Pilot Test For Digested Sludge Thickening

A municipal wastewater industry customer approached Heron Innovators with a need to run a treatment system pilot test. We placed our Model SAF125 Suspended Air® Flotation (SAF®) pilot trailer at the customer’s Sacramento, California biosolids recycling facility for three pilot runs. The pilot test runs provided data enhancing the performance of their digested sludge centrifuge operation.

The pilot trailer thickens digested sludge from the treatment plant prior to the centrifuges. This advanced system is constructed from stainless steel and schedule 80 PVC. Complete fabrication was done within ±1/16-inch tolerance. The finished trailer measured 40 ft. long x 8 ft. wide x approximately 12 ft.high and features a flotation tank with internal flocculation agitator and chain and flight skimmer. Three pilot tests were run with significant results. To learn more, see the table below or contact us directly.


Product Name
Trailer mounted Model SAF125 Suspended Air® Flotation (SAF®) Treatment System
Product Description

Trailer-mounted Model SAF125 Suspended Air® Flotation Treatment System. Capable of treating 250 gpm. Contained and fully integrated are:

  • pH Control System with P&ID loops for acid and caustic feed
  • Controlled outlets for coagulant feed/coagulation, polymer dosing/flash mixing/aging system supporting flocculation
  • Flotation separation of suspended solids and associated BOD/COD,
  • Fully automated continuous operation including the starting/stopping system by remote signal/parameter.
System Capabilities and Services Provided
  • Engineering design of process and components
  • AutoCAD drawings
  • In-house mechanical and electrical equipment fabrication
  • Custom fabricated welded stainless steel tanks and components
  • Provision and operation of pilot trailer for 3 pilot runs.
Overall Part Dimensions
Pilot trailer: 40 ft. L x 8 ft. W x 12ft. 4 in. H
Tightest Tolerances
± 1/16 inches
Material Used
Structural: 304 Stainless Steel or ASTM A36 Carbon Steel
Piping/Fittings: Stainless Steel or Sch. 80 PVC
Additional Facts
Trailer-mounted system includes:
Feed System: 7.5 HP, 250 gpm pump, 4-in. magnetic flow meter, pH control system with acid and caustic P&ID loops
Conditioning Tank: 1,800 gallons, 2-compartment with 2 turbine agitators
Flotation Tank: Model CF-125 ClearFloater™ Cross-Flow Flotation Cell with flocculation agitator, chain and flight skimmer, solids hopper, adjustable weir, and observation decking
SAF® Generator: Model F50 (13.6 gpm froth flow rating)
Ancillary Equipment: polymer dilution and aging system; acid, caustic, polymer, and frothing agent metering pumps; float solids transfer pump; and control Panels
In process testing/inspection performed
Bench Testing
Three Pilot Trailer Runs in 2008 through 2010
Thickened digested sludge from 0.9% to 5+% at up to 43 lb/hr/sq.ft. solids flux. Combination of SAF® thickening followed by centrifuge dewatering used 25% less polymer than centrifuge dewatering alone. The SAF® demonstrated the same polymer consumption advantage (i.e., 25% less polymer demand) when compared against Gravity Belt Thickener followed by centrifuge dewatering
Industry for Use
Municipal Wastewater
Delivery/Turnaround Time
3 pilot runs in 2008 through 2010 (trailer on hand)
Delivery Location
Sacramento, California
Standards Met
Customer Specifications, 2D CAD Drawing

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