trailer Mounting OS separators can be mounted on a
trailer for system mobilization.
Trailer design generally
includes corner leveling jacks, bubble levels, walkway,
toolbox, electric or hydraulic brakes, piping and wiring of
Field Skid Mounting DAF systems can be mounted
to a mobile skid with leveling for quick field mobilization.
Skid Mounted System DAFs can be combined with
our other treatment equipment and options into a fully
integrated, custom designed system completely mounted,
plumbed and wired to a system skid.
To simplify your need
to do the wiring and plumbing on site, reducing your time
frames and on site costs, we design around your
Vent Scrubber Separator vapors can be extracted and
scrubbed prior to discharge to atmosphere to remove VOC
Level Sensors Level sensors can be provided to
detect water and oil/fuels.
One or more sensor points can
be provided to perform various functions such as high level,
low level, pump on/off based on liquid levels and level
detection for DCS controls or other functions based on your
Class 1 Div 1 & 2 Systems can be designed for use in
a class 1 div 1 or 2 environment. Controls, components and
wiring are changed to meet the needs of these
environments. Intrinsically safe relays are also used for
DAF Series Dissolved Air Flotation
DAF12 through DAF600
EQUIPMENT DESIGN & CONSTRUCTION
The Pan America Environmental DAF Series systems are designed
to remove fats, oils & greases (FOG) and suspended solids.
Clarification rates as high as 97% can be achieved using the DAF
A percentage of the clean effluent is recycled and super-saturated
with air, mixed with the wastewater influent and injected into the
DAF separation chamber.
The dissolved air comes out of solution,
producing millions of microscopic bubbles. These bubbles attach to
solids and float them to the surface where they are skimmed and
removed from the tank.
SECTION 1.0 EQUIPMENT
The DAF Dissolved Air Flotation system will be designed and
fabricated per the following specifications.
The tank shall be a
rectangular design with features as described.
1.01 Float/Separation Chamber
The separation chamber provides a velocity decreasing horizontal
separation surface area that minimizes turbulence and maximizes
flow and solids throughput.
The mixed wastewater enters this
chamber where separation and flotation occur.
The Separation chamber includes the float storage chamber, float
baffle, water baffle with adjustable water weir, settleable sludge
hopper, surface float skimmer, clean water effluent chamber and
the skim ramp.
1.02 Float Storage Chamber
As the surface float skimmer continuously skims float from the water
surface it conveys float up the skim ramp and deposits it in the float
storage chamber which is provided to allow temporary float storage.
The chamber has sloped sides to allow solids to slide to the bottom
1.03 Effluent Chamber
The waste flow and float run into the float baffle at the effluent end
of the tank. The float is contained while the water is directed under
the baffle and over the adjustable 304 stainless steel weir plate. The
clean water accumulates in this chamber and is discharged.
1.04 Sludge Hopper
A sludge hopper is located under the separation chamber to provide
temporary storage of any settleable solids.
A sludge auger is
provided to convey sludge to the sludge outlet (auger provided as
standard feature with DAF60 and larger).
1.05 Sludge Auger System
(standard feature on DAF-60 & larger)
The solids hopper is provided with a rotating, screw type sludge
The auger consists of stainless steel shafts with coated steel
screw auger driven by a slow speed gear motor drive assembly.
The auger extends the full length of the solids hopper and conveys
solids to the sludge outlet.
Power required: 230/460V/3ph/60Hz.
Oil Monitor an oil detection system can be provided to
monitor effluent oil content and provide various actions
based on the oil alarm setpoint.
Actions might include:
audible/visual alarm, redirection of influent or effluent via
actuated valve, shutdown of influent pump or your custom
1.06 Surface Float Skimmer
A mechanical surface drag skimmer assembly is provided to sweep
the floating solids (float) from the effluent end of the separation
chamber toward the influent end.
