Odor Control

Aerial View of the Plant

Why do we sometimes smell odors near the wastewater treatment plant?

Odors are a natural part of the substances handled and treated at any wastewater treatment plant.

Odors are typically contained to the wastewater treatment plant site; but occasionally odors drift from the plant site depending on weather conditions and wind direction.

Routine treatment operations are designed to reduce the amount of odors present; however, certain weather conditions and equipment maintenance may lessen the effectiveness of these routine odor control operations.

What causes these odors?

Most of the odors detected in and around wastewater treatment plants are signals that nature’s treatment process is working; organic matter is decomposing and pollutants are being removed from the wastewater.

As the table Odorous Compounds in Wastewater shows, major odorous compounds naturally occurring in the treatment process, hydrogen sulfide, amines and mercaptans, are detectable by the human nose at extremely low concentrations.

Were it not for odor control measures, all wastewater treatment processes are capable of emitting odors.

Several steps in the wastewater treatment process are notorious for emitting odors.  At the South Central Regional Wastewater Treatment Plant (SCRWWTP) these areas are described below and their general locations shown on the aerial photo of the treatment plant area shown below:

  1. The headworks influent building is where wastewater first enters the plant after traveling many miles in the sanitary sewer mains.  At this site raw wastewater is exposed to the air on its way to the downstream treatment processes. This process emits hydrogen sulfide compounds that have a rotten egg odor.

  2. Wastewater undergoing aerobic digestion (decomposition with free oxygen) in the aeration basins emits a characteristically musty odor due to the particular type of biogases released in the process.

  3. Sludge dewatering machines help to thicken the sludge.

  4. Sludge that is stored on site in trailers and kept in a storage building. Hydrogen sulfide h2s will continue to off gas until the trailer is hauled to an approved site to be pelletized. SCRWWTP will be running a pilot program to test a chemical in an attempt to control some of this type of odor March or April 2015.

What can I do if I smell an odor I think is coming from the plant?

You may call our service number, 561-272-7061 , to inform the staff you detect an odor.  The plant staff will ask you for the following information:

  1. Your name, address, and phone number;

  2. Information about the odor; such as, what time you noticed it, is it still noticeable, a description of the odor (refer to the Odorous Compounds in Wastewater table) and how strong is the odor.

What happens when the SCRWWTP receives an odor complaint?

Plant personnel receiving the call will record all of the complainant’s information described above; as well as, temperature, humidity, weather conditions, wind velocity, and wind direction.

All of the information combined helps us determine if the odor is from the SCRWWTP or from elsewhere.

If it is determined to becoming from the plant site, this information will help direct the operators’ investigation to a likely location.  Operators will check all of the odor control equipment for proper operation.  These response tasks are recorded in the SCRWWTP Operations Daily Log and the information is passed on to the next shift and supervisor.  Whenever possible we send a staff person to the complainant’s site to see if the odor is still present.