By AIF Staff

NEERI tries to explain the purifying capacity of Ganga.

“It is the quality of self-preservation and self-purification that differentiates river Ganga from all other rivers on the planet”

In what may provide fresh answer to an old query, the National Environmental Engineering Research Institute (NEERI), an apex research organization under the Indian Council for Scientific Research with headquarters at Nagpur, has been able to decode the Ganges’ self-purifying abilities through its recent studies.

“It is the quality of self-preservation and self-purification that differentiates river Ganga from all other rivers on the planet,” says Dr Tapan Chakrabarti, director-grade scientist and Head of the Biotechnology Division of NEERI. He was part of a team studying the impact of Tehri dam on the purity of the river during which the team accidentally stumbled upon the secret of the sacred river.

A comparison of all parameters shows that the Ganges is unique in its sediment content that is more radioactive compared to any other river and lake water sediments. These sediments release Copper and Chromium and have bactericidal properties that multiply coliphages reducing and ultimately eliminating coliforms from water. The release of copper and chromium, clarifies Dr Chakrabarti, is infinitesimally small and is not harmful. The study says the Ganga ecosystem presents such an excellent biologic fabric that its self-purification capacity exceeds that of any other water.

For times immemorial, the river has possessed a property that does not allow polluting bacteria to survive for a longer period of time. In view of this, the Tehri Hydro Development Corporation Ltd., Rishikesh had asked NEERI to investigate the impact, if any, of the dam, being constructed at Tehri, on the self-purification capacity of the river during post-commissioning phase. Scientists found the dam doesn’t affect the inherent qualities of the river. Dr Chakrabarti, who headed the team of scientists into this study that was over a few months ago, says answer lies in unabated ‘bacteriophage’ activity of the Ganges. In common parlance it means a continuous activity of virus that kills bacteria.

A century ago, scientist Hankin (1896) reported that the waters of the Ganges and Jamuna rivers in India had a marked antibacterial action. Edward Twort (1915) and Felix d’Herelle (1917) independently reported isolating filterable entities capable of destroying bacterial cultures and producing small cleared areas on bacterial lawns seemingly implying that discrete particles were involved. They were jointly given credit for the discovery. It was d’Herelle, a Canadian working at the Pasteur Institute in Paris, who gave them the name “bacteriophages”.

Several explanations for self-purification were put forward, though none of these could justify this unique observation. The investigations carried out by NEERI, claims Dr.Chakrabarti, might provide a credible explanation to the observed self-preservation capacity of the Ganges. Dr Chakrabarti explains: “Ganga sediment adsorbs coliphages and induces their proliferation. The coliphages thus adsorbed predate on coliforms and other bacteria in overlying water column when the sediment and water co-exist in a container under static condition. And all this activity happens quickly and continuously.” This activity is not seen in any other river, which is why under static conditions all other river waters become putrid and polluted, the NEERI report holds.

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