Millions of metric tons of human waste santized by nature annually

Cheryl Santa Maria
·2 min read
Millions of metric tons of human waste santized by nature annually
Millions of metric tons of human waste santized by nature annually

A global assessment estimates 41.7 million tons (about 38 million metric tons) of human waste are processed each year by nature, providing a free service estimated to cost $4.4 billion annually, according to a recent paper published in the journal One Earth.

Researchers looked at 48 cities containing 82 million people worldwide and found wetlands, mangroves, and other ecosystems effectively process untreated wastewater. That accounts for about 18 per cent of the sanitation services in the cities studied.

"Nature can, and does, take the role of sanitation infrastructure," Alison Parker, a senior lecturer in International Water and Sanitation at Cranfield University in the United Kingdom and one of the authors of the study said in a statement.

"While we are not marginalizing the vital role of engineered infrastructure, we believe a better understanding of how engineered and natural infrastructure interact may allow adaptive design and management, reducing costs, and improving effectiveness and sustainability, and safeguard the continued existence of these areas of land."

Wastewater treatment infrastructure is an integral component of modern society, working to reduce pollution and disease. But as of 2017, approximately 4.2 billion people did not have access to safely managed sanitation services. About 14 per cent of the global population uses toilets that dispose of waste onsite, the World Health Organization (WHO) says.

Nature-based sanitation services are especially important in these communities. The study's authors cite Uganda's Naviko wetland as an example, which absorbs wastewater from more than 100,000 households, protecting nearby Murchison Bay and Lake Victoria from contaminants.

In a statement, study author Simon Willcock, senior lecturer in Environmental Geography at Bangor University, said his team realized nature must be providing sanitation services in areas where there is no engineered infrastructure, "but the role for nature was largely unrecognized."

The study's authors hope the research helps highlight the importance of local ecosystems and the overlooked ways they impact daily life.

Thumbnail image courtesy Pexels/Skitterphoto.