Skip to content
Aaron Mauner

The Power of Waste

By Jennifer Brouner

Two years ago, two officials working for the Hallsdale-Powell Utility District, a wastewater plant in Knoxville, Tennessee, approached Professor Barry Bruce, one of the top photosynthesis researchers in the world, with a challenge: they wanted the University of Tennessee professor to find a cost-efficient way to reduce the levels of phosphorus and nitrogen in Hallsdale-Powell Utility District’s wastewater.

At the time, excess amounts of phosphorus and nitrogen found in the wastewater after treatment were released straight into Beaver Creek. Though the wastewater plant had maintained industry standards, the levels of nitrogen and phosphorous being released could eventually lead to the devastation of native algal populations, thereby destroying the foundations of the creek’s ecosystem.

Aaron MaunerIn August 2010, Bruce assigned Aaron Mauner, one of his undergraduate researchers, to the project. Mauner was asked to test six different strains of algae to see if these tiny organisms had any potential for further cleaning up wastewater released from the plant.

Mauner’s mission was two-fold: he needed to search for a strain of algae that loved consuming nitrogen and phosphorus, and he also had to determine the proper nutrients to add to the wastewater to encourage the maximum growth of his algae.

For nearly a year, Mauner could be seen hauling around and testing these strains of green algae to see which could remove harmful chemicals from the wastewater. He assessed the growth of algae solutions by placing tubes of them into a spectrophotometer. This machine shoots a beam of light through the samples and records the amount of light that passes through each one.

The less light transmitted to the other side of the algal solution, the happier Mauner became. Less light meant a thicker, darker green solution. The thicker solution meant more algae present. And the dark green color, in the plant world, signified a healthier organism. All of these were key clues that Mauner’s test was working—he was homing in on the best way to grow and keep his algae healthy in wastewater.
He repeated this process over and over faithfully, thousands of times, until the results finally became clear: the algae Chlorella vulgaris outperformed all of his other subjects in every way.

Now that Mauner had found a solution, it was time to put that knowledge to good use on a larger scale. Mauner has since graduated, but John Greer, another undergraduate researcher at the University of Tennessee, has teamed up with Bruce to ensure that Mauner’s research serves its purpose at the wastewater plant.

On November 2, 2011, Greer was pushing a cart holding a barrel-like glass container filled with 10 gallons of a deep green liquid away from Bruce’s research lab. Once he reached his car, he lifted the container off the cart with a bear hug, deposited the glass container in the front seat of his car, and buckled it up for safety. He then drove from the University of Tennessee to the wastewater plant, where microbiologists at the Hallsdale-Powell Utility District anxiously awaited the newest addition of nitrogen and phosphorus eaters, Mauner’s microalgae Chlorella vulgaris.

After reaching the plant, Greer unbuckled Chlorella vulgaris from the front seat of his car, pulled up the hood of his rain jacket, and snatched up the algae. He carried it through the pounding rain into a small shed located on the edge of the wastewater plant. Upon entering the shed, the sound of whirling water reached his ears as he lifted the heavy 10-gallon container. The glass container, clasped tightly to his chest, hovered over a small pool of water located in the center of the room. As Greer uncapped the lid and tipped the jar on its side, the algae solution spilled into the wastewater. The new vibrant green additions hastily spread as the turbine mixed the algae with the wastewater.

The wastewater and algae circle in this little safe haven constantly—night and day.

Microbiologists at the plant sample the water from this simulated river system, called a raceway pond, twice per day in order to determine the effectiveness of the algae at removing nitrogen and phosphorus from the wastewater.

Mauner selected Chlorella vulgaris for two reasons: it eats the excess amounts of nitrogen and phosphorus in the already treated wastewater and it uses these pollutants to cause the algae to reproduce rapidly. “The hope was that if we could get all this algal biomass,” says Mauner, “then we could turn it into biodiesel.”

Biodiesel is an alternative form of fuel that is made from oils isolated from within plants and algae. Since Chlorella vulgaris will be growing in abundance in the wastewater, Hallsdale-Powell’s microbiologists plan to eventually turn the algae into biodiesel. This biodiesel will then be used to power jets and automobiles.

Mauner’s experiences as an undergraduate researcher enabled him to apply the concepts he was learning in his biology classes to help solve a local problem. “I wouldn’t replace my experience in Dr. Bruce’s lab for anything,” says Mauner. “I really like being on the cutting edge of science.”

Mauner’s undergraduate research experience has helped him land a position in Colorado as a laboratory technician in a research-based fertility lab. He eventually plans to earn a Ph.D. in molecular biology so that he can search for a cure for cancer. “I have been interested in research pretty much since I was a freshman in high school,” he says. “The project really reinforced my love for doing lab work and for science.”

Dr. Bruce is very proud of his undergraduate researchers and takes great satisfaction in the work that they accomplish. “Aaron was a complete self-starter. He would design the experiments and manage the project like a graduate student,” says Dr. Bruce. “He was able to help demonstrate the feasibility of combining wastewater remediation with solving one of the major costs associated with large-scale algal cultivation.”

Though he now lives across the country, Mauner feels a sense of pride when he speaks of his research project that Greer has now taken on. “It’s rewarding to see something that I put a lot of work into be really appreciated by the people that I did it for—the whole reason that I was able to do the project.”

Comments are closed.

The flagship campus of the University of Tennessee System and partner in the Tennessee Transfer Pathway.

Report an accessibility barrier