Design of a Grease-Recovery
Plant for a Meat Packer
Arthur H. Beard, Jr.
University of Arizona
Tuscon, Arizona
Grease recovery from packing-plant waste has received considerable
study in recent years. In view of the increasing emphasis on industrial
waste pretreatment and treatment, the harmful effect of grease on receiving watercourses and sewage-treatment plants has been an incentive
to bring about maximum grease recovery from the liquid wastes.
But few packing plants are specially equipped for complete grease
recovery. The few that have modern systems and attempt to make complete or semi-complete recovery have adopted sewage-treatment methods
both in the recovery of the portion of grease which separates readily
by flotation and sedimentation and that which is recoverable by specialized treatment.
The most practicable and economical means of recovering grease
from packing-plant waste is determined by the particular methods employed within the packing plant and the elements which affect the quantity and quality of grease recoverable. These are the volume of liquid
waste which is to be subjected to the grease-recovery system and the pH
and stability of the liquid waste (especially as affected by its grease content and the temperature and effectiveness of the pre-separation of raw
fats and process fats), which govern the design elements of the recovery
system.
Besides being one of the most putrescible of industrial wastes, packing-plant waste has a high population equivalent. Figures compiled by
the United States Public Health Service^/)* show the population
equivalent per 1,000 pounds liveweight per day to be 95 on the basis
of BOD and 60 on the basis of suspended solids.
Several variable factors are inherent in packing-plant waste discharge : namely, the weight and fat content of the livestock, the quantity
of waste, depending on varying seasonal kill and high instantaneous rates
of production, and the composition of the wastes with special regard to
suspended solids and grease content.
* Italicized figures in parentheses refer to the references on page 140.
129