High School Ecology Class Visits Water Treatment Plant

Brian Sitko, the laboratory director at the Northern Gila County Sanitary District checks bacteria counts.

Photo by Andy Towle. |

Brian Sitko, the laboratory director at the Northern Gila County Sanitary District checks bacteria counts.


Sage Pearce held her nose, wrinkled her forehead and squinted her eyes.

“It smells awful!” said the Payson High School (PHS) ecology student as she and her classmates toured Payson’s American Gulch Water Reclamation Facility off Doll Baby Ranch Road as part of the activities for National Green Week.

The students from sophomores to seniors stood in the section of the treatment plant that separates the solid matter from the water — called the clarifier area.

Pearce has a sensitive nose, which reacted to the smell of the solid wastes being removed from the water as part of the treatment process.

The odor is more like fertilizer than what people might think it would smell like.


Austin Young took a whiff of re-cycled water.

In the area the students visited, the processed waste went up a flume then dumped onto trucks for transport to a Phoenix landfill.

The water treatment plant is part of the Northern Gila County Sanitary District. Its purpose is to collect wastewater flushed down toilets and gurgling down storm drains then separate the toxins and waste before returning water to the water table as reclaimed water used in irrigation, explained David Millien, who works in operations at the water treatment plant.

The plant’s process is a perfect example for the Green Week theme — waste reduction and recycling.

Green Week started last year to teach students sustainability by making choices that support the environment.

Before the tour, Millien explained to the students that instead of using chlorine to disinfect the water, as many water treatment plants do, the Payson plant uses biological processes to clean the water.

“This plant is the third of its kind built in North America,” said Millien. “It uses microorganisms, filters and ultra-violet light to clarify the water.”

Millien explained that when wastewater comes into the plant as the first step to cleaning up the water, microorganisms scour the sludge (wastewater) in a five-part process to remove phosphorus and nitrogen.

Called the Bardenpho Process, which was first developed in South Africa, the water goes from the fermentation zone, to the anoxic zone, then to the nitrification zone, where bacteria turns nitrates into nitrogen gas. The final two processes include another round of the anoxic zone to make sure the water is “polished” by removing microorganisms then to a tank that puts back in the oxygen the four other steps removed.


No one from the Payson High School ecology class had any interest in drinking the water.

If the process doesn’t remove the phosphorus and nitrogen, said Millien, the water would create dangers and smelly blooms of algae in the Green Valley Lakes, a potential environmental hazard.

Just this past September, a bloom of golden algae in Roosevelt Lake killed off fish. Arizona Game and Fish said this type of algae produces a toxin that affects gill-breathing organisms. Officials fear that once a toxic bloom occurs, it can spread quickly to other lakes and streams along the watershed, killing along its path.

Millien showed the PHS students that after the complete purification process, water from the plant is clean enough to drink, although the law does not allow use of reclaimed water for drinking water.

“See, look how clear the water is after it goes through the ultraviolet lights,” he said as he held up a water goblet full of clear liquid.

Unlike her classmates, Pearce refused to sniff the water. Instead, a classmate took a whiff.

“Hmm! This doesn’t smell bad,” he said.

Between that glass of clear water and the sludge removal, the water goes through various clarifiers, including sand filters and ultraviolet light, said Millien.

But first the plant separates the solids from the water.

“We only use one chemical in the whole process,” said Millien. “That is to separate the solids from the water by helping the solids to clump together in the water.”

The clumped-up solids go through a press to remove every bit of water, then up the flume to the waiting trucks.

The water moves onto the three-part sand filters, which remove minute solids that remain after the bacteria do their work.

As a final cleansing, the water passes under multiple ultraviolet lights, which kill any remaining bacteria. This last process creates water that lives up to the standards of the U.S. Environmental Protection Agency and the Arizona Department of Environmental Quality.

In fact, on its Web site, the Northern Gila County Sanitary District reported that it has won five awards from the Arizona Consulting Engineers Association, the Arizona Water Pollution Control Association, and the U.S. EPA for engineering and excellence.

The processing plant also has a state-of-the-art lab to guarantee the microorganisms do their job and remove toxins to an acceptable level.

Beverly Adams, the ecology students’ teacher, loved the science of the process. She would have loved to spend more time discussing the microorganisms and the science behind recycling the water.

“I don’t want to leave — I have so many questions,” she said as the tour came to an end.

Pearce, on the other hand, was happy to remove her sensitive nose from the olfactory abuse.

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