Phragmites, or "common reed," is being used to treat wastewater in Shelburne Falls, Massachusetts. (Photo by Adam Allington.)
Nature is often full of practical solutions to real-world problems. Take the case of sewage and wastewater treatment: for decades engineers have used mechanical means to process wastewater before disposing of the end product in landfills. It turns out that phragmites, a robust wetland reed, can do the job just as quickly and for a fraction of the cost. Adam Allington has more:
Transcript
Nature is often full of practical solutions to real-world problems. Take the case of sewage and wastewater treatment: for decades engineers have used mechanical means to process wastewater before disposing of the end product in landfills. It turns out that phragmites, a robust wetland reed, can do the job just as quickly and for a fraction of the cost. Adam Allington has more:
Brandee Nelson is wearing knee-high rubber boots. She’s wading out into a tiny patch of reeds gently swaying in the wind. They’re planted in a goopy substance that appears to be mud, but is actually…
“Sludge. We’re standing ankle deep in sludge. Sludge is the leftover solids from the conventional sewage treatment process. Things that are very organic in nature, but thin enough that you can’t really scoop it out with your hand. It’s not the consistency of yogurt, it’s more like a thin milkshake.”
That thin milkshake used to be the solid stuff that you flush down the drain. Brandee is an environmental engineer working for the village of Tivoli, New York. Today she is monitoring the growth of two recently planted reed beds. The reeds are an invasive wetland species called “phragmites,” or “common reed”. In most places these reeds are a problem because they crowd-out native plants, but here they’re doing a job.
“The whole reason to have the reed beds is really to get the largest volume reduction of your waste product. Because the sludge tends to have so much water in it, and phragmites sucks up an enormous amount of water. This bed, we’re standing in it now, this bed will be totally dry in one day.”
Even though Tivoli is relatively small at about 1000 residents, the village still produces 100,000 gallons of waste water every day. That waste water translates into a whole lot of sludge, which Tivoli then has to haul to landfills.
“We’ll probably be saving about $45,000 on hauling fees.”
Tom Cordier is deputy mayor for the village of Tivoli.
“At one point we had drying beds, and it took about a week for them to dry, and then we would come in with our backhoe and take out the dried material. But every time we got ready to do that, it would rain and we would have to start the whole process over again, and then in the wintertime it was always freezing, and finally we got to the point where we had to have it trucked away.”
Before they planted the reeds, Tivoli had to remove their liquid sludge once a month. When the reeds are fully grown, the village won’t need to haul anything away for over 10 years. But if reed bed technology is so efficient, why isn’t everyone using it?
The answer has a lot to do with the predictability of mechanics, versus the variables of biology.
“One of the issues with the reed beds is it’s a biological process. Engineers like to typically do things that are mechanical, things that fit into formulas.”
Dan Fleuriel is director of the wastewater treatment for the town of Shelburne Falls, Massachusetts. Shelburne Falls began experimenting with reed bed technology back in the early 1990’s. Unlike the short 3 foot reeds in Tivoli, the mature reeds in Shelburne Falls tower some 6 feet over us as we walk through them.
“We’ve been applying to these reed beds since 1993. It’s been very good for us because we’ve gone from a very time consuming process of de-watering sludge to something that we pretty much leave hands-off that we can rely on.”
Functionality and reliability: they’re fundamental to any civil engineering project. But Brandee Nelson notes that Tivoli’s reed beds also make sense from an environmental perspective.
“This waste product, 150,000 gallons of it, used to go to a landfill somewhere else and it wasn’t our problem any more. Now what we’re able to do is manage that waste product here on site in a relatively small footprint using a natural technology, a very low-energy technology, and in the end we’ll end up with a product that we can use for village landscaping projects.”
Tivoli’s reed beds are expected to reach full maturity by next summer. Success of the project is being followed closely by neighboring towns, who are also considering a switch to reed bed treatment plants.
For the Environment Report, I’m Adam Allington.