Growing pile of human and animal waste harbors threats, opportunities

November 28, 2018 by Josh Brown, Georgia Institute of Technology
While chickens were the most plentiful livestock globally, cattle, with their larger body mass, produced the most fecal waste on the planet. As a result, countries with high numbers of cattle, such as those in the Americas, produced the most waste by mass. Credit: Ibra Osa

As demand for meat and dairy products increases across the world, much attention has landed on how livestock impact the environment, from land usage to greenhouse gas emissions.

Now researchers at Georgia Institute of Technology and the Centers for Disease Control and Prevention are highlighting another effect from raised for food and the humans who eat them: the waste they all leave behind.

In a paper published November 13 in Nature Sustainability, the put forth what they believe is the first global estimate of annual recoverable human and animal fecal biomass. In 2014, the most recent year with data, the number was 4.3 billion tons and growing, and waste from livestock outweighed that from humans five to one at the country level.

"Exposure to both human and animal waste represent a threat to public health, particularly in low-income areas of the world that may not have resources to implement the best management and sanitation practices," said Joe Brown, an assistant professor in Georgia Tech's School of Civil and Environmental Engineering. "But estimating the amount of recoverable feces in the world also highlights the enormous potential from a resource perspective."

Metals, phosphorus, nitrogen and potassium are all among the resources that could be recovered from human and animal waste. The researchers pointed to an earlier analysis that estimated the value of recoverable metals alone reaches $13 million a year from the waste of one million people.

The researchers looked at data from 2003 to 2014 as well as projections through 2030. The study combined global animal population data from the United Nations, human population data from the World Bank as well as earlier research on animal-specific estimates of fecal production.

The global amount of recoverable fecal waste harbors risks, such as water contamination, as well as opportunities to harvest natural resources. Georgia Tech Assistant Professor Joe Brown with (left) and Graduate Research Assistant Andy Loo. Credit: Gary Meek

From 2003 to 2014, the amount of waste biomatter produced grew annually by more than 57 million tons as both human and livestock populations grew. The researchers estimated that by 2030, the total amount of global fecal biomass produced each year would reach at least five billion tons, with livestock waste outweighing that from humans six to one at the country level.

"This paper demonstrates that building more latrines in developing parts of the world isn't going to solve all of our waste management problems," Brown said. "Animal waste has the potential to negatively impact health in many of the same ways as with human waste, from spreading enteric infections to hurting growth and cognitive development of the humans exposed."

While chickens were the most plentiful livestock globally, cattle, with their larger body mass, produced the most fecal waste on the planet. As a result, countries with high numbers of cattle, such as those in the Americas, produced the most waste by mass.

The researchers estimated that by 2030, the planet's total annual fecal and urinary biomass could contain as much as 100 million tons of phosphorus, 30 million tons of potassium, 18 million tons of calcium, and 5.5 million tons of magnesium, to name a few recoverable materials.

While much of the attention on reducing has focused through the decades on pathogens associated with , much less attention has been given to , the researchers wrote, despite livestock accounting for 80 percent of the global fecal biomass generated.

"Ultimately, shining a light on the amount of waste that we produce is the first step toward shaping policies and regional planning geared toward maximizing and resource recovery," Brown said. "This is an area where there's a huge need for attention and investment—to help develop next-generation management innovations, for both large-scale and small-scale animal husbandry operations, that will enable us to maximize human health and meet the global demand for natural resources."

Explore further: Scientists calculate impact of China's ban on plastic waste imports

More information: David M. Berendes et al, Estimation of global recoverable human and animal faecal biomass, Nature Sustainability (2018). DOI: 10.1038/s41893-018-0167-0

Related Stories

Paris, Tokyo, New York and others pledge to slash waste

August 28, 2018

By slashing food waste and improving waste management and recycling, 23 global cities and regions representing 150 million people pledged Tuesday to significantly cut the pollution-causing garbage they generate by 2030.

Pulling valuable metals from e-waste makes financial sense

April 4, 2018

Electronic waste—including discarded televisions, computers and mobile phones—is one of the fastest-growing waste categories worldwide. For years, recyclers have gleaned usable parts, including metals, from this waste ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...


Adjust slider to filter visible comments by rank

Display comments: newest first

Thorium Boy
1 / 5 (1) Nov 29, 2018
I'd say greenloons should lead by example and give up all meat, but if they did, they try to force it on everyone else.
Da Schneib
3 / 5 (2) Nov 29, 2018
A world of shiit.
not rated yet Nov 29, 2018
and if pony_biy & the atomic priesthood have anything to say about it? It will be glowing shit!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.