Bacteria-Coated Nanofiber Electrodes Clean Pollutants in Wastewater

Date: June 28, 2017
Source: Cornell University
Summary: Researchers may have created an innovative, cost-competitive electrode material for cleaning pollutants in wastewater.

Cornell University materials scientists and bioelectrochemical engineers may have created an innovative, cost-competitive electrode material for cleaning pollutants in wastewater.

The researchers created electro-spun carbon nanofiber electrodes and coated them with a conductive polymer, called PEDOT, to compete with carbon cloth electrodes available on the market. When the PEDOT coating is applied, an electrically active layer of bacteria -- Geobacter sulfurreducens -- naturally grows to create electricity and transfer electrons to the novel electrode.

The conducting nanofibers create a favorable surface for this bacteria, which digests pollutants from the wastewater and produces electricity, according to the research.

"Electrodes are expensive to make now, and this material could bring the price of electrodes way down, making it easier to clean up polluted water," said co-lead author Juan Guzman, a doctoral candidate in the field of biological and environmental engineering. Under a microscope, the carbon nanofiber electrode resembles a kitchen scrubber.

The electrode was made by co-lead author Meryem Pehlivaner, currently a doctoral student at Northeastern University, with senior author Margaret Frey, professor of fiber science and an associate dean of the College of Human Ecology. Pehlivaner fabricated the carbon nanofibers via electrospinning and carbonization processes. After a few hours electrospinning, a thick nanofiber sheet -- visible to the naked eye -- emerges.

Pehlivaner reached out to Guzman and senior author Lars Angenent, professor of biological and environmental engineering, for collaboration in applying the carbon nanofiber electrodes to simultaneous wastewater treatment and production of electrical energy.

The customizable carbon nanofiber electrode was used for its high porosity, surface area and biocompatibility with the bacteria. By adhering PEDOT, the material gets an improved function, according to the researchers.

Guzman said wastewater treatment plants do not employ this method -- yet. On a large scale, the bacteria at the electrode could capture and degrade pollutants from the wastewater that flows by it. Such a technology can improve wastewater treatment by allowing systems to take up less land and increase throughput.

Concepts like this happen on campuses where faculty and students want to communicate and collaborate, Angenent said. "This defines radical collaboration," he said. "We have fiber scientists talking to environmental engineers, from two very different Cornell colleges, to create reality from an idea -- that was more or less a hunch -- that will make cleaning wastewater better and a little more inexpensive."

Story Source: Cornell University. "Bacteria-coated nanofiber electrodes clean pollutants in wastewater." ScienceDaily. ScienceDaily, 28 June 2017. www.sciencedaily.com/releases/2017/06/170628144829.htm

Algae: The Final Frontier

Date: June 21, 2017
Source: Carnegie Institution for Science
Summary: Algae dominate the oceans that cover nearly three-quarters of our planet, and produce half of the oxygen that we breathe. And yet fewer than 10 percent of the algae have been formally described in the scientific literature, as noted in a new review.

Algae dominate the oceans that cover nearly three-quarters of our planet, and produce half of the oxygen that we breathe. And yet fewer than 10 percent of the algae have been formally described in the scientific literature, as noted in a new review co-authored by Carnegie's Arthur Grossman in Trends in Plant Science.

Algae are everywhere. They are part of crusts on desert surfaces and form massive blooms in lakes and oceans. They range in size from tiny single-celled organisms to giant kelp.

Algae also play crucial roles in human life. People have eaten "seaweed" (large macroalgae) for millennia. But algae can also represent a health hazard when toxic blooms suffocate lakes and coastlines.

Despite the pervasiveness of algae and their importance in our planet's ecology and in human health and nutrition, there is so much that scientists don't know about them. This lack of knowledge is mostly due to limited support and the need to develop methodologies for probing the various algal groups at the molecular level.

The term 'algae' is used informally to embrace a large variety of photosynthetic organisms that belong to a number of different taxa. To effectively reveal the mysteries of each of these organisms would require creating research processes that are effective for each of them (what works with one often doesn't work with another).

However, some of the latest molecular techniques have allowed scientists to elucidate major genetic processes that have shaped algal evolution. And this improved knowledge has implications beyond basic scientific discovery.

For example, in the future, algae may be used to produce biofuels or to synthesize high-value therapeutic compounds or plastics. Furthermore, with an improved understanding of metabolism in the various algal groups, scientists can better develop strategies to exploit algae for the production of materials -- using them as "cellular factories," in a sense.

Many studies have shown that algae can also adapt to changing environmental conditions. But what are the limits of this ability? And how will the effect of climate change on the world's oceans impact algae and the oxygen that we derive from them?

"In the process of reviewing the state of algal research, we feel that we are on the cusp of a revolution in understanding this group of organisms, their importance in shaping ecosystems worldwide, and the ways in which they can be used to enrich humankind," said Grossman.

Story Source: Carnegie Institution for Science. "Algae: The final frontier." ScienceDaily. ScienceDaily, 21 June 2017. www.sciencedaily.com/releases/2017/06/170621165931.htm