Dissolved Air Flotation | Experience

The right DAF – Dissolved Air Flotation – for your application.

P-TEC offers equipment and system designs to meet the exact nature of each of our clients’ needs.  Whether your flow is 5 GPM or 3000 GPM, we have a custom solution for your need. Custom Built dissolved air flotation to fit your exact application based on extensive expert experience in DAF design and innovation.  From grease removal in a restaurant to water recovery in a paper mill, we can offer the solutions that will solve your problems.  We have experience in:

Can Your DAF Pump Aerate A Shirt? This One Can… | Dissolved Air Flotation At Low Cost

On one of the early Keystec DAF Pump tests, a client was simply too cheap to install screens in his wastewater system.

During a pilot test one of the workers accidentally dropped his shirt into the whitewater. Later the shirt was retrieved from the processed water- the Keystec Airwhip® pump unharmed.

Multi-stage pumps used to make whitewater cost exponentially more. The in-use pumps at this pilot test were getting clogged within weeks. The company was producing microwave bacon. The plant had five DAFs. The Keystec trial pump that started out as a test, and then placed into service five years ago is still running strong today.

Can Your DAF pump perform like this? Are you saving hundreds of thousands on your DAF processes?

We’re talking price ranges from $2,500 to $10,000 depending on size and application. Pumps that last far beyond competitors at economic cost.

If you want serious data driven, proven information about highly efficient, fractionally priced DAF pumps, check out the Keystec Airwhip® DAF pump series at Keystec. Innovative DAF design pump specialists.

Overall dissolved air flotation related service provided by PTEC.

Dissolved Air Flotation | Secret To Solving The Solids Problem

Dissolved Air Flotation for Solids? How to cope with the problem of white-water systems and pump blockage.

A true DAF generates dissolved air.  The process involves dissolving atmospheric air to the greatest saturation possible under pressure and then releasing the dissolved air in the form of microscopic bubbles with the shock developed in a back-pressure valve or valves.

Modern DAFs operate the white-water system at about 95 to 120 PSI when operated in a recycle mode to achieve the greatest practical degree of air saturation.  There are numerous ways to create the necessary interface between air and water to do this, but the most popular lately is to inject metered air into the inlet of a multi-stage pump.  A saturation tank follows the pump.  Older designs saturated the full inlet flow at about 35 PSI with a larger saturation tank and a back-pressure valve.

All “white-water” systems can be trouble due to the solids that are entrained in waste water.  They can also be very expensive with tight clearances, unable to tolerate solids passing through the pump.

Dan Keys of Keystec developed a new, solids tolerant white-water DAF pump which can work with unscreened waste streams and is low cost and very easy to repair if it’s needed.  As a DAF design engineer, it had long been one of Dan’s goals to solve this old problem.  The development is now complete and the pump is enjoying great success in every place where it has been applied.  Its ability to handle solids has made it possible to return to full flow inlet aeration and split flow inlet aeration, thus increasing the DAF throughput capacity by freeing the throughput capacity used by recycle flow.

To summarize, proper white-water is achieved by aggressive air saturation which involves maximum air to water interface under pressure and some residence time in the pressurized state to complete the saturation, followed by a high-shock back-pressure valve or valves to force the sudden release of the saturated air.

This represents a revolutionary advance in applications of Dissolved Air Flotation technology.

There are also “entrained air” systems on flotation devices.  Be aware that while this approach can work many cases, the bubbles produces by spinning discs and blowing air through porous filters have different surface charges and are often too large for good flotation.  The ideal environment is produced by 30 to 50 micron bubbles combined with good chemistry that attracts the bubbles to the flocs formed by the chemistry. If the bubbles are able to coalesce while entraped in the floc, the rise rate can increase and allow more aggressive separation.  So, chemical choices are also key to good performance.

Partners in Dissolved Air Flotation Applications

Dissolved Air Flotation – Applications and Limitations in Wastewater Treatment

Dissolved Air Flotation is widely used in Wastewater Treatment as well as in less traditional applications such as:

•   drinking water clarification and color removal
•   Algae removal
•   By-product recovery  (i.e. metals, etc.)
•   Dissimilar solids separation

Within Wastewater Treatment, DAF application can be divided into
•   Primary Treatment
•   Secondary Treatment
•   Tertiary Treatment

In all cases, DAF (dissolved air flotation) is used to separate fine solids (any constituents that are not dissolved) by flotation, assisted by the attachment of microscopic bubbles.  Often, solids that would normally settle are forced to the surface for removal through the attachment of those fine bubbles.

