Published: August 26, 2006 10:35 pm            

Wastewater treatment plant aims to cut down emissions

Terre Haute — While driving down Interstate 70 last weekend, Becky Lankford couldn’t help but notice an odor near the south end of Terre Haute.

“When you hit [Interstate] 70 at a certain point on the bridge, you can smell it,” Lankford said. “You always notice it right there, where the [wastewater] systems are.”

But now the city’s wastewater treatment plant near the highway has taken steps that might change what Lankford smelled.

Plant workers recently renovated some machinery, known as digesters, in a move that will reduce emissions of hydrogen sulfide and methane. The two gases are byproducts created in the machines that break down sludge carried in wastewater.

Half the plant’s digester system has been modified, changing the previous anaerobic process, which created the two gases, to the aerobic process, which will eliminate both byproducts.

The replacement came after an emergency struck part of the plant. The anaerobic system has several protective devices to safely contain the methane, but a mid-summer storm caused damage to one of those devices, creating a potential fire risk.

Workers then quickly created plans to modify the digesters as a repair to the emergency, which were approved by the Board of Public Works and Safety.

“This just meant that, as far as I remember, just speeding up what they were going to do anyway,” board president Bill Lower said.

The hydrogen sulfide was produced when sludge just sat in the tanks; the new modifications include blowers, which will send air into the tanks.

“When it goes to aerobic, everything is being mixed,” operations supervisor Robert Elkins said. “It’s not going to be allowed to sit there and [produce hydrogen sulfide.]”

In the 1960s, the plant produced methane as a heating and energy source for the facility, but the gas needed to be cleaned to be burned.

“It was the original process,” Elkins said, “but they had abandoned the use of methane gas in the 1980s … because of how dirty the gas was.”

The plant can afford the current renovations because of the user fee increases passed by the City Council nearly two years ago. The city passed a $30 million bond in January 2005 based on the sewer rate increase, said city controller Bill Long.

In 2004, when only part of those increases were in place, Long reported that $5.2 million was generated by user fees; Long noted that $10.4 million was generated in user fees in 2005, with the entire increase in place.

This year, the city is on pace to generate about $10.1 million from user fees.

“In the 10 years I’ve been here, I’ve yet to see the kind of revenue that we have in line in the budget to fix this [facility],” Elkins said. “Now it’s playing catch up.”

Utility workers expect that the second part of the digester system will be replaced within the next few months.

“We’re headed the right way,” the plant’s utility director Billy Goodrich said. “We’re not going back. We finally got the equipment to move forward.”

Austin Arceo can be reached at (812) 231-4214 or austin.arceo@tribstar.com.

        

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