Researchers in the Tulane School of Public Health and Tropical Medicine are working on a new way to sanitize sewage effluent from New Orleans and St. Bernard Parish so that the nutrient-rich water can help replenish and regrow depleted cypress swamps along the coast. The fertilizer, which is currently discharged into the Mississippi River, can boost wetland growth by more than 50 percent.
A similar diversion project in Hammond, La., showed 10 years worth of growth in cypress trees—roughly three to nine feet — in the first season. "It's amazing," says Gordon Austin, chief of environmental affairs for the New Orleans Sewerage and Water Board. "It is really the kind of project that has presented fantastic opportunities in every aspect."
Environmental Health Sciences professors Robert Reimers and A. J. Englande are using a $150,000 grant from the Louisiana Department of Environmental Quality to experiment with ferrate, an iron compound that shows promise as an environmentally friendly oxidizer.
The problem with using effluent on a large scale is that current systems disinfect wastewater with chlorine, which creates harmful byproducts and reduces the availability of nutrients. It also requires additional processing to de-chlorinate the water before it is discharged into swamps. Small amounts of ferrate safely sanitize waste without killing nutrients or creating harmful byproducts. And, unlike chlorine, ferrate neutralizes pharmaceuticals and chemicals from personal care products that could harm fish and wildlife.
Reimers says that ferrate hasn't been used widely for wastewater treatment because it is typically expensive to produce. He and Englande are working with a Florida-based company that has developed a cheaper way to manufacture it. If initial effluent treatment tests are successful, the two professors expect to get a larger grant to use the technology in New Orleans and St. Bernard Parish treatment plants.
The project would discharge effluent into the 28,000 acres of swamp that once served as a natural buffer between New Orleans and the Gulf of Mexico. With an average discharge rate of 122 million gallons per day, the project would become the largest effluent restoration project in the world, Austin says.
Even so, the project's size is eclipsed by the staggering scale of wetland loss. The state loses about a football field of coastline every hour. Can diversion projects be enough to gain ground?
"We don't know," Reimers says. "We do know that it will inhibit the loss."
Tulane University, New Orleans, LA 70118 504-865-5000 firstname.lastname@example.org