TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Process: The process of drying algal biomass is carried out inside a substantially closed structure, where the substantially closed structure comprises at least one hydrophobic surface. The hot air is at a temperature of 60-90 degrees C. The aqueous suspension of algal biomass is derived from the cultivation of unicellular algae (microalgae) carried out in: wastewater coming from industrial and/or civil wastewater; or sea water. The concentration of the aqueous suspension of algal biomass is carried out by means of: gravitational separation by means of sedimentation and/or thickening apparatus typically used in the water treatment plants; flotation; gravimetric separation by means of cyclones or spirals; centrifugation; filtration by means of membranes for ultra-filtration, micro-filtration or vacuum filtration; and treatment by means of filter presses or belt presses. The aqueous suspension of algal biomass is subjected to a flocculation treatment carried out by means of: bioflocculation; the addition of at least one flocculating agent to the aqueous suspension of algal biomass. The hot air is heated using solar energy (preferred) or waste vapors coming from other processings. The layer of concentrated aqueous suspension of algal biomass is put in contact with hot air for a time of 30 minutes to 10 hours, preferably 1-6 hours. In the process a metal grid, a net of polymeric material or a sheet of paper, are placed at a distance of less than or equal to 5 (preferably 1-4) cm with respect to the hydrophobic surface. The hot air moves inside the substantially closed structure at a flow-rate of 0.2-10, preferably 0.3-4 m/minute, or 15-250, preferably 18-240 Nm3/hour. Preferred Components: The layer has a thickness of 0.2-0.6 cm. The flocculating agent is metal salt, which include iron chloride, aluminum sulfate or iron sulfate; cationic polyelectrolytes, which include polyethylene imines or polyacrylamides; and/or chitosan. The concentrated aqueous suspension of algal biomass has a concentration of dry algal biomass of 5-25, preferably 8-20 wt.% with respect to the total weight of the concentrated aqueous suspension of algal biomass. The concentrated aqueous suspension of algal biomass has a water concentration of 75-95, preferably 80-92 wt.% with respect to the total weight of the concentrated aqueous suspension of algal biomass. The hot air is anhydrous air. The layer of dried algal biomass has a thickness less than or equal to 0.1 cm, preferably 0.02-0.06 cm. The layer of dried algal biomass has a content of residual humidity less than or equal to 5, preferably 0.5-3 wt.% with respect to the total weight of the layer of dried algal biomass.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The substantially closed structure is equipped with tilted side panels (hut covering), or with at least one upper panel (flat covering) and at least one side panel.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The hydrophobic surface comprises at least one hydrophobic polymer having a melting point of greater than or equal to 110 degrees C, preferably 120-380 degrees C. The hydrophobic polymer is polyolefin, which includes polypropylene or polyethylene; polyester, which includes polyethylene terephthalate; halogenated polymer, which includes polyvinyl chloride or polytetrafluoroethylene; polystyrene; and/or polysulfone. The hydrophobic surface has a thickness of 0.2-5, preferably 0.5-3 mm. The hydrophobic surface is: a conveyor belt; or applied on a conveyor belt. Preferred Process: The conveyor belt moves at a rate of 0.1-130 m/minute. The conveyor belt moves at a rate of 90-120 m/minute, when operating batchwise and 0.2-1 m/minute, when operating continuous. EXAMPLE - Aqueous suspension of algal biomass obtained from Scenedesmus sp. grown in a culture medium. The aqueous suspension of algal biomass was then centrifuged in a disk centrifuge obtaining an aqueous suspension of algal biomass having a concentration of dry algal biomass equal to 10 g/liter. The aqueous suspension of algal biomass was subsequently subjected again to centrifugation in a rotor centrifuge until a concentrated aqueous suspension of algal biomass was obtained, having a concentration of dry algal biomass equal to 18 wt.% with respect to the total weight of the concentrated aqueous suspension of algal biomass. A sample of the concentrated aqueous suspension of algal biomass was poured onto a tray covered by a polyester film, in order to obtain a layer of concentrated aqueous suspension of algal biomass having a thickness of 0.5 cm. The tray was then covered by a metal grid having meshes positioned at a distance of 2 cm with respect to the layer of concentrated aqueous suspension of algal biomass and was placed in a ventilated oven under air temperature of 65 degrees C, residence time of 4 hours and air flow rate of 20 Nm3/ hour. At the end of drying, the tray was extracted from the oven, where the layer of dried algal biomass was in the form of leaves detached from the polyester film. The leaves were collected and subjected to thermogravimetric analysis, with an operating temperature of 120 degrees C, in order to determine the content of residual humidity which proved to be lower than 1.5 wt.% with respect to the total weight of the layer of dried algal biomass.