Method of Obtaining of Concentrate of Rapidly Reproducing Microalga for Converting of the Emitted Carbon Dioxide into Oxygen and Food Biomass for Feeding of the Crew of an International Space Station during Long Flights

Abstract

It is known that the use of microalga solves the problem of utilizing carbonic acid formed during the life of astronauts and replenishing oxygen in the spacecraft atmosphere. There is evidence that among the mass of microalga used for research as oxygen products for space flights, chlorella and spirulina are suitable. In the field of creating a life support system (LSS) of the International Space Station (ISS), research is being carried out mainly for the current support of manned flights on the Russian segment of the international station. Basically, spirulina is used as a biological supplement in a mixture with various components. In the experimental complex "Bios-3" a number of hermetic-chamber experiments were carried out. Today, the space photo bioreactor is conducting experiments on the ISS for determination of the possibility of using microalga to convert carbon dioxide emitted by astronauts into oxygen and food biomass through photosynthesis. However, only the cultivation of microalga in microgravity conditions is not enough, due to the fact that a concentrate of live microalga is needed to add to the diet of astronauts, and to maintain the cultivation of microalga during a long flight, it is necessary to add a part of the obtained concentrate and the separated nutrient medium to the cultivator (photo bioreactor) for growing microalga in a closed loop. The paper presents the developed method of obtaining of concentrate of rapidly reproducing microalga for converting of the emitted carbon dioxide into oxygen and food biomass for feeding of the crew of an International Space. The developed method uses the effect of a constant electric current on a nutrient medium with microalga, which permits to simultaneously generate microdispersed negatively hydrogen bubbles and a negatively charged catholyte near the cathode, which, as a result of the electrostatic force of attraction between the electrodes, form strong complexes: living cells of microalga + microdispersed hydrogen bubbles concentrating along the entire the cathode zone separated from the nutrient medium, which is localized along the entire anode zone. The conical shape of the vessel containing the complexes: living cells of microalga + microdispersed hydrogen bubbles concentrated along the entire cathode zone and a nutrient medium localized along the entire anode zone permits to move the separated components into different ampoules under microgravity conditions. The separated nutrient medium and a part of the concentrate of living microalga cells are returned to the cultivator through a closed circuit for further cultivation of microalga, removal of carbon dioxide and replenishment of oxygen in the ISS atmosphere during a long flight. Most of the remaining concentrate is used to feed the astronauts for their performance during a long flight.