utilization of alternative testing methods in the evaluation of pulp and paper mill effluent toxicity
abstract
pulp mills are required to perform routine regulatory testing to ensure the effluent they release
from their water treatment plants is not harmful to humans and the environment. the key components
within the effluent that cause toxicity include factors such as total suspended solids, chemical oxygen
demand, concentration of resin and fatty acids and the colour of the effluent. in december 2013 a pulp
mill in terrace bay, on experienced three failures when their effluent caused 90 to 100% mortality to
tested rainbow trout. in this study, the objective was to determine the potential cause of this failure.
prior to this failure, mechanical issues resulted in an increase in pulp fibre with in the mills secondary
treatment system. since mortality was observed in trout tests and not daphnia tests, the increase in
fibre was suggested as a likely cause. acute toxicity screenings were conducted using effluent that had
been spiked with sludge obtained from the primary clarifier, mimicking concentrations observed during
the failure. there was 10% mortality in one of the untreated samples and no mortality occurred in any
of the spiked samples. the lack of fibre induced mortality combined with increased levels of sulphur
suggested volatile sulphur compounds as a potential cause for the failure. given their volatile nature,
current test methods are not suitable for testing these compounds especially at low concentrations.
another objective of this study was to determine if the toxicity of effluent could be measured using a
crystal violet staining (cvs) assay applied to piscine cell lines as an alternative to in vivo methods. [...]