Odor Control in Wastewater

June 11, 2020
Plants, treatment facilities, landfills and other wastewater sites are facing increased pressures to reduce odor emissions around their workers and communities.

There’s no doubt about it — wastewater smells. Even on a cold day with no wind, odor still emanates from a wastewater treatment plant. Plants, treatment facilities, landfills and other sites are facing increased pressures to reduce odor emissions around their workers and communities. Because of this, odor control is evolving into an essential component of the wastewater treatment process.

However, finding the right solution to eliminate troublesome odors from large facilities is easier said than done. Some wastewater treatment facilities implement multi-million-dollar ventilation systems, which often see mixed results for the level of investment. Others use methods like masking agents that do little other than temporarily cover odors and provide limited relief.

Time to Get Proactive

Facilities managers who fail to take a proactive approach to odor control run the risk of alienating themselves from the community and facing harsh penalties. Much of this is a result of today’s social media environment. It’s easier than ever for neighbors to go online and complain about the odor surrounding your site. These complaints can lead to unwanted attention, and possibly regulatory fines or penalties. The proactive approach is to control odors before they ever become an issue.

Each site and its odor problems are unique, and the odor control solutions must be tailored to meet these individual challenges. Both the neighboring community and treatment plant employees will benefit from a properly implemented odor control solution.

Starting at the Source

Depending on the size of your facility, you might have many sources of odor that require multiple systems to control. There’s also the possibility that your odor could be controlled with a singular system around the perimeter of your wastewater treatment plant. It’s important to understand where odors come from and what sort of system you’re trying to treat. Both factors must be taken into account to determine the correct odor control technology.

Common Sources of Odor in Wastewater Treatment

In general, most areas of a wastewater treatment facility contain some level of odor. Depending on the location of your site, you’ll most commonly have issues in primary treatment and sludge-handling areas, in addition to these areas:

  • Headworks
  • Clarifiers
  • Sedimentation basins
  • Lift stations
  • Lagoons
  • Biosolids treatment
  • Wastewater septage dumping 

These processes can produce various odors, the most common of which found include hydrogen sulfide, ammonia, sulfur dioxide, skatoles, mercaptans, amines and indoles. Thankfully, there are various natural treatments and deployment technologies that can keep these odors at bay.

Headworks and Primary Treatment

Hydrogen sulfide odor is a serious issue found in the headworks and primary treatment area of wastewater treatment facilities. Vapor or fan systems can solve this issue when installed at the bar screens and digesters. In some cases, the biochemical can be diluted with plant water to form a more cost-effective solution.

Activated Biosolids Basins

Basins for activated biosolids are often large and uncovered. This means smells are free to drift into nearby areas. Custom biochemical delivery systems can be developed to neutralize these previously uninhibited odors naturally. With both low-or high-pressure atomization systems, plant-based solutions can be dispersed over these large areas.

Wastewater Septage Dumping

Raw septage from haulers can present odor problems for plants that otherwise would have their industrial emissions under control. Fan or nozzle atomization systems posted near the unloading point and vented or opened downstream locations provide effective removal of these odors.

Vapor Phase technology is also an effective odor control dispersion method in these areas. Vaporization creates small particle sizes to increase surface area of the odor control method, increasing your chance of controlling the odor.

Weigh the Elements

Geography and outside conditions play significant roles in how odor is emanated and treated in wastewater facilities. It’s important to take temperature, humidity, precipitation and wind into consideration when determining the delivery method for your odor control.

For example, if you’re in an area with frequent rain, you have a significant amount of water running into the plant. Rainwater helps dilute some of the odor somewhat, but not completely.

Heat is also a big factor. If you’re located in a hot, humid area, you most likely deal with significant odor issues that are caused by the bacteria producing more odorous compounds. On hot days, your facility pumps out hydrogen sulfide, ammonia and mercaptans odors. Heat also exacerbates odor problems as volatile organic compounds in your facility start vaporizing.

After identifying the sources of odor in your facility, the next step is determining the cause of the odor. Odor production contains many characteristics, including its concentration or molecular weight, that can deem whether it’s detectable or not. Once the cause of the odor is determined, the next step is to identify the solution that will effectively remove the odor.

Finding Your Solution

Considering all of these factors, the best way to begin implementing odor control at your facility is to bring your odor control partner on-site to help determine the best solution. OMI engineers start at your facility to determine odor sources, causes and environmental considerations to identify the correct plant-based solution and any application-specific equipment needs.

This process may entail taking a look at a specific lagoon, factoring in its size and location, to determine that a system with ducting around it will be required to control the odor. Another option might be a smaller system installed in one of your pump stations.

Agility is also important in odor control. Once a system is installed, it should be flexible. For example, if you only have neighbors to your north, equipment that can be set to only to disperse chemical solutions when the wind is blowing that direction can be a helpful solution.

Natural Odor Control

The Water and Sewer Authority (WSA) in Douglasville-Douglas County, Ga., has been delivering quality water and wastewater service to more than 90,000 county residents over the course of 17-plus years.

The facility treats about 2.5 to 3 million gallons of wastewater per day. As part of their operation, the WSA began receiving complaints stemming from the neighbors surrounding the Southside Water Pollution Control Plant. As is often the case, the increase in complaints about offensive odors was due more to the urban sprawl than to additional odors created by the plant.

Odors given off from the activated sludge plant, treatment of biosolids and between operating the digesters and belt filter press were believed to be the culprits. Based on a referral from another wastewater utility, WSA tested Ecosorb®, a natural, plant-based odor control solution created by OMI Industries.

The facility implemented a concentrated form of Ecosorb, which they diluted with water and applied via atomization into odorous areas.

The ratio applied varied between 1 and 1.5 parts Ecosorb to 55 gallons of water. A 5-gallon supply of concentrated Ecosorb typically treats odors at the plant for 10–14 days.

Since implementing the plant-based solution, the facility has seen a dramatic decrease in odor complaints from the surrounding neighborhoods, and WSA is realizing success throughout the entire plant, including particularly odorous areas such as the sludge handling facility.

Your site and its odor control challenges are unique. As you begin to consider odor control, it’s important to use all resources at your disposal. OMI helps site managers understand their facility’s odor sources to effectively and efficiently neutralize troublesome odors and provide a friendly environment for your works and community. WW

About the Author

Dr. Laura Haupert

Dr. Laura Haupert, Ph.D. serves as Director of Research and Development at OMI Industries. For the last seven years, she’s worked to formulate, direct and coordinate all R&D of new odor control products. 



OMI Industries

May 18, 2020