In 1669, German alchemist Hennig Brand was looking for a way to create gold when he boiled down gallons of urine and heated the smelly residue to a high temperature. The result was not the hoped-for precious metal but a pale solid that glows in the dark and burns brilliantly when exposed to air. Brand dubbed his discovery phosphorus, the Greek word for “light bearer.”
What Brand didn’t know was that phosphorus is one of the essential nutrients that supports life – a fact that would transform the world centuries later when fertilizer made from phosphorus in mineral form revolutionized agriculture, enabling a steep rise in population growth.
Today, scientists are again bubbling and baking human and animal waste in an effort to purposefully enact what Brand achieved by accident. But their goal is not merely to produce phosphorus – it is to capture and reuse as much of it as possible in anticipation of a time when the global supply becomes scarce.
The work is especially relevant to Canada, which has only 0.1 per cent of the world’s phosphorus reserves and relies heavily on foreign sources of the resource, according to a new report from the environmental organization Pollution Probe.
The federally sponsored report, issued last month, is one part of a continuing effort to create a management plan for phosphorus in Canada, something that is already under way in the European Union, which faces similar constraints.
“Even though phosphorus is non-renewable, there really hasn’t been a lot of attention paid to recovering it,” said Sidney Omelon, an associate professor of chemical engineering at McGill University and a co-author on the report. “But if you just look at the numbers, it’s going to be important.”
A hint of that importance can be seen in the escalating cost of rock phosphate, a raw ingredient used in fertilizer production. The current price, about US$320 per metric tonne, has more than doubled in the past year. The price spike has been attributed to a combination of factors, including energy costs, export quotas imposed by China, and the impact of Russia’s invasion of Ukraine on the global fertilizer market. But over the long term, the finite supply of rock phosphate on the global market will inevitably put the same kind of pressure on Canada.
The report, intended as the first in a series that will cover all of Canada, offers a comprehensive look at the flow of phosphorus through Ontario’s economy with a view to identifying opportunities for phosphorus recovery.
“It’s really a foundation for better understanding where we’re seeing phosphorus and where it may be available,” said Melissa De Young, Pollution Probe’s director of policy and programs.
In effect, the task is to replicate what farmers have been doing for centuries when they use manure to recycle phosphorus back into depleted soil, but in a way that operates across economic sectors and lowers Canada’s overall reliance on phosphorus imports.
The report suggests some of the most important gains to be made are in places where phosphorus is already being concentrated by human activity – as sewage in large cities and in livestock manure.
In these settings, the challenge is managing phosphorus levels – and this is not a new problem. Since phosphorus is used to stimulate plant growth, too much of it released into the environment can cause algal blooms in aquatic ecosystems, starving fish of oxygen and producing methane, a greenhouse gas. Lake Winnipeg and Lake Erie are two examples in Canada where elevated phosphorus levels have created a persistent threat to water quality.
Water treatment plants in Canada already apply chemicals to precipitate phosphorus from wastewater and prevent its escape. In some cases the results are sold as fertilizer. However, the output isn’t always optimal since the most common method for doing this involves an iron-based chemical reaction that makes it difficult to return the phosphorus to a dissolved state that can be used by plants.
Another process, pioneered by researchers at the University of British Columbia, requires ammonia and magnesium to turn wastewater into a phosphate mineral called struvite. The process is now employed by Ostara, a Vancouver-based company that generates fertilizer from wastewater and has installations at 23 locations in North America and Europe, including Edmonton and Saskatoon.
But not every treatment plant is suitable for such a process, so the search is on for new ways to maximize how much phosphorus can be recovered and how it can be done cheaply.
“The way I look at it, there’s no one silver bullet,” said Dr. Omelon, whose lab is one of those working on the question.
In the agricultural sector, manure provides a ready source of phosphorus, but in a low density form that is bulky and costly to move. This was not an issue in previous generations, when a family farm might have a cow that could provide manure as a ready source of fertilizer. But now, manure is more often produced in large quantities at industrial-scale livestock farms, which makes the phosphorus it contains hard to distribute.
“The ideal solution would be recovering the phosphorus from manure in a material that is much easier to transport,” said Edgar Martin Hernandez, a postdoctoral researcher in green process engineering at Laval University in Quebec, and a co-author of the Pollution Probe report.
The report highlights preliminary work in this direction, including an electrochemical process developed by Muddy River Technologies Inc., a B.C.-based company, which is being demonstrated at a dairy farm in Alma, Ont.
But Dr. Hernandez said that more can also be done to ensure that fertilizers are not overused, causing excess phosphorus to run off into the environment.
“I think that the main actions are preventive because once the phosphorus is in the soil it’s very difficult to recover it,” he said.
Because phosphorus makes up a portion of virtually all plant and animal tissue, food and slaughterhouse waste represent additional areas where phosphorus recovery could be pursued, according to the report. Phosphorus is also present in a range of industrial processes, from steelmaking to the brewing of beer, though each presents its own set of challenges for recovery.
Richard Grosshans, a research scientist at the International Institute for Sustainable Development in Winnipeg who was not involved in the report, said the main benefit of the analysis is that it quantifies and compares how much phosphorus is flowing from each sector, which can help to prioritize recovery strategies.
“It really takes a systematic approach,” Dr. Grosshans said. “It shows where the low hanging fruit is, the biggest sources of waste, the places where we can be more efficient.”
Dr. Omelon said she hopes the report stimulates more co-ordination and work on the issue across Canada. “It’s going take time to come up with these new technologies,” she said. “That’s why we’ve got to get on it now.”
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