Microbiologists might comprise the vast majority of people who get excited about sewage and other putrid-smelling places. A sample of activated sludge or a treatment pond make wonderful presents for bacteriologists and protistologists alike. The ickier, the better. Icky smells mean something’s there to create them, and more often than not, their creators are weird and fascinating. When something rots particularly intensely, the oxygen tends to get rapidly depleted — meaning mysterious organisms appear whom we don’t normally see. Oxygen is nasty, chemically-reactive, stuff, and exposure of defenseless, strictly anaerobic creatures to it results in obvious pain: the victims bloat, get gassy and generally explode in un-pretty ways. Thus, there are entire swaths of diversity we rarely encounter in our familiar poisonously oxygenated worlds. These diverse assemblages happen to be quite proficient in biochemistry, and thus produce a variety of products we may be unfamiliar with — including noxious-smelling gasses, such as methane and hydrogen sulfide. This is why it is usually easy to excite a biologist friend with a vial of particularly foul-scented liquid!
It’s also quite pretty. We’ll look at specific weird organisms some other time, but for now — a couple general views of a particularly dense mat from a sewage treatment pool. A prime tourist destination, hands down!
Perhaps the next time you encounter a putrid odour, think for a moment about its makers and their worlds alien to our oxygen-tuned smell receptors.