Using Beneficial Bacteria, Iron To Treat Water

Kayleigh Millerick is looking at ways to degrade pollutants in water by injecting iron and controlling the growth of certain helpful bacteria.

Kayleigh Millerick, an assistant professor of environmental engineering through the Edward E. Whitacre Jr. College of Engineering at Texas Tech University, is looking at how bacteria might be used beneficially to treat water and degrade pollutants.

“I run an environmental microbiology lab,” she said. “Right now, we're looking at two different clusters of problems. The first is the idea that, if you give bacteria the right surfaces to grow on, you can control the type of bacteria that grow and create a biofilm of beneficial bacteria. From an environmental perspective, I look at pollutants and strategically growing microorganisms that will degrade the pollutants. A lot of times, these organisms are already present in the environment, but there aren't enough of them to really make a difference.

“I'm working on tailoring different surfaces, such as small, spherical particles for groundwater aquifers, filtration media for water pumped from wells and particle-based confinement layers for contaminated lakebed sediments. These surfaces would strategically attract and allow desirable bacteria, or a group of desirable bacteria, to grow and improve water quality. This approach would naturally lead to better water in such a manner that it's self-sustainable and it would last over time.”

Water is usually treated chemically on a one-and-done basis with the hope it stays clean in the long run, but it's not a permanent solution, Millerick said.

“Creating a biofilm of beneficial bacteria would be a more sustainable and more long-term solution to treating water,” she said.

Millerick also uses iron to help with groundwater cleanup.

“Nanoscale particles of iron are something that are frequently injected into the water subsurface,” she said. “It will help with groundwater cleanup but, like chemically treated water, it's one and done. So, I'm working with a collaborator to see if there's a way to coat the iron in something that would allow the microorganisms to grow so that once the iron is exhausted, you have these microbial biofilms that will persist for very long periods of time.”

The second cluster of problems Millerick is investigating involves the microbiology of West Texas.

“I've never seen microbial consortia do what you can see out here,” she said. “What started as my working on a grant with Ken Rainwater looking at corrosion of West Texas wells has turned into my learning more about West Texas, what the aquifers here do and what the microbial potential is inside these systems, with the idea that this is essentially a living laboratory for future water quality issues.”

The aquifers in West Texas are high in salts, specifically sulfate and chloride. Many of the organisms Millerick has identified and characterized have only previously been observed in marine environments. These organisms have unique implications and potential when it comes to water chemistry and quality.

“You might not be looking at high use of sulfidic wells in most other parts of the country yet,” Millerick said. “Maybe you're looking at wells with lower salts than what we're used to out here. But as we see more and more water depletion, we're likely going to see more and more utilization of groundwater that has properties consistent with the high salt and sulfur concentrations that are typical of West Texas.

“What can we learn from these microbial consortia? What are they going to do and how are they going to affect groundwater long-term if we're withdrawing from these systems?”

Millerick, Rainwater, and assistant professor of environmental engineering Amrika (Amy) Deonarine also are examining arsenic fate – that is, how different microorganisms affect dissolved arsenic within West Texas groundwaters. Arsenic concentrations can be highly variable.

“What's causing these fluctuations?” Millerick asked. “Why are we seeing elevated arsenic in some places but not in others? Why do we see elevated arsenic in areas that tend to have high microbial activity?

“Searching for these answers is interesting to me because it's regionally specific. This is a very West Texas issue, but it also has national implications. We're not the only place that has these types of conditions, and in the future, more and more water systems are going to take on some of the characteristics of what we're seeing here.”

Working at Texas Tech has allowed Millerick to narrow her focus when it comes to researching microorganisms.

“I love looking at all the different things that microorganisms can do,” she said. “They never fail to surprise me. But seeing them put into place and be applicable to the area in which I now call home, that has been really neat.”