How does water purifying work?

Large objects are filters out - so bottles, bags etc are removed.

Flocculation may be used to clump smaller particles.

Sedimentation might be used to allow heavy particles to separate and skin to the bottom.

Smaller floating objects are filtered out using sand or membranes.

Sodium carbonate might be used to remove calcium carbonate.

Ultra violate light can be used to sterilize.

Hydrogen peroxide / chlorine can also be used to sterilize.

A common design for a water filter is one that incorporates gravity as the powering element. Tap water is held inside the water purifier atop a filter, allowing gravity to pull the water through the filter. As the water is pulled through, the contaminants remain on the top side of the filter.

Modern improvements on home water purifying systems add aspects such as additional metal strainers that help ensure that virtually all contaminants are blocked.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.