In early 2010, Hanoi’s authorities launched a movement on socializing the protection and improvement of the lakes in the inner city, which raised the active response from the community. The Hanoi Environment Protection Sub-department, cooperating with other units in the city, tried to treat the polluted lakes. Twelve lakes have been treated over the last two years.
Ngo Thai Nam, Deputy Head of the Hanoi Environment Protection Sub-department, the most popular method to treat the pollution is to sprinkle the lakes with microbial preparations to reduce the pollution index. Besides, experts can use precipitates, aquatic plants to purity the water.
There are three elements in the lake water environment: animals, microorganisms and aquatic plants. Animals only eat organic materials. Microorganism is responsible for making the resolution of organic matter into inorganic. Aquatic plants are the ones with leaves and roots. Most of them have very large root systems. These are the units which can absorb organic matters and heavy metals in the water.
Therefore, growing aquatic plants like water hyacinth would help significantly improve the water quality. This species help absorb and metabolize the harmful bacteria to clean the water, explained Nam.
The Ngoc Khanh Lake in Ba Dinh district was one of the first lakes in Hanoi that used the method. Phuong, the owner of a tea shop on the lakeside, said that the method proves to be very useful. In the past, the lake water was black and gave terrible smell, while dead fish were floating white on the water surface. Since the day the lake was dredged and improved, the terrible smell has been eased.
“As the lake has got cleaner, more and more people have come here to do physical exercises,” Phuong said.
The analyses have shown that though the improved lakes’ water still cannot meet the standards, the quality of the water has been much improved. However, it is not easy to keep the lakes clean forever.
Nguyen Ngoc Ly, Director of CECR, said that the quality of the water can only get better right after the treatment. However, the pollution indexes have got increased again because local residents continue discharging waste water to the lakes.
The Truc Bach Lake is a typical example. Its status now is “semi-polluted.” On the area that faces the Thanh Nien Road, the lake is really green with beautiful landscapes.
However, on the other side of the lake, things are quite different. The water gives terrible smell, and dead fish float on the surface. This is because of the waste water discharged from the 30 sewage pits and underground sewers. Therefore, rafts of aquatic plants have been put into the surface which helps purify the water.
The Quynh Lake in Hai Ba Trung district has become cleaner after it was treated with the water treatment technology. However, as local residents continue discharging waste into the lake, analysts have warned that the lake would get polluted again soon.
Nam from the Hanoi Environment Protection Sub-department said that everybody needs to join the protection of the lakes. Nothing will change if local residents continue discharging waste water and throwing rubbish to the lakes. Meanwhile, a lot of lakes have been leased to individuals for breeding fish for profit. As a high amount of feed is thrown into the lakes every day, the lakes will certainly get polluted.
“Heavy punishment and lake improvement will not help keep the lakes clean, if people do not cooperate,” Nam said.