is the biological decomposition and stabilization of the
biodegradable component in organic matter under controlled
conditions. It is an
aerobic process (requires oxygen) and is carried out by
microorganisms which metabolize organic waste as an energy
source. The effectiveness of the process is dependent upon the
environmental conditions present within the composting system.
composting process is directly affected by oxygen,
temperature, moisture, material disturbance, particle size,
surface area, physical properties of the wastes and the size
and activity of microbial populations. Litter
that is too fine will limit the oxygen supply to the
microorganisms and growth will be significantly reduced.
Slower microbial growth results in lower composting
temperatures. At a temperature of 155 degrees F, carcasses
will decompose about twice as fast as at 130 degrees F. Smaller
carcasses, or those which have been ground will require less
time to stabilize than large, whole carcasses.
essential elements required by the microorganisms are carbon,
nitrogen, oxygen and moisture . If any of these elements are
lacking, or if they are not provided in the proper proportion,
the microorganisms will not flourish and will not provide
adequate heat. A
composting process that operates at optimum performance will
convert animal carcasses into a stabilized material that is
odor and pathogen free, and a poor breeding substrate for
flies and other insects. In addition, it will significantly
reduce the volume and weight of organic waste as the
composting process converts much of the biodegradable
component to gaseous carbon dioxide.
is already an acceptable method of recycling organic wastes
and is rapidly becoming a preferred alternative for
sanitizing animal carcasses. The cost associated with set up
and maintenance of an animal carcass composting system is
composting method is determined by individual requirements and
animal mortality rates. Several methods including aerated
windrow, static pile and in-vessel (bin) are currently in use.
smaller operations, where the mortality rates are relatively
low, a single stage composter may suffice. It can be
constructed using 4' × 4' pallets fastened together to form a
box and lined with wire mesh.. One side should be detachable
to facilitate loading, mixing and unloading. The composter
should be waterproof and located in and area that is protected
from the wind.
larger operations where the mortality rates are higher, a two
stage or three stage composter may be required. The size of
the bins is dictated by mortality rates. The bins should be
constructed to facilitate loading, mixing and unloading and
should be waterproof and located in an area that is protected
from the wind.
composting is a relatively low management alternative to
static-bin composting. In-vessel mechanical composters can be
constructed using a rotating drum designed to turn at the rate
of three to five revolutions per hour. This configuration will
decompose and stabilize animal carcasses in three to eight
optimum odor control the blended material should have a pH at
or slightly below neutral. Odors can also be eliminated by
inoculating the mixture with CBPA stock solution (CBPA
concentrate mixed with water at a rate of 1:200).
time required to compost animal carcasses is directly
proportional to the size of the carcass and the composting
method. For example, in-vessel composting can stabilize
smaller carcasses in three to eight days while windrow
composting may take 21-28 days.
is the primary indicator of biological activity within the
compost pile, and is easily measured with the aid of a digital
thermometer and a probe. Moisture content, oxygen
availability, and microbial activity all influence
the temperature within the composter continues to increase,
the composting process is operating at optimum performance.
When the temperature peaks and begins to decrease, the pile
should be turned. Turning introduces oxygen into the pile and
causes the temperature to rise. Turning should continue until
the temperature fails to rise. This indicates that the compost
material is biologically stable. Sustained temperatures above
130 degrees Fahrenheit favors destruction of pathogenic
bacteria, viruses, fly larvae and weed seeds that might be
present in the waste.
conditions within the pile change due to an unfavorable
moisture content, change in the C:N ratio, or a decrease in
oxygen supply, the temperature may drop and the microbial
population will shift back to a regime of lower temperature
microbes, causing the compost pile to go anaerobic.
in the composting process is critical. Proper aeration
introduces oxygen and evacuates excess heat, gas and moisture.
As oxygen becomes depleted,
microbial growth will slow and the temperature of the mass
will decrease. Proper
aeration may be achieved by passive air exchange, forcing air
through the material or mechanical turning. In addition,
aeration minimizes nitrogen loss by denitrification.
The carbon /
nitrogen ratio (C:N) directly affects the composting process.
C:N ratios of 15:1 to 30:1 are acceptable. If however the C:N
ratio is less than 25:1, the microorganisms cannot metabolize
all of the available nitrogen, and it is lost as ammonia. This
may result in unpleasant odors, and loss of fertilizer value.
When the C:N ratio exceeds 30:1, the composting process slows
content is critical to the composting process and determines
whether the process will be "aerobic" (with oxygen)
or "anaerobic" (without oxygen). For animal carcass
disposal, aerobic composting is preferred because it is faster
and produces less odors. Ideal moisture content for aerobic
composting is about 40 - 50 percent. When the moisture content
reaches 65 percent, the process begins to go anaerobic. High
moisture level can be controlled by adding bulking agents to
the mixture. Low moisture contents are increased by sprinkling
the pile with CBPA STOCK SOLUTION (CBPA concentrate mixed with
water at a rate of 1:200).
the composting process is relatively easy and is not labor
intensive. Daily labor requirements for operating a poultry
carcass composter designed to handle 1000 pounds per day is
about thirty to forty minutes. This includes loading, turning,
monitoring and unloading. Managed
properly, composting can be an odorless, disease free,
environmentally friendly process that produces a value added
product suitable for use in numerous fertilizer applications.