Water Quality Modelling and Evaluation at Marine Outfalls

Abstract The increasing water demand of urban and industrial areas in most semi-arid and arid coastal cities led planners to seek renewable alternative water sources and resources. In the past decade, Egypt has launched many large-scale projects along its Red Sea and Mediterranean coasts to cope with the continuous increase of population and urban and industrial developments. Desalination is the most feasible solution to the huge water demand in the region, especially due to the known and limited water resources of the Nile and expected drought due to climate change and upstream dams’ construction. Reverse osmosis desalination plants have become an important source of freshwater production in Egypt. However, the treatment of brine wastewater is still a challenging problem. Hyper saline water effluent as a by-product of seawater desalination, has a negative impact on the marine ecosystem, if discharged inadequately. In this work, a simulation method was proposed to design a safe disposal system for brine effluents. This study uses the model of (CORMIX v 9.0) near-field hydrodynamic model to simulate, predict and manage the brine discharge dispersion and dilution behavior, and assess the initial dilution discharged into coastal water areas through different outfall systems configurations. The research will be applied to desalination plants located along the Red Sea and the Mediterranean Sea coasts. Based on the simulation results, the design of desalination plants reject brine removal system with a multi-port diffuser will be determined. The design parameters are the, diameter, length and number of ports in the effluent system. These optimized simulation frameworks provide planners with effective tools to meet environmental standards while achieving economic or cost-effectiveness and Hydrodynamic performance that is appropriate and up to date. Applicability of the proposed method was demonstrated by a case study.