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How to Control Odors at Wastewater Treatment Plants

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As seen in August/September 2017 Issue

By: Victor Cormier, President of Geomembrane Technologies Inc. (GTI)

Foul odors are an unfortunate reality at wastewater treatment plants. If left uncontrolled, nuisance odors can waft into public spaces and residential areas located around the plant.

How far odor emissions drift depends on several factors, including wind velocity or direction and temperature inversions.

Odors from wastewater treatment plants cause neighbors to complain. These complaints can escalate, gaining traction with public officials and even the media, negatively impacting the plant’s reputation. Odors are typically worse at higher temperatures, so it’s no surprise that plant management usually receives more odor complaints during the warmer months of the year. The community wants the odors gone. The plant wants the complaints to stop. But how?

What can be done to control odors?

The first step in solving any odor problem is identifying the source. Since the culprit could be a number of different things, it’s best to pinpoint the source of odors with the help of a professional.

Once the source of the odors has been identified, there are many different solutions that can be applied to control the odors. Some options, such as adding chemicals to the water or using deodorizing misting systems, reportedly work well—until they don’t. A sudden change in wastewater composition or weather can cause the odors to intensify. Fine-tuning the wastewater treatment process itself is another odor control tactic, but this can be complex and costly.


Often the most reliable solution to controlling odors is also the simplest: literally covering the problem. Many wastewater treatment plants choose to seal the source of odors—whether that’s a tank, basin, or lagoon—with an industrial-grade cover, thereby preventing the diffusion of odor vapors. Covering a tank or lagoon to control odors is a rare example of when covering up a problem makes perfect sense.

Selecting the Right Odor Control Cover

There are a large number of cover styles available on the market, including fixed covers, floating covers, inflatable covers, retractable covers, covers made from flexible geomembranes, and covers made from rigid materials such as aluminum, fiberglass, or steel.

Just as there is no “right” wastewater treatment solution, there is no “right” odor control cover. It all depends on the application and the unique needs of the plant. To help guide your decision, below are a few examples of successful odor control cover applications.

Retractable Tank Covers Minimize Odor Threats from Plant Expansion

A regional wastewater treatment plant in the USA was embarking on a $353 million project to expand treatment capability and replace aging infrastructure before it wore out. The increased treatment capacity meant that the plant could treat more wastewater—but with that came the threat of more odors. In response to concerns from neighboring properties, part of the expansion project included upgrading the plant’s odor control measures.

Geomembrane Technologies Inc. (GTI) was selected to custom-design and supply 49 structurally supported covers for the plant. The project consisted of 24 covers for the plant’s primary clarifiers, nine covers for its launder tanks, and 16 covers for its equalization tanks. These tanks are all part of the early stages of wastewater treatment when odors are at their most intense, so it is crucial that the tanks be securely covered. The retractable covers are tensioned across a low-profile aluminum arched frame spanning the tank opening, but can easily be rolled open.

The covers have helped minimize odors as intended. The odor from wastewater treatment is reliably contained within the tanks so that it can be removed and treated, helping to reduce complaints and maintain a positive perception of the plant in the community.

Sugar Company Finds Sweet Solutions for Odor Control

A large sugar company in the USA was in need of an odor control solution because its high-strength wastewater was causing odor concerns. Odors were especially bad during the company’s peak season in the spring and summer. It was important for the sugar company to minimize the effects of its operations on the environment and community.

The company was using a series of basins, such as ponds and ditches, to cool, equalize, settle, and digest the organic wastewater. GTI designed, fabricated, and installed two modular cover systems for the sugar company’s mud ditches. The covers utilize flexible polyethylene foam and HDPE to suppress odors while standing up to tough conditions.

The modular cover systems are an effective odor control measure for the sugar company.

Combined, the two covers consist of 74 removable rectangular panels connected using a stainless steel cable lacing system. The panels can be individually removed or shifted to allow for easy access and cleaning of the mud ditches. The covers are safe to walk on and they are expected to last 10-15 years, making the investment that much more worthwhile.

Wastewater Treatment Plant Controls Odors without Limiting Access

When houses were developed within a few hundred feet of the Georgetown Wastewater Treatment Plant property line, it didn’t take long before new residents complained about odors. Plant management made a public commitment to address the problem, and focused on its grit tanks. “We can’t chase odors in the wind. A cover makes logical sense. We were convinced capturing and treating odors was the way to go,” says Wendy Derjugin, Plant Operations Supervisor at the Georgetown Wastewater Treatment Plant.

The solution was GTI’s custom-designed, structurally supported covers. The covers easily retract, meeting the plant’s access requirements. It takes only one person to easily open the covers for routine inspections. “Retracting the covers is not labor-intensive. It isn’t the type of equipment that deters people from doing their work because opening the covers is very simple. Covering the grit tanks was one of the most effective things we could do to further reduce the potential for odors,” says Derjugin. Foul air is captured underneath the grit tank covers, and it is then withdrawn and treated in a carbon system.

“Capture and treat” technology is a proven, simple way to alleviate odor concerns at wastewater treatment plants, benefiting both plant workers and the neighboring community. If your plant is struggling with odors from wastewater treatment, combat the problem by covering the tank or lagoon with an air-tight cover.


For more information on odor control covers, visit GTI’s website at www.gticovers.com or contact us: covers@gticovers.com,

1.506.452.7304, or 1.855.484.4630 (toll-free USA/CAN)

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