ASU expert to deliver call to action keynote on sustainability at Phosphorus Forum

Bruce Rittmann, director of the Biodesign Swette Center for Environmental Biotechnology at Arizona State University, is slated to be the keynote speaker at the Phosphorus Forum 2019 in Washington, D.C., on April 5. Rittmann will discuss “Minimizing P loss and Maximizing Value.”

The annual conference attracts scientists and NGOs focused on water quality issues, nutrient recovery technology companies, fertilizer manufacturers, food producers, water utilities, farm consultants, government regulators, agricultural suppliers and phosphate mining companies.

Matthew Scholz, the program manager of the Sustainable Phosphorus Alliance at ASU’s Julie Ann Wrigley Global Institute of Sustainability, and Jim Elser, the director of the Sustainable Phosphorus Alliance and professor in the School of Life Sciences, are orchestrating the forum.

Rittmann, also a Regents’ Professor in the ASU School of Sustainable Engineering and the Built Environment, was awarded the 2018 Stockholm Water Prize along with Mark van Loosdrecht for his pioneering work in environmental biotechnology. His presentation will be a call to arms, urging attendees to actively engage with solving issues related to the world’s use of phosphorus. 

In his keynote, Rittmann will present a new way of thinking about the world’s relationship with phosphorus and emerging threats from unsustainable practices for using it. He will draw from a paper written by leading experts in the field and published last year in Environmental Science and Technology. The paper, “Managing diffuse phosphorus at the source versus the sink,” discusses practical solutions to a phosphorus-centered problem: overfertilization of the world’s waters.

Phosphorus: Why should I care?

All life needs phosphorus. The human body contains about 1% of this mineral; it is found in the teeth, bones, DNA and cell walls. Phosphorus deficiency can cause heart disease, joint pain and fatigue. Phosphorus, combined with nitrogen and potassium, constitutes fertilizer, a substance vital for meeting the world’s food requirements. Researchers and their partners are looking for new and better ways to mine phosphorous.

Rittmann explains that phosphorus traditionally has been a major limiting factor for the productivity of plants.

“It is hard to pull the element from phosphate rock in the soil,” Rittmann said. “By utilizing mined and processed phosphorus in fertilizer, we are introducing easier access to the element.”

Morocco: Land of 'P'lenty 

Taking millions of years to form, phosphorus deposits are found in the Earth’s lithosphere. More than 70% of the world’s phosphorus supply is sourced in the Western Sahara, primarily in Morocco. The chalky, white substance is mined from sedimentary phosphate rock in the Earth’s crust.

As with all finite materials, source production will eventually peak, decline and then diminish to a deficiency. This concern about phosphorus mining occurred in the U.S. in the 1980s, according to the U.S. Geological Survey that now estimates that there is only a 30-year supply in the U.S. The U.S. now imports most of the phosphorus it needs for fertilizer. Currently, the U.S. depends heavily on phosphorous from the Western Sahara and we are at a potential sustainability risk in the future.

Although phosphorus is not currently in short supply, it will become progressively harder to access the element with our current methods. This will cause the cost to increase and therefore hinder access to it. In the near future, it will directly affect the supply of fertilizer and cause a downward spiral for global food security.

Rittmann travels annually to Morocco, where he is initiating a research project to find ways of using his membrane biofilm reactor to recover valuable elements in the wastewaters from phosphate-ore processing. 

The true phosphorus problem

The true problem of phosphorus sustainability is that most of the mined phosphorus ends up in the world’s waters. The agricultural industry tends to apply large volumes of fertilizer to guarantee high-yield crops. Today, people enjoy a variety of foods that were previously scarce due primarily to the generous use of fertilizers. One example is the year-round availability of out-of-season fruits and vegetables.

“We have worked out many excellent solutions for food security using phosphorus fertilizers, but now we have real concern about the resulting polluted waters,” Rittmann said.

In a tragedy of the commons, the quest for successful harvests often overshadows concerns about water quality. Rittmann points out that we are seeing alarming levels of phosphorus loss to the Earth’s waters, in which it is difficult to recapture for future use. This dilemma is a direct result in how and what we choose to eat.

“We are not just producing more food to eat; we are also generating crops to feed the livestock that we consume,” he said.

Dead zones: An unintended consequence

The unintended consequences of phosphorus loss can be dire. Phosphorus is rapidly consumed by photosynthetic microorganisms, allowing them to cause eutrophication, which is readily observed as slimy green “blooms.” Sometimes, these blooms release toxins into the waterways, rendering them dangerous. Large blooms deplete the water’s dissolved oxygen content, resulting in so-called “dead zones,” or waters uninhabitable by fish.

According to a January 2018 study published in Science, the dead zones worldwide have quadrupled in size since 1950. The second largest dead zone in the world is the U.S. northern Gulf of Mexico. Today, dead zones can also be found along the East Coast and the Great Lakes. More than 400 dead zones have been identified worldwide.

Finding a more sustainable path

There are no easy solutions to overcoming phosphorus pollution from non-point sources, such as from agricultural fields and urban storm water. However, solutions are possible, including more effective methods for applying agricultural fertilizer and intercepting the water at its source.

“We can certainly reduce demand for phosphorus by changes to fertilization practices and to the human diet,” Rittmann said. “Phosphorus losses through run-off are hard to do anything about once they occur. Instead we need to examine means to minimize the causes for the losses.

“The smarter solution is not looking just at the end of this story,” Rittmann said. “It requires looking to the beginning. It is important that we find a way to use less phosphorus and to keep the phosphorus we use from being lost to the Earth’s waters, where it becomes a pollutant, not a resource."