ORGANIC ASSIMILATION CAPACITIES OF LAND TREATMENT
SYSTEMS RECEIVING VEGETABLE PROCESSING WASTEWATERS
William J. Jewell, Associate Professor
Cornell University
Ithaca, New York 14853
INTRODUCTION
The land application of wastewaters has been a common practice for many years in
the fruit and vegetable processing industry.    This industry was the first to take advantage of this inexpensive and relatively simple treatment alternative.   The recent emphasis to attempt to eliminate all pollutant discharges by the use of land application
has raised questions about the fate of pollutants in soil treatment systems.   In reviewing
the older land treatment systems in the food processing industry it can be observed
that many systems were designed and implemented without knowledge of the capacity
of the soils to assimilate the pollutants.   Monitoring was used in a few cases to determine the fate of the pollutants once the system had been installed.   The most common
criteria for judging "successful" operation of a system was based on whether the wastewater would disappear without odor formation.   Today state and federal pollution control agencies have developed approaches which require that the ultimate fate of the
pollutants be known and that any significant quantities that are passed into the air,
land or water be identified and reported.
The lack of comprehensive data on the many land treatment systems of food processing wastewaters and the absence of techniques to predict the fate of many pollutants in these systems has created problems for the food processor and for pollution
control programs.   From the processors' viewpoint much evidence is available to demonstrate that land application is useful and has caused few obvious problems.   Without
large-scale monitoring data or fundamental predictive capability this argument does not
provide evidence required to indicate the potential impact of these systems on environmental quality.   The control agencies are concerned that pollutants placed in soil systems can accumulate and cause serious unpredictable problems.   For example, if organics
reach the ground water the lack of oxygen and the lowered temperatures prevent
both significant aerobic and anaerobic organic removal mechanisms from operating.
Thus small quantities of organics potentially could degrade large volumes of the ground
water for long time periods.   A growing number of treatment guidelines are presently
responding to this situation by either requiring that the bulk of pollutants (mainly organics) be removed prior to land application of wastewaters and/or that the water that
reaches the ground water must be of drinking water quality.   For a medium-size food
processor presently using land application of wastewaters, implementation of secondary
treatment could increase pollution control costs $500 per day [this is equivalent to an
increased treatment cost of $0.50 per 1000 gal   treated (1)1.   This study was conducted
to determine the assimilation capacities of food processing wastewaters in soil systems
and to relate this capacity to the need for organic removal processes prior to land application of these wastewaters.
OBJECTIVES
This paper contains a summary of information developed in an on-going study of the
fundamentals which define the capacity of soil systems to assimilate wastes.   The emphasis of this study is the assimilation of vegetable processing wastewaters.   The specific
objectives of this paper are to:
1.   review, briefly, the food processing industry and its relation to land application of
wastewaters;
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