The appliance of science cleans Lake Taihu

New technologies are helping the famous landmark in East China to recover from years of severe pollution. Zhang Zhihao reports from Wuxi, Jiangsu province.

For generations, poets used the term bishui, or "emerald water", to describe Lake Taihu, China's third-largest freshwater body, famed for its scenery and clear water that reflected the surrounding green hills.

The lake, which straddles the provinces of Jiangsu and Zhejiang in East China, is a cradle of fisheries and tourism. It is also the water source for industries and cities, from Wuxi in Jiangsu to Shanghai, nurturing more than 44 million people.