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Capturing Value-Added Byproducts from Poultry Processing Liquid Streams

18 March 2011

Georgia Tech Research Institute

Millions of gallons of water are used daily in poultry processing operations, according to Poultry Tech from Georgia Tech's Research Institute.

To help conserve this natural resource, federal guidelines provide that water from processing liquid streams can be reused as long as measures are taken to prevent product contamination or adulteration. As such, treatment technologies are designed to filter and disinfect the water to ensure its safe reuse. In an effort to further foster environmental sustainability, researchers at the Georgia Tech Research Institute (GTRI) are investigating techniques to more selectively capture target impurities from the liquid streams in a way that facilitates the recovery of value-added byproducts while still meeting or exceeding reuse guidelines. They believe the answer may lie in two novel separation technologies: adsorption chromatography and dynamic filtration.

Aklilu Giorges, GTRI research engineer, performs bench-scale testing for dynamic filtration.

Project Overview

“This project seeks to enable recycling and/or reuse of poultry processing liquid streams and capture of entrained contaminants, preferably in a manner that yields value-added byproducts such as fats, proteins, oils, and free fatty acids,” explains John Pierson, GTRI principal research engineer and project director.

According to Pierson, methods similar to those used in biopharmaceutical protein purification may hold keys to advancing liquid stream reuse in poultry processing. However, two key challenges must be overcome. First, there is the need to improve yields with continuous separations combined with lower costs through new and/or improved resins and buffers. Here, he believes adsorption chromatography can play a role. Second, there is the need to improve membrane flux rates for separations, for which dynamic filtration may be the answer.

Adsorption Chromatography

Adsorption chromatography (adhesion onto the particle or adsorbent surface) is being investigated as a method for separating proteins and fats from processing liquid streams. Researchers are using relatively inexpensive silica media to perform adsorption tests on surrogate chiller water.

“To get a higher yield, we are functionalizing the silica with acid groups and others to remove the target groups, in this case protein. We then separate the protein by shifting the pH,” explains Robert Wallace, GTRI research chemist.

The method appears promising not only for protein separation but also for process water reuse, says Wallace.

Dynamic Filtration

Membrane filtration technology is recognized as an effective method for separating organic and inorganic impurities from water streams. It is widely used in the pharmaceutical industry in both upstream and downstream applications. For use in poultry processing applications, challenges include limitations on throughput and membrane degradation with time as the concentration increases leading to cake buildup.

“Membrane separation is differentiated via the associated pore sizes used for target impurities and distinguished from filtration where media are used to capture contaminants. In both cases, surface contaminant buildup decreases flux, so innovations are sought that decouple flow from separation and filtration rates,” explains Aklilu Giorges, GTRI research engineer.

Giorges conducted a computational fluid dynamics (CFD) analysis of a dynamic filtration process. He found that the cake buildup is strongly affected by the balance of the shear force, transmembrane pressure, and the cake strength and firmness at the membrane surface.

Initial Results and Future Directions

“Our preliminary assessment is that adsorption and dynamic filtration novel separation techniques can be applied to selected poultry processing liquid streams,” says Pierson. “The expected outcomes are combined liquid quality improvement, front-end sampling, and target contamination reduction and concentration at specific insertion points.”

The research team is currently expanding adsorption work to functionalized adsorbents and simulated moving bed technologies, while dynamic filtration research is examining methods to improve separations, especially when pre-treating liquid streams in advance of adsorption systems.

Longer term the team hopes to develop a pilot-scale system to demonstrate dynamic filtration with preparative chromatography for improved liquid stream quality and safety.

March 2011

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