This weekend I got to go on a tour of the SF Oceanside Water Treatment Plant, which handles about 20% of San Francisco’s waste water.
That includes everything from your shower, bathroom, and sinks, as well as rain water from storms—that’s known in the biz as a “combined” system. A lot of cities nowadays will have two separate sets of pipes, one for rain water and one for everything else.
The downside: basically if SF has a big storm and the system gets overwhelmed, a combination of sewage and rain water (mostly rain water, but still some sewage) might get dumped into the bay. Consequently, the city has massive storage tanks underneath The Great Highway and a couple of other places to keep that from happening.
The upside is that SF treats its rainwater, which often has all sorts of pollutants mixed into it from the streets or people’s lawns. In cities that don’t treat their rain water, often the “first flush” or first big rain of the season can cause a bunch of nasty chemicals to get dumped into the environment.
This is the first step of the cleaning process; the sewage sits in this massive room and is allowed to settle for a few hours. Solids sink, oils float, and water (ish) sits in the middle. Just though waiting around and letting gravity do its work, they’re able to remove 60% of the total waste.
I laughed when I saw this life preserver. I guess you need to have it around, but man that’s a bad day. This photo is actually from a secondary set of vats where the processed fluid sits for another nine hours before being finally released.
Being in the room was.. definitely smelly. It felt like something that’d get used in a bad action movie/video game.
But it wasn’t as smelly as it could’ve been thanks to what are essentially massive Brita filters (full of activated—what’s that mean?—carbon) that the air gets constantly pumped through.
Here our guides are showing us the post-digestion biosolid that the plant produces. This material gets used as a fertilizer afterwards.
Lastly, I always love the hecka-analog interfaces that industrial machines have; no smartphone button has ever wanted to be pushed as badly as these big start and stop buttons. Why the backwards colors, though?