ASU report contributes to water reuse policy dialogue

In an attempt to inform policy conversations around wastewater use in Arizona, Arizona State University’s Decision Center for a Desert City (DCDC) released a new technical report this week. The report, "Water Reuse in Central Arizona," authored by Ariane Middel, Ray Quay and Dave White, explores issues critical to water reuse, along with challenges and opportunities for the future.

Covering topics such as existing and projected wastewater supply and demand, potential for increased competition and costs, the role of public perceptions and industrial perspectives, the report highlights issues vital to the water sustainability of Arizona and presents a framework to address public policy issues.

“Several recent reports and commissions have pointed to increased water reuse as an important strategy to address projected water supply deficits resulting from droughts and anticipated climate change impacts,” said White, co-director of the Decision Center. “While we share this common goal, this report demonstrates, however, that effluent reuse is certainly not a silver bullet to water sustainability. Many issues remain that must be addressed as we move forward. There are technical, economic, environmental, cultural, legal and political dimensions.”

The publication is the result of a collaboration between ASU, Intel Corporation, and CH2M Hill’s WaterMatch.

“Sustainable water management is a key focus at Intel,” said Gary Niekerk, director of Corporate Citizenship at Intel. “We created the collaboration with CH2M HILL‘s WaterMatch, ASU’s Global Institute of Sustainability and ASU’s Decision Center for a Desert City to increase awareness of water sustainability issues in our local community.”

Once thought of as just a waste product, communities across the United States are increasingly considering wastewater as a valuable resource. In these communities, the effluent from wastewater treatment plants can relieve the stress on overstretched water supplies by replacing other sources for non-potable, or sometimes even potable, uses.

Effluent is currently used in Arizona for urban and agricultural irrigation, industrial purposes and for recharging groundwater aquifers. According to the new report, effluent reuse in the Phoenix Active Management Area may be as high as 82 percent.

A majority of effluent is used to cool Arizona Public Service’s Palo Verde Nuclear Generating Station. Some of these processes use effluent that has been treated for higher quality, resulting in reclaimed water. Reclaimed water is used to water parks and golf courses, as well as non-edible agricultural irrigation (i.e. for cotton).

This report highlights the current use of effluent as a key water conservation strategy for Arizona’s Sun Corridor – the combined metropolitan areas of Phoenix and Tucson. Though beneficial for helping curb the demand for water in Central Phoenix, effluent offers many challenges for future water managers and decision-makers.

A key challenge for producers of effluent will be cost. Wastewater treatment is currently the largest consumer of energy in Central Phoenix. In the future, this process will become even more expensive as wastewater treatment becomes more sophisticated to remove the brine (salt) and pharmaceuticals from water. A key challenge for effluent consumers will be competition.

“Here in central Arizona, as in southern California and northern Florida, most effluent is already being reused," says Quay. "As the price of water supply goes up, so will the value of effluent. In an open market this may put it economically out of reach of current effluent users, who may find ground water cheaper to use.”

Thus, the key to keeping water management sustainable is to continue to keep effluent cost-effective in comparison to the cost of pumping groundwater.

In addition to the authors, contributors to the report include Rob Melnick, executive dean, and John Sabo, director of research, each from the ASU Global Institute of Sustainability, along with DCDC staff Sally Wittlinger and Liz Marquez, and student interns Rud Moe and Saad Ahmed.

The review is based in part on a series of interviews and expert reviews by representatives from public, private and nonprofit agencies.