City council members in Washington, Mo., have been concerned in recent months after receiving complaints about odors emanating from the modern wastewater treatment facility that replaced an old trickle filter system that was operating over capacity and showing signs of wear. A new Vertical Loop Reactor (VLR) treatment and Cannibal sludge reduction system (both from Siemens Water Technologies) were installed three years ago.

Water/wastewater superintendent Kevin Quaethem was hired as the new 4 mgd system was being built. He was asked at a recent council meeting what could be causing the odors and why they persisted. Quaethem set out to find the source of the problem and determine what could be done to correct it.

Quaethem says his staff members have experimented with routing incoming wastewater through the system to locate the source of the odors and in doing so they concluded that the source is not in the treatment plant, but rather in the collection system. They reached that conclusion when they were able to eliminate the odor problem by routing wastewater coming from the north side of the city of 15,000 people.

Two primary sewer mains deliver wastewater to the treatment plant located near to the Missouri River. Quaethem says the city normally routes wastewater to a wet well for collection before entering the plant. From there, wastewater is pumped to the headworks well inside the plant. When staff members routed wastewater from the north side of Washington directly to the headworks inside the treatment building the odors outside the plant dissipated, says Quaethem.

“Our building’s all closed up and we have an air scrubber system that takes care of most of the odor,” says Quaethem.

He says it is preferable to send all wastewater straight to the wet well. By going that route, he is able to save on energy costs and equipment costs.

Although the immediate problem has been resolved, Quaethem does not see the rerouting of the wastewater from half of the city as a long-term solution. “I’ve just created a new job for myself,” he says. “We need to see where the odor is generating from and see what we can do to control it at the sources.”

Quaethem is not sure what might be causing the new odor problems. He doesn’t want to point a finger at anybody, but says the system could have a commercial or industrial customer who has changed a system or the nature of its waste. “We won’t know until we’ve tracked back through the collections system and located a source,” he says.

For now, however, Quaethem is happy to have eliminated the new treatment system as a culprit in the case of the foul odors.