You may know that Scottsdale is a leader in water recycling. About 23 millions gallons of sewage is sent down drains and toilets in Scottsdale every day and 100 percent of that water is reused: Some is processed through our Advanced Water Treatment Plant and turned into ultrapure water used for aquifer recharge, some is used for irrigation, and some is sent to the 91st Avenue Wastewater Treatment Plant in Phoenix through a multicity partnership agreement known as the sub-regional operating group (SROG).
About 99 percent of what comes through the sewer is just water, so of course we clean and reuse it. But what about that other 1 percent? The solids (human waste, food scraps from garbage disposals, salts from water softeners and everything else that makes it into the sewer system) also have value. We don’t process the solids here in Scottsdale. Instead, we send them back through the sewer system to the 91st Avenue Treatment Plant where, as of this month, they are turned into renewable natural gas, or RNG.
On April 25, Scottsdale City Councilwoman Solange Whitehead and Scottsdale Water Executive Director were both on hand on for the ribbon cutting of a The plant is the largest biogas-to-RNG facility in the nation with a processing capacity of 3,250 standard cubic feet per minute of raw digester gas produced at the wastewater treatment plant.
The 91st Ave WWTP and the new RNG facility are owned by the SROG member cities – Scottsdale, Phoenix, Glendale, Mesa and Tempe. The treatment plant is operated by the City of Phoenix. Water from the treatment plant is used for several purposes, including cooling the Palo Verde Nuclear Generating Plant, the only large nuclear power generating plant in the world not located on a major body of water and instead cooled with recycled water. The RNG plant is operated by Ameresco though a public-private partnership with the SROG cities.
Pictured from left to right: Scottsdale Water Executive Director Brian Biesemeyer, Tempe Public Works Director Holly Rosenthal, Ameresco Senior Project developer Jim Bier, Scottsdale City Councilwoman Solange Whitehead, Phoenix Mayor Kate Gallego, Phoenix City Councilman Michael Nowakowski, RNG Coalition CEO Johannes Escudero, Phoenix Water Services Director Kathryn Sorensen.