LETTING NATURE TAKE ITS COURSE
Researchers aim to let Mother Nature clean up and treat wastewater

Outdoor recreation is a favorite activity among many Americans. Active outdoorsmen have a variety of venues at which to hike, fish, and camp. U.S. national parks and state parks are among these venues and constitute millions of acres of land and water in the U.S.

Many such parks lie in coastal areas and have a different set of environmental and human concerns than parks located further inland. One such concern is the disposal and treatment of human waste in rural areas, where treatment facilities may not exist.

Nestled just outside New Orleans on the West Bank of the Mississippi River, five residential camps on Bayou Segnette State Park in Westwego, Louisiana, are serving as test sites for a group of LSU engineers who are developing a new wastewater treatment method that uses the natural sediments of the marsh to treat wastewater.

Kelly Rusch, director of the LSU Institute for Ecological Infrastructure Engineering and the Formosa Professor of Civil and Environmental Engineering; Frank Tsai, assistant professor of civil and environmental engineering; and their research staff are combining computer simulation and lab experiments to better understand bacterial movement mechanics in groundwater and investigate the fate of viruses within the Marshland Upwelling System (MUS).

The operation of MUS consists of collecting wastewater from a bathhouse or restroom and intermittently injecting it below ground surface to a depth of about four meters. As wastewater moves through porous sediment, the micro-organisms are filtered out or absorbed into the sediment.

“We’re basically looking to refine methods to allow nature to safely take its course, to use the environment to keep the environment clean,” says Tsai, who, along with Rusch, is being funded by the Louisiana Sea Grant College program, a part of the National Oceanic and Atmospheric Administration.

Observation wells are constructed over the transport site so that researchers can continuously monitor the environmental impact. Members of the research team, including doctoral student Haibo Cao, who has worked on the project for three years, collect soil samples to analyze factors such as bacterial levels, groundwater movement, and saltwater interaction.

The data that researchers collect from test sites, like the ones at Bayou Segnette, are fed into a computational model of the environment. After running improved simulations, they will be able to determine the optimal MUS system operations at which Mother Nature can purify the ground, thus preventing such events as groundwater contamination and movement of dangerous, pathogenic micro- organisms to surface waters.

Once the final models are complete, the group can then make recommendations to state departments of environmental quality on how to best implement the technology in camp and recreational sites across the country.

ON THE WEB:
LSU Department of Civil & Environmental Engineering
LSU Institute for Ecological Infrastructure Engineering

from Fall 2006 Issue