The skimmer consists of 304
stainless skimmer flights and neoprene or Buna-N wiper blades,
carbon steel flight chain, sprockets and chain guides, variable
speed drive, sprocket shafts, bearings and chain adjustment
The flights will be bolted to two roller chains
spanning the width of the tank and will be designed to wipe the tank
sides and float ramp.
UHMWPE flight wear bars are provided to
reduce tank and flight wear.
1.07 Air Saturation System
The DAF is provided with an air saturation system that is designed
to direct a portion of the water from the effluent end of the tank,
super-saturate the water with air and then mix this solution with
incoming wastewater facilitating intimate mixing of both flows.
Recycle saturation pump and schedule 80 PVC piping are mounted
on DAF tank with a bypass line to the effluent chamber.
1.08 Recycle Pump
A high head, coated cast iron centrifugal, 100 psi recycle pump
mounted to the DAF tank is included to provide air saturated water
under pressure to the air/wastewater mixing inlet prior to entering
the separation chamber.
A Nema 4 control panel is provided
mounted to the DAF tank.
Power required: 230/460V/3ph/60Hz. The
recycle pump draws ambient air into the pump and saturates the
water with this air under high pressure.
No external air source is
required. A fine air-metering valve with rotometer are provided to
control and measure the air flow into the recycle pump.
control valve and suction control valve are provided to facilitate
adjustment and operation of the air saturation process.
and suction pressure gauges are provided. Pump on/off operation is
based on an on/off switch in the control panel.
If another on/off logic
is required based on other processes within the installation site this
can be integrated on an optional basis (contact PAE for quotation).
Once adjusted the recycle system can be turned off and on at will
without losing settings and saturation process is virtually
instantaneous upon startup.
1.09 Influent Mixing Chamber
The saturated flow mixes with the wastewater flow at the DAF
influent via a mixing chamber.
Chamber to be constructed of same
material as DAF tank.
A Nema 4 control panel with pump and auger control switches,
lights, starters, variable speed motor control for flight skimmer and
power disconnect are provided mounted and wired to the DAF tank
for convenient operation. 230/460V/3 ph/60Hz power required.
Control of any options can be integrated into this panel for
centralized control by the factory prior to shipping.
SECTION 2.0 MATERIALS OF
2.01 Steel Construction
Tank shell, baffles and internal structural members shall be
constructed of A-36 carbon steel.
Weld joints are to be double
welded and dye penetrant tested.
2.02 Surface Preparation
Interior surfaces shall be prepared to an SSPC-SP10 near white
metal blast. Exterior surfaces shall be prepared to an SSPC-SP6
Interior coating to be a self-priming coal tar epoxy (14-16 mils dft).
Exterior coating shall be primer coat followed by industrial
polyurethane enamel coat (6 mils DFT)
. Finish color is Green.
2.04 Internal Piping
Internal piping shall be ASTM A53 black steel.
All wetted hardware to be ANSI, 316 stainless steel. All non-wetted
hardware to be zinc plated.
2.06 I.O.M. Manuals
Two copies of the Installation, Operation and Maintenance manuals
will be provided.
Dissolved Air Flotation (DAF)
Dissolved Air Flotation (DAF) is the process of
removing suspended solids, oils and other contaminants via the use
of air bubble flotation.
Air is dissolved into water, mixed with the
wastestream and released from solution while in intimate contact
with the contaminants.
Air bubbles form, attach to the solids,
increase their buoyancy and float the solids to the water's surface.
percentage of the clean effluent is recycled and super-saturated
with air, mixed with the wastewater influent and injected into the
DAF separation chamber.
The dissolved air comes out of solution, producing millions of
These bubbles attach to the solids and float
them to the surface where they are mechanically skimmed and
removed from the tank.
air flotation systems are designed to remove fats, oils & grease
(FOG), suspended solids, food/animal production/processing
wastes, industrial wastes, hydrocarbon oils/emulsions and many
Clarification rates as high as 97% or more can
be achieved using our dissolved air flotation systems. Chemical pretreatment
can often help to improve the performance of contaminant
Conventional DAF saturation design uses a recycle pump
combined with a saturation vessel and air compressor to dissolve
air into the water.
