Soil-like substrate fertility restoration method in bioregenerative life support systems

The research focused on chard plants grown in a vegetation chamber under irradiation of 600 μmol/(m2s-1) FAR and elevated CO2 concentration in the range of 1500-2000 ppm. The objective is to determine the feasibility of incorporating gaseous nitrogen-containing products of physicochemical mineralization of human exometabolites into the cycling process in relation to the conditions of bioregenerative systems of human life support. To replenish the Impoverished soil-like substrate with available forms of nitrogen, we introduced NH4NO3 into the irrigation solution. This can be obtained from NH3, which is a part of gaseous intrasystem mass exchange products. The incorporation of NH3 into the intrasystem cycle comprised three main steps. 1) Some of the NH3 was oxidized to nitrogen oxides, which dissolved in water and formed acid solutions; 2) Another part of the NH3 was barbotaged through a nitric acid solution to obtain NH4NO3; 3) The obtained ammonium salts were used as fertilizer and added to the irrigation solution for the cultivation of chard plants, which represent the phototrophic link in the bioregenerative life support system. The results clearly demonstrated that replenishing the available nitrogen forms in the Impoverished soil-like substrate to match the original substrate levels resulted in plant mass comparable to that of plants grown on freshly prepared substrate. The research results prove the potential of the developed technologies for involving dead-end gaseous nitrogen-containing waste from human activity in the intrasystem mass exchange of the life-support system.