An excellent article in the Globe and Mail about a recent wastewater conference in Canada where capturing phosphorus was one of the main topics of discussion. And quite rightly. As conference organizer Ken Ashley told a press conference (which I suspect was not particularly well populated), recovering phosophorus from sewage “may be the biggest uncovered news story on the planet.” Why? Because without phosphorus we can’t grow enough crops. We can’t feed enough animals. We won’t have enough food. And phosphorus is running out.
“The United States, historically the world’s biggest producer, is expected to exhaust its reserves in 25 years. China recently slapped a 135 per cent export tariff on phosphate, choking off exports. That leaves Morocco sitting on one-third of the world’s remaining supply – and reserves there are declining in quality and quantity. ‘Phosphate production is going to peak around 2035 and then tail off,” Dr. Ashley said. “If we don’t do something we are looking at mass starvation.’”
Hyperbole? I don’t think so. I had a long conversation with a very sensible Dutch wastewater expert who didn’t think so. I know plenty of extremely fertilizer knowledgeable people who don’t think so. Oil is running out too but there are alternatives to oil. There are no known alternatives to phosphorus. Hence the struvite. Magnesium ammonium phosphate – also known as struvite – forms inside sewage pipes (and composting toilets) and is usually seen as a pain in the neck. Wastewater treatment managers have to pay to remove it. Now researchers at the University of British Columbia have discovered how to recover it. Hey presto: A lot of phosphorus which otherwise gets lost in the treatment process can be saved and used. A struvite recovery system costs a lot, but it pays its way, because within five years, a sewage treatment plant can recover its costs by selling the struvite as fertilizer.
More on the dim future of phosphorus here.
And no, I don’t know why the Globe and Mail put a piece about sewage in its sports section.
I did not know that struvite formed in composting toilets. How do they remove the scale? I’ve been testing a product from Jenfitch to dissolve struvite scale from digester lines. Do you think this product might work in composting toilets?
I couldn’t say without knowing more about a) engineering and b) struvite. But I’m sure there are plenty of composting toilet experts findable online who might be happy to test it. They won’t want many man-made chemicals in their system though.