But the more important ...

But the more important question is :

Answered your question in a response above.

But here is the real deal. It is not possible to clean up the Ganges. If you have seen the volume of pollutants, sewage etc. that enter it right through its whatever 500 mile long journey - it is a big ganda nallah.
We have to stop dumping this stuff into it. No drainage should flow into rivers. It should be directed outwards (of cities) treated and even the sullage should not be dumped into rivers.