Abstract: The invention relates to an apparatus for the purification of a liquid effluent containing pollutants, particularly metals and/or radionuclides, as well as to a process for purifying the effluent.An object of the invention is to provide a continuously functioning purifying apparatus.This object is achieved with the aid of an apparatus incorporating a confinement enclosure containing a support in which are immobilized living cells of photosynthetic microorganisms. The support is made from a material transparent to light rays. The apparatus also incorporates a mechanism for introducing and circulating the effluent to be treated and a culture medium within the enclosure.

Abstract: The invention relates to a process for the selective production of polyunsaturated fatty acids from a culture of microalgae of Porphyrium cruentum. The process comprises growing a biomass by culturing the microalgae in a photobioreactor under optimum culturing conditions, removing a portion of the resulting biomass, and subjecting the removed portion to a temperature decrease. The result is the selective increase in the quantity of a given polyunsaturated fatty acid within the microalgae biomass.

Abstract: The process consists of culturing in a closed photobioreactor (2) microalgae suspended in a culture medium (1), the oxygen produced by the microalgae by photosynthesis being collected and then reinjected into the culture medium, separating (6) the microalgae from the culture medium (1), dissolving (12) the microalgae, grinding or crushing (14) the solution of microalgae, adding (16) a solvent to the ground or crushed solution for solubilizing the antioxidants produced by the microalgae and then separating (18) the liquid phases present.

Abstract: Process for the production and extraction of polysaccharides from a porphyridium cruentum culture and apparatus for performing the process.This production and extraction process comprises a stage of concentrating the polysaccharides consisting of leaving the culture medium (1) in a photoreactor (22) exposed to sunlight under stagnant conditions and at ambient temperature, leading to the formation of a polysaccharide-rich cream (23) and recovering said cream by skimming, a stage (24) of heating the concentrate obtained at a temperature between 60.degree. and 100.degree. C., a stage of separating the solid and liquid phases formed (26), a stage (30) of precipitating the polysaccharides contained in the liquid phase and a stage (16) of drying the precipitate obtained.

Abstract: The invention relates to a transparent polyurethane foam wall optionally containing microorganisms, and a process for the preparation thereof, and the use of this wall in a biophotoreactor. This wall has pores, in which are distributed microorganisms and the pores are closed on one of the faces of the wall, in such a way that said face is impermeable to liquids and gases, while the other face of the wall has an open porosity. Thus, by circulating a liquid nutrient medium and a gas along the second face of the wall and exposing the first face thereof to light, it is possible to culture microorganisms and collect the metabolites formed by them in the liquid medium.