There could be 9.9 billion people in the world by 2050. Such a population explosion would strain many of the Earth’s resources — crops, water, timber, and more.

It would also force humanity to become extremely efficient at handling human waste.

Currently, the way humans manage feces disposal can be improved in some way almost everywhere.

For most people, toilets and sewage systems are readily available and the end-result of feces is out-of-sight. In this situation, waste can be better processed and recycled to minimize the environmental impact.

For 2.5 billion of the world’s most vulnerable, sanitation facilities are hard to come by, causing feces to become an unavoidable and hazardous problem of everyday life. In this situation, basic sanitation is the near-term goal.

But by 2050, every country should strive for a feces management system that has as little impact on the environment and human health as possible.

“When it comes to creating misery and poverty, human waste mismanagement has few rivals,” said Zafar Adeel, the director of United Nations University. “If we can demonstrate a simple, cost-effective new approach…we can enhance development, protect the environment and help reduce sanitation problems causing one-tenth of all world illnesses.”

The Worst Way to Deal With Shit

Open defecation is the worst form of waste management. This basically means humans shit outside in the open, usually in pits or directly into bodies of water.

This feces is never treated in a way that removes and minimizes pathogens, so it contaminates waterways and the soil, and it pollutes the air.

More than 200 million tons of human waste is untreated every year. Not all of this waste is a result of open defecation, but 90 percent of all sewage in the developing world is at some point emptied into lakes, rivers and oceans. Even in some areas with waste collection programs, the feces may stay untreated by the time it is released in waterways. 

In some places, this turns rivers and lakes into swamps festering with disease.

But since lack of sanitation is generally paired with lack of clean water, people living in these areas end up having to drink this contaminated water, which leads to widespread disease and death.

The second leading killer of children under the age of five is bacterial diarrhea contracted from contaminated water.

Ultimately, open defecation is both a cause and effect of poverty. It riddles people with debilitating diseases, preventing them from leading full, healthy lives, and it generally only affects people who are mired in poverty.  

The Best Ways to Deal With Shit

Humans have devised ingenious ways to handle their waste throughout time. And the modern sewage system — toilets connected to a vast network of pipes — is impressive in the way that it eliminates the immediate health risks of feces.

But not all waste that begins in a toilet is processed in a sustainable manner. Oftentimes, feces and other human waste is ultimately disgorged into oceans, huge pits, and other out-of-the-way spaces.

Sewage treatment plants are elaborate systems that involve physical, chemical, and biological processes to create environmentally safe wastewater and dewatered sludge. The treated byproducts can then be incinerated, disposed in a landfill, or used for agricultural purposes.

The best treatment systems manage to get a sustainable benefit from shit. The most common repurposing takes the form of fertilizer. After sewage is diluted, broken down, and treated to remove harmful pathogens, it can becomes a very effective and cheap form of fertilizer.

For years, fertilizer created from New York’s sewage system was shipped across the US to Colorado and led to an agricultural boom.

Elsewhere in the world, treated feces is used to directly irrigate fields.

Perhaps the most ingenious use of shit, however, is when it is turned into energy that can power electrical grids.

In Manchester, a fecal sludge processing plant uses “thermal hydrolysis” technology to generate enough clean energy to power 25,000 homes. The leftover waste is then used as a clean fertilizer.

Elsewhere in Britain, a public bus is powered by human waste.

In Grand Junction Colorado, renewable natural gas from human waste is used to power a fleet of 40 service vehicles, including garbage trucks, street sweepers, and transit buses.

In parts of Africa, a prototype of a waterless toilet that powers itself is being rolled out. Basically, the toilet separates and incinerates the waste, creating enough power to operate and having enough energy leftover for charging household appliances and mobile phones.

For more uses of fecal matter, check out this list!

The two extremes of how humans deal with shit couldn’t be farther apart. On the negative side, feces is a constant source of disease and contamination, holding people back in life. On the positive side, feces enables agriculture or is used as an energy source, allowing people to thrive.

Making sure that all humans are shielded from bad sanitation won't be easy, but it's fundamental to ending extreme poverty.