These Webpages are no longer maintained. We are keeping the pages here to preserve some of the early years of ProjectDragonfly, to honor the students who created the interactives in the early days of the Web, and because many of the activities are fun and people are still using them. For current Project Dragonfly work, go


The ProjectDragonflyteam.

How Does Sewage Treatment Change the Sewer's Dirty Water into Clean Water?
The sewage we produce in our homes is carried by drain pipes to a sewage treatment plant. The treatment plant specializes in cleaning up dirty water.  To make the water clean, the treatment plant takes the water through a process with several steps.

In the first step,  the heavier waste in the water (called "sludge") is allowed to sink to the bottom. The sludge is removed, leaving only the cleaner water.

Next, the water flows through a mesh screen, which removes dirt and dust.

Now the water has no more solid waste. But it still isn't clean.  The water has dangerous microorganisms, like bacteria, living in it. These microorganisms could make you sick if you tried to drink the water.  To remove bacteria, we need to use a little bit of science know as "microbiology."  Let's see what happens!


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