Treatment Alternatives for the Fruits and Vegetables
Processing Industry
CURTIS J. SCHMIDT, Principal
ERNEST V. CLEMENTS, Staff Engineer
KENNETH LACONDE, Chief Chemist
SCS Engineers
Long Beach, California 90807
INTRODUCTION
During 1974, SCS Engineers performed the EPA Effluent Guideline Development
Study for the fruits and vegetables processing industry (EPA Contract No. 68-01-2291). As
part of the project, treatment alternatives were analyzed to achieve the pollutant reductions
required by use of the Best Practicable Control Technology Currently Available
(BPCTCA) by July, 1977, and the Best Control Technology Economically Achievable
(BCTEA) by July, 1983. In performing this task, existing fruits and vegetables industry
wastewater treatment plants were evaluated to determine the proven performance of
various system designs. The purpose of this paper is to aid in the development of sound
wastewater treatment systems for the industry by summarizing our findings from this
project.
The fruits and vegetables processing industry operates approximately 1,400 plants and
processes about 30 million tons of raw fruits and vegetables annually. Approximately 55
percent of the fruit and vegetable plants discharge to city sewer systems, and about 30
percent discharge to land. Only about 15 percent discharge directly to surface water after
treatment, including land disposal systems that collect and discharge runoff.
WASTEWATER CHARACTERIZATION
Figure 1 provides a basic flow diagram of some of the typical manufacturing processes
utilized by the industry. As shown, the major wastewater generating processes are washing,
fluming, trimming, peeling, blanching, can washing, cooling, and plant cleanup. Water
recirculation is usually practiced in the washing, fluming, and cooling operations.
Naturally, wastewater characteristics varied tremendously depending on the
commodity being processed and the type of processing used. In general, however, the
effluents were highly organic and biologically treatable. However, nutrients (N and P) are
often deficient and must be added for satisfactory biological treatment. Frequent surges in
organic loadings and wide flow variations are typical. pH fluctuations can be significant for
plants using caustic peeling methods and those processing acidic fruits with natural, low
pH. Non-compatible, toxic pollutants (heavy metals, etc.) are not present in concentrations
of any significance.
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