Cognitive Waste

Getting past the 'yuck factor' in wastewater reuse

With proper treatment methods in place, wastewater reuse is a real solution to global water needs. But will society ever be able to see beyond this valuable resource’s sordid past? WWD Associate Editor Leslie Streicher recently discussed the significance of perspective with Brent Haddad, Ph.D., professor of environmental sciences at the University of California, Santa Cruz.

Leslie Streicher: Why is wastewater reuse an important topic for today?

Brent Haddad: Water supply reliability has grown in importance globally for all sectors—residential, industrial, commercial, agricultural, even open space management. Reliability includes both the quantity available and its qual- ity. Wastewater reuse provides regions with additional control over their water supply by allowing them to treat waste- water to the quality they desire and use it as they see fit.

Streicher: You have described the public’s aversion to wastewater reuse as the “yuck factor.” How do you propose we get past this stigma?

Haddad: Our studies have identified a number of approaches that allow people to break their perception that water that has already passed through a city is undesirable. The essential steps begin with a set of facts: The treated water is, in fact, safe and meets water quality criteria for the intended uses. If agencies can demonstrate this, then they are well along.

Next comes a discussion of the origins or source of the water. Many people are more likely to accept a water supply if they associate its origins with purity and safety: a splashing river, a protected groundwater source or a snowy mountain. People can frame out the prior pas- sage of water through a city if they also understand that the water originated in a pure place and has retained or reestablished its original purity.

Streicher: What are some common misconceptions of wastewater reuse?

Haddad: The biggest misconception is that it doesn’t happen “around here.” Wastewater reuse happens nearly everywhere because everybody is downstream from someone else. We count on natural processes to do a lot of the water treatment for us, but people have taken over the major responsibility for water quality.

Streicher: What technologies have proven most effective in treating wastewater for reuse?

Haddad: The common treatment approaches—physical separation followed by biological treatment—begin the process. What follows depends on the end use but will include combinations of membrane and media filtration and disinfection steps.

Luckily, H2O molecules are small. They can fit through pores in membranes when undesirable molecules and microorganisms get blocked. That makes it possible to filter out nearly all the undesirable constituents.

Streicher: Where do you see wastewater reuse evolving in the future as water supplies become more limited?

Haddad: We will look for the least costly ways to integrate water reuse into our water supplies. In some areas, like big cities, that means very large-scale treatment plants will transition water into large urban water systems. In other areas, very small-scale advanced treatment will occur before specific uses. This could occur in places where the vast majority of uses can be met with lower-quality water, but a small amount of potable [water] is needed for direct contact human use. Both of these models are in place today.

Economics will drive what happens where. There’s plenty of room for technology innovation as well as innovation in public-private partnerships and management of integrated water systems.

Brent Haddad, Ph.D., is a professor of environmental sciences at the University of California, Santa Cruz. Haddad can be reached at bhaddad@ucsc.edu or 831.459.4149.

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