DAF is used in a wide range of situations where the suspended material  can be as little as 20 mg/l (as in algae or color removal) to tens of thousands of mg/l as in rendering or some petro-chemical oil/water separation situations.  Each case must be evaluated for size, flow, and chemical requirements.

To further complicate the issue, the general term, DAF, no longer covers all the approaches to separating solids with microscopic bubbles.  Other similar technologies that are frequently referred to as DAF are:

•   CAF (cavitation air flotation)
-Bubbles produced by a spinning disk without pressure
•   BAF (bubble air flotation)
-Bubbles produced by blowing air through a micro-filter into the water
•   SAF (saponification air flotation)
-Bubbles produced with the aid of a surfactant for more aggressive attachment
•   EAF (entrained air flotation)
-Bubbles produced with relatively low pressure and high shear, entrained in the water

Dissolved Air Flotation

DAF Pumps

DAF Design

Dissolved Air Flotation DAF Solutions For The Dairy Industry, BOD & TSS Removal In Milk Wastewater

Here is a summary of an actual recent pilot test study.  The pilot test demonstrated the effectiveness of DAF treatment of fluid milk wastewater.

PROCESS DESCRIPTION:

Fluid milk, cottage cheese, fruit juices, and other dairy products.

OBJECTIVES

The objective of this study was two-fold:

1. To determine the effectiveness of chemical treatment and Dissolved Air Flotation (DAF) for the removal of BOD, suspended solids, and oil and grease from the plant´s wastewater.

2. To determine coagulant and/or flocculant dosing levels required to treat the wastewater.

EQUIPMENT USED:

Plant effluent was pumped from a manhole to a 300 gallon coagulation / pH buffer tank with a flash-mix agitator. The coagulated / pH adjusted water then gravity-flowed to a 300 gallon flocculation tank with a slow-mix agitator where a flocculant was dosed. The flocculated water then gravity-flowed to a P-TEC Model MD-2442 20 GPM Dissolved Air Flotation (DAF) System. Additional ancillary equipment was also provided; (feed pumps, chemical pumps, tanks, etc.).

TESTING PROCEDURES:

Prior to each test run, the water was jar-tested to determine optimal chemical dosing rates, then the system was started-up and stabilized before sampling took place. Flow rate, chemical dosing, aeration system, etc. were monitored to insure consistent operation.

500-ml samples of the raw wastewater influent and treated effluent were taken every hour to produce daily composite samples. A sludge sample was collected for moisture analysis in order to estimate volume produced.

Sample Analyses

600 PPM aluminum chloride (AlCl3) coagulant and 10 PPM anionic flocculant.

Influent – 3930 mg/l BOD; 1420 mg/l TSS; 514 mg/l O&G

Effluent – 1870 mg/l BOD; 100 mg/l TSS; 16 mg/l O&G

Reductions – 52% BOD; 93% TSS; 97% O&G

Sludge – 15.5 % dry solids; 21.8 % O&G on a dry basis

80 ppm epi-amine coagulant, 12 PPM cationic flocculant, & 6 ppm anionic flocculant.

Influent – 2560 mg/l BOD; 796 mg/l TSS; 616 mg/l O&G

Effluent – 880 mg/l BOD; 22 mg/l TSS; < 5 mg/l O&G

Reductions – 66% BOD; 97% TSS; 99% O&G

Sludge: 39.2 % dry solids; 32.1 % O&G on a dry basis

Dissolved Air Flotation only (no chemicals).

Influent – 1420 mg/l BOD; 608 mg/l TSS; 274 mg/l O&G

Effluent – 1220 mg/l BOD; 232 mg/l TSS; 105 mg/l O&G

Reductions – 14% BOD; 62% TSS; 62% O&G

Sludge – 34.1 % dry solids; 54.2 % O&G on a dry basis

Chemical Cost Comparisons and Estimated Sludge Production

Assumptions: 100,000 Gallons per day water treated.

