Certain plants absorb pollutants from wastewater for their metabolism. A team from the National Botanical Research Institute in Lucknow, planned a plant-based project to clean the Ganga. U N Rai, environment scientist who heads the team, speaks to Savvy Soumya Misra

On how the project began

With the help of a non-profit in Pune, our group of four scientists submitted a project on cleaning the Ganga through all the states to the Planning Commission in 2005. We made our presentation to the Prime Minister in May this year.

On what phytoremediation entails

Utilizing plants to mitigate environmental problems is called phytoremediation. We have identified 20-25 plants that can efficiently remove heavy metals like chromium from the soil. These include bulrushes such as Scirpus lacustris and Typha latifolia that grow in wetlands.Phragmites karka, an aquatic reed, has roots with bacteria and fungi living on them. The microbes use the heavy metals as food source.

On the first experiment

In 2003, we executed a project at a common effluent treatment plant in Uttar Pradesh. The aquatic plant Vallisneria spiralis (Indian red sword) was grown in a sludge pool for 14 days and then uprooted. Its roots accumulated 358g of chromium per gramme of dry weight of the plant. The plant was composted for manure which had high mineral content. The pool showed a heavy loss in chromium concentration.

On the project