The Masai are learning to harvest rainwater in Kenya. Wool from Welsh sheep is just right for making organic mattresses. A town in Sicily turns to donkeys to replace its trash-collecting vehicles. China’s Yangtze is one of the world’s longest rivers, but also one of the world’s dirtiest. In Chile, earthworms are remarkably effective at treating human and industrial waste. Heavy metals and other toxic materials make the disposal of electronic devices a potential health hazard. An offshore wind farm in the U.K. powers more than 30,000 homes.