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Pure Science

ONU engineering students seek a simple solution to a very complex problem.

Right now there are more than three quarters of a billion people on the planet without daily access to clean water. 1 While it may not seem like it, this is an engineering problem. Engineers will have to solve it.

There won’t be one solution to a problem this large. There will be many. These solutions, be they new methods, devices or discoveries, will chip away at the problem one family or community at a time until clean water is widely available.

Senior civil engineering majors Sarah Thompson and Mary Purvis researched the viability
of using electricity to purify water as part of the ONU Honors Program.

All ideas are on the table.

The table is where Ohio Northern University senior civil engineering majors Sarah Thompson and Mary Purvis found themselves at this year. Under the guidance of Dr. Bryan Boulanger, associate professor of civil engineering, the pair worked on research looking to see if electroporation, the process by which electricity is used to puncture a cell membrane, could be an effective means to purify water.

Boulanger has long been interested in a finding an inexpensive, effective water treatment system that can fit into a backpack and be delivered anywhere in the world. An ambitious goal to be sure, but Thompson and Purvis were willing to try.

Normally, electroporation is used to introduce a substance into a cell, and the thought is that if the process was severe enough it might damage a cell sufficiently to kill it. Since many of the disease-causing microbes routinely found in contaminated water are single-cell organisms like cryptosporidium, giardia lamblia or choliform bacteria, Thompson and Purvis believed it had a chance for success.

Like all research, theirs did not exist in a vacuum. It was actually an extension of research done by some of Boulanger’s graduate students at Texas A&M University, where he taught before joining ONU this fall. His students successfully killed microbes in water by running it through electrically charged silver-impregnated fabric.

“[Those students] didn’t look at the causative effect of why they were having positive outcomes. They were just running their experiment, and it was working, but they didn’t know why,” says Boulanger. “Mary and Sarah’s research tries to explain why this process yielded the results that it did.”

Specifically, Thompson and Purvis looked at the electricity component of the experiment. They wanted to know whether current or voltage was responsible for killing the microbes. While current and voltage are both properties of electricity, the current is the flow of electrons or ions, and the voltage represents the power behind the flow. According to Purvis, she got the idea from power company warnings that current, not voltage, is what causes electrocution. It seemed reasonable to her that, if current can kill a person, perhaps the same could be true of individual microbes.

"The beauty of engineering is that you can help in so many different ways. It may take you a really long time ..., but you can."

The students built a small reactor in the civil engineering environmental lab in the Biggs Engineering Building that used the same conductive fabric that the Texas A&M students used, a product called ArgenMesh™ that is 55 percent silver and 45 percent nylon. It is marketed primarily as a means to block radio waves, but its conductivity, low cost and availability met the criteria for developing a system that could fit into a backpack.

They fed the fabric into a plastic tube and connected a power source to either end. As electricity is applied to the fabric and completes a circuit, water collected from one of ONU’s campus ponds is poured into the reactor and left to sit. Then the water is piped out one milliliter at a time and placed onto reactive plates that grow bacteria into colonies large enough to see with the naked eye.

Thompson and Purvis varied the experiment for voltage and contact time with the silver mesh over the span of several weeks in October and November. Due to inconclusive results, they continued the research into the spring semester, this time looking closer at current.

“It started out just looking at voltage. Then we found out that our current was really small because we were using way too much resistance, so we started to look at that. Then we found out that the fabric itself has properties that might be killing the microbes, so we thought about contact time,” says Thompson. “So, just looking at those things forced us to adapt our research. You don’t really realize all the different variables that come into play until you are in the middle of it.”

As often happens in research, the results Thompson and Purvis recorded didn’t match their expectations. They could find no discernable correlation between variations in voltage or current and the number of microbes in water. They did, however, see fewer microbes in the water they ran through their reactor than in the control samples, leading them to believe that the silver in the fabric can kill microbes by itself. Were they not graduating, both students would like to do more experiments to answer newfound questions.

“Now, it’s back to the drawing board,” says Purvis. “There are things we could change in this experiment. For instance, we could use more of the fabric and run tests to see if it is really what’s making a difference here. Also, we could see how long we could make that fabric work.”

Boulanger is pleased with his students’ research even though they themselves were a bit disappointed. He sees undergraduate research as part of the educational process and not necessarily as something that always has to work perfectly, because that just doesn’t happen.

From left: Dr. Bryan Boulanger, Mary Purvis and Sarah Thompson in their laboratory.

“When undergraduate research is doing what it should, we are utilizing it for education,” he says. “Mary and Sarah did a lot of work. They had to go look up all the literature on the research that had come before. They sourced materials from vendors and figured out what equipment they needed. When problems arose, they reached out to me or one of the electrical engineering professors or students. They did more statistical work than my grad students did, and they did more individual experiments as well. It’s a process, and that’s where the educational value comes in.”

If the science is a process, than the motivation for doing it is something else entirely. For Purvis, her motivation came from her love of engineering and what she feels is its inherent capacity for good.

“The beauty of engineering is that you can help in so many different ways. This project could really help people, but it has an environmental application as well,” she says. “It may take you a really long time to make a difference, but you can. And that’s the reason I wanted to do this.”

Boulanger weighs the motivation behind any research or engineering project heavily. He has done research all over the world and knows that engineering can change lives for the better when done correctly, and that it can ultimately harm people if done poorly or with the wrong motivation. He is critical of projects that don’t ask questions beyond the science and neglect the people that the project is intended to help. Here at Northern, he has found a college that shares those values.

“I think our engineering students are more motivated by knowing they can make a difference in the world than by the economics of being an engineer, or the long hours of being an engineer, or the recognition that may or may never come from a project that you worked on,” he says.

The partnership between Thompson and Purvis doesn’t end with commencement. This summer, both begin careers at Marathon Petroleum in Findlay, Ohio, where they will apply what they’ve learned over the past four years as project managers. They are excited for this new chapter of their lives to begin and, particularly, that their jobs will vary so much from project to project, just the thing for a couple well-rounded engineers who are always up for a challenge.

1. Estimated with data from WHO/UNICEF Joint Monitoring Programme (JMP) for Water Supply and Sanitation. (2012). Progress on Sanitation and Drinking-Water, 2012 Update.