DIRECT COMPARISON IN PHYSIOCHEMICAL TREATMENT OF
PACKINGHOUSE WASTEWATER BETWEEN DISSOLVED AIR
AND ELECTROFLOTATION
Ernest R. Ramirez, Manager, Environmental Evaluation
Research and Development Center
Swift & Company
Oak Brook, Illinois 60521
Dennis L. Johnson, Project Engineer
Swift Fresh Meats Company
Chicago, Illinois 60604
Ogden A. Clemens, Director of Engineering
Research and Development Center
Swift & Company
Oak Brook, Illinois 60521
INTRODUCTION
This article deals with a Swift beef slaughterhouse plant in Grand Island, Nebraska.
Plant construction was completed in 1965 and the original design called for discharge of
its wastewater into the municipal waste treatment system.   The plant, as later expanded,
was designed to have several options on modus operandi.   One involved the ability to
either brine cure and/or dehair hides, depending on the market demands and profit
margins available.
The plant was designed to handle 600 head of beef per 8-hr shift.   In the first stages
of its operation, only one shift was employed.   In later years, two shifts were carried
out and it was found that at this point the load discharged to the municipal sanitary
district was beyond their capabilities.   It became evident that the Grand Island plant
would have to install improved primary wastewater treatment prior to discharge to the
municipal waste treatment.
Work on selecting an improved advanced primary system for treating Grand Island's
wastewater was initiated in the late 1960s.   In a series of evaluated tests, hydrosieves
and other devices were studied. In addition to treating its wastewaters, the plant was
especially interested in recovering as much of the fats and oils from the wastewater as
possible.   Swift Fresh Meats management was, above all, interested in evaluating primary
wastewater treatments under the worst conditions of the plant, namely that of processing 1200 head/day including dehairing the hides.   These two operations combined constituted the worst possible discharge conditions from the Grand Island plant.
The problem of wastewater treatment and selecting the proper primary process is,
without question, an engineering selection that involved the following three variables:
(a) performance of primary wastewater treatment as reflected by the surcharges levied
by the municipality (cleaner waters up to a point had less surcharge levies); (b) maximum recovery of marketable fats and oils values; and (c) ability to dehair hides and/or
brine-cure hides, depending on market demands.   The above three factors are interwoven.
In the ultimate analysis, profits at the plant will reflect on the primary treatment used.
It was, therefore, important that a careful evaluation program be assembled in order to
establish lowest operating costs at minimal capital investment in the long run.
OBJECTIVES
Objectives of the plant manager at the Grand Island packinghouse plant were the
following:   (a) reduce pollutant loading to the city wastewater treatment plant so that
the discharge from the city wastewater treatment system would not continue to degrade
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