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Waste not, want not. A new method for turning faeces into plastic could come in handy for people living on Mars.
Interplanetary travellers face two big challenges: how to transport all the tools and equipment they need from Earth, and what to do with all their waste. at the University of Calgary and her colleagues wondered if they could find a simple solution to both.
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They genetically-engineered Escherichia coli bacteria to convert human faeces to a type of plastic called polyhydroxybutyrate. Using a 3D printer, they showed this plastic could be made into small tools like wrenches.
鈥淲hen you鈥檙e planning space missions, there鈥檚 no way you can predict everything you鈥檒l need,鈥� says Arcellana-Panlilio. 鈥淭he nice thing about this plastic is that it can be moulded into whatever you want.鈥�
Sewage to usage
The team envisages astronaut faeces being collected by vacuum toilets into tanks. There, bacteria would feed on fatty acids in the stool and produce plastic for tool-making. Any leftover solid waste could be used to make radiation shields.
The storage tanks, pumps and filters would need to be transported to Mars, but this hassle would be offset by limitless tool production, says Arcellana-Panlilio. The total weight of the equipment would be less than one-fifth of that of the water processing unit on the International Space Station, she says.
In July, two of Arcellana-Panlilio鈥檚 students will climb aboard Canada鈥檚 Falcon 20 aircraft to test the plastic-making process in low gravity. Because the aircraft can only simulate microgravity for a few minutes at a time, their aim is to see if they can extract the nanosized plastic granules from the bacteria without the normal pull of gravity.
The researchers are also looking at ways to make different types of plastic. Their plan is to engineer E. coli bacteria that can convert faeces into plastics with varying strengths and flexibilities for different applications.
But it鈥檚 not just people on Mars who could benefit 鈥� sewage could also be converted into plastic on Earth, says Arcellana-Panlilio. Unlike other plastics, polyhydroxybutyrate is not made from fossil fuels and is biodegradable, meaning it is kinder on the environment, she says.
Reference: bioRxiv,
