Effect of pulpmill effluent on dissolved oxygen in a stratified estuary—II. Numerical model

A numerical model is presented which simulates the biological and physical processes of oxygen supply in a stratified inlet. The results of the model show that the introduction of pulpmill effluent into the upper layer of the inlet causes a decrease in the dissolved oxygen concentration of the water due to blockage of photosynthesis in the stratum of water immediately below the halocline. Removal of the biochemical oxygen demand from the effluent has very little effect on the oxygen concentration in the upper layer since the supply of oxygen from the lower layer is blocked by the stain. Removal of 90 per cent of the stain from the effluent restores the oxygen concentrations to near normal.