Sacred turtle will be safe in any lake clean-up

It aims to remove sludge in the lake to provide a sustainable, clean environment for underwater species.

There was an attempt to clean the lake in 1993, when the Ha Noi Water Drainage Company manually collected 7,100cu.m of garbage and sludge from its waters.

According to Dr Le Hung Anh, the project secretary, the highlight of the technology is that underwater species and water would be kept together within the lake itself, while the whole process of sludge removal is carried out.

The device, a Serditurtle, will use buoyancy to dip and rise like a submarine. Minimum turbulence and release of toxic compounds will be ensured, the surrounding water and eco-system are thus left unaffected.

Vietnamese and German experts have said that they would use the device to suck several metres of toxic sludge from the bottom of the lake. The device will crawl along the lake bed using two corkscrew-like spirals that dig up and funnel the mud into a pipe while also propelling the device forwards.

The liquid mud will then be pressed into solid blocks and transported outside the capital without any harm to the environment. The processed clean water will be put back into the lake without disturbing the water balance. Investigations on the geological, hydrological, biological and chemical situation of the lake have been thoroughly carried out since last year to check for its suitability and readiness for the new technology. Scientists have analysed water and sediment samples from the lake every four hours each day.

Anh further added that sludge removal technology had been successfully proven in removing the sludge from Uncle Ho’s fish pond this month.

"The pond houses a large population of fish and there has not been a single fish reported dead as a result of the sludge removal," he said.

Turtle professor

Sharing the same view, Associate Professor Ha Dinh Duc, Viet Nam’s pre-eminent authority on turtles at the Ha Noi University of Science - better known here as the "Turtle Professor"- and project head of the work group in Viet Nam, said the German technology was the most suitable among those presented from Japan, Thailand and elsewhere.

Duc was an active figure in pushing for efforts to save the turtles. He added that even though the technology had been approved, there was only a limited area in Hoan Kiem Lake that would be dredged in order to observe the reactions of the old turtles and the eco-system.

Situated in the heart of Ha Noi, the algae-green lake is home to an elusive turtle that plays a key role in Viet Nam folklore. It depicts the story of a Vietnamese emperor trying to fight back an invasion by the Chinese with a precious sword. As he sailed upon the lake, after his country had regained independence, a turtle surfaced and took back the sacred sword, in case the next generation needed to use it to defend the nation. The lake and the turtle itself are famed for their beauty and have become symbols of Viet Nam’s struggle for independence. This is why the municipal People’s Committee has sought assurance that the underwater species are protected during the clean-up.

Deputy director of the Science and Technology Department Vu Nhu Hanh said: "We are taking the cautious approach in this project, because it’s highly sensitive. We are still accessing the suitability of the technology and taking into consideration everything related to the lake."

Hanh said his department could not give any official confirmation about technology to be used in the project or when it would kick off.

There is little doubt something has to be done to improve the state of the lake. Duc summed it up by saying: "If nothing is done for the lake, it will become more polluted and stagnant. Sooner or later, the lake could become a marsh.

"There will come a time when not only the existence of the old turtle is threatened, but also the very existence of the lake itself." There is, however, an equally important need to ensure that nothing is lost during the restoration work.