Earth-friendly flushing - sewage processing plant at Corkscrew Sanctuary, Florida has produced a delicate wildlife environment which uses fertilizer from the result of algae and bacteria breaking down sewage sludge - Brief Article

Science World, Oct 4, 1996 by Pamela Tan

"Loud, smelly, and unsightly." That's how Neil Harden describes traditional sewage-treatment plants. With the help of strong chemicals, these factories purify the water and waste you flush down your toilet. But ask Harden about the sewage-treatment plant he operates at Corkscrew Sanctuary in Florida, and he brags, "The only smell you can detect is the sweet fragrance of its flowers."

Flowers? At a sewage-treatment plant?

Yes! At Corkscrew, flowering plants, trees, ferns, and other greenery "eat up" the nasty waste particles in the toilet water. As a result, the water is odorless and clean enough to be recycled back to the restrooms.

Thousands of visitors flock to Corkscrew Sanctuary each year to marvel at one of Earth's last cypress-tree forests. Corkscrew recently needed a new sewage-treatment system to keep up with the visitors' frequent flushes. But the chemicals used by most sewage plants are toxic and could harm Corkscrew's delicate, wildlife-rich environment. In contrast, the "living machine" of plants at Corkscrew can harmlessly treat 10,000 gallons of wastewater a day.

The water that swirls down the toilets enters a series of large canisters filled with wetland plants (see diagram, below). Immersed in water, the plant roots create a lush environment for algae and bacteria. These microorganisms supply oxygen to the waste, turning it into food the plants can absorb.

Flushing to feed flowers may seem too far-fetched to be practical. But since 1986, nearly a dozen sewage systems like the one at Corkscrew have sprouted successfully at sites around the country. Would you want one in your backyard?

RELATED ARTICLE: Flush the toilet to feed the flowers!

The Florida Corkscrew Sanctuary sewage-treatment system purifies wastewater without using toxic chemicals. Follow the steps in this diagram to see how greenery absorbs the waste particles in the water people flush down the Corkscrew restrooms toilets.

1. UNDERGROUND TANKS

* Human waste and water flushed from toilets enters underground tanks.

2. PURIFYING PLANTS

* Wastewater enters a series of canisters filled with trees, like cypress and red bay, that usually grow in swamps.

* Bacteria and algae living in plant roots turn waste particles into plant food.

3. WASTE AWAY

* Last canister returns any remaining waste to the underground tanks to be cycled through the system again for additional treatment.

* Treated water and plant nutrients drain into human-made wetlands.

4. WASTE-EATING WETLANDS

* Wetland plants like ferns, cattails, and swamp lilies absorb plant nutrients.

5. CLEAN AND CLEAR

* Water leaving the wetlands is treated with chlorine to kill leftover bacteria.

* Non-toxic sodium sulfite is added to neutralize chlorine, leaving water pure and odorless. Water is recycled to toilets, fresh for the next flush.

FAST FACT

The only time worker at Corkscrew need to draw water from an outside source is when water evaporates from the wetlands of the wastewater-treatment system.

Sludge, solid leftover human waste from treated toilet water, is loaded with nutrients essential for plant growth. In fact, 45 percent of U.S. sludge is used to fertilize crops.

Each day, a large city like New York creates enough sewage to fill more than 3,000 Olympic-size swimming pools.

WINGS OVER WASTE

* A screen covers the entire system to contain dozens of butterflies that thrive in the "garden."

RELATED ARTICLE: EARTH EXPLORER

Meet Marcia McNutt, a geologist who studies earthquakes and mountain formation.

Rock Revolution: When McNutt was in college during the early 1970s, the world of geology was rocked by "a scientific revolution"--the theory of plate tectonics. McNutt was fascinated. She became a geologist, or earth scientist, to learn more.

Cracked Egg: The theory of plate tectonics says Earth's outermost layer, the crust, looks like a cracked egg shell. Each piece of shell represents an enormous slab of rocky crust--a tectonic plate. These plates move extremely slowly over Earth's next layer, the mantle (see diagram). When two plats rub together, they sometimes cause earthquakes or buckle up to form mountains.

Rumbling Mystery: Sometimes quakes shake in surprising places--like the region McNutt has studied between Las Vegas and Salt Lake City. This region is all part of the same slab of crust--the North American plate--so it should be quake-free. What could be causing the slab to shake?

Slow Breakup? McNutt's explanation: Perhaps the North American plate is slowly breaking apart. In a few million years the area may crack into two tectonic plates, splitting the United States in half with a new ocean in between!

The Grean Outdoors: "The best thing about being a geologist is doing science outside," McNutt says. Sound like fun? You can get more info on careers in earth science by writing:

U.S. Geological Survey

Earth Science Information Center

507 National Center

Reston, VA 20192