Living sensor can potentially prevent environmental disasters from fuel spills

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NEW ORLEANS, March 18, 2018 — The Colonial Pipeline, which carries fuel from Texas to New York, ruptured last fall, dumping a quarter-million gallons of gas in rural Alabama. By the time the leak was detected during routine inspection, vapors from released gasoline were so strong they prevented pipeline repair for days. Now, scientists are developing technology that would alert pipeline managers about leaks as soon as failure begins, avoiding the environmental disasters and fuel distribution disruptions resulting from pipeline leaks.

The researchers are presenting their work today at the 255th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 13,000 presentations on a wide range of science topics.

"The advantage with our sensor is that it can detect very small leaks, and operators can take quick action to repair them," says Veera Gnaneswar Gude, Ph.D., leader of the project. "We no longer have to wait until the leak is out of hand. Plus if we are able to develop this system on a larger scale, the same unit would be able to treat the waste and to remediate the soil and water that has been contaminated."

Pipelines are currently inspected by a device called a smart pig, an electronic sensor that travels through the pipe detecting cracks or welding defects. Despite regular inspection, leaks still occur. Gude, who is at Mississippi State University, is developing a sensor that would complement this process by providing additional information about the integrity of the pipes. This sensor adheres to the outside of the pipe, and takes advantage of the metabolic process of bacteria to detect gas leaks in real time.

In previous research, Gude studied the use of microorganisms in wastewater treatment, and he has recently turned his focus to building biosensors from similar species. In the current study, he is testing bacteria that will elicit an adequately measurable cathode voltage while also being able to survive in a marine environment for the application of offshore oil spill detection. For this to work, the bacteria have to remain robust through a range of alkalinity, pressure and pH conditions.

One type of bacteria he is testing is referred to as "electrogenic," which means that it releases electrons to its environment through metabolic processes. Gude created an organic sensor composed of an electrogenic anode made up of bacteria that consume carbon-based material (gas or oil) and expel electrons. The electrons then travel across a resistor to a cathode. A different set of bacteria, hungry for electrons, resides at the cathode encouraging electron flow. An increase in the metabolic processes of the anode bacteria will correspond to a voltage increase in the sensor, which could alert a technician to a potential leak.

"The sensor is not difficult to implement," says Gude. "Placing the sensor onto a pipe is not a big challenge. It is a very versatile technique."

Currently, Gude is looking for a medium in which to immobilize the bacteria. He is testing high-porosity plastics and bio-based films that optimize the surface area that the electrogenic bacteria can cover.

Once rugged bacteria are identified and immobilized, they can be used as leak detectors in a range of oil transport and drilling applications, including fracking. It is possible that at some point in the future the sensor could be sprayed as a coating on the exterior of pipes insuring that the entire length is continuously monitored.

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A press conference on this topic will be held Monday, March 19, at 11 a.m. Central time in the Ernest N. Morial Convention Center. Reporters may check-in at the press center, Great Hall B, or watch live on YouTube http://bit.ly/ACSLive_NOLA. To ask questions online, sign in with a Google account.

The researcher acknowledges funding from the National Science Foundation.

The American Chemical Society, the world's largest scientific society, is a not-for-profit organization chartered by the U.S. Congress. ACS is a global leader in providing access to chemistry-related information and research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio.

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Title

Novel microbial biosensor platforms for early detection and treatment of oil leakage and produced waters

Abstract

Marine environments are constantly exposed to smaller oil releases which represent a major fraction of the total quantity of petroleum hydrocarbons entering the aquatic environment. Early detection of small oil leaks or spills can help avoid occurrences of major spills, thus eliminating environmental disasters related to marine environments and coastal communities. Organic contaminant sensors are difficult to employ under certain settings due to the material or function related limitations. In this research, a microbial biosensor cell was developed exploiting the benefits of microbial biodiversity and their metabolic functions. The biosensor is essentially created using exoelectrogenic bacteria in an anode that survive on organic matter and a photo or autotrophic, or sulfur reducing bacterial consortium in the cathode which will enable continuous transfer of electrons from one compartment (anode) to the other (cathode). This will create a voltage across a resistor which can be detected to identify possible contamination. The microbial biosensor cell will generate high voltage spikes when availability of organic compounds increases. In this study, a variety of hydrocarbons were used as substrates to understand the voltage generation potentials and to optimize and stabilize the sensor operations. We will discuss the development of millimeter scale microbial biosensor suitable for marine, soil and surface environmental settings and their performance using different combinations of exoelectrogenic and auto and phototrophic microbial consortia in terms of voltage generation potentials using various hydrocarbon and petroleum based compounds under the influence of environmental stressors including pH, water depth, temperatures and substrate and nutrient concentrations.

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