Michigan Tech Research Magazine 2011

Undergraduate Research

Grass that removes antibiotics from water

What goes in must come out, and when animals are given antibiotics, they can find their way into the water supply. Last year, a Michigan Tech student identified one way to sop them up.

Antibiotics pass through the digestive tract largely unchanged. The resulting drug-laden waste from farms and feedlots (or for that matter, apartments and subdivisions) may be treated, but conventional methods don't break down excreted antibiotics.

The concentrations are small, probably not enough to effect anyone drinking a cup of water. But by releasing antibiotics indiscriminately into the environment, scientists fear we are encouraging antibiotic-resistant strains of bacteria and making it harder to treat deadly infectious diseases.

"There are also problems with using this contaminated waste to fertilize crops, or the water to irrigate," says Stephanie Smith, who graduated in May with a BS in Biochemistry and Molecular Biology.

Working with Rupali Datta, an associate professor of biological sciences, Smith designed an experiment using sterile vetiver grass to address the issue. Vetiver, a native of India, is grown in artificial wetlands to cleanse wastewater. It is vigorous and noninvasive. Plus, it's also been used to clean up some tough customers, including TNT.

Smith grew vetiver in a greenhouse, exposing the plants to various concentrations of tetracycline and monensin, two antibiotics commonly used to treat dairy cattle. At the end of the study, all of the tetracycline and 95.5 percent of the monensin had disappeared from the hydroponic solution. Tests showed that the vetiver had taken and metabolized both drugs. The results are preliminary, says Smith, but they show that vetiver holds promise for remediating antibiotics in wastewater.

Smith also recorded a peculiar side effect. "The plants in the tetracycline solution grew faster, much faster than the controls," she says. "The plants in monensin grew somewhat faster, but not as much."

"When I came to Tech, I honestly didn't think I would be able to work on a project like this," Smith adds. "It's been very cool to be involved."

A new way to date old ceramics

If you are an archaeologist, determining when a pot was made is not just a matter of checking the bottom for a time stamp. Dating ceramics recovered from archeological sites can be time consuming, not to mention complex and expensive.

Patrick Bowen, a senior majoring in materials science and engineering, is refining a new way to date ceramic artifacts that could one day shave thousands of dollars off the cost of doing archaeological research.

Called rehydroxylation dating, the technique was developed by researchers at the University of Manchester and the University of Edinburgh. It takes advantage of ceramics' predictable tendency to bond chemically with water over time.

"It's simple," says Bowen. First, weigh the sample. Then dry it using a two-stage process. Finally, weigh the sample again and leave it alone. The ceramic will react with water in the air and gradually gain weight. Plot the gain against a time constant, and the shape of the curve tells you the age of the ceramic. Theoretically.

But, says Bowen, "the dating process turns out to be more complicated than the literature suggests." Using shards of nineteenth century pottery, Bowen dried the samples at different temperatures and got significantly different "ages." He then developed a new equation that addresses those temperature differences, as well as the fact that rehydroxylation is actually a two-step process: First, water vapor physically penetrates the pottery. Then, it bonds chemically to the pottery's constituent minerals.

Bowen's equation yielded better results, but, due to humidity differences, not good enough to generate definitive dates. Now the team is running experiments to address that issue.

They won't only be using antique pottery this time. "We are using broken pieces of brick from the Houghton Parking Deck; it's easier to come by," says Bowen. "Somebody hit it with their car, and when I saw the pieces, I thought, 'Oh! Sample!'" If all goes as planned, each of those samples dated by Bowen and fellow undergraduate Tyler Botbyl will turn out to be about forty years old.

Bowen's advisors, Jaroslaw Drelich, an associate professor of materials science and engineering, and Timothy Scarlett, an associate professor of archaeology and anthropology, believe their work has huge potential. "This will be a new, low-cost tool allowing archaeologists to derive dates from objects made over 10,000 years of human history," said Scarlett."