January 2010, Vol. 22, No.1

Research Notes

Microbial Electrolysis for Renewable Hydrogen Generation

Researchers have developed a cutting-edge way to use microbial electrolysis to generate hydrogen. A demonstration plant has been installed at the Napa Wine Co. in Oakville, Calif. At the plant, a hydrogen generator uses winery wastewater, bacteria, and electricity to convert the organic material into hydrogen, according to a Pennsylvania State University (Penn State; University Park) news release.

“This is a demonstration to prove we can continuously generate renewable hydrogen and to study the engineering factors affecting the system performance,” said Bruce Logan, Penn State Kappe professor of environmental engineering. Hydrogen produced from the refrigerator-sized generator will be vented, except for a small portion that will be used in an attached hydrogen fuel cell, he explained.

Microbial electrolysis cells consist of two electrodes immersed in liquid, the news release says. To minimize costs, instead of using one electrode coated with a precious metal, such as platinum or gold, Logan uses a stainless steel cathode paired with a carbon anode.

The demonstration plant is a continuous-flow system that processes approximately 1000 L/day of wastewater, the news release says. It includes 24 modules, each with six pairs of electrodes.

When wastewater enters the cell, bacteria convert the organic material into electrical current. Slightly increasing the voltage produced by the bacteria — with auxiliary electricity — creates hydrogen gas electrochemically on the stainless steel cathode, the news release says.

Napa Wine Co. wastewater is generated by such processes as equipment cleaning, grape disposal, and wine-
making, according to the news release. The company already uses onsite wastewater treatment and recycling. The effluent from the microbial electrolysis system will be discharged into the company’s regular wastewater system for further treatment and use in irrigation.

The composition of the winery’s wastewater changes throughout the year. Sometimes it contains more sugar, and sometimes it contains more remnants of the fermentation process. However, the bacteria in the electrolysis cells consume either organic material, according to the release. Eventually, the company’s goal is to use the hydrogen generated to power vehicles and other winery systems, the news release says.

The winery was chosen for the project because “people go there all the time to experience winemaking and wine, and now they also can see a demonstration of how to make clean hydrogen gas from agricultural wastes,” Logan explained in the news release.

The project is supported by Air Products & Chemicals Inc. (Allentown, Pa.), the Water Environment Research Foundation (Alexandria, Va.) Paul L. Busch Award, and other donors. Brown and Caldwell (Walnut Creek, Calif.) was contracted to build the demonstration plant, and Napa Wine Co. donated its facilities and wastewater for the demonstration.

For more information, see www.engr.psu.edu/ce/enve/logan/default.htm.

 

Genome Technology Exposes the Cause of Brown Tides

Researchers at the Woods Hole (Mass.) Oceanographic Institution plan to use genome technology to examine how nutrient pollutants may cause brown tides and influence their duration on the U.S. East Coast. The U.S. National Oceanic and Atmospheric Administration (NOAA) awarded the institution $120,000 for the anticipated 3-year, $500,000 project to determine how nitrogen and phosphorus promote brown tides, according to a NOAA news release.

According to NOAA’s project summary, despite many years of study and knowing that brown tides are caused by the algae species Aureococcus anophagefferens, fundamental questions remain regarding how nutrients drive harmful algal blooms (HABs).

The Woods Hole Oceanographic Institution’s research uses the recent completion of the HAB genome sequence for A. anophagefferens and preliminary gene expression work on the species to track the nutritional physiology of the algae in its natural environment.

“Until gene activity of individual organisms could be monitored, it was only possible to measure nutrient utilization of the whole community of organisms in the water,” said Quay Dortch, an oceanographer at NOAA’s National Center for Sponsored Coastal Ocean Research office. “It was nearly impossible to determine what specific nutrient(s) were fueling the growth of the brown tide. This new approach will allow the specific nutrient requirements of the brown tide to be determined.”

Brown tides cause damage to coastal habitats and to scallop and hard-clam fisheries from Rhode Island to Virginia, the news release says. However, brown tides are unusual because they occur when a certain type of inorganic nitrogen is in low supply.

It is hypothesized that excesses of other nutrient types, mainly organic phosphorus and nitrogen in aquatic ecosystems, contribute to the development of brown tides, the news release says. Determining the nutrient conditions that trigger brown-tide blooms will help with predicting and preventing them. Knowing the genome sequence of the brown-tide organism also enables researchers to observe changes in the cells’ genes as conditions change, the news release says.

The Woods Hole Oceanographic Institution’s research seeks to answer the question of what types of dissolved inorganic nitrogen and phosphorus are preferentially transported and metabolized by cells during blooms, and how nutrient transport and metabolism change as a function of ambient conditions as blooms initiate, are sustained, and decline, according to the project summary.

“Gene activity of all organisms changes as they respond to their environment,” Dortch said. “In this project, knowing the genome sequence allows researchers to observe changes in the genes being actively used by the cell as nutrient conditions change in nature. By monitoring which genes are ‘turned on’ over the course of a bloom, they can track how and which nutrients are used by the organism for growth.”

Brown-tide algae are unusual, blooming when inorganic nitrogen, usually preferred by algae, is in low supply. The algae also grow well when consuming organic nutrients, such as urea and amino acids, Dortch explained.

“The aim in the long run is to understand the nutrient requirements of the brown tide so well that you can predict their occurrence, or even better, prevent them from occurring,” Dortch said. The approach developed in the study is expected to provide a blueprint for monitoring other HABs, according to the expected results from the study description.

The research is funded through the Ecology and Oceanography of Harmful Algal Blooms program, a multiagency partnership among NOAA’s Center for Sponsored Coastal Ocean Research, Office of Protected Resources, and Sea Grant, as well as the U.S. National Science Foundation, U.S. Environmental Protection Agency, NASA, and the U.S. Navy Office of Naval Research.

 

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