What do dog poo, human urine and the digestive juices of worms have in common?
Once upon a time, dog faeces were collected as ‘pure’ and used to tan leather. And if I haven’t already put you off your lunch, it seems that it was not just random poop-scooping, which apparently meant the pure-finders had a pretty good income:
The ‘dry limy–looking sort’ fetches the highest price at some yards as it is found to possess more of the alkaline or purifying properties; but others are found to prefer the dark moist quality.
Human urine was used as a colour fixer for fabrics, to kill lice in clothing and, believe it or not, as an ingredient in cheese- and bread making. It is still used, um, informally by gardeners as a compost accelerant. If you want more uses for pee, check out the amusing book Liquid Gold by Carol Steinfeld.
Worms have great digestive juices and earthworm enzymes have been used to dissolve blood clots and prevent cardiovascular disease in Hong Kong, Japan, Korea, and China. The Zero Emissions Research Initiative (ZERI) harvests them to make detergents.
Feel yourself going ‘ugh’ yet? Well it is the very properties of these substances that make you recoil that make them useful in the first place. Back in pre-industrial days, you didn’t have much choice but to use what was to hand and there was no place for squeamishness.
This mentality – of seeing ‘problem’ qualities as opportunities – is essential for the uptake of industrial symbiosis (one company’s waste becoming another’s raw material) and to develop a circular economy. If you have, say, an acidic waste stream, the question you should be asking is not “how do we neutralise this?”, but “who needs an acid?”
In other words, get over it!