DESCRIPTION:
The City of Thibodaux's Sewage Treatment Plant is an innovative experimental plant using natural processes to treat sewage. In 1992 the plant was adapted so that adjacent wetlands could be used for tertiary treatment. The plant guide will lead nt. The plant guide will lead you past a series of outdoor open treatment tanks, including the aerated lagoon, the primary clarifier, the biological rock filter, and the final clarifier. From here you will see the ultraviolet light treatment chamber, and the control room. You will also see the sludge drying beds, with sewage sludge in various stages of composting. Next, you will drive to the levee separating the swamp from pastureland. Here you will see the spillway, where every 50 feet, effluent (liquid discharge) is released into a beautiful cypress-tupelo swamp for tertiary treatment. This swamp had formerly been cut off from its supply of fresh water, and was in danger of dying. Now it is receiving fresh water from the sewage treatment plant and is thriving. Wetlands areas such as this act as biological filters for pollutants including nitrogen wastes from sewage pollutants and nutrients which are trapped in the soils where they are taken up by the roots of plants.

There are several features which make this plant a unique experiment. One is the recharging of a freshwater swamp with the effluent. This plant also uses ultraviolet light as a disinfectant, rather than chlorine. Chlorine forms toxic compounds, and, therefore, in traditional plants which use chlorine as a disinfectant, both a chlorination and a dechlorination process must take place.

(See Louisiana Environmentalist July/August 1993 for an article on the Crowley, LA "Innovative Wastewater Treatment" which is similar to that in Thibodaux)

ACTIVITIES:

• Discuss route of storm water, from neighborhood to the lagoon. Include the importance of keeping toxic materials (used motor oil, etc) from entering this system.
• Record the types of trees you see in the swamp. Look for evidence of animals along the levee (bones, tracks, scat).
• Conduct a storm drain stenciling project to educate others about pollution from storm water. Contact the Barataria-Terrebonne National Estuary Program at 1-800-259-0869 for more information.