As the saying goes, “Everything is bigger in Texas”. Water reuse, including direct non-potable and indirect potable reuse (IPR), is no exception. In 2010, Texas water reuse projects recycled over 260B gallons of water. That’s enough water to completely fill the new Dallas Cowboys Stadium 335,076 times over. This number is expected to double by 2060, comprising 14% of the state’s total water supply and over a quarter of the water in the Dallas/Fort Worth area. Within Texas, more than twenty-five local water agencies have existing water reuse plans.
Where indirect potable reuse treats wastewater to drinking water standards, but uses an environmental buffer prior to use, direct potable reuse delivers water directly to a water systems raw water or treated delivery system. (See Water Reuse for an overview of water reclamation technologies)
The Texas Commission on Environmental Quality approved a project for the City of Big Spring. Effluent from the city’s wastewater treatment plant will undergo advanced treatment, including microfiltration, reverse osmosis and advanced oxidation. This water will be blended with raw water and delivered directly to a water treatment plant for potable water.
The Big Spring project has intrigued other water suppliers. To repeat, “Everything is bigger in Texas”. Everything! Droughts included. At least a couple of towns resorted to trucking in water.
So it makes perfectly good sense that the Texas Water Development Board (TWDB) wants to examine opportunities for direct potable reuse (DPR). Most scientists and authorities have determined that water reuse is safe and feasible. But since practically every existing potable reuse project is indirect, TWDB would like to learn more about direct potable reuse.
To that end, TWDB has selected Alan Plummer Associates for one of their 2012 Priority Research Projects, titled “Evaluating the potential for direct potable reuse in Texas”. Dr. Ellen McDonald, PE, of Alan Plummer Associates will lead the research team. The research project will explore six important factors:
1. What water quality constituents should be measured to assess the suitability of reclaimed water for potable use in Texas?
2. What are reasonable target levels for these constituents?
3. How many and what kinds of treatment barriers are appropriate for potable reuse projects?
4. How many and what types of multiple barriers are appropriate for potable water reuse projects?
5. What treatment process trains can be used to meet the target levels identified in the answer to question 2?
6. Which treatment trains provide the best overall balance between protection of human health, product water quality, energy consumption, cost and secondary(energy, environmental) impacts?
With a population projected to double in under 50 years, Texas has no choice other than to find innovative means to develop additional water resources including waste water and storm water reuse.
cc image courtesy of crowt59 on Flickr