Spray Irrigation of Dairy Wastes
FRANK J.  MCKEE
Sanitary Engineer
Kraft Foods Company
Chicago, Illinois
The disposal of dairy wastes by spray irrigation is causing a great
deal of interest in the dairy industry for several reasons. First, it
offers a method of disposal, as contrasted with treatment, by which all
of the waste is removed from the stream. The degree of treatment is
100% and there is no effluent problem to be concerned about. In many
situations a 100% degree of treatment is necessary to eliminate a
nuisance.
Second, there is a possibility of recovering some value, however
slight, in the form of better pasture for grazing of livestock from use
of the waste for pasture irrigation. In some cases where the waste
can be used to irrigate row crops, it has a very definite value.
The third reason for interest is that the installation and operation
of such a system is reasonable in cost, certainly lower than any conventional type of waste treatment plant. At present we have six spray
irrigation installations located at Berwick, Ontario; Alexandria, Tennessee; Owenton, Kentucky; Shirley, Indiana; Paoli, Indiana; and
Milan, Wisconsin.
In cases where a level well-drained piece of ground is available the
spray irrigation process will dispose of 100% of the waste. The dosage
of waste on the land can be in the range of 2,500 gallons to 6,200 gallons
per acre per day. This amount may be applied at a daily rate of as
much as 25,000 gallons per acre per day provided a three or four day
resting period between applications is allowed.
In all cases we have practiced waste saving and water volume reduction by use of automatic shut-off nozzles on hoses and separation of
clear water waste. The magnitude of the spray irrigation problem is
determined by the volume of waste rather than the strength. Accordingly we have made every effort to reduce waste volumes. We have
rerouted cooling water and roof drain water to bypass the processing
waste sewer. We have also rerouted sanitary sewers to keep sanitary
sewage out of the spray irrigation installation.
Our first spray irrigation installation was made at a Canadian plant
using only about three acres of land and two fifty gallon per minute
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