The Past, Present, and Future of Poop

Top: “The Silent Highway – Man,” an 1858 cartoon from Punch magazine showing Death rowing the waters of the River Thames, which were choked with human and animal excrement. Visual: The Cartoon Collector/Print Collector/Getty Images


IN OSAKA, JAPAN, in the early-1700s, neighboring villages fought over rights to city residents’ excrement. Much of Japan’s soil, sandy and poor in nutrients, produced feeble crops and supported few animals, so farmers depended on human fertilizer to grow food. And they were willing to pay for it. Often in exchange for a fee paid to each household, farmers collected what was called night soil at regular intervals to fashion into fertile compost. Poop was precious. Defecating at a friend’s house was considered an act of generosity — a gift. Landlords earned extra income by retaining collection rights from tenants: Often the bigger the household, the lower the rent. As the city of Osaka grew, so did the value of residents’ waste, until prices climbed to such extremes in the early 1700s that some desperate farmers resorted to stealing it, despite potential prison time.

Roughly a hundred years later, London’s River Thames was choked with human and animal waste, emitting noxious methane, ammonia, and the rotten egg smell of hydrogen sulfide. Seemingly more sewage than water, the river’s banks swelled with refuse, interfering with marine navigation and making life miserable for many Londoners. Finally compelled to act, city authorities contracted boats to carry the sludge out to sea and dump it — at the approximate cost of a million pounds, or more than $170 million in today’s U.S. dollars.

Why are these stories of human excrement so different? The key, according to science journalist Lina Zeldovich in “The Other Dark Matter: The Science and Business of Turning Waste into Wealth and Health,” is that one culture regarded poop as trash, the other as treasure.

With plenty of flat land and rich soil, the British could afford to chuck out their excreta, and so they did. In the absence of the invertebrates and microbes in dirt that transform dung into harmless compost, Londoners’ excrement flowed to the river and festered. And when cultivation exhausted the soil, British farmers simply tilled another square. But Japanese farmers could not. Limited land and livestock necessitated soil replenishment with nitrogen, phosphorus, and other nutrients — all of which are present in poop. So excrement was recycled into the same ground that created the food it came from.

Inspired by childhood memories of watching her grandfather turn septic waste into garden compost in Russia, Zeldovich takes readers on a historical tour of human sanitation, then positions the ideas and practices of the past in the present. Sanitation challenges to health, the environment, and the economy have grown globally, and the book highlights entrepreneurs working to solve these problems. Its last section describes the relatively recent discovery of the human microbiome and poop’s life-saving role in human health. Throughout, the book presses the reader to reexamine how we understand human waste.

“We may think that we have solved the excrement problem in the Western world with our massive sewage plants,” writes Zeldovich. “But the bitter truth is that we have solved only one problem — ensuring that our excrement no longer endangers our health.”

Today, Zeldovich argues, we find ourselves at the intersection of Japan’s need and Britain’s overabundance. Increasing food demand strips our soil of nitrogen and other nutrients, while sewage pollutes land and water. We continue to frame poop as waste and ignore its value at our peril — creating a “ticking time bomb” that perpetuates a broken cycle of dirt, food, and fertilizer.

The closed cycle of the old Japanese system, in which waste is plowed back into soil, is not as ubiquitous in today’s farmlands. In towns and countries without water treatment facilities, excrement can accumulate in streams and even people’s yards. “The World Health Organization (WHO) estimates that 2.4 billion people on this planet still lack access to basic toilet facilities, and that nearly 1 billion still head for the bush,” Zeldovich notes.

Modern sewage treatment removes pathogens but often leaves nitrogen, phosphorous, and minerals. Centuries ago farmers were forced to add waste back into their fields as soil became depleted, but in the early 1900s German scientists Fritz Haber and Carl Bosch discovered a way to pull nitrogen from the air to produce synthetic fertilizer. Easy to transport, less smelly, and effective, synthetic fertilizer quickly replaced poop.

“We may think that we have solved the excrement problem in the Western world with our massive sewage plants,” writes Zeldovich. “But the bitter truth is that we have solved only one problem — ensuring that our excrement no longer endangers our health.”

In China, one of the largest global fertilizer consumers, about “80 percent of the nitrogen in Chinese bodies now comes from food produced with the aid of chemical fertilizers,” Zeldovich writes…


F. Kaskais Web Guru

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