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A New Pretreatment Technology

Nov 6, 2023

A New Pretreatment Technology Case Study:
Suspended Air® Flotation

Simmons Foods in Siloam Springs, Arkansas

Andy Brashear, Area Environmental Manager, Simmons Foods

  • SAF® = Suspended Air® Floatation
  • Uses froth made from an anionic surfactant, water, and air instead of
    air bubbles for flotation.
  • One gallon of froth = 0.8 ml soap = 
  • 0.6 gal water and 0.4 gal (0.05ft3) air.
  • Bubbles have an anionic charge so are attracted to the floc.
  • Increases flotation rate so units can float 20-40 lbs (spec’ed at 30lbs)
    of solids per square foot per hour (lbs/hr/ft2).
  • Decreases the size of the unit vs. DAF; no lamella style plates
  • Less Maintenance
  • More Highly Dewatered Skimmed Solids
  • Better Results – Water Clarity

What is SAF®?

  • Installed two new units in Siloam Springs*One primary
  • One Secondary
  • Installed one new unit in Van Buren
  • Primary treatment.
  • Converted two existing DAF units to SAFs in Southwest City.
  • One primary
  • One Secondary

Simmons has gone SAF®

New SAF® Units for Siloam Springs.

Siloam Springs SAF® Effluent

  • ClearFloater Model CF250
  • 35ft2 Float Cell – rated for 700 gpm @ 3000Mg/L TSS
  • 350 gpm – current actual flow
  • From Secondary SAF
  • Influent flow contained 3000 mg/L MLSS.

Froth Generator

Model F-200 Froth Generator Shown

Froth Flow Meter & Froth

Froth Generation Summary

  • Tote of Anionic Surfactant.
  • Froth Generator.
  • Surfactant metering pump.
  • Water line.
  • Froth pump.
  • Holding tank.
  • Flow meter.
  • Flow control valve.
  • Floc Mixer – Active Mixing Chamber.

DAF to SAF Conversion:
Froth Generator & Floc Mixer

Floc Mixer – replaces previous connection from floc tube to DAF inlet flange

Secondary SAF®

  • Secondary DAF

  • 216 ft2 of surface area.

  • At 1.8 MGD before SAF conversion it could handle 1500 mg/L influent suspended solids.

  • It now handles 3500 mg/L with no carry over  Average effluent TSS = 15 mg/L.

  • Specified Maximum Flow @ Current Loading ~3500 gpm

Secondary SAF® Effluent

Secondary DAF to SAF® Cost Comparison

Secondary DAF

60 HP Recirculation Pump $31,367/yr @ $0.08/KWHR
Coagulant Consumption: $350,000/yr
Cationic Polymer Consumption: 120Lbs/Day; $87,600/yr
Total O&M Costs/yr: $468,967

SAF® Conversion

Equivalent – 10HP; $5,230/yr @ $0.08/KWHR
Frothing Agent Consumption @ 25 GPM Output; (1)-tote/6wks; $38,780/yr
Coagulant Consumption: $140,000
Cationic Polymer Consumption: 60Lbs/Day; $43,800/yr
Total O&M Costs/yr: $227,810
Net Savings/yr: $241,157

*Difficult to quantify savings associated with directly reclaiming water vs requiring additional treatment

Primary DAF to SAF® Conversion

  • Converted Primary DAF.

  • It was maxed out at 1250 gpm and 2000 – 2500 mg/L influent solids.

  • It now treats an additional 700 gpm.

  • Specified to treat a maximum 2400 gpm.

  • Cost effective way to increase capacity.

Primary DAF to SAF® Cost Comparison

Primary DAF

40 HP Recirculation Pump $20,920/yr @ $0.08/KWHR


Organic Coagulant Consumption: 700Lbs/Day; $130,000/yr

Cationic Polymer Consumption: 120Lbs/Day; $87,600/yr

Anionic Polymer Consumption: 110Lbs/Day; $50,000/yr

Total O&M Costs/yr: $288,540

SAF® Conversion

Equivalent – 10HP; $5,230/yr @ $0.08/KWHR
Frothing Agent Consumption @ 25 GPM Output; (1)-tote/6wks; $38,780/yr
Organic Coagulant Consumption: 350Lbs/Day; $65,000/yr
Cationic Polymer Consumption: 120Lbs/Day; $87,600/yr
Anionic Polymer Consumption:  0-Lbs/Day; $0.00/yr
Total O&M Costs/yr: $196,610
Net Savings/yr: $91,930


  • SAF is mechanically simpler than a DAF:

  • Removes recirculation pump, header, compressor, and air lines.
    (No more air lines plugging in header which would also cause packing to blow out on recirc pump.)

  • No requirement for lamella style plates

  • Less maintenance


  • It’s operator friendly.

  • It’s 6 times more efficient than a DAF (20-40 lbs/hr/ft2 vs. 5 lbs/hr/ft2).

  • You can adjust the froth flow (i.e. floatation air) to the loading.

  • Feed less chemical (less polymer mixing).

  • Better results

  • Thicker Solids

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