The first global assessment of the role ecosystems play in providing sanitation found that nature provides at least 18% of sanitation services in 48 cities around the world, according to researchers in the UK and India. The study was published in the journal on February 19 One earthIt is estimated that more than 2 million cubic meters of human waste in cities is processed every year without technical infrastructure. This includes pit latrine debris that gradually filters through the soil – a natural process that cleans it before it reaches the groundwater.
"Nature can and does play the role of sanitation," said Alison Parker, senior lecturer in international water and sanitation at Cranfield University in the UK and one of the study's authors. "While we do not marginalize the critical role of technical infrastructure, we believe that a better understanding of the interaction between technical and natural infrastructure can enable adaptive design and management, reduce costs, improve effectiveness, sustainability and ensure the survival of these areas." Country."
The wastewater treatment infrastructure that converts human feces into harmless products is an important tool for global human health. More than 25% of the world's population had no access to basic sanitation in 2017, and a further 14% used toilets where waste was disposed of on site. While some of this waste can be dangerous to local populations, previous research has shown that natural wetlands and mangroves, for example, provide effective treatment services. The Navikubo Wetlands in Uganda processes untreated wastewater from more than 100,000 households, protecting Murchison Bay and Lake Victoria from harmful pollution, while the U.S. coastal wetlands in the Gulf of Mexico are removing nitrogen from the Mississippi.
"We realized that nature needs sanitation because so many people in the world don't have access to technical infrastructures like sewers," added Simon Willcock, senior lecturer in environmental geography at Bangor University in the UK and another author on the study . "But the role for nature has largely not been recognized."
To better understand how natural ecosystems process waste, the team at Bangor University, Cranfield University, Durham University, University of Gloucestershire, University of Hyderabad (India) and Fresh Water Action Network, South Asia quantified the services of Sanitary ecosystems in 48 cities of approximately 82 million people use Excreta flowcharts, which use a combination of face-to-face interviews, informal and formal observations, and direct field measurements to document how human feces flow through a city. Researchers evaluated all of the charts available December 17, 2018, and focused on those encoded as "undischarged fecal sludge" (FSCNE), where the litter is contained in an underground pit latrine or septic tank but does not represent any Groundwater hazard, for example, because the groundwater level is too low.
Willcock and colleagues conservatively estimate that nature in these 48 cities processes 2.2 million cubic meters of human waste annually. With more than 892 million people around the world using similar toilets for on-site disposal, nature estimates that around 41.7 million tons of human waste are remediated each year before the liquid reaches the groundwater – a service valued at approximately US 4.4 billion Dollars per year. However, the authors note that these estimates are likely to underestimate the real value of ecosystem services to sanitation, as natural processes can contribute to other forms of wastewater treatment, although these are harder to quantify.
Willcock and colleagues hope their results will shed light on an important, but often unacknowledged, contribution nature has made to many people's daily lives and promote the protection of ecosystems such as wetlands that protect downstream communities from wastewater pollutants.
"We want to encourage better collaboration between ecologists, sanitation practitioners, and urban planners to balance nature and infrastructure and to protect nature where it provides sanitation services," said Parker.
This work was prepared as part of the ESRC and ICSSR funded Rurality project as a vehicle for the Urban Transformation Sanitation (RUST) project.
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