Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Near-Field Transport and Fate of Pulp Mill Effluents
G. Lawrence, B. Marks, W. Evans, J. Vine and L. Gomm
Department of Civil Engineering
University of British Columbia
We are working on three sub-models of the transport and fate of effluent discharges into the Fraser River.
1. Bonnie Marks is investigating the initial dilution of effluent from the point of discharge to the point at
which the effluent is mixed throughout the depth. In this region, the initial momentum and buoyancy of
the effluent are important. Bonnie has found existing numerical models of this region inadequate, and is
performing laboratory experiments to improve our understanding and modeling capability. Results
obtained from the experiments will include the concentration distribution across the plume at the end of
the initial mixing zone for different seasonal conditions; this will be used as an input for the second submodel.
2. Wayne Evans has found that existing flocculation/particle aggregation theory is not capable of
explaining an aggregation phenomenon noted by field researchers as a result of the discharge of pulp mill
effluents into a sediment-laden river. In view of this, previously obtained field and experimental data
have been analyzed and simple experiments in jars and settling columns conducted to see if aggregation
is indicated. The addition of pulp mill effluents to sediment-laden waters resulted in a turbidity reduction
almost instantaneously in the jar tests. It was found that the most significant effect occurred when the
effluent and river water were added to one another in equal quantities. Whether this indicates an increase
in aggregate sizes is still unknown. Reliable aggregate size measurements cannot be completed at UBC.
More recent settling tests, completed in a settling column, indicated that the settlability of illite (a
primary component of the