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Water recycling can reduce pressure of urban usage on fresh water resources

April 28 (UPI) — Enhanced water recycling efforts could significantly reduce the reliance of major cities and their water demands on fresh water resources, including rivers, reservoirs and wells, according to new research.

Scientists at Rice University developed models to simulate the impact of water recycling on the water usage patterns of a major urban center like Houston. The analysis — detailed this week in the journal Nature Sustainability — showed recycling wastewater could reduce fresh water usage by 28 percent.

Authors of the new study acknowledged that water purification systems are expensive, but models showed the costs of installation and long-term energy demands would be offset by savings from municipal wastewater reuse.

Houston is currently planning to reconfigure their wastewater treatment system, consolidating their current arsenal of treatment plants from from 39 to 12. Authors of the new study hope their research will move city planners to consider incorporating wastewater recycling technologies into the reconfiguration plans.

“All the technologies needed to treat wastewater to drinking water quality are available,” Rice environmental engineer Qilin Li, co-author of the new study, said in a news release. “The issue is that today, they’re still pretty expensive. So a very important part of the paper is to look at how cheap the technology needs to become in order for the whole thing to make sense financially and energy-wise.”

Much of the water used to meet the demands of cities and their residents are drawn from distant resources.

“Another way to improve potable water would be to cut its travel time,” Li said.

The farther away fresh water is from users, the longer the water has to travel. Each time water passes through a distribution point, the chance of chemical and biological contamination increases. Recycled wastewater, after being made potable, would have to travel only a short distance.

Researchers suggest their model can be used to consider the challenges of designing an effective and efficient water treatment and supply systems in various cities and environs. In every scenario, planners must evaluate the trade-offs between fresh water acquisition, energy use and transportation.

The model could help city planners in other cities decide whether they would be best served by one big centralized water source or several smaller distributed sources.

“In that case, how many sources should there be, how big of an area should each supply and where should they be located? These are all questions we are studying,” Li said. “A lot of people have talked about this, but very little quantitative work has been done to show the numbers.”

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