Humans need water to survive but inevitably, waste water is always
produced. It would be nice to find a way to solve the waste water
problem and recycle water.
It
was a good thing that researchers from the Pennsylvania State
University invented an astounding machine that can not only clean waste
water, but also produce enough energy to keep itself running. The
machine is a hybrid comprising of microbial fuel cells and reverse
electrodialysis.
The microbial fuel cells uses two chambers
separated by a semi-permiable layer. One side of the fuel cell contains
the waste water and a microbe-covered electrode. The microbes
digest organic material in the waste water. This produces electrons,
protons and CO2. These electrons move through the microbe-covered
electrode, through the circuit, end up on the other side of the chamber
where these electrons recombine with protons and electrons—this reaction
produces water. The IEEE spectrum explains the science behind this machine: Imagine
dividing a channel into three parts by separating one side using the
negative-ion membrane and the other side with the positive-ion membrane.
If you flow saltwater through the center channel and freshwater through
the two side channels, osmotic pressure will drive the ions across
their respective membranes. One side channel becomes negative and the
other positive—essentially creating a battery.”
Penn
State uses ammonium bicarbonate salt in lieu of saltwater. This can be
easily separated from water by heat then recycled in a hybrid fuel cell. Pure
electrodialysis batteries need a 20 membranes or more, and microbial
cells produce little power. This hybrid device requires only five
membranes and this resulted in a 7-fold increase in power. With this
machine, the future of cleaning waste water will be self sustaining,
affordable, and a thing to look forward to. Source: Geekosystem |