Disposal of Animal Wastes
E. PAUL TAIGANIDES, Assistant Professor
Agricultural Engineering Department
Iowa State University
Ames, Iowa
The trend toward confinement production of farm animals has been firmly established in the United States. A parallel phenomenon has been the steady trend
to increased concentrations of animals per farm and per production building. Livestock and poultry confinement production units with population equivalents of
10, 000 to 30, 000 are already in existence, and the number of such units is steadily
increasing. The largest single problem resulting from this increase in the number
of animals reared in confinement units under a single management involves waste
disposal.
Confinement units, as they are being developed presently, represent an initial
investment for buildings and equipment alone in the range of three dollars - six
dollars per hen, $20 - $40 per hog, and $1, 000 - $1,500 per dairy cow. Such
large investments, working on close profit margins, cannot tolerate second-guessing
in the design of any phase of the production operation, including waste management. On the other hand, the producer is limited in his effort of manure management both by lack of information and funds. The farmer is willing, more than is
generally accepted, to adopt new ideas to combat the waste disposal problem.
However, new and experimentally proved ideas have not been advanced by the
few engineers and scientists who only recently became interested and started working in the field of animal waste disposal. It would take a coordinate effort by researchers from disciplines related to animal production, engineering, and public
health to find some satisfactory solutions. No satisfactory method of farm waste
disposal has been advanced.
The term, animal waste disposal, as used today refers to most everything associated with manure. Actually, disposal is but one of several states orgroupsof
considerations; i.e., properties, handling, treatment and final disposal. This
paper will examine each of these components individually and in combination.
PROPERTIES OF ANIMAL WASTES
An understanding of the properties of animal wastes is essential in the search
for solutions to the problem of their disposal. In the past, procedures used in the
disposal of municipal sewage have been applied without modification to the treatment of animal manures. These procedures failed because of the unrecognized
basic difference between sewage and manure; i. e., sewage is water which contains some solid matter while manure is solid matter which contains some water.
The properties of manures can be classified as physical, chemical, and biological. Physical factors, such as weight and moisture content, were originally
considered the most pertinent characteristics. Chemical composition has emerged
as an equally important property,   as have the biological constituents of manure.
The physical and chemical properties of animal wastes are affected by the
particular characteristics of the animal, the feed ration, and the environment.
The size of the animal, as measured by its live weight, is perhaps the most important parameter.    The sex and breed of the animal affect the manure properties
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