9420.pdf

meet toxicity limits. However, biological treatment is generally not recommended
treatment option for the following reasons:
● seasonal nature of fish processing;
. generally low temperature of wastewater which is detrimental to biological
treatment, especially biological vitrification of ammonia;
. high cost of biological treatment, especially with seasonal production.
Biological treatment may be considered in individual cases, due to site-specific
constraints.
Water and wastewater minimization procedures should be implemented prior to upgrading
existing wastewater treatment facilities. This is expected to be the most economical way
to reduce the contaminant loadings discharged to the environment from fish processing
facilities. It also results in a payback due to decreased water consumption costs.
However, as these modifications reduce the water consumption and contaminant loadings
to the same extent, effluent contaminant concentrations may not be reduced substantially
although the mass loading would be.
Best management practices for fish processing plant effluents include dry processing and
transport, and prevention of mixing of solid waste material with water. Implementation of
in-house modifications to ‘achieve these practices is expected to decrease the water
consumption and contaminant load by as much as 50 % In addition, it will allow the
installation of smaller and, therefore, less expensive treatment equipment. This is of
particular importance because of the seasonal nature of the fish processing industry
which increases the time required to amortize equipment.
A detailed water and wastewater audit should be carried out prior to implementing major
process modifications in order to identify the areas where the greatest improvements can
be achieved. It is important for regulatory agencies to realize that a substantial amount
of time may be required to audit a plant, develop and implement recommendations, and
evaluate the impact of the changes made, due to the generally relatively short processing
seasons.
At the present time, fine screening is generally considered to be the best economically
achievable technology for treating fish processing effluents. More advanced forms of
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