When you think about ways to combat water pollution, you probably think about filtration systems or centrifuges — but a surprising adversary is also in the fight: pollution-eating bacteria.
Oh, and they also produce energy.
The bacteria was discovered in August 2018 by a team of microbiologists from Washington State University. Led by Abdelrhman Mohamed, the group made the 7 mi (11.2 km) trek through Yellowstone National Park’s Heart Lake Geyser Basin. This area is home to pools of hot water, ranging from about 110 to nearly 200 degrees Fahrenheit (43.4 to 93.3 degrees Celsius), that contain the unique bacteria.
"This was the first time such bacteria were collected in situ in an extreme environment like an alkaline hot spring," said Mohamed.
A New Ally
Collecting these microbes was no easy task. Mohamed invented a cheap portable and highly heat-resistant potentiostat — an electronic device required to control the electrodes that were submerged in the pools.
The researchers left the electrodes in the water for 32 days. In the end, the experiment succeeded in capturing the bacteria in their natural and optimum environment.
The bacteria “breathe” electricity by passing electrons to outside metals or minerals, using protruding wire-like hairs. This is why the bacteria were attracted to the solid carbon surface of the electrodes. As the bacteria exchange electrons, they produce a stream of electricity that could possibly be harnessed for low-power applications. In theory, as long as the bacteria have fuel, they can continuously produce energy.
This isn't the first time scientists have used bacteria to generate energy. Other experiments have seen bacteria combined with sewage to produce electricity, while others have resulted in microbes that can create high-energy carbon rings.
Pollution by the Numbers
Water pollution is a serious issue for both animals and humans.
Most ocean debris (80%) comes from land-based trash sources. These pollutants have impacted 86% of all sea turtle species, 44% of all seabird species, and 43% of all marine mammal species, according to Clean Water Action. The effects range from entanglement and suffocation to poisoning.
Beyond physical trash and debris, The Mussel Watch Program tracks the types of contaminants found in coastal areas. Because mussels don’t have a liver to break down foreign materials, they concentrate the chemicals they ingest, showing a clear picture of what’s in their environment. Pollutants found included some chemicals that have been banned for decades, such as the pollutant DDT. Scientists have also found antibiotics, SSRI drugs, and cancer drugs.
And of course, there’s the story of the Flint, Michigan water crisis that began in 2014. Water samples collected from Flint homes indicated high levels of lead — with nearly 17 percent of samples registering above the federal “action level” of 15 parts per billion.
But the lead wasn’t the only contaminant. There was also an outbreak of Legionnaires’ disease — the third-largest ever recorded in the U.S, as well as the discovery of fecal coliform bacteria, and elevated levels of total trihalomethanes, cancer-causing chemicals that are byproducts of the chlorination of water.
As of October 2020, officials say the water quality has “stabilized” and shows low lead levels. Still, the EPA and other health authorities agree that there is no safe level of lead in water.
Solutions on the Horizon
The above are just a few examples of what's going on with the Earth's oceans, lakes, rivers, and aquifers. It's evident that humans are having a massive negative impact on the water supply, and if we don't act, we'll soon be in trouble.
In addition to these impressive energy-breathing microorganisms, there are also promising organic solutions to the challenges of water pollution. For example, a super-enzyme has been discovered that can break down plastic bottles.
At the University of Bristol, a bacteria-filled robot is designed to paddle over water, funneling waste and pollution into its “stomach” to be decomposed. In the process, it produces the energy needed to continue operating.
Another bot called “Mr. Trash Wheel” was designed by Clearwater Mills, LLC to capture trash in rivers, streams, and harbors. It consists of a conveyor belt powered by solar panels that moves trash into a floating barge. When the trash reaches the barge, it is converted into electricity. To date, it has prevented 1.6 million pounds of debris (725 tonnes) from entering the ocean.
Could the key to solving both our energy and pollution crises truly lie in these microorganisms or technologies? Time will tell.