PIONEERING RESEARCH ON DESALINATION OFFERS REASON FOR HOPE

By Ms. Lauren Nicole Core, Climate and Water Writer and Filmmaker

The world is united by the quest for energy-efficient, affordable, and sustainable supplies of freshwater. From the Middle East and North Africa to Latin America and the Caribbean, water stress, scarcity, and insecurity are significant points of concern. Potential approaches to addressing the large-scale and multilateral challenges facing water security and sustainability are—and must be—varied, ambitious, and innovative.

Desalination is in the limelight, as it holds the potential to meet the freshwater needs of communities, nations, and industries for a water-secure future. The United States Department of Energy's (DOE) National Alliance for Water Innovation (NAWI) is driving the research and development of a new suite of desalination and water treatment technologies. These technologies will enable 90% of our current non-traditional water sources to achieve pipe parity – when the levelized cost for treating and reusing nontraditional water sources, such as wastewater, are equal to the cost of today’s marginal water supplies.

“When most people hear the word desalination, they think of producing fresh water from seawater,” said Peter Fiske, executive director of NAWI. “We think that desalination should be thought of more broadly as a critical tool in a climate resilience toolbox – enabling a wide range of salty and impaired waters to be treated and reused, potentially over and over again.”

Founded in 2019, NAWI is a five-year, 110 million USD program headquartered at Lawrence Berkeley National Laboratory and supported by the DOE in partnership with the California Department of Water Resources, the California State Water Resources Control Board, and numerous industry and academic partners. With over 430 partners, 1400 members, and more than 50 projects, NAWI is on the leading edge of technological developments that are unlocking new capabilities for distributed desalination and localized reuse. will allow desalination and advanced water technology to achieve pipe parity and adoption in the San Joaquin Valley and other important agricultural regions of the United States.

The rest of this article highlights three NAWI-supported projects. These research initiatives are helping to develop a circular water economy by supporting water reuse and valorizing constituents we currently consider to be waste. The first project is about the reuse of agricultural wastewater, the second concerns small-scale and decentralized water treatment, and the third looks into membrane fouling.

Bringing Advanced Desalination To Agriculture Runoff

Managing salinity is a complex undertaking in California’s San Joaquin Valley. Salt management is complicated by the presence of selenium, arsenic, and uranium in drainage water. Water in deep underground aquifers is highly saline, and pesticides and nitrates from livestock farming are major sources of water pollution.

One NAWI-supported project employs a multidisciplinary approach that considers tradeoffs among alternatives and spatial differences in land use across the region. The researchers involved are analyzing irrigation drainage water management strategies, including policy measures and available and emerging desalination technology applications. The researchers are also identifying performance enhancements and policy strategies that

The project is already raising awareness among water managers about the potential for desalination to solve problems related to agricultural runoff management, and could make the San Joaquin Valley the first location in the country where next-generation desalination is applied to agriculture at scale.

SCALING DOWN DESALINATION PRE-TREATMENT

Desalination systems are delicate, and highly vulnerable to fouling and scaling. As such, water must be pretreated before desalination begins. It is filtered to remove particulate matter such as microorganisms and suspended solids, and treated with coagulants, chlorination, antiscalants, oxidant scavengers, and other chemical additives. Current pretreatment equipment typically involves multiple separate processing steps.

One research endeavor is working on downsizing those processes. The proposed solution is an integrated, modular pretreatment system that combines both electrocoagulation and electrooxidation with antifouling membrane separation. The novel element is combining these components into a singular, modular, and electrified unit. If the project is successful, it will reduce capital costs and operation and maintenance costs for desalinating brackish water.