ATA Corp. is an Aiken-based chemical engineering firm utilizing technologies that are capable of providing waste reduction and recycling options for municipal and industrial solid waste and/or wastewater problems. Technology examples include:

1. Browns of Carolina, LLC.
2. Prestage Farms, Inc.
3. Southeast Paper Co.
4. International Paper
5. Riley Stoker Corp.

Disposal of animal mortality is an issue that is becoming a very large problem for these industries. This is primarily due to the fact that very few acceptable, cost-effective options exist. Carcass disposal via burial is rapidly disappearing as an option in most states. Incineration is another option, but incinerators have a relatively short life cycle (typically three years), have odor problems, and leave the grower with nothing of value after disposal. Composting is an option, but has not gained widespread acceptance for stabilizing animal mortality due to the negative aspects of static pile and/or windrow techniques.

ATA Corp. recently procured a rotary in-vessel composting system (shown below in Figure 1) to assist the Swine and Poultry industries in the Carolinas and Georgia with their waste problems. This system can be utilized to process a wide variety of solid wastes. For example, the rotary composter has been successfully demonstrated on animal manures and mortality, institution food wastes, poultry hatchery wastes, and pulp and paper sludge. Eleven commercial units are presently in use across the country stabilizing various animal and institution wastes, producing valuable composts. The composted products can be used as soil amendments, or in certain cases have significant value as cattle feed supplements.

A demonstration-sized unit was procured from the manufacturer in Texas. This unit is capable of producing roughly 1 yard/day of finished material. The composter consists of an insulated drum that continuously. The unit is fed a mixture of animal mortality and manure with bulking agents (e.g., wood shavings), and thermophilic bacterial action breaks down the manure and carcass. The unit is sized to compost ~250-300 lb./day of mortality mixed in with ~300-400 lb. of manure/bulking agent mix. While the unit is being referred to as a demonstration unit, this system could be a full-size unit for smaller farming operations. Systems can be obtained through ATA Corp. that can process upwards of 6,000 lb./day of animal mortality.

This report will summarize composting turkey carcasses, using turkey litter:

Summary of Turkey and Litter Composting Demonstration.

The unit was loaded with 13 turkeys weighing 14-50 lb. (obtained from Prestage Farms of South Carolina, LLC) with an aggregate weight of ~360 lb. of turkeys. Figure 2 is included to give the reader a feel for how large a 50-lb. turkey carcass is, as well as a view of the collection of carcasses that were later loaded into the unit. The unit was loaded with ~590 lb. of turkey litter (litter loaded into 5-gallon buckets, as shown below in Figure 3, left frame). The litter was then loaded into the unit and water added to bring the moisture content up to ~45%, and can be seen in Figure 3, right frame, beginning to cover the emplaced turkey carcasses

The composting reaction began to occur almost immediately, and the mixture temperature had already climbed to 123 ° F within 23 hours after startup. Significant breakdown of the carcasses began to occur at the same time the temperature was increasing. Figure 4, left frame shows the composting mixture at 23 hours (left frame) and a turkey leg that had fallen off during the first 23 hours (right frame). It is evident that significant breakdown was already occurring.

The mixture was monitored frequently for temperature, moisture, and carcass breakdown. The onset of carcass breakdown resulted in excessive moisture release into the composting mixture, and additional wood shavings had to be added. This would not have been a problem had we kept the initial moisture content of the compost mix at ~35%, rather than 45%.

Monitoring the compost temperature gives a quick check of moisture levels. Turkey/litter mixtures with moisture contents of 55+% resulted in temperatures reaching, but not exceeding, ~120° F. Moreover, the temperature would actually decrease from 130+° F down to ~120° F for mixtures that had increasing moisture content due to carcass breakdown. These composting mixtures also had much more objectionable odors, due to the onset of anaerobic composting action at elevated moisture levels. Additionally, moisture levels below 40% resulted in declining temperatures. The composting temperature rapidly increased to 140° F after adding the shavings, because the excess moisture was absorbed by the shavings. The optimum moisture content was 45-55%. Moisture content in full-scale composting mixtures could be controlled by fresh, dry (moisture ~20%) litter being added periodically during the carcass breakdown. The above discussion should point out the critical nature of moisture levels on the success of a composting process.

The mixture was monitored throughout the composting process, and materials were extracted from the mixture for examination. Figure 5 (left frame) shows that significant breakdown had occurred by 57 hours; an entire tail-and-legs section of a large turkey carcass can be seen, along with several smaller legs. The flesh is essentially gone from the smaller legs, and the larger leg/tail section was significantly broken down; the flesh was very mushy to touch and could easily be torn from the bones. Further analysis of the mixture at 81 hours indicated that flesh removal from all carcasses was essentially complete, as evidenced by the bones extracted from the mixture (Figure 5, right frame).

A final photograph is included in Figure 6 to show the mixture that was removed from the unit. The entire compost pile was examined and all bones removed and collected. A total of six gallons of bones was found, typically breast bones and large leg bones. The total composting time was roughly six days to decompose and "stabilize" the 13 turkeys carcasses. The term "stabilize" as used in this context means that the flesh was converted to materials that will not decay. The rotary composter performs about 80% of the total composting process; it will take animal wastes and produce a stable material that can be land-applied as-is or dried further for bagging. The material piled up in Figure 6, right frame was still somewhat biologically active, with a temperature of ~114 ° F one week after being offloaded. Thus, ATA Corp. recommends that the mortality composts be stored in open sheds to allow the composting process to completely break down any residuals.
 
 

We were able to successfully demonstrate that whole mortality from turkey operations could be converted from a waste problem to a potentially profitable commodity through in-vessel composting. The carcasses can be broken down rapidly and completely, except for the larger bones (that could easily be disposed of). Grinding the materials prior to adding to the composter would eliminate the bone problem, as well as accelerate the composting process. It is extremely important to monitor the moisture of the compost mixture prior to starting and periodically during the process. Moisture spikes resulting from carcass decomposition could be controlled by periodically adding fresh, dry materials, such as litter or bulking agents (e.g., hay, wood shavings, etc.)
 
 

Thank you for taking the time to read our literature. ATA Corp. is committed to helping you reduce or eliminate your wastes. If any of these ideas hold interest for you, we would be glad to discuss them further. We can be reached at the above address and phone number. Once again thank you and we look forward to hearing from you!

Sincerely,

Jeff Siler, Ph.D.

Vice President, ATA Corp.