Hanoi will build a sewage collection system on both sides of the To Lich river, which is heavily polluted for decades, VnExpress quoted Hanoi Department of Construction Director Le Van Duc as saying.

The director said that sewage water in the collector will then flow to Yen Xa wastewater treatment site where a centralized sewage treatment facility is under construction.

A city environment worker picks up trash along a section of the To Lich river in Hanoi. Photo: Ngoc Thanh

Duc informed that the municipal government has recently studied three options to revive the To Lich river which is dying due to heavy pollution and massive accumulation of mud in the river bed.

At first, the authorities thought of collecting wastewater at sewer outfalls along the river. However, this option seems unfeasible because of the large number of outfalls.

The second option was using a nano-biotech application by Japan-Vietnam Environmental Improvement Company (JVE). After the pilot period of treating water in some sections, JVE’s report showed that the improvement of the river’s water was not tangible. The water from the river still smells bad and retains the black color. The pilot of this technology has ended and the local government has no intention to apply it widely on the river.

In addition to the above-mentioned technology, Hanoi also piloted cleaning up the To Lich river with Germany's Redoxy3C inoculant. However, the head of Department of Construction did not mention the results.

"Currently, building a sewage collection system along the river banks is the last and the best option," said the director.

He added that the construction of the system must be completed by 2020, but it lags behind schedule. It is expected that by 2021 the collection system will be put into operation.

At a meeting on November 13, an offical said the Hanoi government was consulting experts on a scheme to pump water from the Red river to dilute the pollution of the To Lich river.

The plan is to direct water from the Red river, which flows from Yunnan province in China through northern Vietnam to the Gulf of Tonkin, to the West Lake via a penstock system for processing. Then, from the West Lake, the biggest freshwater lake in Hanoi city, water will be pumped to the To Lich river. It's not clear when and for how long the project will be conducted.

The To Lich river used to be a branch of the Red river but was delinked by the French in 1889 as part of an urbanization plan. The river runs 14 kilometers through the downtown districts of Thanh Xuan, Hoang Mai and Thanh Tri and has become infamous for its stench and blackish water.

Hanoi has tried in vain to clean the To Lich river many times in the last decade.