Environmental Protection

NSF Funds Arizona Study on Water Reuse and Supply

Kevin Lansey, head of the department of civil engineering and engineering mechanics at The University of Arizona, and four of his UA colleagues have been awarded $2 million by the National Science Foundation to research water reuse and supply systems.

The NSF's Office of Emerging Frontiers in Research and Innovation is funding the research project, "Optimization of Dual Conjunctive Water Supply and Reuse Systems with Distributed Treatment for High-growth Water-scarce Regions," which will ultimately produce a computer model for water managers who are grappling with the problem of using less energy while meeting increased demand for water.

The U.S. Government Accountability Office has reported that as many as 36 states will experience a water shortage in the next five years. This research project is particularly relevant to the serious problems faced by water managers in Arizona, which is already experiencing explosive population growth coupled with drought.

Arizona's surface-water supplies, especially near urban areas, are all spoken for, and many communities rely on water pumped up from aquifers.

Such a resource is unsustainable, and some of Lansey's research revolves around the question of how willing we are to reuse wastewater and to what extent.

"In water-scarce areas, people will eventually have to use reused water as part of their water supply," said Lansey. "And now the question is how much further people will use it."

The research group will work with the City of Tucson, Pima County and Global Water, a private water provider.

Tucson has two wastewater treatment plants within a mile of each other in the northeast part of the city. One of the problems with clustering facilities in this way is the prodigious amount of energy required and greenhouse gases emitted to move the vast volumes of water between consumers and treatment plants.

"Instead of having one centralized plant, choose a decentralized design," said Lansey. "You could have multiple satellite wastewater treatment plants based on a dual distribution system that provides potable water for consumption and nonpotable water for reuse."

Lansey's group will look at where to locate these decentralized plants. The group will also consider how to make such systems reliable, and how to ensure that the water being served is of the appropriate quality. "We're going to show what's cost-effective at what scale," said Lansey.

Another hard choice will eventually have to be made regarding the reuse of water for drinking. People have made it very clear that the notion of drinking former sewage water can be hard to swallow.

The city of Los Angeles tried it in the 1990s, but a newspaper headline – "Toilet to Tap" – scared so many residents that the plan was scrapped virtually overnight.

The technology does exist to fully purify wastewater and make it safe and potable, but tangible resistance remains, despite photographs of nervous-looking politicians standing in front of filtration ponds drinking a beaker of water from whatever purification plant they are opening.

In the desert Southwest, Lansey can see the day coming when demand for clean drinking water makes it a costly commodity. "We either accept expensive water or we leave the desert," he said.

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