Vast amounts of valuable energy, nutrients, water lost in world's fast-rising wastewater streams

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Vast amounts of valuable energy, nutrients, water lost in world's fast-rising wastewater streams

Vast amounts of valuable energy, nutrients, water lost in world's fast-rising wastewater streams

Annual volumes of wastewater produced per capita across regions; calculated as a function of volumes of urban wastewater production in 2015 and the urban population in the same year in each region. The world average is based on the total amount of urban wastewater produced and the urban population at the global level in 2015 Credit: UNU-INWEH

Vast amounts of valuable energy, agricultural nutrients, and water could potentially be recovered from the world's fast-rising volume of municipal wastewater, according to a new study by UN University's Canadian-based Institute for Water, Environment and Health (UNU-INWEH).

Today, some 380 billion cubic meters (m3 = 1000 litres) of wastewater are produced annually worldwide—5 times the amount of water passing over Niagara Falls annually—enough to fill Africa's Lake Victoria in roughly seven years, Lake Ontario in four, and Lake Geneva in less than three months.

Furthermore, the paper says, wastewater volumes are increasing quickly, with a projected rise of roughly 24% by 2030, 51% by 2050.

Today, the volume of wastewater roughly equals the annual discharge from the Ganges River in India. By the mid-2030s, it will roughly equal the annual volume flowing through the St. Lawrence River, which drains North America's five Great Lakes.

Among major nutrients, 16.6 million metric tonnes of nitrogen are embedded in wastewater produced worldwide annually, together with 3 million metric tonnes of phosphorus and 6.3 million metric tonnes of potassium. Theoretically, full recovery of these nutrients from wastewater could offset 13.4% of global agricultural demand for them.

Beyond the economic gains of recovering these nutrients are critical environmental benefits such as minimizing eutrophication—the phenomenon of excess nutrients in a body of water causing dense plant growth and aquatic animal deaths due to lack of oxygen.

The energy embedded in wastewater, meanwhile, could provide electricity to 158 million households—roughly the number of households in the USA and Mexico combined.

The study's estimates and projections are based on theoretical amounts of water, nutrients, and energy that exist in the reported municipal wastewater produced worldwide annually.

Among many findings:

SOURCE PHY.ORG by UN University Institute for Water, Environment and Health

This is a paid article available on Wiley https://onlinelibrary.wiley.com/doi/abs/10.1111/1477-8947.12187

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