L’impact de la saumure rejeté SUR L’écosystème marin

Abstract

Seawater desalination represents a strategic response to the growing freshwater scarcity in Algeria. This thesis studies the diffusion of brine discharged from a seawater desalination plant and proposes an optimised design for the discharge system (submarine outfall and diffuser). The work is structured in four chapters: (I) environmental impact of brine on Mediterranean coastal marine ecosystems — osmotic stress on Posidonia oceanica and Cymodocea nodosa seagrass beds, residual chemical contaminant effects, long-term biodiversity impacts; (II) brine management and valorisation strategies, from advanced membrane technologies (HPRO, electrodialysis, membrane distillation) to the Zero Liquid Discharge (ZLD) concept; (III) dispersion techniques — discharge pipelines, submarine outfalls, inclined multiport diffusers, hydrodynamic modelling; (IV) in-depth case study of the Chatt El Hilal plant at Beni Saf (200,000 m3/day, reverse osmosis) using CORMIX v.4.2GT modelling, assessing the impact on Cymodocea nodosa meadows and validating the optimal diffuser configuration (P1: depth 8 m, D3=1.07 m, v=3 m/s, inclination 45°, S max=1,707 mg/L < threshold 2,000 mg/L).