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Photograph: Abir Mahmud, University of Dhaka
Our thanks to Hannah Richter for her reporting and writing, as well as to Wired for publishing what sounds not like garden variety too good to be true, but quintessentially ridiculous.
Kudos to Nepal for testing out this idea in spite of how it sounds:
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Groups of platforms installed in Nagdaha lake in Nepal. PHOTOGRAPH: SAMYAK PRAJAPATI/THE SMALL EARTH NEPAL
Polluted Lakes Are Being Cleansed Using Floating Wetlands Made of Trash
Platforms combining plants and recycled garbage could offer a cut-price solution for reviving polluted bodies of water.
ON THE BANKS of Nagdaha, a polluted and lotus-infested lake in Nepal, Soni Pradhanang is putting trash back into the water—on purpose.
A floating treatment wetland system loaded with plants. PHOTOGRAPH: SAMYAK PRAJAPATI/THE SMALL EARTH NEPAL
She carefully assembles a platform of styrofoam and bamboo mats, then weaves it together with zip ties and coconut fiber, refuse from nearby tech stores. Then, she pokes 55 plants lush with red flowers through 2-inch holes in the platform, each plant set 6 inches apart. Though Pradhanang’s creation isn’t high-tech, it is effective, and one of the most affordable water-filtration systems available. “I’m cheap,” she says, laughing.
Pradhanang, a hydrologist at the University of Rhode Island who studies water-quality monitoring and modeling, has spent the past seven years working on her trash-based contraptions. Called floating treatment wetland systems (FTWS), these are 4-foot by 6-foot buoyant platforms topped with plants. When their roots are submerged in contaminated water, the plants suck pollutants into their stems and leaves as they grow. In turn, they leave behind dissolved oxygen captured during photosynthesis, which supports life beneath the surface.
The hope with these devices is two-fold: that they will cleanse waters and recycle rubbish in parts of the world where budgets for either are incredibly tight.
Pradhanang is also the chief scientific technical adviser to The Small Earth Nepal, a Kathmandu Valley–based research and community engagement group. It has spent around five years building, testing, and implementing the first known trash-based wetland water-cleaning systems here in Nagdaha’s polluted waters, which contain high concentrations of nitrates and phosphates due to agricultural and urban runoff. Pradhananag and The Small Earth Nepal also operate sites with collaborators in Ajmer, India, and Dhaka, Bangladesh…
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Read the whole article here.
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