Industrial odor control systems remove the compounds that cause odor from process exhaust and ventilation air before they are released to the atmosphere. An odor complaint can often be traced to compounds in a few common chemical families: reduced sulfur compounds such as hydrogen sulfide and mercaptans, ammonia and amines, and organic compounds such as aldehydes, fatty acids, and solvents.
PCC applies Dual-BioPhase™ bio-oxidation, packed tower scrubbing, and regenerative and recuperative thermal oxidation to eliminate odorous compounds. Because the same plant often has odor and VOC limits on the same stack, PCC designs for both at once, ensuring that addressing an odor problem does not leave VOC emissions uncontrolled, or vice versa.
Bio-oxidation with no burner and no fuel, with a single unit treating more than 250,000 acfm
Treatment of H₂S, ammonia, and organic odors
Synthetic media and a separate water phase for higher gas velocity, smaller size, and no fouling compared with a conventional biofilter
Packed tower scrubbers that absorb odors and gaseous compounds through countercurrent flow
Regenerative thermal oxidizers that destroy HAPs, VOCs, and odorous emissions in the same stream
Applications:
Industrial wastewater and industrial compost
Food manufacturing
Engineered wood: OSB, MDF, and pellet mills
Specialty chemical, bioenergy, asphalt shingle, and textile plants
Pulp and paper, including TRS incinerator exhaust
Contact us by phone at (412) 655-0955 or request an engineering consultation to discuss your industrial odor control needs.
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What Causes Industrial Odor?
The compounds that cause most industrial odors are well documented. In wastewater solids handling, for example, EPA identifies organic and inorganic forms of sulfur, mercaptans, ammonia, amines, and organic fatty acids as the most offensive odor-causing compounds, which can be released during heating, aeration, and digestion (EPA, Odor Control in Biosolids Management). Anaerobic processes produce hydrogen sulfide and other sulfur gases; alkaline and high-temperature processes release ammonia.
Two factors distinguish odor from other air pollutants. First, people detect many of these compounds at very low concentrations, so a stream that easily meets a mass emission limit can still generate complaints at the fence line. Odor strength is measured by how many dilutions with clean air are needed to bring a sample to its detection threshold, not only by concentration. Second, the compounds present determine the appropriate control technology. A water-soluble, biodegradable odor and a sulfur-bearing waste gas may require very different equipment.
How to Select an Odor Control Technology
Start with the stream profile to identify the applicable technology. Then, compare its performance and suitability. Below are PCC's published figures for each system.
| Stream Profile | Technology PCC Applies | Published Performance | Why It Fits |
|---|---|---|---|
| ✓ High flow, low odor concentration (typically under 50 ppmv), biodegradable compounds | Dual-BioPhase™ bio-oxidation | 25 to 500 ppmv; single unit treats more than 250,000 acfm; 40 to 200°F inlet | No burner and no fuel; products are CO2 and water; handles ammonia and H2S |
| ✓ Water-soluble or reactive gases such as H2S, ammonia, or acid gases | Packed tower scrubber (acid gas absorber line) | Countercurrent gas and scrubbing liquid over packing absorbs odors and gaseous compounds | Scrubbing solvent depends on odor-causing compound |
| ✓ Odorous VOCs and HAPs in continuous process exhaust | Regenerative thermal oxidizer (RTO) | Destroys HAPs, VOCs, and odorous emissions; 1500°F chamber | Ceramic media heat recovery minimizes fuel consumption |
| ✓ Concentrated or complex waste gas, including mercaptans and other sulfur compounds | Thermal oxidizer with downstream scrubbing | Guaranteed 99.9+% VOC destruction; mercaptans are among the wastes PCC oxidizers handle | Destroys the odor compound; a scrubber removes the SO2 that sulfur oxidation creates |
| ✓ Digester gas and biogas at wastewater treatment plants | Packaged combustion system (PCS) | PCS thermal oxidizers are designed for digester gas at agricultural and municipal wastewater plants | Packaged, factory-built unit for a well-defined gas |
Sulfur Odors and TRS
Reduced sulfur compounds are particularly difficult to control because people can detect them at such low levels. When a sulfur-bearing stream is oxidized, the odor-causing compounds are destroyed, but the sulfur can be converted to SO₂, which is a regulated pollutant in its own right. The control train therefore continues past the oxidizer to an acid gas absorber that removes the SO₂.
For example, Kraft pulp mills normally collect their total reduced sulfur (TRS) off-gasses to be destroyed in TRS incinerators, and the flue gas from this treatment process is then the feed to PCC's wet scrubber systems. Other feed streams that can be treated by PCC's wet scrubber systems include off-gasses boilers, lime sludge kilns, dissolving tank vents, and slakers (pulp and paper). Gas streams with lower concentrations of hydrogen sulfide (and other sulfur containing compounds), such as those from wastewater treatment, can be treated with bio-oxidation (such as PCC's Dual Bio-Phase system) or a packed tower scrubber without combustion.
What PCC Needs to Size a System
Odor sources and the compounds behind them
With concentration ranges
Odor panel results (detection threshold or dilutions)
If measured
Gas flow, temperature, and humidity
Normal and maximum
Sulfur, nitrogen, and VOC content
Of the same stream
Operating schedule
And how the load varies
Permit conditions, nuisance requirements, or complaint history
Utility and water availability
And any space limits
If the odor-causing compounds are unknown, an engineering study can identify them before equipment is specified.
