With so much global wastewater treated, rates in developing countries continue to decline

A new study by scientists at Utrecht University and the United Nations University concludes that about half of the world’s wastewater is treated, instead of the previous estimate of 20%. Despite this promising finding, the authors warn that treatment rates in developing countries remain very low. The study and the database Open Access were published in the journal Earth system science data.

People and factories make a lot of waste water every day. If not collected and treated properly, wastewater can pose a serious threat to human health and pollution of the environment.

144 million swimming pools

The authors use national statistics to estimate the volumes of wastewater production, collection, treatment and reuse. “Globally, approximately 359 billion cubic meters of wastewater is discharged annually, equivalent to 144 million Olympic swimming pools,” said Edward Jones, PhD researcher at Utrecht University and lead author of the inspection. “About 48 percent of that water is currently released untreated. This is much lower than the commonly quoted figure of 80 percent.”

Although the results show a more optimistic outlook compared to previous work, the authors confirm that many challenges remain. “Especially we see in the developing world, where most of the future growth will take place, that treatment rates are lagging behind,” Jones said. In these countries in particular, wastewater production is likely to rise at a faster pace than conventional development of collection infrastructure and treatment facilities. This poses a significant threat to human health and the environment. There is still a long way to go! ”

Creative reuse

The main problem, especially in the developing world, is the lack of financial resources to build infrastructure to collect and treat wastewater. This is especially true for advanced handling technologies, which can be too costly. However, the authors highlight potential opportunities for creative reuse of wastewater streams that could help fund better wastewater treatment practices.

“The most obvious reuse of wasted water is by adding to freshwater water supply,” Jones says. Wastewater reuse is already an important source of irrigation water in many arid countries, especially in the Middle East and North Africa. However, only 11% of the global wastewater generated is currently reused, which represents great opportunities for expansion.

From ‘trash’ to utility

“But rising freshwater is not the only opportunity,” Jones said. “Wastewater also has great potential as a source of nutrients and energy. The identification of wastewater as a resource, rather than as ‘waste’, will be critical in driving better treatment going forward.”

However, the authors stress the importance of proper inspection of wastewater treatment plants, accompanied by strong legislation and regulations, to ensure the safe reuse of wastewater. The authors also acknowledge the public’s acceptance as another major barrier to increasing wastewater reuse.

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The data and the related journal article are freely available through PANGEA and Earth system science data), separately.