An Article from The Conversation: U.K. tests phytoremediation potential of fast-growing Eichhornia crassipes (water hyacinth) with promising results. Because the water hyacinth is invasive, testing plants were arranged in pods in the river to keep the species contained. Tests demonstrated more than 60% of the aluminium and zinc polluting the subject river that entered the testing pods was removed within just seven hours.

http://theconversation.com/invasive-tropical-plant-removed-metal-pollutants-from-british-river-new-study-100403