Recently Sales Representative Bill Moran was able to set up tests with Vincent dewatering screw presses at a Cargill [now Tysons] poultry processing plant. This was a broiler plant that runs two eviscerating lines at 91 birds per minute (bpm), two shifts, five or six days a week.

The plant had two applications in mind. Their greatest need was to press moisture from sludge. This sludge is produced when flocculents are added to the plant waste water. Unfortunately this sludge appears to be a colloidal suspension, and colloidal suspensions cannot be separated by mechanical means. Despite adding a variety of press aids we were unable to press water out of the sludge.

Much greater success was achieved with the second application, dewatering feathers. Poultry feathers are removed in defeathering machines that sluice the feathers away with a great deal of water. The feathers are then transported to a rendering plant where they are cooked (hydrolyzed) in the process of producing a high protein animal feed.

At the Cargill plant the feathers are drained by sluicing them through the inside of a rotating drum scalper. Then they are loaded by screw conveyor into trailers for the trip to the rendering plant. We found that the feathers in the truck had 70% moisture. In running these through the press, 40% of the inbound material was removed as waste water. The final press cake moisture (feathers) was down to 50%, an excellent result.

In this case the dirty water that comes from the feathers will add an acceptable load to the plant sewage treatment plant.

There are three economic benefits to this pressing operation: (1) Cargill can transport their feathers in two 20-ton trailer loads a day, instead of the present three, for a savings of $375.00 a day, (2) Most important, the two truck loads a day of feathers are going to have significantly more value than the present three because the renderer will eliminate the need to steam evaporate approximately 20 tons of water per day, and (3) Maintenance associated with the rotary drum scalper can be eliminated by replacing this machine with a press.

June 1997 update: We are seeking to test the much more suitable KP presses in raw feather dewatering.