As I look out over the Port of Los Angeles with its shipping cranes and waterways, I think about the 800,000 gallons of water similar in quality to drinking water lying in tanks under my feet. Less than 24 hours earlier, it had been raw sewage entering the plant, where environmental engineer Lance Thibodeaux is showing me around so I can see high-tech filtration in action.
What made the water’s transformation possible? Advanced purification systems, constantly and automatically run by a centralized computer program housed in a small office a few hundred yards away.
Between heat, fluid dynamics, bacteria, and gravity, nature has its own tools for safely reabsorbing human waste back into the environment. But to speed up the process, keep the systems functioning, and even glean health insights from our sewage, humans have created machines capable of automating and intelligently managing this absolutely critical — if sometimes stinky — process.
“What a wastewater treatment plant does is use natural processes, but accelerate it,” Thibodeaux said.
The robots that handle our poop aren’t of The Jetsons variety. They’re devices that sit on top of sewage containers, automatically taking samples at regular intervals. They crawl through pipes to scrub off buildup, ensuring a smooth flow. They’re computer systems that adjust the output of minerals, dim or brighten UV light, and adjust the pressure in a boiler to keep purification systems in balance. They extract DNA from the waste of a college dorm to detect the presence of disease.
And in the realms of both public health and environmental stewardship, they’re absolutely critical. Without computer-powered advanced wastewater treatment, “the alternative is there won’t be enough water when our kids are adults,” Thibodeaux said. “So we need to look at reusing the water as much as possible.”
Where your poop goes, the robot knows.
As with most wastewater plants, egg-shaped containers the size of multi-story buildings, called digesters, dominate the landscape as you approach the Terminal Island Water Reclamation Plant. Digesters are where all the filtered-out human waste goes to get heated up and “digested” by bacteria, which is why they’re such an iconic feature at most sites.
Terminal Island’s digesters sit at the intersection of the appropriately named Primary and BioSolids lanes. But there’s much more to the site, including multiple waterways, tanks, and so many pipes.
The Terminal Island Water Reclamation plant has two main sections. The first is a traditional water treatment plant, where toxic materials and solids are filtered so the water can be released back into the environment. The second is the Los Angeles Department of Sanitation’s technological crown jewel: The Advanced Water Purification Facility.
Completed in 2017, this facility involves an additional three-step process (after traditional cleaning) that makes water so pure minerals have to get added back to restore the pH balance. Currently, the city is using the water to keep ocean water from leaching into groundwater at California’s Dominguez Gap Barrier. It’s also getting sold to Los Angeles harbor area industrial and agricultural customers as a source of energy and for watering non-human crops.
Currently, Los Angeles drinking water comes from natural sources, like the Colorado River. But if Mayor Eric Garcetti gets his way, Angelenos will . As of now, the recycled water isn’t allowed for human consumption because local governments have not established regulations and standards. Thibodeaux said municipal guidance is in the works, but another hurdle is public nose-wrinkling at the thought of drinking previously poopy water.
“The customers aren’t ready,” Thibodeaux said.
City representatives described Terminal Island as Los Angeles’ most high-tech plant, so I half expected the advanced filtration system to have machines on wheels turning knobs, or to showcase pools with robots swimming around and doing the scrubbing themselves. And, in fact, there are some isolated projects that have created robots that physically do sewage cleaning and water purification. Robotics companies have developed machines that to keep them from getting gummed up. A city in Denmark partnered with a robotics company to explore drone surveillance and automated cleaning of plants. In 2012, one city in England joined with Bristol Robotics to create the : a robot that purifies water by, according to ZDNet, “pooing out” the waste.
However, none of these projects have achieved the scale necessary to turn a city’s waste into water. Which is why the technology powering purification plants like Terminal Island’s doesn’t look anything like I’ve imagined. Instead, there are boxes that hold electronic measurement and control equipment at key points along the plant. These points all feed data to a centralized computer system, where engineers constantly monitor and control sensitive moving parts to keep the delicate system in balance.
In traditional waste processing, sewage sits in large waterways where slow-moving filters trawl for the non-water particles that sink to the bottom and float to the top. Advanced purification takes it much further.
Processes called micro-filtration, reverse osmosis, and advanced oxidation — which uses UV-C light, a form of electromagnetic radiation with a particular wavelength that kills pathogens including coronavirus — get the water to a level of purity that customers will hopefully accept in the next decade. Essentially, water passes through filters with openings so small they keep out particles you can’t see with the naked eye. In the final purification step, it gets blasted with UV-C light for a final cleaning.
There’s a separate section for each method at the plant. In the micro-filtration section, thousands of tiny tubes that look sort of like plastic bucatini get gathered together in one long pipe. In reverse osmosis, pipes contain spiraled layers of filters that only allow water particles to pass through. Finally, the double-purified water travels through tanks pierced with UV-C bulbs that shine pathogen-killing radiation through the water.
In all three systems, flow, capacity, and pressure need to be kept at consistent levels. Two engineers monitor it all from a low-ceilinged office building on the plant. They’re able to view a digital representation of every tank and waterway on the plant, keep an eye on capacity, tweak controls, assess when something’s not going right, and analyze key trends and data points.
“You need a computer system in order to operate it and be able to maintain the parameters that have to be met, so that we can produce the quality of water that’s required,” Thibodeaux said. “There’s a lot that a computer system can do — like repeatability, being able to make adjustments instantaneously based on the data that goes in — that a person can’t.”
