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Remaking America’s Urban Water Systems
In the dry heat of August 2011, postdoctoral researcher Justin Lawrence, Ph.D. ’11, hiked into the woods above campus with a group of Cal students to set up experimental structures in Strawberry Creek, which had become water-stressed from a half-dozen rainless months. The group hammered plywood and rebar into funnel-shaped contraptions to test the hypothesis that augmenting the flow of stream water can provide ecosystem benefits in urban streams — a first step in a larger plan to eventually use recycled water for urban creek restoration projects.
Lawrence, who works for a new engineering research center (ERC) on urban water systems that was funded by the National Science Foundation (NSF) last July, measured the amount of water flowing through the experimental apparatus, and also measured the quantities of aquatic insects, which are widely used as indicators of both water quality and biodiversity.
The humble tools and narrowly focused goals belie a purpose on a much larger scale. Lawrence’s project is just one line of inquiry connected with the new ERC, which is called Re-inventing the Nation’s Urban Water Infrastructure (ReNUWIt). Budgeted at $18.5 million over the next five years, plus the same amount on renewal, ReNUWIt is the largest project on urban water ever funded by the NSF. The NSF’s goals for the ERC are as ambitious as its nearly $40 million budget: fundamental, systemic, and far-reaching changes in the United States’ aging urban water infrastructure.
“The NSF is expecting more from the ERC than just academic papers,” says David Sunding, an agricultural and resource economics professor involved in the project, and the Thomas J. Graff Professor in the College of Natural Resources. “They want transformational research. They want to look back in five or ten years and see actual things that changed in the U.S. water sector because of our project. So our work is absolutely about delivering relevant technologies and having them adopted.”
The ERC is a four-university partnership that is based at Stanford and includes UC Berkeley, Colorado School of Mines, and New Mexico State University. The project has three key focuses, called “thrust areas” in NSF parlance: natural systems, engineered systems, and resource management. It’s fully collaborative and interdisciplinary — the four universities are working hand in hand on every project, and the thrust areas overlap as seamlessly as issues like technology, the environment, and delivery schemes commingle in real-world urban water systems.
New Era, New Challenges
Most experts agree that our current urban water system is inadequate to meet society’s changing needs. It is only going to get worse.
“The NSF... wants transformational research. They want to look back in five or ten years and see actual things that changed in the U.S. water sector because of our project.”
David Sunding, Thomas J. Graff Professor in the College of Natural Resources
Sunding, who heads the project’s resource management component, ticks off a litany of challenges currently facing the United States’ urban water systems: Population growth will increase water demand, further taxing supplies and infrastructure. Climate change is likely to increase the incidence and severity of drought. Environmental problems, such as the ecological collapse of California’s Sacramento-San Joaquin River Delta and habitat loss for endangered species, will continue to escalate. Rising energy costs will demand new energy efficiencies within the system.
There’s consensus that the current system fails to harness the enormous potential for innovations in recycling, technology, and policy to create efficiencies.
“In California, we send most treated wastewater right into the ocean,” Sunding says, instead of capturing it for recycling. And for the most part we don’t differentiate between various water needs. “In most cities in the state, we are providing high-quality drinking water for use in air conditioners and landscaping.”
David Sedlak, professor of civil and environmental engineering and ReNUWIt’s deputy director, says that the infrastructure cannot be fixed simply by replacing rusty pipes.
“We have a 19th-century technology that was designed to address a 20th-century problem, and now we’re facing a series of 21st-century challenges,” he says. “Urban water systems were designed at a time of low population, unlimited energy, and a lack of complete understanding of the public health and environmental consequences.”
While the current system represents tremendous accomplishments in engineering and public health that were appropriate for their times, Sedlak says, scientists’ understanding of waterborne pollution has increased, technologies have advanced, and societal challenges have shifted.
“We have a 19th-century technology that was designed to address a 20th-century problem, and now we're facing a series of 21st-century challenges.”
David Sedlak, professor of civil and environmental engineering
“We are now facing the start of a new era, where the drivers of the system are changing,” Sedlak says.
A Renewable Resource
The Strawberry Creek project, for example, seeks to move beyond a past where wastewater releases into urban creeks caused pollution, to develop the scientific evidence for a potentially valuable recycling use.
“Because wastewater discharges to streams were of considerably lower quality than they are today, there’s almost no information on how to use recycling constructively, for ecosystem renewal,” Lawrence says. “This knowledge gap has been a huge barrier to progress.”
Using high-quality, low-cost recycled water to rejuvenate ecosystems could be a valuable management approach, Lawrence says, with widespread applications for restoring depleted wetlands and creating new habitat for endangered species.
And while the water treatment and delivery infrastructure uses a lot of electricity, scientists think that balance sheet can change. The ERC’s engineering facet will study ways to improve the system’s energy efficiency and generate new energy from renewable sources — everything from harvesting energy from the process to developing smart grid–type technologies that differentiate water use based on seasonal or even building-specific demands.
