Technical Notes: Odor Control

ENVIRONMENTAL        We Treat Water Seriously     1728 Trade Drive Ruston, La 71270


Cell 318-243-1022

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(Technical Note No. 1701)


Odor control is a major problem in wastewater collection systems and treatment plants in almost every municipality and many industrial wastewater treatment plants.  The control of hydrogen sulfide (H2S) is especially troublesome because it is odiferous and is a health hazard.

Most collection systems contain little or no oxygen.  This oxygen-poor or anaerobic condition allows microbes known as “sulfate-reducing bacteria” to thrive. These bacteria utilize the sulfate ion (SO42-) that is naturally abundant in most waters as a source of oxygen for respiration. The by-product of this biological activity is hydrogen sulfide (H2S).

In this document, we will discuss two confirmed treatment processes for the control of such odors – the use of nitrates and the use of a proprietary chemical named WOW-Air B™ (



The use of nitrates is a proven technology for providing oxygen molecules and consequently preventing the formation of hydrogen sulfide.  It has been used for over 15 years.  The technology is well understood.

In order of preference, bacteria utilize free molecular oxygen (FMO), then nitrates, and finally, sulfates.  The preference is based on energy required to free the oxygen molecule so that it can be used in metabolic processes.  Since there is no FMO available in most sewer collection systems, the bacteria select nitrates over sulfates to provide alternative source of oxygen because less energy is required in breaking the N-O bond.

Nitrates are readily available in granular and liquid forms.  They are safe to handle and to feed into a sewer system.

Some disadvantages to the use of nitrates are as follows:

  • Inefficient for gravity lines.
  • Increases nitrogen levels in the influent to the WWTP.
  • Resultant nitrogen gas (or residual NO3) may present problems downstream at the wastewater plant.
  • Costs for prevention mode may be excessive in long retention time lines.
  • Reactions may require several hours.
  • Costs may be high in applications with high oxygen uptake rates (higher temperature, etc.)
  • Costs for prevention mode impacted by high BOD levels.


WOW-Air B™ is a propriety chemical manufactured by FreshAWL®.

It is considered to be the clean green alternative solution for anaerobic odor reduction and elimination in collection systems and wastewater treatment plants.  It binds the available sulfur in solutions and replaces it with oxygen thereby eliminating the bacterial production of (H2S) and the resulting malodors.

Some of the advantages of WOW-Air B™ products are as follows:

  • Instantaneously reacts with sulfur preventing formation of H2
  • Friendly to waste treatment systems and the environment.
  • Specifically designed to remove hydrogen sulfide (H2S), selenides, and mercaptans.
  • Effective immediately and specifically to bind and inactivate sulfur.
  • Beneficial bacteria are no longer exposed to high sulfur concentrations and acidic conditions.
  • Provides a natural increase in the system oxygen.
  • Frees the beneficial bacteria to perform better.
  • Anti-corrosive.
  • Cleans grease from surfaces and improves flow conditions while reducing maintenance.



If you are receiving complaints about collection system and/or WWTP hydrogen sulfide odors, join with us and many others and control its formation by using the clean, green alternative, WOW-Air 28™.


For questions or more information, please contact ENVIRONMENTAL PROCESS USA, LLC at or telephone 318-243-1022.

The information contained in this article is the exclusive intellectual property of Donald G. Adams and may not be used for anything except for its intended purpose.