Environment workers collect mud and water samples from the Tô Lịch River to examine the effectiveness of Japanese technology that is being piloted and aims to clean up the heavily polluted river. — VNA/VNS Photo Huy Hùng

HÀ NỘI — Nguyễn Thị Hoa, a resident living on Hoàng Quốc Việt Street, is enjoying a rare reprieve from the rotten smell that has plagued the neighbourhood for decades.

The polluted Tô Lịch River is undergoing experimental treatment with Japanese technology to restore the purity of a river long considered ‘a dead river’ and a serious health hazard.

“The putrid odour gets even worse during hot, sunny days,” Hoa told Vietnam News Agency.

“As someone living by the river, we really hope the Tô Lịch cleanup project will yield results and our concerns for so many years will finally clear up.”

Nearly two weeks after the nano-biotechnology began cleaning a 300m stretch of the river, residents have reported a noticeably improved smell and clearer water.

Clean river

According to Hà Nội’s Department of Natural Resources and Environment, 240 sewage outflows are emptied into the 15km river that courses through many several districts of the capital city.

The river receives some 150,000cu.m of wastewater daily, with a third of this volume untreated industrial wastewater.

Having been cut off from the Red River and West Lake during the French colonial era and urban expansion narrowing the river has only made the pollution worse.

Without a proper exchange of water, thick sludge has accumulated on the riverbed and is the primary source of the river’s pollution.

Dr Tadashi Yamamura, UN environment expert and President of the Japan Environment and Trade Promotion Organisation, who has brought up the project in a meeting with Prime Minister Nguyễn Xuân Phúc and worked with Hà Nội's authorities to obtain permission to pilot the project, said the nano-bioreactor has proved its worth in similar cases in Japan, China and the US and believed their technology could be of use here after two years of surveying.

“In Việt Nam, one of the biggest problems with the Tô Lịch River is the thick sludge at its bed that is the source of the smell, and this could be solved by the nano bioreactor,” he said.

The technology involves two main components – nano air blowers and nano-bioreactor panels made from porous volcanic rocks in Japan.

According to Tadashi Yamamura, the bioreactor panels serve to “activate” the micro-organisms in the water, encouraging them to break down H2O particles to release oxygen.

With the increased level of oxygen in the water, fish and other water creatures can thrive.

The air blowers, pumping nano air bubbles into the mud, are meant to prevent mud settling down on the riverbed.

The system, which is also being piloted at a corner of the city's West Lake, could be seen as “a wastewater treatment facility” on the riverbed, the Japanese expert said.

“We use electricity to run the air blowers, after the river reaches a certain level of purity, the blowers might just need to run for 15 minutes each hour, or for a total of six hours a day,” he said, adding that a conventional facility would need to run 24/7.

The system also doesn’t cost much or require land to build on, while it can clean 1.3 million of cu.m of water a day, nine times the amount of wastewater discharged into the river daily, Dr Yamamura said.

Đỗ Thanh Bái, deputy chair and general secretary of the Chemical Society of Việt Nam, said he and many Vietnamese colleagues are “thrilled” with the project.

There is no telling for sure whether the river can be completely cleaned but Bái said he believes in the Japanese technology.

“It must be the real deal when they are so confident. There has not been anyone tackling the Tô Lịch issue who dared to make such a claim before,” Bái said.

A nano air blower installed on Tô Lịch River that aims to increase oxygen levels in the water. — VNA/VNS Photo Huy Hùng

Time needed

However, not everyone is convinced and some have voiced concerns about the long-term viability over the project, especially over the possibility that the river might need constant pumping of air to avoid pollution.

Đào Trọng Tứ, director of Việt Nam River Network, an organisation which aims to protect rivers in the country, said the Japanese technology is not anything novel and many methods have been tested on polluted lakes and rivers across the country, including the Tô Lịch River, but the results failed to live up to the high expectations.

“If the technology’s endgame is to improve the smell or the colour of the river’s water, then it is nothing new. Everyone knows how a pond or a lake’s water can be cleared up significantly if treated with alum,” Tứ said.

He also noted how it would be more complicated as the Tô Lịch is no longer a true river, given that the freshwater supply that goes into the lake is dwarfed by other sources, namely wastewater and rainwater.

Tứ remarked that if the issue of wastewater discharges into the river is not dealt with, any solution would just be temporary.

In the short-term, Hanoians might no longer have to turn up their nose at the rancid smell, especially during the hot summer, but testing is needed before declaring the project successful, he added.

Phạm Văn Cường, former director of Hà Nội’s water discharge project management unit, said the city is building the 4,800ha Yên Xá wastewater treatment factory with daily capacity of 270,000cu.m.

Once operational, the facility would collect and handle all wastewater discharged from households alongside the Tô Lịch River, which means the river would no longer have to bear the polluted water, Cường said.

City authorities are also considering pumping water from West Lake to flush out the pollution from the Tô Lịch River.

Previously, Lê Công Thành, deputy minister of environment and natural resources, said the Japanese technology being piloted at Tô Lịch River is merely a test and the results remain to be seen.

“The ministry has assigned relevant units to constantly monitor the water’s quality and assess the efficiency as well as the practicality of the technology,” Thành said.

According to the environment ministry, the pilot project will go on for two months with expenses borne by the Japanese side. — VNS

The stretch of Tô Lịch River near Hoàng Quốc Việt Street was choosen as the site for the cleanup operation project by Japan. — VNA/VNS Photo Huy Hùng