• 03.27.12

Extracting Nutrients From Raw Sewage, To Grow Our Plants Extra Big

There’s gold in them toilets! And Ostara is mining it and then creating fertilizer (and saving cities money in cleanup costs).

While peak oil and peak water are terms that have entered our lexicon, peak phosphorus is a bit more of a stretch. But, says Philip Abrary, CEO of Ostara, the world will reach a point when phosphorus is too difficult or expensive to mine. One of the problems is that phosphorus, which is needed to give nutrients to grow plants, is mined from the ground. Morocco and the Western Sahara possess 77% of the world’s reserves of phosphorus, and many countries have no supplies at all. Turning all that phosphate rock into fertilizers loses about 60% of the nutrient. That’s not a great model.


And then there’s what happens when phosphorus and other nutrients are put in the ground: They aren’t completely taken up by plants. Much of it runs off from agricultural areas into local waterways, creating dead zones that destroy aquatic life, disrupt fisheries, and threaten the water supply.

“The way we’re consuming it is that we dig it out of the ground, turn it into fertilizers, and then discard it through our waste systems where phosphorus where it ends up in waters or soils,” says Abrary. “It’s a broken system the way we’re doing it today.”

Ostara wants to repair that cycle by extracting nutrients like phosphate from wastewater streams (yes, that means raw sewage) and turning them into viable fertilizer. The company was founded in 2005 when it licensed the nutrient recovery technology created at the University of British Columbia to develop and market the process and the fertilizer. “We can recover phosphorus from a variety of sources as long as it’s in liquid form and in a concentrated form,” explains Abrary.

This is how it works: The company takes water from municipal and industrial treatment facilities (the cities pay them for this), and extracts phosphorus, nitrogen, and even ammonia from the stream. Chemicals are added to the nutrient-rich streams to form small particles. Those seeds grow in diameter until they reach the desired size: 1.0 mm to 3.5 mm.

In a municipal wastewater treatment plant, up to 90% of the phosphorus and 40% of the ammonia load is pulled out of sludge using this process, and the result is a commercial fertilizer called Crystal Green. Abrary says this fertilizer helps halt some of the damaging environmental issues because the pellets are designed to release their nutrients slowly, over the course of nine months, which is both more efficient and will cause less runoff.

The future is bright for the alchemy of waste. With declining minerals to be mined and increasing need, companies that can recycle sewage into a commercial product will be needed. Right now, the company is operating at four sites in North America, and has several more projects underway, including one in London.