A Circular Economy to Mitigate Long-Standing Drought

Circular thinking in a public sector water agency may hold the key to addressing California’s 1,000-year drought.

By Marc Lefkowitz, SWE Contributor

For California, the world’s fifth-largest economy, no more precious resource exists today than water. Since 2006, the state has experienced three, multiyear stretches of life-altering drought, leading some experts to call it “the worst drought in 1,200 years.”

This past winter brought on several feet of precipitation that produced snowpack that slowly melted its way to population centers. Despite this relief, the drought has forced farms in the Imperial Valley, where much of the country’s broccoli, carrots, spinach, wheat, grapefruit, onion, potatoes, and honeydew, among other food, is grown, to become fallow.

California has experienced cycles of drought since 1841, but the recent shortage of clean, potable water has raised the prospects — like the gold and oil rushes before — for California and its Western neighbor states to pursue unconventional methods to manufacture their own supplies of water. In the process, California is investing billions, including large-scale pilots.

Los Angeles is moving with purpose to address its critical water shortage by embracing circular economy principles of reuse and “upcycling.” It is right in line with what economists think should be done about the crisis. In fact, the World Bank, in a 2021 report titled “Water in Circular Economy and Resilience,” warned that “urban water supply and sanitation services, which are often provided by public entities, will bear the brunt of these challenges, on top of the performance issues observed in many public sector entities.” They emphasized the need for scaling up water reuse in cities, with economic and energy upsides, concluding, “when it comes to building water-secure cities, we need to focus on innovative solutions and diversify the portfolio of water resources available in a creative, cooperative, and collaborative way.”

Within the population centers of Southern California, two emerging paths for water prospecting have emerged. One is desalination, or removing salt from seawater through a process of reverse osmosis. The other is recycling wastewater to a condition as clean as water that comes from a tap. Both are moving Southern California to the forefront of unconventional water conveyance, in contrast to Arizona and Northern California, which are considering pipelines to move water long distances.

Traci Minamide, COO, L.A. Sanitation, center, is building on a recent direction change and breakthrough innovation in water recycling that was driven by circular economy principles, including community engagement, as shown in this recent activity. CREDIT: L.A. Sanitation

Cities take lead in water innovation

San Diego has its Carlsbad Desalination Plant. Built in 2015 at a cost of $1 billion, it is an energy-intensive operation requiring 40 megawatts of power with an associated cost of $50 million annually. Carlsbad manufactures a supply of 50 million gallons of drinking water through a desalination process from seawater, representing one-third of the consumption needed in San Diego County.

Meanwhile, Los Angeles and agriculture-heavy Orange counties, which form the second most populous region in the United States, are pursuing their own novel path to manufacture drinking water. With the sheer volume of the region’s water use — Los Angeles County consumed 495 million gallons per day and Orange County consumed 281 Mgal per day — California’s southern tier is betting its investment in recycling wastewater-to-drinking water in an age of uncertainty brought on by climate change pays off. (For perspective, 1 Mgal/d equals one million gallons of water per day.)

Los Angeles completed its first water reclamation project in 2006, bringing its Harbor Water Recycling Project at Terminal Island from an old plant dating to the 1930s up to modern standards. The civil engineering and emerging tech imported from places such as Israel and the Netherlands made it possible to bring a small-scale, 5 million gallons per day of recycled water operation online.

The water is sold as a potable water replacement in industrial and environmental applications. It represented the city’s embarking on a new course, one steeped in circular economy principles. And it has led to novel methods of water treatment that today other municipalities have adopted from LA’s research and development. The next step is a big one: The city plans to update its oldest and largest wastewater treatment plant, Hyperion, to produce 240 million gallons of potable water per day.

“We used to call our plants ‘wastewater treatment plants,’” said Traci Minamide, chief operating officer of LA Sanitation & Environment. “Now they’re water reclamation facilities. It’s no longer a linear treatment of a waste to be discarded, that nobody wants, that we have to clean up to be good enough so we can then throw it out into the ocean. It’s changed,” she said. “It’s now more of a circular concept of how do we take a waste and turn it into a resource?”

California’s circular water economy story includes another important chapter. In 2008, Orange County received regulatory approval for its advanced treatment technology and launched a Groundwater Replenishment System. The system places highly treated water back into groundwater supplies. Going directly from wastewater treatment plant to aquifer, rather than placing it into a large body of water such as the Pacific Ocean, represented a major shift in operation.

The City of Los Angeles managed the process that led to an early breakthrough on wastewater recycling on a municipal scale at its Terminal Island facility. The technology is now standard practice in the industry, as shown in the above illustration. CREDIT: Franco Illustration

Origins of wastewater recycling

Roshanak Aflaki, Ph.D., P.E., helped direct the shift to water recycling in the Los Angeles region. Minamide credits Dr. Aflaki, her predecessor, with bringing an innovation mindset to LA Sanitation’s first water recycling plant at Terminal Island and in the followup in Los Angeles County, the Donald C. Tillman Water Reclamation Plant.

Reflecting on the origin of water reclamation, Dr. Aflaki, who has since retired to take a position with the engineering firm CDM Smith, said the climate crisis changed the calculus on what Los Angeles was willing to do in pursuit of potable water.

“It was innovative,” she said. “At the time, we were the first municipality designing at full scale for UV chlorine oxidation in the U.S. It was, you would say, a risk.”

Minamide added that the problem they were seeking to solve was how to reach the state and municipal goals of 100% recycled water and the state’s stringent wastewater regulations.

When LA Sanitation ran a cost-benefit analysis, introducing advanced wastewater treatment at Terminal Island penciled out because the alternative — to extend the effluent pipe from Terminal Island — would not have solved lowering total maximum daily loads of pollution into the Santa Monica Bay.

