Metro biology Professor Rebecca Ferrell spent part of her summer on Mexico's Yucatan Peninsula studying composting toilets and the effectiveness of constructed wetlands in filtering human wastes from septic systems.

Ferrell and Todd Bergren, director of the biotechnology program at Community College of Aurora, discovered that wetlands designed to treat and dispose of septic system waste were, in fact, not effective in reducing groundwater contamination.

"We found that the ammonia levels were the same going in (to the wetland system) as coming out," Ferrell said. "The constructed wetland wasn't working; it wasn't getting rid of the bacteria or the nitrogen."

The researchers concluded that the waste is not being filtered as anticipated. Consequently, the contaminated groundwater, filled with fertilizers, continues to seep into the ocean. The fertilizers are causing algae to overgrow on and suffocate the world's second-largest coral reef, the Mesoamerican.

Ferrell has been researching compost toilets and fecal decomposition since the mid-1990s. She initiated the Yucatan study earlier this year when she contacted the Centro Ecologico Akumal, a nonprofit organization that provides a base for environmental studies, cultural exchange and ecotourism activities. A leader in the area in researching and implementing advanced waste treatment systems, the organization invited Ferrell and Bergren to study the site's composting toilets. The researchers found the toilets worked fine and began studying the constructed wetlands.

A constructed wetland is a system that uses plants and microbes in the soil to remove pathogens and reduce nutrients and toxins in septic tank water. Composting, on the other hand, uses little or no water and produces a nutrient-rich soil enhancer.

"My focus in composting and fecal decomposition research is the public health and ecological impacts," Ferrell said.

She said the need in the Yucatan for alternative waste treatment systems is urgent. The tourism business is booming and the area plans on adding up to 50,000 hotel rooms over the next 10 years. Ferrell sees an opportunity for the area to use a combination of well-constructed compost toilets and good wetland construction to meets its sanitation needs.

Ferrell, with the help of a few students, continues to research composting and wetland construction. She and Bergren hope to secure financial grants and visit the Centro Ecologico again.