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Disneyland of Poop: Tour of the Los Angeles Water Treatment Plant

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The Hyperion Water Treatment Plant (all photographs by the author)

What happens when you flush the toilet or use the the bathroom sink? I arranged for the Los Angeles Obscura Society to have a docent-led tour of the Hyperion Water Treatment Plant in El Segundo, California, to answer that question.

Our docent and LA Department of Sanitation representative Nancy Carr shared a common phrase to describe what happens after the toilet is flushed: “Zero to 48 hours.” Meaning it takes about that long for the water and solids, both contained in raw sewage, to travel from your home’s sewer pipes all the way to Hyperion to be processed. The goal and function of Hyperion is to treat the raw sewage and separate solids from water. This must take place so that when the wastewater is treated it is clean enough to be pumped into Santa Monica Bay. The solids are reused as an energy resource for methane gas and fertilizer for crops.

article-imageThe museum had some displays made from recycled trash. Some were cute and some were creepy.

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The museum inside the Hyperion plant focuses on water conservation and recycling of waste.

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A map in the museum

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LA Obscura Society participants playing a digital simulation recycling game.

Four major sewer lines carry sewage to Hyperion for treatment from homes and businesses of about 2/3 the total population of Los Angeles County. On an average day without rain, about 350 million gallons flow into the plant. The plant can treat up to 1,000 million gallons per day. These sewers are some of the largest in the wastewater system world. Over the past 15 years, Los Angeles has invested $1.6 billion for improvements to this system in order to make the final effluent pass environmental regulations. 

Anything can be found in raw sewage. At the headworks, bars and screens remove the largest solids — things as big as branches, plastics, and rags — and as small as sand and other gritty solids. Some of the stranger things that have been filtered out include telephone poles, a motorcycle, human body parts, and money. This is called preliminary treatment. After leaving the headworks, the wastewater continues to move by gravity to primary treatment.

Most of the solids are removed at primary treatment. After the sludge sinks to the bottom of covered, underground tanks, it is then pumped to the digesters. The tanks are covered to reduce odors. Other wastes are skimmed from the surface. The liquid is then pumped to the secondary system for further treatment.

article-imageThe control room where we could watch the trucks pick up newly minted fertilizer.

Secondary treatment is a two stage process.  First, it occurs in covered, oxygen rich reactor tanks, where bacteria living in the wastewater consume most of the remaining organic particles (solids). These bacteria settle to the bottom of the tanks where they are sent to the clarifiers for final settling and collection.  

At almost 200 degrees below zero, oxygen liquefies and is separated from the air. Liquid oxygen is pumped into the reactor tanks in the secondary treatment process to help the bacteria grow.

In the second stage of biological treatment, the bacteria are separated from the wastewater during a settling process in clarifiers.  Some of the biomass (for example, processed sludge) is sent back to the reactor tanks to perform additional secondary treatment, and some is thickened and then sent to the anaerobic digesters. The biosolids are placed in storage tanks and heated to sterilize them. A few weeks later, the processed solids are picked up by trailers and shipped north to Bakersfield, where they are used as manure to fertilize crops that are then fed to farm animals. We humans eat those animals, thereby completing the circle of life, food, and sewage. There is some controversy in that many neighbors in Bakersfield don’t like the manure being dumped in some of their farm fields.

article-imageMost of the animals collected for tests are preserved for identification and future reference.

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It looks like a mutant creature but its a crustacean collected from the bay where the wastewater is piped into the ocean.

 Most of the wastewater that leaves secondary treatment is pumped from the plant into Santa Monica Bay through two five-mile long pipes at a depth of 190 feet. The effluent more than meets all federal and state clean water standards, and is compatible with Bay waters and the creatures that live there.

Here are more photographs from our visit to the treatment plant:

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article-imageIt almost felt like a theme park ride, getting to ride a tram while touring the HUGE Hyperion plant.

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The tour required the use of safety helmets in case of falling objects.

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The pipes served as ‘odor scrubbers’, and were very effective at keeping the raw sewage smell to a minimum.

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Some of the buildings looked like they were assembled from giant LEGO blocks.

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The LA Obscura Society got to enter several buildings — each one was a step in the raw sewage treatment process.

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We watched as one of the final byproducts of raw sewage was transformed into manure and being dumped into trailer trucks to be shipped straight to Bakersfield.

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Water samples of raw sewage are regularly taken to monitor what’s being piped in from the sewers.

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Nothing can be so captivating as watching raw sewage being processed

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Many of the buildings that we visited were large and almost cavernous to handle the billions of gallons of raw sewage piped.

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An Obscura Society member does her best impression of Vanna White while she showcases effluent. If the docent didn’t lead her away from that spot, she would have been splattered with sewage.

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No smoking or fires allowed on the campus because of the methane gas and other combustibles that are byproducts of sewage treatment.

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The odor scrubbing pipes and lights made for beautiful industrial symmetry.

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They looked like giant cigarettes, but this section was near where they injected liquid oxygen to feed the bacteria that broke down and digested the biosolids.

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This is one catwalk you do not want to fall from because you will end up in treated sewer water. The docent said in the event of falling inside the tanks, do not swallow the water.

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For whatever reason, the seagulls like to swim and feed on the treated wastewater right before they were pumped into the Pacific Ocean.

article-imageLA Obscura Society at the treatment plant


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The Obscura Society is the real-world exploration arm of Atlas Obscura We seek out secret histories, unusual access, and opportunities for our community to explore strange and overlooked places hidden all around us. Join us on our next adventure!

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