C+S June 2022 Vol. 8 Issue 6 (web)

Indirect Potable Reuse and the Treatment of NDMA

industrial and natural processes. Except for research purposes, NDMA is no longer intentionally produced in the United States, but through chemical reactions is still unintentionally produced and released from industrial sources such as tanneries, pesticide production facilities and rubber manufacturing plants. Listed as a priority pollutant by the EPA, it also can be an unintended byproduct at wastewater treatment plants, when wastewater is chlorinated during the disinfection process. Be - cause of its toxicity, the Scottsdale Water Campus identified NDMA as a compound to target for treatment. Treating NDMA With UV Advanced Oxidation For the primary purpose of increasing capacity for aquifer replenish - ment, the Scottsdale Water Campus completed a major upgrade to the advanced water treatment plant in 2012. The upgrade added Ultraviolet (UV) Advanced Oxidation to the system for the treatment of NDMA. UV AOP technology can treat several contaminants that are not easily removed by other technologies. Among these contaminants are NDMA and other “contaminants of emerging concern” (CECs), which are caused mostly by industrial sources, pose danger to human health, have an impact on aquatic life and ecosystems, are a challenge around the world, and are seeing increasing EPA regulation. Through degradation by direct photolysis, UV AOP technology can effectively treat NDMA, which does not respond well to such technologies as air stripping or granular activated carbon (GAC). It is readily treated by UV because it absorbs photons directly and breaks down through a cleaving of the N-N bond, yielding nitrite and small quantities of dimethylamine. No oxidant is needed but is often added to oxidize other potential contaminants.

Just northeast of Phoenix, Arizona, the City of Scottsdale Water Campus was built in the 1990s and quickly became a state-of-the-art wastewater treatment/recharge facility in the western United States. The Water Campus facility initially consisted of a 20 million gallons per day (MGD) water reclamation plant and a 10 MGD advanced wa - ter treatment plant utilizing microfiltration (MF) and reverse osmosis (RO). The upgrades to the advanced water treatment facility in 2011 and 2012 to 24 MGD included a 20 MGD UV reactor to treat NDMA and other potential contaminants. Continuing commitment to the vi - sionary Water Campus concept is allowing Scottsdale to ensure that a reliable, long-term water supply remains available. Targeting NDMA NDMA (N-Nitroso-dimethylamine) is a semivolatile organic chemi - cal that is a toxic and carcinogenic water contaminant created by both

Sentinel 48 AOP unit at Scottsdale

Computer model predicts performance of NDMA destruction


June 2022 csengineermag.com

Made with FlippingBook Annual report