Iowa

Dissolved Air Flotation Improvements

  • Client Confidential
  • Type Industrial
  • Services Review, Design
  • Project Manager Keith Hobson, P.E., BCEE

Challenge

This pork slaughterhouse facility had a 35-foot diameter dissolved air flotation thickener and an 11’ x 52’ rectangular DAF unit for wastewater pretreatment. FOX was hired to review the DAF performance and recommend improvements. The DAF systems had utilized a conventional air saturation tank with compressed air and one had been converted to use an air turbo mixing pump for air saturation. The units are treating a flow of 1200 gpm each.

Solution

Several alternatives were evaluated and a pilot unit utilizing a new flotation technology was also brought in to evaluate its effectiveness. The new system utilizes Gas Energy Mixing (GEM) to entrain the air in the waste stream prior to release in the flotation tank. The system proved to be more efficient utilizing less polymer and had a much smaller footprint. The pilot testing data was used to size and design the new units because of their application to this waste stream. The existing DAF units were replaced with two much smaller GEM units along with waste supply pumps, thickened sludge pumps, polymer system, and controls.

Outcome

Improved operation and performance with the new GEM units has allowed the plant to increase production and reduce discharge concentrations and fees.