From A Farewell to Alms:
One crucial economic problem for hygiene in preindustrial Europe was that human waste had little or no market value, because it was not socially acceptable to use it as the valuable fertilizer it was for farm and garden purposes. As Alan Macfarlane notes, "where in Japan, night soil could be used in lieu of rent, in England one had to pay to have it taken away." Its disposal was thus a major social problem in Europe. Samuel Pepys, for example, complains in his diary in October 1660 that "Going down to my cellar ... I put my feet into a great heap of turds, by which I find that Mr. Turner's house of office is full and comes into my cellar." Neighbors' overflowing turds were apparently nothing more than an everyday nuisance in seventeenth-century London.That is amazing that in Japan night soil could be used in lieu (or should that be "in loo", heh) of rent.
In contrast in China and Japan human waste, urine as well as feces, was a valuable property which householders sold to farmers, and which various groups competed for the right to collect. Waste was not dumped into cesspits, sewers, and streams, contaminating water supplies. Instead in cities such as 18th century Osaka contractors found it profitable even to provide public containers on street corners in order to profit from the waste deposits. In China and Japan the waste also seems to have been carried away daily, as opposed to being stored in cesspits below houses which were only periodically emptied.
Human waste poses danger as a fertilizer, but the Japanese at least, aware of this, stored the waste in pits and tubs for months before use, allowing fermentation the time to destroy many of the infectious organisms.
I am now fascinated by the economics of human waste. I wonder how much a person in Japan got for their night soil? Was it really enough to pay for all of the rent? Somehow I don't think so. But, apparently it was enough to keep the streets clean.
I wonder how the numbers would look today. Could you make a profitable enterprise out of this in one of the 3rd world slum cities today? Has artificial fertilizer become so cheap that this business no longer makes sense? Are their enough farmers within a close enough radius that you could distribute to them economically? Do the pharmaceutical products that modern people take impact the quality of the fertilizer? If you did use humanure, could you still sell your produce as organic?
If you could clean up the slums, remove the costs of a sewer system, and at the same time increase the yield of farmers, this seems like a good thing to do.
Since my dream of being a cow fart tycoon has come to an end, I think I might have to replace it with being a humanure tycoon. I've got my tagline ready to go: Turning honey buckets into money buckets.