In the capital city of the Mexican state of Veracruz, a group of scientists are rescuing two lakes from water pollution with plants that float on the surface of the lakes.
Three years ago a lake in the Mexican city of Xalapa was a cesspool-a toxic soup of storm water runoff and sewage from homes surrounding the lake.
“Before we started, there were lots of micro-algae floating on the surface. There were bad odors. There were some dead fish. So it was really very polluted,” said Eugenia Olguin, director of Ecology Institute of Veracruz.
Thanks to these floating carpets of vegetation, the lake, Los Lagos del Dique, the fish are back.
"They removed nutrients though the roots and they also stopped the chloroform, the bad bacteria lets put it in that way from going into the rest of the lake. They are acting as a filter, they are improving the water quality," Olguin said.
They are called “constructed wetlands.” Scientists at the Institute of Environmental Biotechnology in Veracruz built their wetlands, using papyrus and a plant called Galapagos leaf. Their roots filter contaminants, reduce pollution and increase oxygen levels. Contaminants were killing the fish. Now the fish are thriving.
The scientists behind the project are hoping that this system can serve as a model to other communities to help decontaminate their lakes and rivers.
Researchers anchored the plants in a bed of volcanic gravel inside plastic crates. Empty plastic water bottles keep the crates afloat. It is a low-cost solution to a massive problem. Olguin says it only costs 20 dollars per square meter to build the wetlands. Similar floating wetlands have been growing in popularity in Europe, China and the U.S.
“The idea is to replicate this water treatment system, which so far has been very efficient in this area and that’s the plan to extend it to other bodies of water in the city,” said Victor Hugo Garcia, Director of the Xalapa Water Commission.
It is a green solution in more ways than one. Unlike conventional water treatment plants, the only energy the artificial wetlands consumes from the sun.
