July 12, 2015

Photo Essay: Wastewater in the Time of Drought

I'd like to refute the adage, "Seen one, seen 'em all." Sometimes, when I think I've been there and done that, I realize I haven't really been anywhere at all, and I haven't done nearly as much as I could.

So although I'm always looking to experience something new, sometimes it's in a familiar setting – like a wastewater treatment plant.

I know it's weird, but after exploring the municipal facilities of Los Angles County, I couldn't resist venturing down to Orange County to see what they do with their poop. It's an underbelly of public works that the public doesn't often get to see.

The OC Sewers systems, dating back to 1912, have actually been designated a historic civil engineering landmark. This includes the Joint Outfall sewer system, created in 1923.

And it's not just about where the poop goes when you flush the toilet, but what happens to it after that. It must not only be collected, but also treated, and disposed of – or recycled.

Two hundred million gallons of wastewater comes into Orange County's Sanitation District daily, and are treated and disinfected within 10-12 hours.

After the wastewater goes through the traditional preliminary treatment (removal of trash, large objects, big pieces of food which can't be recycled and are sent to the landfill), it goes into the Grit Chamber to remove sand, gravel, eggshells, coffee grounds, and other small matter.

It then receives primary treatment, where chemicals help separate sludge (poop, which sinks to the bottom) and scum (which rises to the top) from the water.

One thing I hadn't seen before was the types of filter media they use, including this plastic ball, and another 3D honeycomb-shaped piece of plastic.

It's still a stinky process...

...whether it's the fumes from the trash or the poop...

...or the hydrogen sulfide (the rotten egg / sulfur smell) given off in the process.

Other areas smell like bleach, from the chlorine used to disinfect water that gets pumped out into the Pacific Ocean (being dechlorinated first, of course). They've even got to filter the air at the plant in order to not create an odor nuisance to neighboring communities.

For some reason, the secondary treatment tanks and settling areas seemed to attract more birds than any other I'd seen. Previously, I'd spotted a duck or two, but these tanks were full of flocks of birds.

Meanwhile, the sludge and scum separated out from the water in the primary treatment process are sent into digester tanks, where they decompose in 98 degree heat over the course of 20 days, and are reused later as nutrient-rich biosolids (compost, fertilizer, etc.). Some of those biosolids are even turned into dried pellets that are used as an energy source at a cement factory in Rialto, CA.

Perhaps the most fascinating aspect of Orange County's wastewater treatment... how some of the fully treated water is recycled.

Once it's as clean as they can possibly get it, they pump it over to their Groundwater Replenishment System, where the water replenishes the aquifer deep underground, and acts as a barrier to prevent salty seawater from contaminating the groundwater.

But that also means that once it's back in the ground, eventually it's going to become drinking water again – though most are reticent to use the phrase "Toilet to Tap" to describe the process. Fortunately, the cleaned, disinfected, and recycled water goes through another, natural filtration process in the ground, making it safe to drink. We think.

OC Sewers tries to recycle as much as possible, even using byproducts like digester gas (methane) as an energy source for their own facility. Methane provides about two-thirds the electricity needed to power the wastewater treatment plant.

By now, you'd think I'd be pooped out after taking so many tours like this. But long gone are the days of drawing water from your own well. Water is such a rare commodity these days, it's important to know where it's coming from, and where it goes, after it swirls down the drain.

It takes a lot of work, money, and energy to make that water – some of it wasted – usable again. So maybe we shouldn't use more than we actually need.

That would be a start.

Related Posts:
Photo Essay: The Final Frontier for LA's Wastewater
Photo Essay: Hyperion Wastewater Treatment Plant
Photo Essay: West Basin Water Recycling Facility

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