Abstract

Chile is the largest producer of desalinated water in South America, where 100% of the installed capacity is based on reverse osmosis technology. Despite the numerous benefits of RO and its widespread use, seawater desalination by means of RO is still controversial, mainly because of the management and disposal of its main waste product, known as brine, which contains high salinity levels and is continuously discharged in large amounts during the desalination process to the near-coast environment. The concern with this practice is that as brine is denser than the receiving water, it tends to accumulate in the bottom near the outfall, hence exposing benthic habitats to the effluent discharge (Clark et al., 2018). To date, available information regarding the behavior of desalination effluents in Chilean coastal systems, their potential effects on the benthic ecosystems and how to measure/detect it, it is scarce. The aim of the present study is to assess brine discharge potential impacts from a desalination plant in north Chile on local coastal systems, by means of fieldwork monitoring and traditional probabilistic environmental risk assessment. A predicted no-effect concentration was calculated for brine effluent from a local plant in Antofagasta (PNEC=37.46 PSU), compared with the predicted environmental concentration (PEC) from on-site brine discharge salinity measurements and later a spatial projection of the risk quotient (RQ=PNEC/PEC) was determine. Results obtained, suggests that probabilistic risk assessment models are coherent with physical dispersion models and observed benthic community response to the brine discharge, validating traditional ERA as an appropriate tool to determine brine plume effective influence area.