Flushing money down the drain; Innovations can turn biosolids into profit, reduce municipal expenses

From left: Scottsdale Water Director Brian Biesemeyer; Tempe Public Works Director – Water Utilities Holly Rosenthal; Ameresco Senior Project Developer Jim Bier; Scottsdale Councilwoman Solange Whitehead; Mayor of Phoenix Kate Gallego; Phoenix Councilman Michael Nowakowski; RNG Coalition CEO and Executive Director Johannes D. Escudero; and Phoenix Water Services Director Kathryn Sorensen cut the ribbon during an April 25 ceremony for the new renewable natural gas facility at the 91st Avenue Wastewater Treatment Plant, 5615 S. 91st Ave., Tolleson. The innovative project will reduce emissions and turn a profit for the public-private partnership, according to company officials. [Courtesy of the Arizona Municipal Water Users Association]

By Matt Roy, Independent Newsmedia

This is some good stuff — at least, Valley leaders believe so as they pursue innovations to turn our waste into money.

Water treatment creates an inevitable expense for municipalities and millions of homeowners flush their toilets day after day; but a pair of local projects aim to use solid waste by-products to reduce emissions and save money for local taxpayers.

Last week, a group of municipal leaders cut the ribbon on a new facility at the 91st Avenue Wastewater Treatment Plant, 5615 S. 91st Ave., Tolleson, which will capture methane naturally produced by collected biosolids and turn it into usable natural gas.

Built through a public-private partnership with international renewable energy concern Ameresco, the facility provides a boon to the community, according to Phoenix Mayor Kate Gallego.

“This innovative partnership allows us to turn waste into resource by converting biogas, a by-product of wastewater treatment, into renewable energy. This not only benefits our regional economy, but also reduces greenhouse gas emissions,” stated Ms. Gallego in an Ameresco release.

Company officials claimed the plant is the largest of its kind in the U.S. and is capable of processing 3,250 cubic feet per minute of gas from the treatment plant.

The “cleaned” biogas is compressed and shipped to market via pipeline, while a portion of the resulting profits will benefit the partner municipalities, including Phoenix, Glendale, Mesa, Scottsdale and Tempe.

“This renewable energy resource will not only provide valuable environmental benefits to the local area, it will also provide tangible economic benefits to the partner cities through a royalty payment from Ameresco for the purchase of the raw biogas,” according to an Ameresco-produced fact sheet.

The company said the plant, in addition to creating revenue for the project partners, will provide a significant reduction in emissions — resulting in a carbon dioxide emissions  reduction equivalent to more than 70,000 passenger vehicles or nearly 900,000 barrels of oil on an annual basis.

Warren Tenney, executive director of the Arizona Municipal Water Users Association, praised the new facility in a release yesterday (read his entire guest commentary about it in the Opinions section on page 6 of today’s edition).

“Wastewater goes down your drains and enters your city’s collection system, where gravity and pumps help it flow to a local wastewater treatment plant. With innovation and sustainability as a continual priority for all the AMWUA cities, nearly 100 percent of their treated wastewater is put to use,” Mr. Tenney stated.

Civic duty

Meanwhile, leaders in Surprise are poised to approve a plan, which will invest $500,000 in a solar biosolids drying facility aimed at dramatically reducing the cost of wastewater treatment in that community.

Terry Lowe, water resources director at the city of Surprise, explained the project to city leaders at a March 5 budget workshop.

“In the wastewater treatment reclamation business, we have two by-products. When you flush the toilet, take a shower, clean the sink, all that stuff goes down drain and ends up at our plant and the goal there is to reclaim the water into a usable product,” Mr. Lowe said.

The new solar dryer system will dramatically reduce the water content of those biosolids and, thus, the weight and cost of their disposal, Mr. Lowe explained.

“When you separate out the water, which is a usable product, you have the biosolids, also known as cake – don’t eat it – but that cake is very saturated, it is 90% water in its present state,” Mr. Lowe said. “Our current mode of disposal of that cake is to landfill it, to throw it out. What we’re moving there is essentially a lot of water. It’s heavy. And, so, the dryer essentially will give us the opportunity to reduce that waste. It reduces the volume.”

Currently, the city pays about $400,000 annually to transport and dispose of the biosolids created during the wastewater treatment process.

The reduced weight of the waste products will save the city up to $300,000 of that cost annually, Mr. Lowe said during a tour of a city wastewater treatment facility earlier this month.

He suggested the capital improvement project should pay for itself over the next three to four years, based on his department’s projections.

Surprise leaders will consider and, potentially, adopt the project along with the overall budget at the City Council’s regular meeting 6 p.m. Tuesday, June 7 at Surprise City Hall, 16000 N. Civic Center Plaza, Surprise.

The new renewable natural gas facility at the 91st Avenue Wastewater Treatment Plant, 5615 S. 91st Ave., Tolleson, is the largest of its kind in the U.S. and will extract gases naturally produced during wastewater treatment for delivery to the energy market. [Courtesy of the AMWUA]

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