Down by the bay

Today I took the very wonderful tour that San José offers of the San Jose / Santa Clara Water Pollution Control Plant. Now, it’s true that you need to be interested in water and water treatment to enjoy it; I didn’t take my kids. But about 30 people were interested enough to join in the second tour of the day, and it really was a great tour. We got a bit of a talk at first, with lots of time to ask questions, and then hopped aboard minibuses to see what there was to see.

First stop was the outflow.

It’s really obvious how much water is flowing into the slough; it’s a very strong-looking current.

Then we went back into the plant and saw where the raw sewage comes in:

Only about 3% of the raw sewage is solids.

The bar screens are huge devices that take out big stuff, like sticks and rocks and what is euphemistically referred to as “rags:”

After the water dawdles through the grit chambers, and settling tanks to let heavy solids settle, it goes into the digesters, where bacteria break down organics into methane:

The plant uses the methane to produce more than 2/3 of its own power. A huge use of power are these mammoth motors, that drive the compressors that aerate the water for the biological treatment:

The water is clarified is large pools:

After further filtration and disinfection, it flows into San Francisco Bay. Some 10 million gallons a day (out of 110 million gallons a day treated) is further treated to become the recycled water that is sold by South Bay Water Recycling, which is the reason I went on the tour.

The tour used to end with a walk in Don Edwards San Francisco Bay Wildlife Refuge but today we just took a look at it from the minibus:

I really do recommend the tour.