An Effluent Study of a Fresh Water
Fish Processing Plant
M. J. RIDDLE, Project Engineer
Food and Allied Industries Division
Water Pollution Control Directorate
Environmental Protection Service
Department of Environment
Ottawa, Canada
K. L. MURPHY, Professor
Department of Chemical Engineering
McMaster University
Hamilton, Ontario, Canada
INTRODUCTION
Current methods of processing fish require the use of considerable quantities of water
for: cleaning the fish, transporting the waste material, plant clean up, and for use in
deodorizers. The discharge of this waste water directly into adjacent lakes and rivers solved
the disposal problem of the fish processors for many years. In the last ten years the
expansion ofthe fish processing industry and the improvement ofthe by-product recovery
techniques made it economical to remove the large solid material from the waste water by
screening. The screenings were processed, the resulting fish meal was sold as animal feed,
but the remaining waste water still has been discharged to receiving waters.
The characterization of wastes from various types offish plants has been the subject of
a number of studies. These have been reviewed by Riddle (1) but almost all the plants
handled seafood as opposed to freshwater fish. Further the information on treatment was
mainly confined to screening and flotation, in other words physical treatment, of waste
from seafood processing plants. There is very little information available on biological
treatment as applied to any type of fish wastes.
The Canadian Department of the Environment with the cooperation of the
Department of Chemical Engineering, McMaster University, agreed to undertake a study
to: 1) characterize the effluent from a freshwater fish processing plant, and 2) determine its
biological treatability.
FRESHWATER FISH PROCESSING WASTES
Omstead Fisheries, 1961, Limited, of Wheatley, Ontario, was chosen for study.
Omstead Fisheries processed some 34 million pounds of perch and smelt in 1969. The plant
is situated about one mile south of the village of Wheatley, Ontario, and some twenty miles
south east of Windsor, on the Lake Erie shoreline.
The various steps for processing perch and smelt are shown on Figure 1. Perch are
normally filleted whereas smelt are eviserated. As the processing operations are carried out
by machine the company attempts to keep a steady flow of fish through the processing
machines. If the supply of perch is low, hand filleting is employed, while smelt processing is
discontinued until the supply is replenished. Following processing the fish are placed on
trays in large boxes for freezing and eventually packaged in small boxes for the consumer
market.
The offal from the fish processing plant is transported by auger to the fish meal plant
(Figure I), where it is processed into animal feed and high grade fish oil. Only washdown
water is discharged from the fish meal plant. As many fish meal plants do not recover
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