Ammonia (NH3) and ammonium compounds are among the most common sources of nuisance odor complaints around the world.
The largest source of global ammonia emissions is in agriculture, either from large-scale concentrated animal feeding operations or in the production of fertilizers. Ammonia release is also common in pharmaceutical production, waste-to-energy processing, some food processing operations and municipal wastewater treatment plant sludge processing.
As populations spread toward outlying industrial districts, it’s critical that facilities implement appropriate, effective ammonia treatment solutions. Below, we’ll examine common sources of ammonia odors and discuss the range of ways they’re treated.
Sources of ammonia release
More ammonia is released in the form of animal waste from large farms than any other source. However, ammonia odor treatment techniques on farms are relatively rudimentary compared to those in industrial settings due to their location in rural areas where population encroachment has historically not been a problem.
Production and application of nitrogen-rich fertilizers used to boost crop yields also result in released ammonia compounds.
However, ammonia nuisance odor complaints most often come from urban or suburban environments near waste-to-energy processing facilities, pharmaceutical manufacturing plants and food processing operations.
Sometimes, ammonia itself is the culprit. The molecule is stable in ambient environments and its nuisance threshold is very low—as low as 0.04 ppmv.
Other times, molecules containing ammonia or ammonia derivatives like amines cause foul smells. Amines are precursors to proteins, so their release can be expected in settings where proteins are present, such as meat processing and packing plants or in waste collection and processing. However, amines are also critical building blocks for popular medications like decongestants and some light sedatives, so pharmaceutical plants also often experience ammonia odor issues.
In addition to odors, ammonia is harmful to humans in high concentrations. In the U.S., the Occupational Safety and Health Administration regulates its release in workplaces. It’s also corrosive in high concentrations and can damage processing equipment if it isn’t collected and treated. Ammonium compounds are also responsible for much of the world’s fine particulate pollution.
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Ammonia odor treatment
Biological, chemical and physical pathways exist for the elimination of ammonia odors. Which pathway will be most successful depends on the nature of the problem and how clean a site owner needs the air to be.
Most often, successful ammonia odor treatment consists of a combination of the methods described below.
Chemical ammonia odor treatment via ammonia scrubbers
Probably the most effective ammonia odor treatment is via the application of acids in an ammonia scrubber. That’s because ammonia and its derivatives are slightly basic and could readily be removed through solution in acidic conditions.
Phosphoric acid (H3PO4) and sulfuric acid (H2SO4) are the most common acids used in ammonia scrubbers. They’re mixed with water so that ammonia compounds transfer out of the air phase and into the water phase prior to the chemical reaction. Ammonium salts are the byproduct. These systems are colloquially known as “wet scrubbers.”
BioAir recommends chemical ammonia treatment via its Qimi® chemical scrubber. Engineered media inside the scrubber ensures the most efficient transfer of unwanted ammonia compounds from the air to the water phase. It also optimizes the ratio of water to acid used during treatment, keeping costs in check.
Note that some jurisdictions require that sites obtain permits before discharging ammonium salts into local wastewater treatment.
Physical ammonia odor treatment
Physical treatment refers to the collection and disposal of unwanted compounds without destroying them. Adsorptive carbon filters are the most common means of eliminating a wide range of odors, but they don’t always work well when ammonia and amines are the target.
Ammonia and amines’ molecular size and ionic properties are not conducive to conventional adsorption removal. Minerals made of silicon, aluminum, barium, calcium and sodium feature properties that have showed better ammonia adsorption as compared to activated carbon. Further improvement of the adsorption properties is often achieved by impregnating the media with acid, essentially creating a media that removes ammonia and amines through both physical and chemical means.
For these treatments, BioAir recommends its EcoCarb® adsorptive filter featuring proprietary Optia® media instead of carbon.
Biological ammonia odor treatment
Biological breakdown of ammonia or other reduced nitrogen compounds occurs via nitrification. It happens in two steps: First, ammonia-oxidizing bacteria (nitrosomona bacteria being the most common) oxidize the compounds with nitrites as the byproduct. Then, nitrobacter bacteria oxidize the nitrites into nitrates.
In industrial settings, biological treatment can work, but it’s rare. For instance, we prefer to recommend our EcoFilter® biotrickling filter to solve odor problems because it’s an environmentally friendly alternative to chemical and physical treatment that’s proven to work just as well. But the kinetics of biological ammonia treatment are such that building a biological system is only viable in select settings.