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Reusing Everything: Phoenix Wastewater Treatment Plant To Net $1.2M From Biogas

Lauren Gilger/KJZZ
editorial | staff
The Tres Rios wetlands, which is 450 acres of man-made wetlands just across the street from the Phoenix wastewater treatment plant, where wildlife has flourished.

It’s something we all like to forget about, but, every day, 130 million gallons of wastewater is sent from our sewer system to a treatment plant near 91st Avenue and Broadway Road.

There, it’s broken down, treated, and almost entirely reused.

“Everything here is really re-purposed, we try to be as sustainable as possible,” said Dennis Porter, assistant director for Water Services with the City of Phoenix’s wastewater operations.

When wastewater comes into the plant, a lot of it is turned into fertilizer – not for food – and, after the water is treated, much of it goes to the Palo Verde Nuclear plant, which uses it to cool their reactors.

The rest of the water goes to the Tres Rios wetlands,  450 acres of man-made wetlands just across the street from the treatment plant, where wildlife has flourished.

“You see a lot of different plant life, some we planted ourselves, some grew naturally because the water’s here, the blue heron, you see a lot of snowy egrets, there’s geese, we have pelicans, there’s beaver out here,” Porter said. “You know, when you put water out somewhere, the animals and the birds will find it.”

The water from the plant is treated with chlorine and then, when it’s sent to the wetlands so it can be made natural again, before it can flow back into the Salt River.

“The wetlands themselves do some cleaning,” Porter said. “A lot of the cattails you saw, they can take up some metals and other contaminants.”

Porter said the wetlands are a biological environment that has to be maintained. “It’s a combination of science and magic,” he said.

New revenue from existing byproduct

Now, the plant has announced it will start a new project that will make it even more sustainable.

Soon, the city will also reuse the biogas created there, which is a byproduct of the treatment process, and sell it as a renewable energy commodity. The city signed a deal with a company, Ameresco, to build a new plant on site there to take the gas, treat it, compress it and pipe into a commercial gas pipeline nearby to sell on the market.

Currently, biogas produced at the plant is burned off, which isn’t great for air quality and misses an opportunity, Porter said.

“Right now, it’s just not reused, so hopefully in the spring of 2018, it’ll be in operation the new plant that will take that gas, scrub it, clean it, send it to the Kinder Morgan pipeline and we’ll start making some money," he said.

The city expects to make about $1.2 million in annual revenue from selling the gas, which will be shared among the cities that jointly own the treatment plant- Glendale, Mesa, Tempe, Scottsdale and Phoenix.

While he knows most people don’t want to know what happens to their wastewater, Porter said it’s an important role they play.

“It’s important. It’s important for the environment. It’s important that we can continue to grow as a city,” he said. “Without these facilities, we couldn’t do that.”

Lauren Gilger, host of KJZZ's The Show, is an award-winning journalist whose work has impacted communities large and small, exposing injustices and giving a voice to the voiceless and marginalized.