Canadians produce about 3-trillion litres of raw sewage per year coming from households, industry, commercial establishments and institutions. This wastewater is brimming with human and organic waste, biosolids, nutrients, pathogens and chemicals, all of which flows to city or regional wastewater treatment plants. Some solids and chemicals have to come out of this mess before the water returns to the environment. Ostara Nutrient Technology Inc. is turning them into fertilizer.
The Vancouver-based company is specifically interested in phosphorous and ammonia-nitrate. These chemicals aren’t particularly good for the environment, and when they find their way into lakes and rivers they cause excessive algae growth, which depletes the oxygen supply needed for aquatic life. Municipalities and industry are employing biological nutrient removal (BNR), which extracts these chemicals with the biosolids. What the industry calls sludge—or even more appetizing, cake—is then re-circulated through the plant for additional treatment. The liquid within the biosolids contains compounds such as magnesium, ammonium and phosphate. Combined they create a chemical compound called struvite, which forms inside the pipes and equipment resulting in a concrete-like buildup that becomes an onerous maintenance issue.
Ostara’s operation in Portland, Ore. processes about 20-million tons of sewage into pellet-sized Crystal Green fertilizer during its peak season (May to November).
But in 1999 a group of researchers at the University of British Columbia (UBC) looked for a way to harness the materials for a more environmentally responsible end use. They came up with a process that captures the nutrients and transforms them into slow release fertilizer called Crystal Green. Ostara, formed in 2005, saw the value in this process and licensed it from UBC.
“Right now there are only two exits from a wastewater treatment plant. Raw sewage goes in, clean water comes out. We’ve essentially given them a third exit,” explains Phillip Abrary, Ostara’s president.
The technology uses a fluidized bed chemical reactor that crystallizes the phosphorus and ammonia and converts it into struvite.
“When you concentrate nutrients, which is what happens inside [wastewater treatment systems], that compound can be taken out in a pearl form. The trick was to get it out of the pipes and harvest the nutrients into a form that could be used by the fertilizer industry,” says Abrary. “Now, we’re forcing the reaction to happen within our vessel.”