News | June 4, 2021

Water Scarcity Will Require Agriculture To Tap 'Unconventional' Sources Like Seawater, Wastewater

By Anne Manning

Though about 70% of the Earth is covered in oceans, humanity’s water needs are met by less than 1% of the planet’s total water, in the form of aquifers or snowpack-fed rivers. We pump it from the ground, treat it, drink it or spray it on our crops, and dispose of it.

With a population expected to exceed 10 billion by 2050, and water scarcity a critical challenge of our time, it’s time to rethink that model.

Colorado State University is a founding partner in a $110 million U.S. Department of Energy research network, called the National Alliance for Water Innovation, focused on treatment and reuse technologies for nontraditional source waters like municipal wastewater, seawater, brackish (salty) water, water produced as a byproduct of oil and gas drilling, meat and dairy processing wastewater, and agricultural drainage water.

Tapping into such sources could solve many water scarcity challenges for years to come, but there are currently no large-scale, economically viable ways to do so. The alliance leaders’ vision is a “circular water economy” in which recaptured water would be used for everything from farm fields to fracking sites at a cost and energy intensity comparable to – or even better than – current conventional fresh water sources.

CSU focused on agricultural sector
Thomas Borch, professor in the Department of Soil and Crop Sciences and a researcher in environmental and agricultural chemistry, is heading a CSU team providing varied expertise to the alliance, which will complete its work over the next several years. Other CSU contributors: Todd Bandhauer, associate professor in mechanical engineering; Brandi Grauberger, engineering Ph.D. student and InTERFEWS trainee; research scientist Robert Young and Ph.D. student Sean Stokes in Borch’s lab; Tiezheng Tong, assistant professor in civil and environmental engineering, and Daniel Herber, assistant professor in systems engineering.

The CSU team is primarily focused on the agriculture sector, which is one of five broad areas of study for the alliance; the others are power, resource extraction, industry, and municipal water. Borch recently served as a “cartographer,” with Dion Dionysiou at University of Cincinnati, on the creation of an “Agriculture Sector Technology Roadmap” that addresses current status and challenges for treating and reusing water in agricultural applications like irrigation and meat processing. The roadmap lays out the enormity of agriculture’s water needs, and the various areas of opportunity for using “nontraditional” water, such as recycling drainage from crop fields, or treating and reusing wastewater in meat and dairy operations.

Meanwhile, water managers in 40 U.S. states expect water shortages over the next several years. In 2017, more than 900 million acres of farmland in the U.S. used over 27 trillion gallons of water per year, according to the agriculture roadmap. Agriculture accounts for 80% of the nation’s water consumption, varying from state to state.

“Agriculture is the biggest sector with respect to freshwater withdrawals in the world,” Borch said.

Alliance focused on desalination
The National Alliance for Water Innovation is headquartered at Lawrence Berkley National Laboratory, with partners all across the U.S. Its stated focus is scalable technologies for desalination, or the removal of salts and contaminants from nontraditional water sources.

“When we say nontraditional water, we mean everything that is not fresh water,” Borch said. “That includes municipal wastewater, produced water from oil and gas – both conventional and unconventional – brackish groundwater, seawater, agricultural drainage, etc. We have a lot of it, but in order to use it, we need to treat it first.”

While desalination plants exist across the world, including the San Luis Demonstration Plant in California, they are not widespread because desalination is notoriously expensive and energy intensive. The costly process of desalination creates a salty brine byproduct, which is toxic to plants and humans and can include heavy metals that are difficult to dispose of. Brine management is a major area of concern for the research alliance, and there are many researchers working on solutions.

Desalination is typically performed through a process called reverse osmosis, in which contaminated water is forced through a membrane to separate out fresh water. Tong heads a lab in the Department of Civil and Environmental Engineering at CSU focused on developing and improving new membrane materials and processes to improve treatment of industrial wastewater through desalination.

The challenges are technical, legal and economical, Borch said, but beyond that are social considerations. Will there be public trust in irrigation water that had a former life as wastewater? Will people be willing to invest in water sources that didn’t originate from a freshwater resource?

Moving forward, the National Alliance for Water Innovation will fund both internal and external research projects that address varied areas of research with the goal of innovating the next generation of technologies for treating and reusing nontraditional source waters.

Source: Colorado State University