Dense Discharges

Desalination is a growing activity that has introduced a new impact on the marine environment, brine discharges, which may affect benthic communities.

Disposal of brine into coastal waters is an economical option for desalination projects. After discharge, dense brine water flows below the less-dense ambient water to form a stratified cap over the bottom sediment. Typically, it is not the quantity of salt discharged that causes a problem but the mixing rate and the brine’s fate prior to complete mixing that determines impacts. If natural forces of plume flow, wind mixing and tidal currents are slow to mix the brine with the overlying water, biogeochemical processes in the sediment may deplete the available dissolved oxygen near the bottom, causing hypoxic conditions that harm aquatic life.

Considerations
Several factors can play a large role in finding the optimum discharge location to minimise the extent of the discharge plume and maximise the diffusion into the seawater. The assessment of the various factors requires detailed three dimensional numerical models for computing the fate of brine given variations in wind speed and direction, wave celerity and heights, and the variation in tidal currents over depth.

Services
MarCon have considerable experience in applying state of the art 3D numerical models to examine the above factors and determine the environmental effects of brine discharges.