November 12, 2009

Researchers at the University of Georgia are exploring ways to convert recovered fat from poultry wastewater streams into an economically viable alternative fuel source for processors, said the Public Service Association (PSA).

Waste fat, oil and grease (FOG) are major components of many food-processing wastewater streams, including poultry production.

According to Dr. Kiepper, recaptured fat can be purified and then burned to hot water in a processing plant's boilers. It can also be used to make biodiesel, which is an attractive option to have available, particularly when petroleum-based fuel prices are high.

Such uses can be very economically attractive for the processor, particularly when compared to the traditional means of disposing the offal by selling it to rendering facilities at approximately US$0.03/pound, a rate which values the fat at US$0.22/gallon. By comparison, once purified, fat recaptured from food processing wastewater can be used instead of fuel oil, which is currently priced at around US$2.00/gallon, to power up plant's boilers. Kiepper estimates that recovering only 10 percent of the 44.6 million gallons of fat produced in the state of Georgia each year would result in an estimated annual savings of nearly US$9 million on fuel-oil purchases.

In a recent study, Kiepper and fellow researchers evaluated five poultry waste streams as potential sources of alternative fuel: float fat after primary screens, secondary screen offal, tertiary screen offal, chemical and non-chemical DAF (dissolved air flotation) skimmings. Of the five, float fat and secondary screen offal were shown to have the greatest potential for further refinement and use as biofuel, given their relative ease of extraction and recovery efficiency.

Because secondary screen offal is already collected and (often inefficiently) belt- or screw-conveyed to offal trucks, modifying the collection system to divert the offal to a FOG extraction-and-purification system should, according to the researchers, be readily feasible.  On the other hand, because float fat is harder to collect because of its tendency to gather in equalization pits and transfer troughs, accommodating float-fat collection for alternative fuels processing would likely require new systems to be installed in most facilities.