Lake Dian in Kunming, the capital of southwest China’s Yunnan province, suffered greatly when, in the 1950s, Chairman Mao Zedong called on the Chinese people to “conquer nature” and reclaim land by filling lakes with soil.Nowadays, Dianchi, as it’s known in Chinese, effectively acts as Kunming’s main sewage dump its pollution is a persistent and at times stinky problem for