The City of Phoenix plans to add a multibillion-dollar direct potable reuse project into the 91st Avenue Wastewater Treatment Plant that will be able to purify 60 million gallons of water per day.
The project, which Phoenix hopes to deliver by 2030, will add a major new drinking water supply to Phoenix and partner cities at a time when supplies from the Colorado River are shrinking and subject to allocation reductions. Purified water from the reuse project will supply enough water annually for approximately 200,000 homes. Without purification, the water would be discharged into the Salt River.
The Colorado River supplies 40% of the drinking water portfolios for Phoenix and Mesa. The new facility’s output could replace half of Phoenix’s annual Colorado River draw. Without new supplies, cities will probably have to resort to nonrenewable supplies, such as groundwater, which would lead to more severe water shortage management plans.
While other cities already engage in indirect reuse for wastewater, directing treated wastewater into the ground for natural filtration, Phoenix’s project will be the first in the area to directly purify and reuse the water for drinking purposes on a significant scale.
The water purification technology will repeatedly clean the wastewater through several processes, including ozone treatment, granular activated carbon treatment and ultrafiltration or reverse osmosis. Sensors will monitor the water and it will be tested at the end of the process to ensure quality. Water that fails testing will be discharged to the Salt River.
Officials in Phoenix have not issued exact cost details for the facility beyond saying the price tag will be in the billions. The City’s share will depend on several factors, including how many other municipalities want to buy in.
The 91st Avenue Wastewater Treatment Plant is co-owned by Phoenix, Mesa, Tempe, Glendale and Scottsdale. There could be as many as 10 cities ultimately benefiting from the new plant.
Mesa officials have already expressed interest in participating. While the two cities could directly send water and wastewater to each other, the more likely scenario would be a water exchange agreement in which Mesa buys into the plant and takes a portion of Phoenix’s Colorado River water while Phoenix, in turn, keeps the purified water.
Funding is expected from a variety of sources. The Arizona Water Infrastructure Finance Authority received $1B last year as part of an unsuccessful attempt to fund a desalination plant. The Federal Infrastructure Investment and Jobs Act has allocated $8.3B for water projects in the Western U.S., including $550M for high-volume water recycling. A portion of the costs will also be paid by water users in the cities using the plant. (Source)
