November 2006, Vol. 18, No.11

Research Notes

Research Notes Floating Plant Mats Help Clean Manure Lagoons

Plants grown on floating mats have been shown to remove excess nitrogen and phosphorus from manure lagoons, according to a press release from the Agricultural Research Service (ARS; Washington, D.C.). ARS scientists have been studying how to most efficiently use these floating plants to extract nutrients from wastewater, so they won’t become an environmental problem. 

The research is being conducted in two phases, the first of which was administered in small tanks where the mats were tested on full-strength wastewater, half-strength wastewater, and an inorganic solution. Vegetation was grown atop floating rafts constructed of PVC pipe and chicken wire that was covered with jute erosion-control matting. In this phase, cattail grew the best on full-strength wastewater, produced the most biomass, and removed the most nutrients. Studies showed that harvesting cattail from the floating rafts could remove an average of 493 g (17.4 oz) of nitrogen and 73 g (2.6 oz) of phosphorus per square meter per year.

The second phase of research is now being conducted at Southern Select Farms, a commercial hog farm in Tifton, Ga., that has a single anaerobic lagoon. A new type of floating mat, consisting of plastic foam covered with braided coir that is made from the coarse fibers from the outer shell of coconuts, will be tested. Several different plant species seem to be good candidates, including St. Augustine grass, coastal Bermudagrass, and giant reed, which all have potential as a source of bioenergy fuel. 

 Read more about the research in the August 2006 issue of Agricultural Research magazine at

Surprising Discovery May Lead to Better Understanding of Water Quality

Scientists at the U.S. Department of Energy’s Argonne (Ill.) National Laboratory  have discovered new ways that ions interact with mineral surfaces in water, opening a door to new knowledge on how contaminants travel in the environment. The insight leads to a better understanding of the factors that determine water quality, according to an Argonne press release.

Contrary to generally held scientific assumptions, the simple textbook description of how ions adsorb to mineral water interfaces has been shown not to be universally true. Argonne physicist Paul Fenter stated, “Ions are known to carry a hydration shell in water. Previously, it was thought that ions either adsorb to a mineral surface with this shell intact as an outer-sphere ion, or remove part of this shell to directly bind to the mineral as an inner-sphere ion. We now know that this is not just a black-and-white difference, but have discovered new shades of gray by showing that outer-sphere and inner-sphere species of the same ion can co-exist.”

This revelation was the outcome of a new element-specific method developed to understand the behavior of ions at the interface between minerals and liquids like water. According to Argonne chemist Changyong Park, “Conventional methods provided no direct sensitivity to observing this behavior. Outer-sphere species were almost invisible and extremely difficult to identify. There was just no way to see the co-existence of both species previously.”

Using the Advanced Photon Source at Argonne, which provides the Western Hemisphere’s most brilliant X-ray beams for research, the team was able to make this new discovery. The findings built on earlier work on cation adsorption using traditional X-ray scattering techniques, according to the press release.
Water is the “universal solvent,” dissolving more substances than any other liquid, the release states. This means that wherever water goes, either through the ground or through a person’s body, it takes ions along with it. A general understanding of this behavior and the development of a new scientific method for studying this phenomenon may lead to better understanding of various other processes that take place at solid–liquid interfaces, including corrosion, erosion, catalysis, and even the biological behavior of cell membranes, according to the press release.

This research is funded by the Geosciences Research Program of the Department of Energy’s Office of Basic Energy Sciences.

For more information, contact Park at

EPA Awards UGA Grant To Study Alternative Uses for Poultry Litter

The U.S. Environmental Protection Agency (EPA) awarded the University of Georgia Department of Biological and Agricultural Engineering (UGA; Athens) a $58,000 grant to research innovative uses of poultry litter to benefit energy, fuel, and environmental and economic demands that, down the line, could protect water.

Georgia currently ranks first in the nation in the production of poultry and poultry litter, and disposing of the litter is a growing environmental concern, an EPA news release states. Most poultry litter is beneficially used as fertilizer for crops; however, applying too much litter to farmland can result in impaired soil and water quality, according to EPA. UGA researchers are seeking useful applications for this excess poultry litter.

One of the potential uses for poultry litter is energy production. This research project is being undertaken to study alternative uses of poultry litter to produce fertilizer pellets, bio-oils for energy, or char to be used as fuel or a fertilizer. If implemented, these approaches can provide cost-effective solutions for waste reduction, protection of water quality, and healthier outdoor air.

EPA is joined by the U.S. Department of Agriculture, U.S. Department of Energy, and the state of Georgia in funding the development and implementation of this approach.

“We appreciate the opportunity to work with the EPA to develop value-added processes to utilize the byproducts of our poultry industry while improving, soil, water, and air resources,” said Mark Risse, one of the primary researchers for the project.

Risse will join Kaushlendra Singh, Sidney Thompson, K.C. Das, and John Worley in this research project to develop an economical and energy-efficient process to convert raw poultry litter into a richer source of nutrients and energy using innovative techniques.

Contact Risse at for more information.