Researchers have started testing “SediTurtles,” a device they say will defend a renowned Vietnamese turtle while at the same time clean the lake where it lives.
Experts debuted the sediment-consuming machines as part of a cleanup program on Hoan Kiem Lake, located at Vietnam’s capital.
The Lake of the Returned Sword houses a mysterious turtle that symbolizes Vietnam’s exertion for independence.
The children’s story of the 15th century rebel leader Le Loi says that he used a sword to fight off Chinese invaders. After Emperor Le Loi went boating on the lake one day, a turtle swam up, took his sword and swam to the bottom, safeguarding the weapon for the next time freedom needed a hero.
Sightings of the turtle are considered lucky, especially when they land on national events. The lake’s historical value therefore needs a special cleanup plan, and the teams of Vietnamese and German experts have plotted cleaning the turtle’s home with smallest possible risk to it.
Leonhard Fechter, of Berlin’s Herbst Umwelttechnik GmbH, knows that people worry about the turtle, so the SediTurtle was made with “soft” technology as not to hurt the animal.
“We are sure we won’t touch the turtle,” he said.
The device has a hose that floats on the water attached to a metal box. A dredging device, hidden below the surface, removes sediment from the bottom by sending it to a different machine that removes sludge from the water.
“That device is moving very slowly. That big turtle can easily escape,” said Celia Hahn, the project manager at the Dresden University of Technology.
Over time, the sediment in the Hoan Kiem Lake has increased and the water level has declined, specifically in urban areas. The experts note that the lake is only five feet deep, but the majority is sludge created by industrial pollutants.
Draining the lake cannot be done because it would harm the water body’s ecosystem, experts insist.
“The big turtle is living from crabs or small fish,” Werner said, noting that sediment removal would occur slowly over time.
Christian Richter, from FUGRO-HGN GmbH, said his firm has already reviewed the lake’s geology. They will map parts of the lake where sediment can be extracted without harming the lake.
“Even if they start immediately, they would need at least one or two years for the removal,” Richter said.