“What we decided to do in terms of the pilot was a calculated investment,” Dr. Aflaki said, adding that Terminal Island incorporated a modification of an existing UV technology. “We had to do a demonstration, at full scale, and we didn’t want to take the risk of not designing the facility adequately.

“When you go to an innovative technology, if you go down that path, you have to bring regulators in from the very beginning and get their input,” Dr. Aflaki said. “You have to have an advisory committee to guide the process. At the end [of the] day, it takes time and money.”

Amy Childress, Ph.D., is professor and director of the environmental engineering program at the University of Southern California (USC) Viterbi School of Engineering. She chairs one of LA Sanitation’s advisory committees, providing technical guidance on the latest water reclamation project — a $20 million pilot project to bench test an advanced bioreactor membrane. The pilot will test whether the tech reduces overall square footage and improves the quality of water treatment.

The question with the proposed upgrade of the city’s oldest wastewater treatment plant, Hyperion, is “how can we upgrade the effluent?” Dr. Childress said of the outflow of treated wastewater. “One way that is being looked at are what’s called membrane bioreactors. These combine two steps, which is a biological reactor that can degrade organic matter and reduce nutrient concentrations, with a filtration step. In this case it’s either microfiltration or ultrafiltration membrane, and that’s in place of a sedimentation process. In combining those two you save a lot on [square footage].”

However, one concern with advanced water treatment, including how water is tested at Hyperion, is whether it will lead to more concentrated “brine” or the waste product that must be disposed of.


Protecting the environmental landscape

Heal the Bay, a Los Angeles environmental nonprofit group that advocates better land-use practices to reduce polluted runoff into sewer systems, tests water samples in the Santa Monica Bay for bacteria and produces swimming beach report cards. Chief Executive Officer Tracy Quinn said the organization is keeping an eye on how the processed brine is handled.

“As we look toward recycling more water from wastewater treatment plants, those of us focused on the marine environment are deeply concerned about what that brine is going to look like,” said Quinn, a licensed civil engineer with more than a decade of private sector experience.

“They now have the benefit of [the old adage] ‘the solution to pollution is dilution.’ They will no longer try to be able to do that as they put water back into the system,” she said.

Brine disposition is in the scope of LA Sanitation, from Terminal Island to Hyperion, Minamide said, driven by California’s stringent state environmental regulations for wastewater.

“With a pressure system, the water comes through the membrane and all the particulates and any kind of other pollutants you’re trying to remove stay on the other side,” Minamide said. “That’s what we call the brine.

“We have to discharge that and that goes to the ocean. We need to make sure we meet standards. There are permit limits, so the fact that [Hyperion is located] at the ocean makes it a lot easier to deal with it.”

A sewage spill in July 2021 from the existing Hyperion Water Reclamation Plant into the Santa Monica Bay resulted in the city facing the largest fine in California’s history, with the Los Angeles Water Board proposing a figure of $21.7 million. It is evidence, Quinn said, that LA Sanitation needs greater support for maintaining the current system.

“The money being allocated now is good, but compared to needs over the next 20 years, honestly, at this point, a lot of munis are doing this on their own dime and maintenance and operating takes money,” Dr. Aflaki said. “Eventually, they have to increase rates and usually those rate changes only pay to keep infrastructure running. A lot of times with these mega projects, at the end of the day, they have to look at the rate change implications.”

Both Dr. Aflaki and Quinn said that water conservation measures could help in lowering the capital cost and operations and maintenance at Hyperion. Quinn insisted that Los Angeles can do more around water conservation to address water affordability concerns, such as discouraging the use of ornamental turf grass.

“Many Californians had their water shut off because they can’t afford it, and that’s why we advocate for efficiency,” Quinn said. “When you build, you can rightsize that facility, but if you overbuild it first, it’s a disincentive [for water conservation] because you have to sell a certain amount of water.

“It is essential for us to meet all Californians’ and Angelinos’ water needs as we try to maintain reliability,” Quinn said, adding that California does not offer a low-income rate assistance program for water. “We probably are not going to run out of water, but we may run out of affordable water.”

Dr. Childress, whose research at USC focuses on stretching what is possible with seawater in meeting efficiency goals, added that she is interested in combining desalination and wastewater treatment.

“Closing the loop on the water cycle is a good thing,” she said, though added that she does not necessarily advocate this for Hyperion. “In order to close that loop, if we need extra water, we can bring seawater into that facility.”

Conservation spurs ripple effect

Dr. Childress, Dr. Aflaki, and Quinn note that conservation has at times produced much less wastewater, which leads to dry weather concerns, such as how to handle excess bromide and issues with seawater infiltration in wastewater facilities located on the coast.

“[We’re] still trying to understand the impact of conservation,” Dr. Aflaki said. “Water conservation was necessary but brought with it certain changes like lower volume of wastewater available and changes in the concentration of water. Many plants responded to that by changing processes.”

Quinn adds that public works, water, sewer, and flood control departments operate in silos. Integrating them will be key to solving Los Angeles’ (and other cities’) water, sewer, and flooding issues.

“The solution is really this concept of One Water LA,” Quinn said, referring to LA Mayor Eric Garcetti’s program name. “We have siloed and disaggregated all the parts of this system. In order for us to meet the challenge of climate change, we have to bring them together.

“Also, as engineers sometimes we think we have all the answers. We took our P.E. exam. We have an idea of what the answer is, but we might not live here and know that this intersection regularly floods.

“Don’t do community engagement in a checkbox. Do it way at the beginning,” she said, adding that engineers and others need to engage community members at the onset to help solve problems and to ensure dollars are supported by other departments and used as intended.