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James Elser hopes phosphate recycling can solve two environmental problems

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ASU Regents' Professor Jim Elser awaits sunrise near the glacial lake beneath the peaks of Torres del Paine National Park in Chilean Patagonia. (Photo: James Elser)

Growing up sailing on a lake near his Connecticut home, AAAS fellow and biogeochemical limnologist James Elser dreamed of a career that would let him work in the great outdoors. But it wasn't until he took a summer field course and discovered liminology, a whole science devoted to lakes and the things that live in them, that he knew where to set sail.

In more than 20 years of highly diversified research on subjects from biological stoichiometry—the study of energy balance of chemical elements in living things—to interdisciplinary astrobiological exploration, Elser has visited and conducted fieldwork in over 20 different countries, from Argentina to Norway—much of it concentrated on sustainability issues. He has learned to adapt to changing field conditions, including improvising his lab in hotel bathtubs and farmhouses. 

No matter which country Elser worked in, he began seeing the same problem affecting his beloved lakes: excess phosphorous. Both a nutrient and a pollutant, phosphorus is used heavily to fertilize crops, where it is absorbed and enters the sewage system as unused food and human waste. High phosphorus levels in sewage enter the water system, causing nitrification of estuaries, algae blooms, fish kills and dead zones.

Unwilling to merely document this growing crisis, Elser decided to try to do something to raise awareness of the unbalanced human phosphorous cycle. He founded Arizona State University's Sustainable Phosphorus Initiative and organized the First Sustainable Phosphorus Summit in 2011, in order to publicize the need to close the human phosphorus cycle.

"By developing robust phosphorous recycling practices, sewage can be treated and the phosphorous removed, so it cannot contaminate lakes. Advanced wastewater treatment plants capture the phosphorus and it is usually disposed of in landfill. So, this phosphorus does not reach receiving waters," Elser says. 

While advanced, or tertiary, plants that remove phosphorous are in place in more than 85 percent of European wastewater facilities, they account for just 30 to 40 percent of U.S. plants, he said.

Removing phosphorous is just half the equation, however. Another environmental cost is the scarcity and expense of mining new phosphorous.

"Phosphorus mines are relatively sparse around [the] globe and are under control of a few countries, who are driving up prices," Elser notes, adding that the cost of phosphorous fertilizers are "incompatible with a sustainable food system, given the narrow budgets farmers operate within."

Additionally, Elser says, "This is especially problematic, because, to achieve food security, there must be a doubling of food production in the next two or three decades."

Elser and colleagues are busy developing methods by which these two phosphorus problems can combine to possibly cancel each other out.

One method involves the recovery of phosphate from struvite—a mineral present in sewage that contains elements of ammonium, phosphate and magnesium. The production of struvite through sewage recycling has long been considered too expensive, but Elser says it could become more cost-effective than mining new phosphorus.

While most people are currently more concerned about the presence of phosphorus as a water pollutant, "once its resale value increases, phosphorus recycling will become economically viable and more attractive," Elser notes. "Closing the human phosphorus, or P, cycle will require increased public awareness, technological innovation, and governmental cooperation."

Looking ahead, Elser says the public will have to realize water is its most important resource. "Fresh water is perhaps the most precious thing we have, perhaps even more precious than food," he says. "A lot of people have an appreciation for food quality, but a lackadaisical approach to water. People [should] know where their water comes from, going back to where on the planet the raindrop fell," Elser says.

Author

Lara Herrington Watson

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