Correction of an Odor Problem by Operational
and Engineering Changes for a
Food Processing Wastewater
Treatment Facility
A. J. DeFALCO, Manager
Industrial Concept Design Division
Betz Environmental Engineers, Incorporated
Plymouth Meeting, Pennsylvania
INTRODUCTION
A septic odor problem nearly forced the shutdown of an East Coast food processing
plant in the summer of 1971.
This presentation recounts the history of wastewater treatment at this plant and the
measures taken to eliminate odors symptomatically. A thorough investigation into the
causes of these odors was ordered and the effort to determine the requirements which would
prevent their re-occurrence began immediately. The outcome of these investigations is the
essence of this report.
It is easy to understand how this Company became involved with such serious odor
problems. The nature of food processing, to begin with, is very conducive to upsets in a
variety of unit processes. Like most food processing firms, this one was engaged in seasonal
production operations which resulted in a complete changeover of production three times
per year. Three principal food items were processed successively during the three
production periods and they included onions, sweet potatoes and fish. Additionally, the
manufacture of another prepared food item of relatively minor consequence in terms of
gross output was continuous and involved slight but unpredictable ingredient changes. The
product mix, therefore, was reasonably stable during each of the three processing periods
during the year. Wastewater characteristics and flow rates were, again like most food
processing companies, widely varying through the day.
Over the course of ten years, this company has managed to finance the construction of
a pretreatment facility prior to final disposal of these wastewaters by spraying on company-
owned land.
It is important to note that the plant is located in the heart of the Atlantic coastal plain.
The hydrogeological features of this particular area are adverse with respect to the surface
disposal of treated wastewaters. The area surrounding the plant is devoid of any streams
large enough to assimilate even a comparatively small discharge. It was evident, therefore,
even at the outset, that the only realistic alternative available to the plant for the final
disposal of their effluent was by land disposal or spray irrigation.
The early years of spraying are somewhat unclear but the periodic addition of
pretreatment equipment, suggested the gradual brewing of difficulties in the spray field. To
be sure, the engineering design of a spray field is not straightforward. At this point in time a
great amount of work,remains to be accomplished in developing the empirical techniques
which will accurately define the interplay among the physical, chemical, biological and
agronomical treatment principles at work in the spray field. Due to a basic unfamiliarity
with these treatment mechanisms, target pretreatment objectives were ill-defined. This
combined with some unfortunate pretreatment design shortcomings eventually caused
ponding of partially treated effluent in the field with resultant obnoxious odors. It is
postulated that the lack of knowledge and poor control have been the probable causes for
the ruination of many spray fields. This is unfortunate because, with reasonable care and
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