What happens after we flush?

I really felt like Ms. Frizzle in a Magic Schoolbus book on this field trip! This was not your usual field trip to the zoo. (That comes later!) No, this time, we went on a rather stinky, but ABSOLUTELY FASCINATING tour of the Redondo Wastewater Treatment Plant in Des Moines to find out what happens after we flush the toilet and how we make sure sewage doesn't end up in the Puget Sound.

 First we looked at some water samples -- on the left is how the water looks when it comes in, on the right is how it looks when it leaves the plant. Quite a difference!

Then we saw how all the garbage (diapers, wipes, and anything else that shouldn't really be flushed) is screened out of the water coming in from the sewage pipes of more than 2,000 homes in this area. This is compacted and is the only waste in this process that gets put into a landfill.

Then we walked over the area where the water flows into the plant. This is where things start to get a little smelly.

Here we head into the first of several settlement tanks - it's a multi-stage process.

 In these huge circular holding tanks, sediment seeps to the bottom and the water on top is filtered out. Bacteria is used to break down the sludge. Big arms sweep around the bottom of the tank and push the sludge to pipes in the center that separate the waste. 

 Here we are heading down the stairs to see what goes on below the tanks.

You can't see it well here, but the sludge (um, yes, that was once poop) from the tanks is coming down through this pipe. It gets separated, treated, and eventually broken down enough to be used as fertilizer.

 These labels say it all!

The water filtered off the top of the tanks goes through several stages before finally going into this room. At this point almost all the harmful substances and chemicals have been removed, and in this final stage it is treated with UV light, which kills off any remaining bacteria.

 Finally, the now-clean water is pumped back out into the sound through a large pipe under this grate.

The sludge that has been separated from the water has a different destination. This truck is holding the waste material, now a class 3 fertilizer, destined for non-food crops in eastern Washington. 

We ended our visit with a great discussion about how "dirty jobs" like the one the gentlemen do at this facility require a scientific background and a whole lot of math. None of the people who work here like the smell, but they said you get used to it after a while, and the fact that they are helping to keep our Puget Sound clean makes their jobs worthwhile. All in all, a worthwhile field trip!