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DU: Plant making progress in reducing stench

By Catherine Godbey
cgodbey@decaturdaily.com · 340-2441

Earlier this year, the stretch of Alabama 20 from Beltline Road to 12th Avenue Northwest motivated drivers into action.

Merging onto the highway, they frantically reached for their automatic window controls and warned passengers to roll up the windows.

Decatur Utilities hopes the days of motorists scrambling to raise their windows are in the past. Stanley Keenum, interim general manager for DU, believes that the plant on Alabama 20 is making progress in eliminating the odor that plagued Northwest Decatur in February, March and April.

“This is a waste-water treatment plant, so you’ll get a whiff of an odor every now and then,” Keenum said. “But the odor isn’t constant like it was at the beginning of the year.”

Hired expert

DU hired ADL Engineering Services in April to analyze the 18 million gallons of waste water entering the plant daily. From its research, ADL discovered the odor occurred because of a disproportionate amount of sulfates.

When sulfates transform into hydrogen sulfides, a “rotten egg” smell occurs, Keenum explained. The excess sulfates damaged the bacteria used to contain the odor and resulted in the creation of more hydrogen sulfides and a more intense rotten egg odor.

To control the odor situation, DU lessened the number of primary clarifiers and added extra bacteria to the treatment process.

“We disrupted the environment that allowed the sulfates to change into hydrogen sulfides,” said Travis Wilson, the plant’s maintenance supervisor.

Of its six primary clarifiers, machines that treat the waste water once it enters the plant, DU uses only two. Decreasing the number of primary clarifiers decreases the amount of time waste water is retained.

“The longer we hold it (the waste water), the more likely the sulfates will turn into hydrogen sulfides. By using only two primary clarifiers, we are decreasing the holding time,” Wilson said.

DU also increased the amount of odor-eating bacteria in order to replace the damaged bacteria.

“The bacteria typically have a life span of 10 days,” Keenum said. “We had to turn them over four times before we started to see a marked improvement in the smell.”

At the Municipal Utilities board meeting July 18, board member Hugh Hillhouse commended DU and challenged it to take a proactive stance in the odor battle.

“We have made many improvements with the smell,” Hillhouse said, “but we want to know what our plan forward is.”

Keenum said that once ADL completes its study of the plant, DU will begin implementing the recommendations. Until it receives those recommendations, plant engineers will continue to monitor the bacteria levels daily.

Nose test

On Aug. 9, students returning to Leon Sheffield Elementary School will determine whether the changes were successful.

Returning from summer vacation, Shundra Morris and Carol Davis, third-grade teachers, said they would need more time to determine whether the alterations made a difference.

“We have to wait for the heat and wind. Those are the main two factors,” Morris said. “If you get a northwest wind, you are going to smell it more, and heat just makes anything stink.”

Morris and Davis agreed students will acclimate themselves to the smell just as students who have attended the school for the past 30 years have.

“Give them a couple of days, and they’ll become immune to it,” Morris said.

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