Facility for treatment of saline water having a salinity greater than that of seawater, meaning greater than 40,000 ppm TDS, and containing oil and/or other contaminants, comprising a feeding duct for supplying the saline water and at least one treatment basin integrated in a natural or artificial topography, characterized in that the at least one treatment basin is a periphyton bioreactor basin being designed as a bioreactor basin, which comprises periphyton, in that the periphyton comprises an assemblage of salt tolerant periphyton grown as mats and attached growth biofilms within a water column of the at least one periphyton bioreactor basin, in that the periphyton bioreactor basin comprising a treatment zone which is provided with a substrate layer adapted to support growth of periphyton and which has a uniformly levelled benthic surface and being formed as a shallow pond, so that the water may flow with a sheet-flow with a depth of 0-500 mm throughout the periphyton bioreactor basin in order to obtain a film of water that spreads uniformly across the benthic layer surface, in that the periphyton bioreactor basin is designed to provide the appropriate conditions, in terms of residence time, hydraulic and flow characteristics, substrate conditions and sunlight exposure, to promote the production of attached-growth biofilms and facilitate the retention of contaminants such as oil and hydrocarbons, subsequentially promulgating the necessary biodegradation processes, so that the periphyton bioreactor basin is adapted for physically and biogeo-chemically eliminating and biodegrading contaminants and is thus adapted for treating the saline water, by which the content of oil and/or other contaminants in the saline water is reduced, in that a calming zone is arranged in an initial part of the periphyton bioreactor basin nearby inlet means, said calming zone being designed as a transverse channel which substantially spans the full width of the periphyton bioreactor basin and is deeper than the main part of the periphyton bioreactor basin, and in particular deeper than the adjacent area of the treatment zone, wherein the water flows from the calming zone into said adjacent area of the treatment zone, and in that an additional calming zone is arranged in a final part of the periphyton bioreactor basin nearby outlet means, said additional calming zone being designed as a transverse channel which substantially spans the full width of the periphyton bioreactor basin and is deeper than the main part of the periphyton bioreactor basin, and in particular deeper than the adjacent area of the treatment zone, wherein the water flows from said adjacent area of the treatment zone into the additional calming zone. a feeding duct for supplying the saline water and at least one treatment basin integrated in a natural or artificial topography, characterized in that the at least one treatment basin is a periphyton bioreactor basin being designed as a bioreactor basin, which comprises periphyton, in that the periphyton comprises an assemblage of salt tolerant periphyton grown as mats and attached growth biofilms within a water column of the at least one periphyton bioreactor basin, in that the periphyton bioreactor basin comprising a treatment zone which is provided with a substrate layer adapted to support growth of periphyton and which has a uniformly levelled benthic surface and being formed as a shallow pond, so that the water may flow with a sheet-flow with a depth of 0-500 mm throughout the periphyton bioreactor basin in order to obtain a film of water that spreads uniformly across the benthic layer surface, in that the periphyton bioreactor basin is designed to provide the appropriate conditions, in terms of residence time, hydraulic and flow characteristics, substrate conditions and sunlight exposure, to promote the production of attached-growth biofilms and facilitate the retention of contaminants such as oil and hydrocarbons, subsequentially promulgating the necessary biodegradation processes, so that the periphyton bioreactor basin is adapted for physically and biogeo-chemically eliminating and biodegrading contaminants and is thus adapted for treating the saline water, by which the content of oil and/or other contaminants in the saline water is reduced, in that a calming zone is arranged in an initial part of the periphyton bioreactor basin nearby inlet means, said calming zone being designed as a transverse channel which substantially spans the full width of the periphyton bioreactor basin and is deeper than the main part of the periphyton bioreactor basin, and in particular deeper than the adjacent area of the treatment zone, wherein the water flows from the calming zone into said adjacent area of the treatment zone, and in that an additional calming zone is arranged in a final part of the periphyton bioreactor basin nearby outlet means, said additional calming zone being designed as a transverse channel which substantially spans the full width of the periphyton bioreactor basin and is deeper than the main part of the periphyton bioreactor basin, and in particular deeper than the adjacent area of the treatment zone, wherein the water flows from said adjacent area of the treatment zone into the additional calming zone.