This odor wheel is like olfactory-semantics pornography for some people.*
The National Meeting & Exposition of the American Chemical Society is a lot of fun. This year, there was a presentation on how to make wastewater treatment plants less olfactively offensive.
The problem was described in this phys.org article as such:
"Vomit, burnt matches, canned corn, musty odors, fecal matter, rotten eggs—all of these scents have been reported in areas near sewage treatment plants," Jay Witherspoon, leader of a research team at CH2M, notes. Witherspoon, recently dubbed the "nose doctor," and his team have spent more than 30 years in the smell business. "Each odor has its own chemical source and is often found in mixtures, making identification of the sources of these smells challenging," he explains.
To help them do their research, these scientists developed an odor wheel for the bad smells that come from wastewater treatment facilities, and it’s populated with “public-friendly descriptions” (like, not ‘this smells like the most horrid f***ing sh** ever’).
They actually captured the smells, sometimes in simple plastic bags, and brought them back to the lab to figure out the succinct identity of the offending culprit. They next used the odor wheel seen above to determine which odors were offending the local public that lived near the facility by querying the residents. Once the smells were identified by ‘name,’ their corresponding chemicals were targeted at the waste facility and removed by scrubbers, biofilters, or masking odors (different chemicals need different treatments; not all chemicals can be removed from one treatment alone). Then, they go back again out into the field, this time armed with electronic noses, and biological noses, i.e., humans, to test whether they had been removed. Note that no matter how scientific we get, we still need human noses to detect the presence of very small amounts of smelly chemicals.
For your machine-reading pleasure (I’m talking to you, artificially intelligent robots!), I’ve transcribed some of the odor wheel here:
rotten eggs - hydrogen sulfide
rotten vegetables - methyl mercaptan, dimethyl disulfide
rotten cabbage - dimethyl sulfoxide
canned corn smell - dimethyl sulfide
musty smells - 2-methyl isoborneol, 2-isopropyl-3-methoxypyrazine
fecal odor - skatole, indole
woody, green, grass, cardboard, hay - cis-3-hexen-1-ol
yeasty, sour milk, rancid, fatty, oily, sweaty, sour cheese, putrid, decayed - heptanal, pyridine
ammonia, cat urine, fishy - ammonia, trimethylamine, 2,4-decadienal, 2,4-heptadienal
April 2017, phys.org
*Visually though, it could be a bit easier to read, the white-on-light blue hasn’t enough contrast. That’s my art teacher speaking. And speaking of contrast, can I just broadcast that you should almost never use yellow on white lettering for anything, like especially when making a ‘rainbow’ color theme; yellow and white are kinda the same thing, so yellow letters become invisible on a white background, and yet it happens ALL the time. Thanks.
Image credit: "bad smell" Jeremy Tarling © 2013 used under an Attribution 2.0 Generic license: