A study by Vietnam’s Institute of Meteorology, Hydrology and Climate Change has suggested using aquatic plants to purify the contaminated water of Hanoi's Nhue River.

A study by Viet Nam’s Institute of Meteorology, Hydrology and Climate Change has suggested using aquatic plants to purify the contaminated water of Hanoi's Nhue River.

The 72km river runs through the capital and two districts of Ha Nam Province. The river water is used for aquaculture production and irrigation of its whole basin. However, the water is badly polluted by increasing amounts of untreated solid waste and waste water.

According to Associate Professor Le Xuan Tan from Hanoi University of Natural Resources and Enviroment, Nhue River is located in Viet Nam’s most densely populated area, with over 1,000 people living in every square kilometre. The area has also experienced strong urbanisation and fast socio-economic development. 

Nhue River receives water from the Hồng (Red) River and waste water from Hanoi and other riverside areas.

Heavy pollution

Five years ago, researcher Vu Thi Phuong Thao started a study of the role of aquatic plants in improving the Nhue River water quality. He concentrated his study in the part of the river that runs from Cau To to Cong Than through five Hanoi districts – Ha Dong, Thanh Oai, Ung Hoa, Thuong Tin and Phu Xuyen.

He found the water heavily polluted by organic substances, excessive concentrations of nitrogen, phophorus and iron.

Thảo found that there were 33 species of vascular aquatic macrophyte species living in the freshwater ecology of the Nhue River Basin. Her study identified 18 of the 33 aquatic plants that played a role in purifying the river water.

Three aquatic plants in particular – thủy trúc (Cyperus alterfolious), rau muống (Impomoea aquatic Forsk) and ngổ trâu (Enydra fluctuans Lour) – could absorb pollutants in the river water, she found.

Rau muống and thủy trúc are useful to treat water that is contaminated by compounds of nitrogen or phosphor, while ngổ trâu and rau muống are effective for water contaminated by heavy metals, she said.

Thảo suggested that the use of aquatic plants should be further studied in trade villages and industrial zones through which the river runs.

Local authorities and residents living along Nhue River have for years been blaming the increased volume of industrial waste and daily waste for the water pollution. Some riverside fishing villages have all but disappeared as a result.

Statistics from Ministry of Natural Resources and Environment show that from last October to early this year, nearly 2,000 waste sources were reported in the river basin, including over 1,660 from production units, 39 from industrial zones, 137 from healthcare centres and 144 from trade villages. Sixty per cent of the waste sources are from Hanoi.

According to the Water Resource Management Department, the Nhue-Day River basin received about 3.81 million cubic metres of waste water last year. About 2.55 million or 67 per cent of the waste water was from farming activities, 16 per cent from household activities and nearly 17 per cent from industrial activities.

According to the Committee for Environment Protection of the Nhue-Day River Basin, in the last two years, the environment ministry has developed a database for the basin, assessed trouble spots and reviewed the implementation of environmental protection regulations.

The ministry and Hanoi's Environment Department built waste treatment stations with a capacity of 400 cubic metres per day each in Phu Ha and Phu Tu hamlets in Tu Liem District.

Hanoi also carried out other projects to curb pollution on the Nhue River, including tackling environmental problems in trade villages in Hanoi, Ha Nam and Ninh Bình, and installation of waste water treatment systems in hospitals. 

VNS