The past, present and future of poo
In Osaka, Japan, in the early 1700s, neighboring villages were competing for the rights to the excrement of the townspeople. Much of Japan’s soil, sandy and nutrient poor, produced poor crops and was home to few animals, so farmers depended on human fertilizers to grow food. And they were willing to pay for it. Often in exchange for a fee paid to each household, farmers collected at regular intervals what was called night soil to make fertile compost. Poop was precious. defecating at a friend’s house was considered an act of generosity, a gift. Landlords earned additional income by retaining tenant collection rights: often, the larger the household, the lower the rent. As the city of Osaka grew, the value of residents’ waste also increased, until prices reached such extreme levels in the early 1700s that some desperate farmers decided to steal it, despite a potential prison sentence.
About a hundred years later, the Thames in London was choked with human and animal waste, emitting harmful methane, ammonia and a rotten egg smell of hydrogen sulfide. Apparently more sewage than water, the banks of the river swelled with garbage, hampering shipping and making life miserable for many Londoners. Eventually forced to act, city officials hired boats to haul the sludge out to sea and dump it – at an approximate cost of one million pounds, or more than $ 170 million in today’s US dollars. .
Why are these human excrement stories so different? The key, according to science journalist Lina Zeldovich in “The other dark matter: science and business transforming waste into wealth and health” is that one culture viewed poo as waste, the other as treasure.
With a lot of flat land and rich soil, the British could afford to dump their droppings, and they did. With no invertebrates and microbes in the dirt that turn manure into harmless compost, Londoners’ droppings spilled into the river and became infected. And when the crop depleted the soil, British farmers simply plowed another square. But Japanese farmers couldn’t. The limited land and livestock required replenishing the soil with nitrogen, phosphorus, and other nutrients, all of which are present in poop. So the droppings were recycled into the same soil that created the food they came from.
Inspired by childhood memories where she saw her grandfather turning septic waste into garden compost in Russia, Zeldovich takes readers on a historical tour of human sanitation, then positions ideas and practices from the past in the present. Sanitation’s challenges for health, the environment and the economy have increased globally, and the book shines a spotlight on entrepreneurs working to address these issues. Its final section describes the relatively recent discovery of the human microbiome and the lifesaving role of poo in human health. Throughout the book, the reader urges the reader to reexamine our understanding of human waste.
“We may think that we have solved the excreta problem in the western world with our huge sewage treatment plants,” writes Zeldovich. “But the bitter truth is that we only solved one problem: making sure our feces no longer endanger our health.”
Today, argues Zeldovich, we find ourselves at the intersection of Japan’s needs and Britain’s glut. The increased demand for food deprives our soil of nitrogen and other nutrients, while wastewater pollutes the land and water. We continue to view poop as waste and ignore its value at our peril – creating a ‘time bomb’ that perpetuates a broken cycle of dirt, food and fertilizer.
The closed cycle of the old Japanese system, where waste is buried in the ground, is not as pervasive in farmland today. In cities and countries without water treatment facilities, feces can accumulate in waterways and even in people’s backyards. “The World Health Organization (WHO) estimates that 2.4 billion people on this planet still do not have access to basic toilets, and that nearly a billion are still heading for the bush,” notes Zeldovich.
Modern wastewater treatment removes pathogens but often leaves nitrogen, phosphorus and minerals. Centuries ago, farmers were forced to put trash back into their fields as the soil became depleted, but in the early 1900s German scientists Fritz Haber and Carl Bosch discovered a way to extract the nitrogen from the air to produce synthetic fertilizers. Easy to transport, less odorous and efficient, synthetic fertilizer quickly replaces poop.
In China, one of the world’s largest consumers of fertilizers, about “80 percent of the nitrogen in Chinese bodies now comes from foods produced using chemical fertilizers,” writes Zeldovich. Nutrients in dung in China and most other industrialized countries do not always return to the fields. Instead, excess nitrogen and phosphorus is released into the water where it creates algae blooms and destroys marshes.
One of these marshes is on a pond near the Quashnet River on Cape Cod. A model of nitrogen glut, its “collapsing banks are so slippery that you have to be careful not to fall into the foul-smelling water, which looks dark blue and opaque like ink,” writes Zeldovich.
Not that long ago, scientists thought swamps were endless sponges, able to recycle as much nitrogen as we could pump into them by simply growing more plants. We now know that with enough pollution, marsh plants grow shallow roots, banks erode, microbial communities turn sour, fish and crabs die and, as Zeldovich notes, “when they are pushed to the edge of the abyss, marshes can “tip over”, transforming from carbon sinks to carbon sinks. carbon emitters – accelerating the terrible cycle of warming and all the evils that go with it. “
Fortunately, there is no shortage of potential solutions. One is Loowatt, a small startup that started out in the Madagascan capital of Antananavrio, also known as Tana, which turns excrement into energy and fertilizer. Sanitation is an urgent problem in Tana, where latrines are holes dug in the ground. After frequent rains, writes Zeldovich, “the dirt rises to the edge and then slowly sinks, seeping into courtyards, streets and people’s living rooms.”
To prevent flooding, Loowatt provides special toilets – for a monthly or pay-per-use fee – that wrap the disposals in biodegradable plastic. Employees collect the poop-filled bags and deliver them to a processing facility, where the bags are broken and chewed by machines, the sludge is mixed with food waste and heated to kill pathogens, and bacteria convert the mixture into biogas and fertilizer.
Loowatt uses its energy generated from biogas to pasteurize sludge, and toilet biodigesters help charge customers’ phones. The fledgling company converts the emissions of 1,000 people into approximately 6 metric tonnes (over 13,000 pounds) of liquid fertilizer per month, with the ambition of becoming the primary supplier of sanitation for the 1.2 million city residents within five to 10 years. Loowatt toilets are already in use in the UK at festivals and other outdoor venues.
On a larger scale, the Newtown Creek wastewater treatment plant in Brooklyn, New York, “serves approximately 1 million people, [and] generates 2 million cubic feet of biogas every day, ”the book notes, while in Washington, DC, the city’s wastewater treatment plant turns the contributions of 2.2 million people into Class A fertilizer which is sold in stores.
Scientists in the Pacific Northwest are working to turn Vancouver city crap into biofuel. When a program to convert algae to oil fell flat over the cost, scientists turned to cheap and plentiful sewage sludge. Unlike fertilizers that have to be transported to farms, “gasoline derived from poop does not have to travel anywhere. It can be used right next to its original source …” writes Zeldovich.
The final section of the book details the use of human waste as a diagnostic tool in medicine, including the fascinating science and history of fecal transplants and how one patient’s passionate speech changed the FDA’s trajectory for regulations.
It would be easy for a book that focuses on the barriers to improving global sanitation, repairing the agricultural waste cycle, reducing pollution and improving health to resort to a gloom. crippling. “The Other Dark Matter” does not shy away from the enormity of the problems, but suggests that solutions are achievable, on the scale of individuals to entire countries. Punctuated quickly by prose animated by the on-site reporting and personal experiences of the author, the book is far from a grim chore through the sewers of the world – it’s more like a thrilling tour in a balloon fueled by water. biogas.
“The moving bowels are a great common ground of equalization that unites humanity regardless of ethnicity, color, religion, diet or tradition,” writes Zeldovich.
“Maybe this generation will not be ashamed of its organic power,” she adds. “They won’t consider it a waste.”
Jenny Morber works as a freelance science journalist on an island near Seattle. His work has appeared in Popular Science, Discover, Glamor, and National Geographic, among other publications.