You can use Vetiver grass(Vetiveria Zizanoids) which is popularly known as Khus grass. It is the most environment friendly solution wo. using any chemicals. You can store the polluted water in a pond, keeping Vetiver on floating decks. Also, Vetiver is to be planted on the banks of this pond. Vetiver absorbs any kind of water & soil pollution including traces of all heavy metals & oils.

Thanks Mr. Kushal for your valuable input.