For example, waste itself is full of energy, Sedlak says.
“There’s a tremendous potential to turn sewage treatment plants from energy consumers to net energy producers,” he says. Biogas, which results from microbes converting the organic materials in waste into natural gas — methane — is reasonably well established, but ERC researchers are trying to improve it. One new method has the added benefit of producing both biogas and nitrous oxide. It involves converting the ammonia present in wastewater into nitrous oxide, which can be used in a combustion process, instead of oxygen. Sedlak also cites a developing technology that generates electricity from mixing freshwater and seawater.
A long-term objective, Sedlak says, is to go beyond “net zero” water and wastewater systems that generate enough renewable energy to meet their own needs, and make energy-positive systems that produce surplus power that can be fed back into the grid.
Decentralizing Treatment Plants
There are even more seemingly obvious possibilities for recycling: for example, why doesn’t everyone water lawns and flush toilets with reclaimed water?
Highly treated wastewater, or sewage effluent, is already broadly used for irrigation, pumped from central treatment plants to nearby athletic fields and farms. But when pipe networks stray too far from sewage treatment plants, infrastructure costs spiral upward. One of the approaches the center is studying is to decentralize treatment plants so cities can reuse water close to where it was first used.
For example, Berkeley’s sewage goes to the East Bay Municipal Utility District treatment plant near the Bay Bridge. Piping the treated effluent back up to Berkeley would be prohibitively expensive, Sedlak says.
“But what if we built a small treatment plant that intercepted the sewage from the Berkeley area and used the treated wastewater to do the landscaping on the Cal campus, or for one of our local industries that needs water for boilers?” The center is working on technologies that would allow small-scale satellite plants to be built as highly automated, low-maintenance substations.
Natural Systems and the Yuck Factor
Drinking water is another huge opportunity for recycling water: sewage effluent has been treated to potable quality for more than 35 years, especially in parts of Southern California. The ERC scientists say there’s tremendous potential for expansion, but first some issues have to be resolved.
On the engineering side, it’s important to make sure that recycled water entering the drinking water supply is free from the chemicals and waterborne pathogens that are in sewage. ERC projects are testing multiple treatment steps and developing high-tech facilities to ensure that high quality.
But there’s a psychological issue as well.
“Recycled water has not been readily accepted by consumers because they perceive it to be ‘kind of yucky,’” says Sunding.
Research has shown that passing water through natural systems decreases the “toilet-to-tap” aversion and can remove contaminants that engineered treatment systems have a tough time removing, so ReNUWIt has several projects in this area. One, in the Delta town of Discovery Bay, is studying the impact of creating a wetland habitat to remove additional contaminants from wastewater that has been treated conventionally. Another is studying the use of soil and groundwater as part of the treatment process.
Tackling Social Issues
The psychology of the “yuck factor” is strong, Sedlak says, and has been the basis for discontinuing projects that made sense from a financial, economic, and public health standpoint. But that’s on the center’s agenda as well: ReNUWIt has an educational component that includes public outreach through high schools, colleges, and local science museums.
“I think one of the strengths of the center is to really start engaging the public in a dialogue about water,” Sedlak says.
It’s all part of the ERC’s mission, says Sunding.
“Reinventing urban water is about more than science and engineering; there’s an important social science and finance component as well. It’s often fruitless to ask a utility to adopt a new technology to deal with water treatment or recycling, absent some kind of pricing, financing, and allocation reforms.”
For example, water from traditional sources is often highly subsidized, resulting in artificially low prices. If customers understood how expensive it is to provide their water, Sunding says, they might make better decisions about how they use it. “Subsidies distort behavior and they make it very hard for people to make informed decisions.”
The project’s resource management component also includes a complex cost-benefit analysis that calculates which new technologies bring the most to the table, in terms of both economics and sustainability. It will also address the extreme fragmentation in the water industry — there are more than 180 retail-level water utilities water providers in Southern California alone, according to a recent study.
Sunding expects his resource management group will make recommendations on pricing structures and financing schemes, on consumer incentives, and on coordination within geographic regions — perhaps something similar to a cap-and-trade system, which would allow agencies to sell water to each other, effectively integrating separate entities without disrupting the current water rights systems.
From Research to Implementation
Water agencies are among ReNUWIt’s many institutional partners; those relationships will be key in moving from research to implementation. From water districts in Orange County, Calif., and Tampa Bay, Fla., to private companies like Bechtel Corporation, partners serve as advisers, test beds, and financial contributors.
“They are completely invested alongside the NSF, and they’re getting more bang for their buck than trying to do it on their own,” Sunding says, referring back to the center’s goal of transformational research.
To meet that goal, the urban water ERC must not only develop new technologies and economic structures, it must slowly remake public perception — creating a shift to the view that wastewater isn’t waste, but rather something infinitely useful.
“As a society we need to start looking at wastewater treatment plants as resource recovery centers,” said Sunding. “Urban wastewater systems can be about turning waste into economically, environmentally, and socially useful products.”