For Immediate Release
November 7, 2000

Wrestling with Rendering's Malodors: Researchers develop model regulations, but still face complicated task of assessing and controlling odors from rendering plants.

EDI researcher Jim Walsh examines packing material from a malodor control biofilter operation at a food processing waste rendering plant near Cumming, Ga. Biofilters take airborne emissions from the plant and push them through a box filled with packing material, such as wood shavings or ceramic balls. Bacteria grow on the packing material, and then they eat and remove most of the odorous chemicals. (300-dpi JPEG version - 1.44k) Photo by Gary Meek

Developed in part by researchers at the Georgia Institute of Technology, Georgia's rules for controlling and assessing malodors from food waste rendering plants could become a model for other states facing the same problem.

Meanwhile malodor control and assessment remains a complicated task. So Georgia Tech and University of Georgia researchers are working to improve treatment of odors so they don't waft into communities surrounding rendering plants.

"The problem of malodors from rendering plants is a longstanding issue. In fact, the industry dates back to Roman times. Today, it is a nationwide issue," says Jim Walsh, a researcher at Georgia Tech's Economic Development Institute.

Every year in the United States, 43 billion pounds of food processing waste materials are sent to rendering plants, where they are converted into pet and animal feeds. Of that waste, 23 billion pounds is from poultry. "The bottom line is if we didn't render this material, it would be in landfills," Walsh says. "Instead, it's turned into usable byproducts."

Dealing with the unwanted byproduct -- that is, malodors -- is the difficult part of the equation. Though the problem is being addressed by the rendering industry, there is not a fix-all solution in sight, Walsh says. "It's just what we expected," he adds. "Odor is a complicated issue."

In Georgia, the malodor issue reached a boiling point in 1999 when citizen complaints prompted the state's Department of Agriculture to develop rules to help manage the problem. Agriculture officials called on Georgia Tech for assistance, and Walsh helped them develop the state's Malodor Control and Assessment Program (MalodorCAP), which became mandatory for rendering plants in August 1999.

The MalodorCAP consists of a control program and a complaint response program. Rendering facilities determine their critical control points (points in the operation where odors are controlled), establish critical limits (operating conditions for control equipment) at each critical control point, and determine corrective actions to be taken if they exceed critical limits. The complaint response program requires a facility to respond to any complaint, record the response on a form approved by the Georgia Department of Agriculture, and keep a log of the complaints. State officials, with Walsh's help, regularly review and help update facilities' MalodorCAPs.

Though Georgia is taking the lead nationally in monitoring malodors, there are no state or federal limitations on malodorous chemical compounds emitted unless these compounds are classified as volatile organic compounds (VOCs) or hazardous air pollutants (HAPs).

"Odor is a subjective and not a quantitative issue right now, so current regulations address odor as a nuisance issue," Walsh explains. "But Georgia's malodor control and assessment rules are unique. They could serve as a model program for other states."

Now the state-funded Traditional Industries Program for Food Processing (FoodPAC) and the Agricultural Technology Research Program are supporting Walsh's efforts as a liaison between industry, researchers and regulators. Walsh is tracking the latest technologies and research, including projects ongoing at Georgia Tech and the University of Georgia.

Recently, the two institutions began a collaborative project to enhance wet scrubber odor treatment technology and improve monitoring for odors and VOCs in the food processing industry. Wet scrubbers transfer odorous chemicals and VOCs in the air to the water and neutralize them using oxidizing chemicals. But wet scrubber operations are often process-specific, and there is limited data available to effectively improve their performance. University of Georgia Professors K.C. Das and Jim Kastner hope their ongoing work in developing methods for chemical characterization of air emissions from rendering operations will eventually advance wet scrubber design. Characterizing malodorous chemicals is difficult because they tend to vary and occur in trace amounts, Walsh explains.

In the current project, UGA researchers are focusing on the mass transfer of specific odorous compounds into water. Specifically, researchers are continuing their chemical characterization studies, and also evaluating the efficiency and appropriateness of water-based treatment technologies. Georgia Tech Research Institute engineer John Pierson is examining potential improvements to the gas-phase pre-treatment of total VOCs. Specifically, he is working with the developers of two different novel chemistries to improve wet scrubber efficiency, and Pierson is developing a predictive monitoring system to better manage rendering plant emissions. Both the U.S. Poultry and Egg Association's Protein and Fats Council and FoodPAC are funding this joint project.

Researchers elsewhere are working on improvements to biofilters, Walsh adds. Biofilters take airborne emissions from the plant and push them through a box filled with packing material, such as wood shavings or ceramic balls. Bacteria grow on the packing material, and then they eat and remove most of the odorous chemicals. In Georgia, rendering plants in Cumming and Cuthbert have installed customized biofilters.

Progress in controlling malodors seems slow sometimes, but Walsh says: "I am constantly hearing of people developing new chemical treatments. A lot of research and development is going on, not only new chemical treatments, but new ways of controlling processing operations to eliminate odors."

For more information, you may contact Jim Walsh, Economic Development Institute, Georgia Institute of Technology, Atlanta, GA 30332-0837. (Telephone: 404-210-5550) (E-mail: jim.walsh@edi.gatech.edu)

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