Nav: Home

Bacteria may supercharge the future of wastewater treatment

May 31, 2017

MADISON, Wis. -- Wastewater treatment plants have a PR problem: People don't like to think about what happens to the waste they flush down their toilets. But for many engineers and microbiologists, these plants are a hotbed of scientific advances, prompting their trade organization to propose a name change to "water resource recovery facility."

That's because wastewater from our sinks, toilets, showers and washing machines can be turned into valuable products with the help of scientists and unique bacteria -- some of which were discovered only by chance as recently as the 1990s.

These latecomers to the research scene, called anammox bacteria, are the subject of a new study led by Daniel Noguera and Katherine McMahon, professors of civil and environmental engineering at the University of Wisconsin-Madison. Results of their research were published today (May 31, 2017) in the journal Nature Communications.

The bacterium's name reflects its function: It turns ammonium into nitrogen gas under anaerobic (oxygen-free) conditions. Researchers and treatment plant operators alike are excited about these microbes because they have the potential to save a great deal of money.

"Being able to remove ammonium anaerobically is pretty important because about 50 percent of a sewage plant's operating cost is pumping oxygen into the water," Noguera says. "Some of this oxygen is needed to remove ammonium with the conventional method."

But anammox bacteria don't tackle their job in isolation. They are part of a community, complex like the microbiome in our gut that breaks down food and keeps us healthy in many other ways. It's this community that was the subject of the new study.

"We knew very little about the role of the bacteria that coexist in anammox granules," Noguera says. "For the first time, our study identified detailed gene expression levels in these granules. This provides important clues on what the anammox bacteria and their partners might actually be doing, and how they interact."

These partners are called heterotrophs, since they rely on the anammox bacteria --which are primary producers (or autotrophs), like plants capable of photosynthesis -- to turn atmospheric carbon dioxide into organic carbon. Among the most intriguing results of the new study are hypotheses for the exchange of biochemical material between these two groups of microbes.

The heterotrophs receive the organic carbon they need to grow from the anammox bacteria in the form of several specific molecules, the researchers discovered in the study. In return, the heterotrophs convert nitrogen into a form that anammox bacteria require for growth.

A conventional wastewater treatment plant converts ammonium, which is toxic to fish, into nitrogen gas and nitrate. Nitrogen gas is released into the atmosphere, while nitrate -- an important plant nutrient -- stays in the treated water. Regulations on the amount of nitrate that may be released vary by state, but excess nitrate contributes to algal blooms in natural bodies of water, depleting oxygen levels for aquatic organisms.

An additional advantage of anammox bacteria, compared to conventional wastewater treatment, is that they convert a larger amount of ammonium to nitrogen gas.

Treatment plant operators now have to weigh the advantages of these new microbes against their implementation challenges. Anammox bacteria grow very slowly, taking about seven days to double in number. And they require closely monitored oxygen and temperature cycles, increasing operational complexity.

But anammox reactors are not the only option for the treatment plant of the future to extract valuable resources from wastewater. In fact, some plants already produce more energy than they need to operate from the biogas that forms during the breakdown of organic material.

"Ten years from now, the typical treatment plant will probably look pretty different from today," Noguera says. "Recovered resources may not only include clean water and energy, but also a variety of chemicals, such as fertilizers and precursors of plastics and fibers. As part of this evolution, I believe anammox reactors will soon become conventional."
-end-
The UW-Madison team, which includes lead author Christopher Lawson, a graduate student in civil and environmental engineering, and Joshua Hamilton, a postdoctoral researcher in bacteriology, collaborated on the study with Ramesh Goel's lab at the University of Utah.This research was funded in part by the National Science Foundation (CBET-1435661, MCB-1518130) and a training fellowship from the Natural Sciences and Engineering Research Council of Canada.

University of Wisconsin-Madison

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".