New Tech Is A ‘Twist' On DPR

A new vision for wastewater treatment uses algae tech to clean sewage in what backers are calling a “twist” on direct potable reuse (DPR).

The idea won an “honorable mention” in Dry Futures, an ideas competition focused on solutions for the California drought. Designer Prentiss Darden paired up with the wastewater treatment firm Algae Systems to present the proposal.

The team set out to make DPR available in a way that does not emit carbon dioxide or consume large amounts of energy. The paper combined existing sustainable technologies.

The proposal drew on Algae Systems technology, which is already in use. “Since 2012, a demonstration plant in Mobile Bay, Alabama has successfully treated 40,000 gallons per day from the Daphne Municipal Utility, using one-third the energy of a typical wastewater treatment plant, producing water quality that exceeds regulatory standards, and producing ASTM-grade diesel and Class A biosolids,” according to proposal, published on Archinect.

In the proposal, the algae technology is paired with DPR technology. “By inserting Algae Systems’ technological choreography into the treatment train of direct potable reuse, we can go beyond a reduced negative impact to a regenerative, beneficial impact. This technology can be bolted on to existing wastewater treatment plants, building in resilience, replacing crumbling, outdated structures over time,”

Charles Andersen, president of the landscape architecture practice WERK and a judge in the competition, praised the idea. “This really does offer an alternative to the effluent issue. I'll drink the Kool-Aid even if it is toilet to tap,” he said.

The "ick factor" around drinking toilet water may be a barrier to making DPR viable, but a handful of cities are pursuing the technology. Texas has led the way on DPR programs. Wichita Falls was among the first U.S. city to deliver recycled wastewater to residences. The city scaled back its program to make way for an indirect potable reuse program.

El Paso is testing a new water purification system that would allow it to begin a DPR program after years of using recycled wastewater to irrigate crops and public land.

For more DPR news, visit Water Online’s Water Reuse Solutions Center.