What Stinks?

Often United-Tech is asked if our products can address a particular odor problem.  Most often the answer is, “Yes!”  To understand how, we must first address the question, “What are odors anyways?

Odors, like tastes, are a result of a stimulation of receptor cells in your body.  These stimuli are chemicals and thus odor is sometimes referred to as a “chemical sense”.  In humans, the system involved is the olfactory system with receptors located in the nasal cavity that allow us to detect (smell) the odorants.  These, along with our taste receptors on our tongue (gustatory system) combine to come up with flavor(s).  That cheeseburger ‘tastes’ good not just because your taste buds are detecting salt, sweet, sour, and umami (all signals to your body that this is good for your survival) but also because your olfactory system recognizes certain chemicals in the air that represent pleasure to you.  Grab that cheeseburger after it has been sitting on the counter for a few days and your olfactory system may warn you otherwise.  Your brain senses ‘danger’ chemicals.

There is a lot of science and industry involved in the ‘good odor’ business, food and fragrances being dominant.  But there is also the other side of the coin, dealing with ‘bad odors’, maybe not so much in creating them, but getting rid of them.  In order to do this, one has to first know what chemicals (odorants) trigger the olfactory sensors in our nose that indicates something is “Stinky” Just as beauty is in the eye of the beholder, what is determined to be good or bad odors is subjective.  But for many industries such as manufacturing, agriculture, or wastewater there are some common chemicals whose presence is considered unwanted.

Below you will find a short list of odorants and associated characteristics, often found to be concerns in odor-reduction situations.  A few even have descriptive names that offer hints towards the nature of their odor like Cadaverine, Putrescine, and Skatole.

Odorant Characteristics
Acetaldehyde Pungent, fruity
Allyl mercaptan Strong garlic
Ammonia Sharp, pungent, prickly
Amyl mercaptan Putrid
Butylamine Sour, ammonia-like
Cadaverine Putrid, decaying flesh
Chlorophenol Medicinal, phenolic
Crotyl mercaptan Skunk-like
Dibutylamine Fishy
Dimethylamine Putrid, fishy
Dimethyl sulfide Decaying vegetables
Ethyl mercaptan Rotting cabbage
Hydrogen sulfide Rotten eggs
Indole Fecal, nauseating
Methylamine Putrid, decomposing fish
Methyl mercaptan Rotting cabbage
Putrescine Putrid, nauseating
Skatole Fecal, nauseating
Sulfur dioxide Pungent, irritating
Tert butylsulfide Skunk-like
Thiocresol Skunk-like, rancid
Triethylamine Ammonia-like, fishy


So what can we do about these odiferous chemicals?  First of all, we need to recognize that these chemicals are classified as Volatile Organic Compounds (VOCs) Volatile Fatty Acids (VFAs) or various inorganic compounds and gases such as ammonia, sulfur dioxide, and hydrogen sulfide created from the bio-degradation of organic compounds.

Our bacteria utilize the VOCs and VFAs as a food source.  They use the organic carbon for cellular growth and for energy under aerobic (available free oxygen) and anaerobic conditions.  That’s half the story.  Our bacteria can also help prevent the formation of these VOCs and VFAs by reducing organic solids buildup.   This also helps reduce the formation of inorganic compounds and gases like ammonia and hydrogen sulfide created by undesirable biological pathways that occur in ‘dirtier’ conditions.