Above: John Suarez (left) and his student team
High levels of the bothersome E. coli in our waterways can make people ill. A new application of a proven technology—lasers—may help safeguard public health.
By Ken Mammarella
High levels of the bacteria E. coli close beaches and discourage the recreational use of waterways, so public health officials watch it closely to prevent people from getting sick. Yet getting results from the water testing that informs waterway managers can take days.
John Suarez, an associate professor of electrical engineering at Widener University in Chester, Pennsylvania, is working on a solution: a simple system to sample, measure, and report levels of E. coli instantly.
Real-time readings of E. coli would allow officials to better protect public health by making swift decisions about when to close or allow use of waterways by swimmers and those who, for example, enjoy paddling their kayaks.
That could improve access to waterways throughout the Delaware River Watershed—a big aim for his funder, the Philadelphia-based William Penn Foundation.
Says Nathan Boon, a senior program officer with WPF, “The techniques that Suarez is pioneering are at the vanguard of what’s possible to collect real-time bacteria data in support of swimmable waterways and improved recreational access.”
Shining a Light on E. Coli
Escherichia coli lives in the intestines of healthy animals. Most strains of the bacteria are harmless, but a few can cause serious gastro-intestinal distress in humans. Those strains, spread through the feces of livestock and other animals that washes into waterways, are the ones that shut down recreation. People can ingest it by eating shellfish from E. coli-contaminated water and by ingesting water while swimming or when floods from storms cause sewage treatment plants to overflow.
“I’ve always been interested in the intersection of biology, chemistry, physics, and engineering,” Suarez says. “While it’s true that there are many different species of organisms, it’s amazing to see that—on a very fundamental level—there’s a common set of ground rules and building blocks shared by many of them. In the case of this project, we’re using well understood principles from physics to detect those building blocks.
“Bacteria are interesting because they’re living organisms in their own right, but they’re relatively simple to study. Yet the presence or lack of bacteria in a given environment can have a profound effect on more complex living organisms, such as plants and humans. I became interested in E. Coli because I knew the health risks it presents when it’s in the wrong place at the wrong time. But I also wanted to work on a problem that—if solved—can have a positive impact on the local community on a larger scale. It was in this way that the William Penn Foundation and I found mutual interest in working together, and the results have been fantastic.”
For a year, Suarez and his students have been combining various proven technologies to devise a system that would immediately read and transmit E. coli levels.
“This project has allowed us—actually, has required us—to design some interesting electronics while trying to solve a profound problem of interest to the community,” Suarez says. “On the one hand, the project’s technical foundation is based on well-understood science, but on the other hand our approach is based on original designs. We’ve applied for a few patents for some of our work.”
The heart of the system is fluorescence spectroscopy, a technology that reveals the identity of specific contaminants in water based on the color emitted when excited by light. The colors are “almost like fingerprints,” Saurez says. A blue input light, for example, gives a green output light after passing through beer or champagne. In tonic water, a violet input light gives a light blue output. In the case of water contaminated with E. coli, an ultraviolet input light gives a dark blue output light.
Science knows the colors well. “The challenge is the engineering and the practical implementation,” Saurez says.
“There are so many things involved in this system that it’s almost ridiculous. You have to understand lasers and light-emitting diodes. Optical sources in general have to be understood. You also have to understand photodetectors, which is the way you detect the light and convert that light from an optical signal, which are photons, into an electrical current.”
His prototype system extracts a water sample, injects it into a small test tube called a cuvette, excites it with ultraviolet light transmitted via fiber-optic cables, measures the intensity of the light color via a photodetector, returns the sample, then reports the results via a wireless interface such as an application for mobile phones. All of that happens from a platform of 12 square inches that could be towed by a small remote-controlled boat or fixed to a navigational buoy. Recently begun field testing will help him refine the delivery system and technology for cleaning the cuvettes onboard.
Water Quality on the Delaware
The smartphone app would interest public health officials and waterway managers, but it would also be available to anyone with an interest in water quality, such as kayakers and recreational anglers.
Suaraez’s project is funded by the William Penn Foundation, which has for many years funded projects and programs to improve the Delaware River Watershed.
“For cities like Philadelphia and neighboring Camden (New Jersey), the rivers and streams that run through their neighborhoods are important natural assets that are essentially unusable for many days out of the year due to contamination and the related risks to human health,” Boon says.
“The William Penn Foundation’s priority, as part of our Environment and Public Space funding, is to realize equitable access to these rivers–which are valuable outdoor spaces for communities–for fishing, boating, swimming, and enjoying. We’re closer than we’ve ever been to recapturing and reactivating the full potential of these urban waterways. We were proud to support this work.”
About the Author: Ken Mammarella is a Delaware native and longtime journalist who in his spare time likes to explore the terrain by bike.
Learn more
William Penn Foundation Environment and Public Space – https://williampennfoundation.org/program/environment-and-public-space
If you want to help
Subscribe here to Delaware Nature Society’s advocacy newsletter to stay informed of emerging policy changes and action alerts.