Abstract: The invention relates to a reactor for growing algae in an aqueous liquid using photosynthesis. The reactor includes a tank for accommodating the aqueous liquid with the algae in it, and a lighting system including a light source with a plurality of LEDs, a mounting structure for supporting the LEDs, and a housing for accommodating the light source and the mounting structure. At least a portion of the housing is transparent for light emitted by the light source. The lighting system is at least partially submerged in the aqueous liquid. Additionally, in operation, the light transmitted through the transparent portion of the housing is of sufficient intensity to substantially prevent growth of the algae on the surface of the transparent portion of the housing.

Abstract: A pump or turbine is disclosed which includes a housing provided with at least one chamber, a rotor, which is rotatably mounted on a shaft in the chamber, an inlet, which communicates with the chamber at least at the location of the shaft, and an outlet channel, which communicates with the chamber at least at the periphery of the rotor. The pump or turbine moreover comprises at least one bypass channel, a first end of which opens into the outlet channel of the pump and a second end of which forms an inlet. The bypass channel may be used for increasing the propelling force or for pumping slurries, for example.