News Feature | December 28, 2016

World's First DPR Plant Inspires U.S. Water Managers

Sara Jerome

By Sara Jerome
@sarmje

glass of water reg new.jpg

With few exceptions, direct potable reuse (DPR) has not been adopted by U.S. water suppliers yet, besides tiny regions of Texas that relied on this water recycling method to survive the recent drought. Several states, including California, are still working on regulatory changes that would make this technology permissible.

But it’s a different story in Namibia, a nation on the southern African border of the Atlantic Ocean where where “evaporation rates exceed annual rainfall,” according to the Los Angeles Times. The Goreangab waste treatment plant in Windhoek, the Namibian capital, takes in wastewater from nearly all of the city’s 300,000 residents in a process that eventually produces drinking water, according to recent report on PRI.

The Windhoek plant is the longest-running DPR plant in the world, operating since 1968, according to a presentation by WateReuse California, an industry group that promotes recycled water.

“Goreangab gets a lot of visitors from developed countries facing water shortages. Experts have come from Australia, Singapore and the U.S. to see where water reclamation started,” PRI reported.

“If you talk about the cradle of water reclamation, potable reclamation, everybody comes and see this. This is where it all started in 1968,” said Windhoek water department head Pierre van Rensburg, per PRI.

Here is the process used at the Namibian facility, per plant officials:

  • Oxidation and pre-ozonation
  • Powdered activated carbon dosing
  • Coagulation and flocculation
  • Dissolved air flotation (DAF)
  • Dual media filtration
  • Main ozonation
  • Biological activated carbon filtration (BAC)
  • Granular activated carbon filtration (GAC)
  • Ultrafiltration
  • Disinfection and stabilization.

Justina Haihambo, a process engineer at the plant, spoke to PRI about the plant, noting that the its process is heavily reliant on bacteria.

“Everything is done biologically, by the organisms,” Haihambo said, per the report. “The plant was originally designed to treat 27,000 cubic meters [of sewage] a day. But now sometimes during peak hours, we have around 41,000 cubic meters a day. Way more than it was designed for.”

Namibia does not struggle with the “toilet-to-tap” stigma that some analysts say dogs adoption of the technology in the U.S.

No one “had any complaints about drinking recycled water. And van Rensburg says locals are now proud to have pioneered the idea,” PRI reported.

For similar stories visit Water Online’s Water Reuse Solutions Center.

Image credit: "A glass of water," Gunnar grimnes © 2010, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/