Combining autonomous underwater vehicle missions with velocity and salinity measurements for the evaluation of a submerged offshore SWRO concentrate discharge

Abstract

High salinity discharges from seawater reverse osmosis (SWRO) plants into the marine environment may adversely affect water quality in the area surrounding the outfall. In general, very little systematic information on the potential impacts from full-scale operations on marine biota is available and even less to quantify such impacts for regulatory purposes. Scientifically validated and efficient planning tools in the form of predictive models and expert systems are normally used to assist regulators with regard to possible impacts on the marine environment. Numerical modeling has always been an efficient tool for predicting wastewater discharges and also more recently for high salinity discharges into seawater. The purpose of this study was to combine a series of propulsion-driven autonomous underwater vehicle missions with velocity and salinity measurements for the effective evaluation of a submerged offshore SWRO concentrate discharge near the campus of the King Abdullah University of Science and Technology. The Cornell Mixing Zone Expert System was additionally utilized in order to assess discharge performance under different ambient velocity magnitudes.The paper therefore focuses on the evaluation of an existing SWRO desalination discharge with emphasis on the regulatory framework of the mixing zone. The objective of this case study is to develop an approach that can be followed by SWRO plant operators and environmental competent agencies for establishing regulatory mixing zones for SWRO plants in the Kingdom of Saudi Arabia and worldwide, based on robust field monitoring.