Out of this world: Russian scientists propose recycling waste in space

Written by: Vladislav Vorotnikov | Published:
At the moment, there is no any useful method of waste reprocessing in space

A group of scientists from the Krasnoyarsk Scientific Center of the Russian Academy of Science have developed a new method of waste recycling that could be applied literary everywhere, including on space stations.

In a series of experiments various household wastes were recycled by the method of wet combustion in hydrogen peroxide with the use of an alternating current electric field. Surprisingly, the best results were achieved when household waste was recycled together with not chemicals, but with human urine.

As explained by Sergey Trifonov, senior researcher of the Krasnoyarsk Scientific Center, the new technology has an important advantage as it is one of the few that could be applied in conditions of the closed biotechnical life support systems, including on space stations. As for urine, Trifonov said, the scientists were focused primarily on cotton waste recycling and were looking for a way to enhance oxidation rate.

Human urine contains urea, which is highly effective in cellulose hydrolysis. This means the entire recycling process takes less than 24 hours.

At the moment, there is no any useful method of waste reprocessing in space. Bacterial fermentation, which is one of the few options available when resources are limited, could take months or even years, depending on the type of waste. The wet combustion in hydrogen peroxide, on the other hand, makes it possible to recycle cotton waste in only several hours, and some valuable mineral nutrients could be obtained as the result.

An important advantage was that the oxidation was not related to the process of synthesis of nitric acid. In the end, scientists managed to obtain a broad range of mineral elements, including potassium, sodium, calcium, magnesium, phosphorus, selenium and iron.

The wet combustion appears to not only be more of an easy-to-use method of household waste recycling in space, but it is also associated with the higher amount of mineral elements obtained in the end, compared to other available methods.

The scientists of Krasnoyarsk say that the wet combustion also compensates the loss of oxygen, hydrogen and carbon dioxide in the closed biotechnical life support systems, while all toxic gases formed during the recycling process are eliminated by the catalytic cleaning system, which makes this method absolutely safe, including for space stations.

In future, Russian scientists plan to adjust the system so it could reprocess all kind of household waste, including various packaging and sanitary materials, according to Alexander Tikhomirov, senior scientist of the Krasnoyarsk Scientific Center.

Waste recycling for colonisation of other planets

In future, waste recycling will play a much more important role in human society than now, and new technologies in this area will be required in order to make possible long-distances space flights and even colonisation of other planets, the Russian scientists believe.

Earlier this year, Krasnoyarsk scientists conducted another study on fish waste mineralization using the same method of wet combustion in hydrogen peroxide. This kind of recycling could become a new source of nutrients for humans. According to scientists, a major advantage of this method is the complete destruction of pathogens, which could pose an issue for human waste processing at low temperature.

Just like with cotton waste, the scientists managed to obtain a nutrient solution that could be used to boost the average yield of plants.

The research showed that wheat plants grown in a nutrient solution prepared from mineralized fish waste and human waste had higher yield as compared to the yield obtained using only mineralised human excreta. Fish waste has also become a source of additional mineral elements for wheat, Alexander Tikhomirov added.

This mineralised fish waste was an additional source of important nutritional elements to variously aged wheat plants grown in the conveyor mode on the inert substrate. In this case, no replenishment of the nutrient solution with mineral salts were needed.

With these technologies, scientists are becoming much closer to establishing a closed-loop system, which means that the closed biotechnical life support systems could run for a long time on its own, with only minimal support from Earth or with no such support at all. This seems to be very important, especially since the Russian Federal Space Agency Roskosmos plans to build the first manned station and launch a rare-earth mining on Moon by 2050.

In the meantime, it is possible that the proposed technology could be tried on Earth. Russia is in acute need of mineral fertilizers and other tools to improve agricultural yields. The scientists, however, so far share no opinion about when the commercial application of their technologies could begin.

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