TSS – 941 mg/l (average of pilot test influent TSS composites)

Treatment with aluminum chloride and polymer:

600 PPM AlCl3 = 60 gal/day X 10.68 lb/gal = 640.8 lb/day X $0.20 /lb = $ 128.16 /day

10 PPM anionic polymer (non-GRAS) =8.34 lb/day X $1.75 = 14.60

142.76 /day

Sludge production:

100,000 gal. X 941 mg/l = 94 gal/day (dry)  15 % dry solids = 627 gals (wet)

Treatment with three organic polymers “3P”:

80 PPM epi-amine = 8 gal/day X 9.5 lb/gal = 76 lb/day X $1.15/lb = $ 87.40 /day

12 PPM cationic polymer (GRAS) =10 lb/day X $2.75 = 27.52

6 PPM anionic polymer (GRAS) = 5 lb/day X $2.50 = 12.50

150 PPM sulfuric acid = 15 gal/day X 15 = 225 lb/day X $0.09/lb = 20.25

147.67 /day

Sludge production:

100,000 gal. X 941 mg/l = 94 gal/day (dry)  35 % dry solids = 269 gals (wet)

NOTES: All chemical prices assume tote or pallet quantities and include estimated freight. “GRAS” – Generally Recognized As Safe (for addition to animal feed).

Note for ALL tests: The pH was maintained at between 6.0 and 7.0 using 150 PPM (by volume) of 66o Be sulfuric acid (H2SO4) during the “3P” and DAF only trials. Little or no acid was required for the aluminum chloride and polymer trial because the 600 PPM dose of aluminum chloride itself lowers the pH to ~6.5. Average influent pH was approximately 9.0, but was observed as low as 4.5 and as high as 11.5.

Dissolved air flotation

Dissolved Air Flotation | Can DAF Solve The Ice Cream Problem?

Can DAF (dissolved air flotation) solve the wastewater problem for ice cream plants? Success is obtained in Dairy Pilot testing.

Dissolved air flotation is an effective application for removal of BOD, suspended solids, oil and grease from wastewater used in Ice Cream production and other Dairy processes. P-TEC ran a pilot test study for this application while determining the coagulant and dosing levels for specific reclamation.

In this test, plant effluent was delivered to a 1100 gallon coagulation pH buffer tank. The coagulated, pH adjusted water then was introduced to P-TEC Model MD-2442 20 GPM Dissolved Air Flotation (DAF) System with an integrated flocculator. Here, flocculant was dosed.

Each test was preceded by jar testing to determine the usual needed chemical dosing rate. During each test, monitoring included, dosing, flow rate, aeration, etc. Hourly samples of influent and effluent were taken in 500ml amounts as well as sludge samples to to estimate produced volume.

Results:

DAF Pilot Test Results - Dissolved Air Flotation

Dissolved Air Flotation for Dairy Applications?

Stay tuned for an upcoming article on Dissolved Air Flotation DAF Solutions For The Dairy Industry BOD & TSS Removal in Milk Wastewater

Study shows cost effective use of DAF system to remove solids from dairy wastewater.

Find out now how DAF Technologies can save you big time. Contact Bob Stone at 800-450-0398.

Dissolved Air Flotation – DAF • Algae Removal Effective?

Dissolved Air Flotation (DAF) has proven very effective for algae removal.  (Full Algae TSS Removal article)

DAF evaluation was prompted by a state imposed limit of 45 mg/l TSS to discharge into a river. The bulk of the residual TSS in the effluent was daphnia “water fleas” that was visible to the eye.

Contact P-TEC at 800-450-0398 for more information on effective use of DAF Systems.

DAF evaluation to solve problems with existing sand filters being plugged with algae floc.

Need A Pilot Test? Dissolved Air Flotation • DAF Solutions and Design

THE P-TEC MOBILE DAF PILOT SYSTEM Complete with the following:

• Mixed Equalization Tank
• DAF Feed Pump
• Flowmeter
• Flocculator
• DAF System
• Sludge Collection Tank
• Sludge Pump
• pH Controls and Pumps
• Coagulant Pump
• Polymer mix tanks with mixers
• Polymer Pumps
• Electrical Control Panel
• Jartesting Lab

Pilot System Cost: $ 2,500/week including PTEC Field Engineer
Plus travel expenses and Freight

**Contact PTEC for a formal Pilot Rental Agreement at 770-530-8313

Dissolved Air Flotation DAF Pumps and DAF Pump Design

Orange County Photography

A Better DAF Pump Design • Low Cost • Economical • Efficient

The KeysTec Air Whip pump. Engineered on the basis of simplicity and economy of design. This pump lasts exponentially longer and is highly tolerant of solids that clog traditional DAF units.

Dissolved Air Flotation

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