This type of system, while effective, is expensive,
labor intensive and can destabilize its point of equilibrium, creating
burps due to incorrect, loss or creeping of EQ set-point in the
This design is slow to recover and can upset the
flotation process in the DAF. Air transfer efficiency is approximately
9% @ 80% entrainment.
This style of operation can increase
chemical use, labor costs, downtime, effluent loadings, production
schedules and other detrimental domino effects due to EQ loss.
Pan America's DAF design incorporates today's "state of the art"
technology in DAF design.
This design simplifies the DAF process, requires
less startup time, less capital cost, instrumentation, labor and maintenance.
The design is process friendly, providing virtually instant saturation upon
system startup without equalization and complex startup
Once the system is adjusted the system can be
shutdown and started up again without any readjustment or
Higher air transfer efficiencies are also realized due to
higher saturation pressures with 12% @ 93% entrainment.
both styles of DAF design depending on
application and customer preferences.
DAF sizing takes into consideration many criteria for sizing:
Flow rate, Water temperature, Waste characteristics, Chemical pretreatment,
Solids loading (LBS/HR/Ft2) , Hydraulic loading
(GPM/FT2), Air to solids ratio (LBS of air/LBS of Solids).
DAFs are designed on the basis of the peak flow rate expected.
flow can range from 1 to 5 gallons per minute per square foot of
surface area (GPM/Ft2).
Bench testing of waste stream samples is
usually the preferred starting point when sizing equipment and
determining proper chemical processes prior to the DAF.
chemical pretreatment will assist and improve the DAF separation
Chemical Pretreatment often improves DAF solids
The use of chemical flocculants with DAF is
based on system efficiency, application (use of DAF) and cost.
Commonly used chemicals include trivalent metallic salts of iron,
such as FeCI2 or FeSO4 or aluminum, such as AISO4.
inorganic polymers (cationic or anionic) are often used to enhance
the DAF process.
The most commonly used inorganic polymers are the
polyacrylamides. Chemical flocculant concentrations used normally
range from 100 to 500 mg/l.
(One mg/l in 1 million gallons per day is
8.34 lbs of material.) The wastewater pH may need to be adjusted
between 4.5 and 5.5 for the ferric compounds or between 5.5 and
6.5 for the aluminum compounds using an acid such as H2SO4 or a
base such as NaOH.
In many applications, the DAF effluent
requires pH adjustment utilizing a base such as NaOH to assure the
DAF effluent pH is within the limits specified by the POTW (6-9
Float Dewatering DAF float often contains 2 to l0 percent
The solids may need to be dewatered before disposal to
reduce the sludge volume by reducing water content.
dewatering is usually performed by using one of the following
technologies: Filter press, Belt filter press, Centrifuge, Drying bed or
Vacuum precoat filter.
Attachment of most of the bubbles to solid particles can be effected
through surface energies while others are trapped by the solids or
by hydrous oxide flocs as the floc spreads out in the water column.
Colloidal solids are normally too small to allow formation of
sufficient air-particle bonding.
They must first be coagulated by a
chemical such as the aluminum or iron compounds mentioned
above and then absorbed by the hydrous metal oxide floc
generated by these compounds.
Frequently, a coagulant aid is
required in combination with the flocculant to agglomerate the
hydrous oxide flocc, increase particle size and improve the rate of
flotation. Mechanical/chemical emulsions can also be broken
through pH and polymer reactions.
Where the float is to be used to feed animals used for human
consumption, organic compounds such as chitosan, carrageenan,
and lignosulfonic acid, or their derivatives can be used. Use only
compounds approved by the Food and Drug Administration (FDA)
Office of Veterinary Medicine.