Amid growing competition for freshwater from industry and cities, coupled with a rising world shortage of potash, nitrogen and phosphorus, an international study predicts a rapid increase in the use of treated wastewater for farming and other purposes worldwide.
However, research shows that treated wastewater -- comparable in North America alone to the volume of water flowing over Niagara Falls -- is mostly unused and, in many nations, not even quantified.
Of 181 countries studied, only 55 have information on three key aspects of wastewater: generation, treatment, and reuse. Another 69 countries have data on one or two aspects, 57 countries show no information on any aspect.
As well, in countries where data does exist it is mostly outdated: almost two-thirds (63%) of the numbers are five or more years old, according to the study led by Japan's Tottori University and the United Nations University's Canadian-based Institute for Water, Environment and Health (UNU-INWEH).
As water supplies fall and stress rises in many areas, the potential resource of wastewater is being widely recognized, says the study published Sept. 5 by Elsevier journal Agricultural Water Management. Water demands already exceed supplies in regions with more than 40% of the world's population and in just 12 years as much as 60% of the world's people may confront water scarcity.
Synthesizing what data there are on wastewater treatment, the study shows that, on average, high-income countries treat 70% of the generated wastewater, upper-middle-income countries treat 38%, lower-middle-income countries treat 28%. Just 8% of wastewater generated in low-income countries undergoes any kind of treatment.
In North America, of the estimated 85 cubic kilometers of wastewater generated each year, 61 cubic kilometers (75%) is treated. (A cubic kilometer is 1 trillion liters -- about 220 billion US gallons). Annually, however, just 2.3 cu
|Contact: Terry Collins|
United Nations University