A stretch of man-made marsh with reeds and cannas in a community park seems nothing extraordinary, but when it serves as a filter controlling water pollution, it attracts environmental protection researchers.
The man-made marsh in Honghu Park in Shenzhen, a city neighboring Hong Kong in south China's Guangdong province, has recently become a shrine for environmental researchers from all over the country. The "pilgrims" come to admire and learn a new way of controlling water pollution.
The lake in Honghu Park used to be seriously polluted by the city's liquid waste. The water stank and was almost black. Now the lake is cleaner and a home to fish, shrimps and other aquatic life, thanks to the artificial marsh.
Researchers said plants in the marsh and sand and gravel fillings helped reduce pollutants in the passing water because of chemical, physical and biological effects.
Local environmental researchers started working on this project in 1997 with help from scientists of the Chinese Academy of Sciences and researchers from Germany and Austria.
Researchers said the 2,300-square-meter marsh can treat 1,000 tons of polluted water daily. But it cost only half the amount needed to build a conventional treatment plant for polluted water, and one-fifth of the daily cost for running such a plant.
The park uses the marsh-treated water to irrigate flowers and grass, saving about one million yuan (US$120,482) each year.
The marsh is now listed among major model projects that demonstrate appropriate technology in environmental protection by the State Environmental Protection Administration.
Shenzhen recently created two other marshes and plans larger areas of man-made marsh to dispose of polluted water. When completed, the city's artificial marshes will be able to treat 42,000 tons of polluted water daily.
(Xinhua News Agency August 29, 2002)
