Value from Sewage? A New Technology Cleans Up Waste Water
by Erica Gies
It may be tricky to see dollar signs or green qualities when you think about sewage, but Vancouver-based company Ostara has found a way to connect the three by pulling commercial value from waste water. Its technology harvests phosphorus and ammonia from municipal sewage treatment plants and turns it into fertilizer pellets. The process saves cities money by keeping sewage treatment plants humming efficiently, and it will likely reduce polluted runoff from agriculture because the fertilizer is easier for plants to absorb than standard fertilizer applications.
Founded in 2005 after licensing its technology from the University of British Columbia at Vancouver, Ostara’s customers thus far have been municipal sewage treatment plants in Canada, the US, and most recently, England. But it soon hopes to expand its business to industrial customers, including commodities-grade phosphorus rock processing plants.
Phosphorus for agricultural fertilizer has typically been harvested from rock, with the greatest remaining reserves in Morocco and Western Sahara, China, and Algeria. The price of phosphorus has tripled since 2006 due to supply shortages. That value has created a key market opportunity for Ostara.
“Waste water is no longer seen as waste,” said Phillip Abrary, president and CEO of Ostara.
The company is offering an important service to municipal treatment plants. State and federal regulations have grown increasingly stringent on the amount of phosphorus that can be in the water a plant returns to nature after processing. That’s because, although phosphorus occurs naturally, when there is too much of it in water – from human or animal waste or from runoff from gardens, lawns, or agricultural – algae – can bloom, sucking oxygen out of the water and killing other aquatic life.
Ostara partners with plants that meet their phosphorus discharge limits by using microorganisms to remove the element from the rest of the sewage, a process called bio-P. The microorganisms are then treated in a digester, which in turn creates a solid “sludge cake” that is given to farmers as a soil amendment or incinerated, biogas, and a liquid waste stream. The latter contains most of the phosphorus and is typically routed back through the treatment plant.
Routing the phosphorus back to the head of the plant is a burden because it causes scale on the pipes and can reduce capacity to manage and process incoming phosphorus and ammonia. “The bugs can go out of balance,” said Abrary.
Ostara’s technology, called the Pearl system, takes that liquid waste stream, known as “dewatering liquors”, and pulls out more than 85% of the phosphorus and approximately 10-30% of the ammonia by adding magnesium to form a precipitation reaction. The end result is crystals composed of phosphorus, nitrogen, and magnesium that Ostara markets as Crystal Green fertilizer.
“We help them dispose of the waste stream in an efficient way,” said Abrary.
Ostara’s Pearl system helped maintain operational stability; save money on the reduced need for amendments to manage the phosphorus, such as alum and lime; and reduce the tonnage of dry tons of sludge, which reduces handling costs, according to a 2013 paper published in Water Science & Technology.
Phosphorus can build up on pipes and equipment, forming a concrete like scale called struvite. Removing it, either manually or with chemicals, is time-consuming and expensive.
Avoiding those costs is part of what makes the Pearl system economically attractive.
Bill Balzer is plant manager of Hampton Roads Sanitation District in Virginia Beach, Virginia. His facility was the second in the US to install Ostara’s system, in 2009. Hampton Roads processes a particularly high phosphorus load because municipal sewage is mixed with waste from a Smithfield meat-packing plant. Balzer said his plant would have spent $328,000 a year on ferric chloride and disposal fees to remove struvite. Likewise, a utility in Slough that just installed a Pearl system, the first in the UK, estimates it will save £200,000, or $332,000, a year.
Utilities can also offset their capital costs on a Pearl system by earning royalties from Ostara in exchange for the Crystal Green fertilizer they produce.
“All product is sold to us on a prenegotiated basis,” said Abrary. “They have no uncertainty about the economics.”
Clean Water Services was Ostara’s first US customer. It operates four waste water treatment plants in the Tualatin River watershed in Washington County, Oregon. It added the Pearl system to its Durham plant in 2009 and later installed the Pearl system at its Rock Creek facility. General manager, Bill Gaffi, said the utility gets $600 a ton in royalties for fertilizer sales on materials from the Durham plant – a special price since it was the first – and $400 a ton for Rock Creek.
Gaffi said the Durham facility cost $2.5m, plus a $1.1m incentive from Ostara because it was the first US installation. The Rock Creek installation cost $3.5m, plus $1m for a new building to house the facility. Gaffi said he anticipates that both will be paid off in seven years.
Balzer, at the Virginia plant, wouldn’t reveal the price his district paid for the Pearl system or its royalties but said they estimate 10 years for their return on investment.
Clean Water Services didn’t have a serious problem with struvite buildup, but Gaffi said the advantage of partnering with Ostara was clear. “The Tualatin River is like a 40-mile long lake in the summer,” he said. “We have to meet very stringent phosphorus discharges.”
Ostara offered his utility a chance to recover an increasingly scarce resource from waste and to return financial rewards to the district. “It seemed like a smart thing to do environmentally and from a business perspective,” he said.
Although utilities were cleaning phosphorus out of water prior to partnering with Ostara – the Canadian company just helped them to operate their facilities more efficiently – there is a way the Pearl system reduces water pollution more directly.
The fertilizer it produces is a controlled, or slow-release type. Traditional fertilizers dissolve when water hits them, via rain or irrigation, and they disperse quickly, often before plants can absorb them. Crystal Green is not water soluble.
“You need to have some acidity for it to dissolve,” said Abrary. Plant roots release organic acid when they want to feed, and Crystal Green releases phosphorus, nitrogen, and magnesium in response to that signal, he said. Plants can better absorb this type of fertilizer, reducing the amount that runs off the land and into nearby water bodies.
Municipal sewage treatment centers are a natural customer for Ostara, and it has new clients in Madison, Wisconsin; Chicago, Illinois; and Gwinnett County, Georgia.
But the company is also looking to branch out into the industrial market. Facilities that process mined phosphate rock into fertilizer also generate a lot of phosphorus-rich liquid waste. Ostara has developed a new process to harvest phosphorus from that water, which the fertilizer company can then reuse in its facility or discharge it into the environment.
According to Abrary, such an operation would be 10 times larger than a typical municipal-scale plant.
Ostara has done pilot projects and commercial demonstrations at phosphate fertilizer plants in Florida and is talking to other processors in China and South America. It has also done pilot studies on animal waste.
It has not yet made an industrial deal, and business models are still under discussion.
Erica Gies is an independent reporter who covers water and energy for The New York Times, The Economist, Scientific American and other publications.