As cities like Los Angeles advance green initiatives in an effort to combat climate change, the need for recycled water will continue to increase. Thibodeaux sees the level of automation at Terminal Island, and other plants, only proliferating. Some plant workers hope robotics will become an even bigger part of sanitation plants: Colleagues have expressed to Thibodeaux that they would very much like sample-collecting robots to take over that time-intensive task. But automating a city plant is its own can of worms.
“You’re going to have a lot of people who will have to get another job,” Thibodeaux said. “Those are some other obstacles, especially in a municipality, that have to be addressed. I think it will be addressed. It just takes time.”
Just over 100 miles south of Terminal Island, there are different poop-sampling robots hard at work at the UC San Diego Campus. That’s where researchers including microbial and environmental engineering expert Smruthi Karthikeyan have pioneered an automated method to predict COVID-19 outbreaks and pinpoint where rapid COVID tests need to be deployed — all by monitoring the sewage.
Yes, there is just as much to be gained from extracting sewage for scientific study as there is for filtering it out to purify water.
Karthikeyan wanted to find a faster (and less icky) way to detect the presence of COVID in sewage than taking samples, purifying them, and testing them by hand. Sewage monitoring is a precise method for anticipating outbreaks, since viruses show up in a person’s waste at the same viral load levels as in their bodies. Sewage, then, can reveal the presence of virus even before symptoms start appearing.
In partnership with the San Diego government, Karthikeyan and her team placed automatic samplers on manholes around the city. These couple-foot-high domes sit on top of manholes, dropping a sampling container into the sewers at regular intervals and keeping it inside its dome for researchers to come collect. The machines record the time and location digitally, creating an automated record of when samples were taken and from where — a key datapoint for the ultimate goal of COVID testing.
The automation allowed researchers to quickly and accurately take samples they could test for COVID. If the sampling indicated a spike in COVID cases, city officials would be able to increase calls for testing and community surveillance. This enabled them to stop outbreaks before they got worse.
“We used wastewater as a surrogate to track the county’s cases,” Karthikeyan said. “We could actually forecast how county cases would look in the next week. That would give the county a good 1-week head start on focusing on testing or preventative measures.”
The success of the forecasting program in helping public health officials get a jump on outbreaks made Karthikeyan want to dive even deeper. She turned to UCSD’s sewer system, which is set up so that dorms have their own lines coming from individual buildings. Placing the manhole sampler robots by individual dorms, Karthikeyan’s team could actually monitor for COVID on a building-by-building basis.
However, the goal of the campus monitoring was not to simply forecast breakouts. It was to prevent them. The idea was to identify if even one person was COVID-positive in a 500-person dorm, so that the whole dorm could immediately get tested and isolation could begin before a person might have even known they were sick.
To detect such low levels of COVID before the virus had a chance to spread, sampling and testing had to be extremely precise, and incredibly fast. Especially when handling poop, those are two requirements humans can’t always achieve. So Karthikeyan turned to a different kind of robot.
Scientific labs use robots called “liquid samplers” to do DNA or other high-tech testing. They can automatically extract from liquid samples whatever they need — DNA, RNA, or other particles — that it would be very time intensive to do by hand.
Although intended for more pristine purposes, Karthikeyan thought, why not use them for sewage?
“Initially it was like blasphemy,” Karthikeyan said. But the method paid off. “When I was processing samples I could not do more than six or seven samples a day. And that was a very long day. Now we’re doing upwards of 120 samples.”
Karthikeyan had to modify the machines to work with sewage. The machines would inject small magnetic particles into the liquid. Those magnets would attract the DNA particles that would eventually reveal the presence of COVID or not. Then the liquid sampler was able to extract the magnets with the useful DNA material from the sewage. Et voila, the robot had a sample ready for COVID testing.
After the liquid sampling robot did its work, Karthikeyan was able to transfer those samples to a machine that conducted “PCR testing.” A PCR test is the laboratory process that identifies diseases, including COVID, by detecting and magnifying the slightest sign of a disease’s DNA. The multitude of highly concentrated samples allowed for the precision to detect even the smallest hint of COVID — one infected person in a building of 500.
Because of the initial automation and tracking of sample collection at the sewer level, the lab could tell which building housed someone who was COVID-positive. While it couldn’t tell who that person was, residents in a building where someone was infected were prompted to take a COVID test through UCSD’s contact tracing app. Residents could take these tests by going to a vending machine in the lobby that distributed DIY COVID tests, with a handy drop box for submitting samples. COVID-positive residents could be identified and isolated within a matter of hours.
Next up for the program? Sequencing the DNA in the samples to identify strains of COVID.
When Karthikeyan explained her sewage surveillance program to me, I thought back to the beginning of the pandemic, when contact tracing and fact-acting isolation still seemed like a possibility. Of course, then the pandemic exposed how under-staffed and under-prepared the American government was for a mass epidemic, and the idea of catching an outbreak before it started seemed laughable.
“Wastewater is a super-involved manual process,” Karthikeyan said. “You’re going to have to dig through piles of crap. Literally.”
Still, Karthikeyan showed that it’s possible. And with robots working both to purify water for the sake of our planet and mining our sewage in the name of public health, our future isn’t looking so crappy at all.