Imagine this: you flush your toilet, and instead of the wastewater being directed into a septic tank or municipal sewage system, it’s channeled into a treatment unit in your basement. Within a few hours, the device has completely filtered all the nasty elements from the water, and converted them into electricity to power your home. The now much-cleaner water is released back into the municipal system where it’s recycled into drinking water.
As fantastic as this scenario sounds now, scientists say they are one step closer to making it a reality. A report presented at the 243rd National Meeting & Exposition of the American Chemical Society (ACS) described a new and more efficient version of an innovative device the size of a home washing machine that uses bacteria growing in municipal sewage to make electricity and clean up the sewage at the same time.
In most cities, wastewater treatment is a long and complicated process. Sewage must be transported from the source to massive treatment facilities designed to separate the solid and liquid components of sewage and clean the wastewater before it is released into a waterway. Between the settling tanks, macerators, membranes to filter particles, biological digestion steps and chemicals that kill harmful microbes these treatment plants use 2 percent of overall energy consumption in the United States.
The new device would virtually eliminate the need for these costly processes, especially in developing countries where the infrastructure has yet to be developed. The device described by the scientists at ACS is essentially a microbial fuel cell (MFC) that could turn waste into energy, with cleaner (but not potable) water as the byproduct.
The most current iteration of this device can turn 13 percent of the usable energy in the sludge into electricity. Researchers explain that while this doesn’t seem like much, a large device running at 20-25 percent efficiency could produce enough power to operate a conventional wastewater treatment plant.