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article imageNew method for turning human waste into clean chemicals in space

By Tim Sandle     Jul 20, 2019 in Science
Astronauts embarking on deep space missions (such as to Mars) or those residing on space stations will need to watch out for harmful microbes. Disinfectants are not easy to come by, so how about making some from human waste?
The idea is to use human waste, as collected from astronauts, and to use microbial fuel cells to produce hydrogen peroxide for use as a disinfectant. Hydrogen peroxide at around 6 percent is an effective surface disinfectant, capable of oxidizing both vegetative and spore-state organisms and reducing microbial numbers down by several logarithms with a ten minute contact time.
Microbes are found in every human habitat and some could pose a risk to the environment inside a space craft such, as Digital Journal has reported, fungi which could trigger allergic reactions. Carrying quantities of disinfectant on a deep space mission adds to the total weight (which adds to fuel costs) and coupled with this carrying large quantities of noxious chemicals can be dangerous. Instead, what if the required quantity of disinfectant could be produced as and when it was needed?
This is possible, according Dr. Sudeep Popat of Clemson University by using microbial fuel cells. It is possible, the researcher tells Laboratory Manager magazine, to use the electrochemical reactions inside microbial fuel cells to produce a tiny amount of voltage, which occurs as bacteria break down organic substances. This mechanism can be harnessed to produce hydrogen peroxide as a by-product.
READ MORE: Efficient microbial fuel cell made from paper
The starting material for the fuel cells could be the urine of the astronauts. With the fuel cell design, this could be wastewater fed into an anode chamber, with a cathode chamber containing a dilute saltwater solution. Bacteria placed inside the anode chamber would then break down organic matter, releasing electrons. As the electrons pass through into the cathode, resulting a modified process (since most microbial fuel cells produce an electrical current) which generates hydrogen peroxide..
The video below explains the conversion process in more detail:
The research is being backed by a $750,000 grant from NASA.
More about Space, Human waste, Hydrogen peroxide, Mars
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