9420.pdf

equipment clean and to flush offal away. Typically, large chunks of offal (heads, tails, fins,
etc.) fall into chutes which direct the offal to flumes, or are washed into flumes, which
transport the offal to a collection sump. However, a certain amount of offal generally falls
onto the floor where it accumulates and must be removed manually. This is typically
done by hosing the offal into a nearby drain or flume.
Apart from resulting in high water consumption, this method of equipment cleaning and
offal transport causes the mixing of the rinse water with offal and blood, which has two
main disadvantages:
1)
2)
Any soluble BOD components (i.e. blood) will be dissolved in the water.
Dissolved BOD cannot be removed by physical treatment such as
screening.
The wastewater pumping action is rough on offal chunks resulting in an
increase of smaller particles which may pass through the following screen.
In addition, pumping is believed to increase the dissolved BOD content by
solubilizing suspended organic material.
5.1.3 Solid Waste Generation
Solid waste generation rates at B.C. fish processing plants are summarized in Table 5.3
(based on values reported by B.C. Ministry of Agriculture, Fisheries and Food, 1992a).
Waste generation from filleting operation varies significantly with species processed.
While salmon filleting generates only 60 to 65 % waste, groundfish filleting generates up
to 75 % waste. Waste generation from halibut filleting in B.C. falls into the range reported
by Green and Mattick (1977). Very high waste generation is reported for herring roe
processing because the balance of the fish is normally disposed of (in addition to all male
fish which are disposed of without processing). Waste generation from shrimp and crab
processing is within the waste generation range reported in the literature (Green and
Mattick, 1977).
The amount of offal generated in B.C. is estimated at 109,000 tons/year (wet weight)
based on 1988 statistics (Aegis Management Services Ltd., 1991) (compared to
587,000 tons generated in 1991 in all of Canada - Canadian Fishery Consultants Ltd.,
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