Planning Considerations for Livestock & Poultry Mortality Disposal: Part 2 - Incineration and Landfilling
By Tom Glanville, Department of Agricultural & Biosystems Engineering, Iowa State University
In the last issue of Odor and Nutrient Management Newsletter, we discussed the pros and cons of on-farm burial of poultry and livestock, with particular emphasis on nutrient loading and risks to shallow groundwater, and on selection of burial sites that help to minimize these risks. In this, the second article in the series, we will review incineration and landfilling.
Incineration uses fuel - typically diesel, propane, or natural gas - to support high temperature combustion that reduces carcasses to ash and gaseous emissions. The primary benefits of incineration are rapid and timely disposal, minimal operational labor, and ability to rapidly destroy bacteria, viruses, and even highly persistent pathogenic materials such as anthrax spores.
On farm incineration is typically done with specially engineered, enclosed, fixed-capacity units employing thermostatic controls. Thermostatic controls are burn chambers lined with refractive materials, and secondary burn chambers - called burners or scrubbers - that reduce emission of odors and particulates.
One of the limitations of engineered incinerators is their fixed capacity. Units typically have fixed batch capacities ranging from 100 – 1500 lbs. Overloading can result in lower than desired combustion temperatures resulting in air pollution. As a result, incinerators are typically used for disposal of routine losses of small or mid-sized species. In the swine industry, for example, incinerators are typically used for losses occurring in the farrowing house or nursery. A 2001 survey conducted by the National Animal Health Monitoring Systems project indicated that nearly 15 percent of pre-weaning losses were handled with incineration, while it was used for only about 6 percent of post weaning losses.
Fuel usage is an important incinerator characteristic; a 2001 report by University of Nebraska Extension listed diesel fuel consumption ranging from 1 to 3 gallons per 100 pounds of mortality. Ash removal and disposal, and routine repairs, are additional factors to be considered.
Because of their fixed capacity, incinerators designed for on-farm disposal of routine mortalities are usually inadequate to handle surges caused by disease or other catastrophic events. Large capacity portable air-curtain incinerators, however, have been used successfully to handle emergency losses.
These units consist of large open-topped refractory-lined boxes, or a temporary trench excavated in the ground, that is fitted with a fan and air manifold system. The fan blows a high velocity air “curtain” over and into the combustion chamber. This results in elevated burn temperatures, and significantly improved retention and combustion of smoke, larger particulates, and odorous emissions.
Air curtain incineration is a fuel-intensive process requiring both liquid fuel and dry wood. Trained operators also are required. As a result, routine use on most farms is impractical, but air curtain incineration service can be obtained through companies specializing in disaster cleanup and recover.
Engineered incinerators used on the farm do not require a permit from the Iowa DNR. But they are required to be equipped with afterburners or other approved devices that limit smoke emissions sufficiently to meet opacity limits set by the DNR. Open burning of carcasses, or use of home-made incinerators, is prohibited in Iowa.
Disposal of livestock mortalities in landfills is usually limited to emergency situations requiring careful management of large quantities of material. The benefit of using engineered landfills for disposal in these situations is that these facilities are carefully sited to avoid environmentally sensitive areas, and are constructed with leachate containment and/or treatment systems that substantially reduce the risks of soil and groundwater contamination.
Small county or municipal landfills often do not have sufficient excavating capacity, or stockpiles of cover soil, to handle large volumes of livestock during an emergency. Furthermore, animal remains are difficult to compact, making proper construction of landfill cells difficult unless large quantities of more stable solid waste are available to bury with the carcasses.Since most landfills are publically owned, public perceptions of environmental risk also can affect the willingness of landfill operators to accept carcasses. During the foot-and-mouth disease outbreak in Great Britain in 2001, opposition from the public limited the use of public and commercial landfills, forcing British authorities to construct special large emergency mass burial sites. With the above barriers in mind, livestock producers are well advised to contact the landfill managers well in advance of the disposal needs to determine if local facilities and services will be made available if needed.