Reflections is a monthly blog series by Canadian Water Network’s (CWN) CEO Nicola Crawhall. This series is designed for decision-makers navigating complex water-related challenges. It helps leaders stay ahead of change and make informed decisions that shape the future of water in Canada.

Last month, I wrote about the potential value of wastewater for heating and cooling buildings. This month, I’m continuing to focus on the value of wastewater but through a different lens: its potential as a source of fertilizer.

A global fertilizer shortage, triggered in part by the Straight of Hormuz blockade, is driving up costs and constraining supply as farmers prepare for the spring planting season. As a result, global food security for some of the poorest nations is at risk.

The blockade affects 20 percent of global trade in phosphate fertilizers and over 40 percent of ammonia, which affect both nitrogen and phosphate-based fertilizers. Much of this supply usually heads to South Asia. Indian farmers are already reducing fertilizer use due to supply shortages, which will result in lower yields.

The price of fertilizer imported into Canada is also affected by the war. Canada produces some fertilizer components directly. The fertilizer components we don’t produce domestically are imported, mostly from the United States. While supply interruptions are not a significant issue here, price increases are definitely hitting Canadian farmers hard.

Price increases can be seen in components like phosphates, an essential feedstock for phosphate-based fertilizers. The cost of phosphates has been fluctuating since the COVID-19 pandemic. Last year, phosphate rock was $420 per tonne. With the blockade in the Straight of Hormuz, the price is now at $700 per tonne — a 60 percent jump.

This level of price escalation is unsustainable. More importantly, it is not a temporary problem that will resolve itself once geopolitical tensions ease. Even without the conflict in the Middle East, food security is at risk. Phosphorus is a non-renewable resource, and current estimates suggest that global reserves of phosphate rock could be exhausted within the next 50 to 100 years. If that happens, the consequences for global food production would be severe.

It is vitally important to secure a reliable source of phosphorus. Canada has recognized the importance of phosphorus as a key resource for food security and the transition to a low carbon economy. It has been added to the 2024 national Critical Minerals List, which prioritizes it for federal support.

What can be done to reduce costs and increase supply in the shorter term? Wastewater sludge can be part of the solution. As organic matter is critical to long-term soil health, fertilizer derived from wastewater with high nutrient value and organic matter is very desirable for farmers.

In addition to cost and supply concerns, another compelling reason to convert wastewater into fertilizer is its lower carbon footprint. Producing mineral fertilizers is highly energy-intensive and a major source of greenhouse gas (GHG) emissions. Globally, the industry contributes an estimated two percent of GHG emissions (source). In Canada, the combined GHGs of the chemical and fertilizer industries is estimated to be 21 metric tons (Mt); this makes it the largest emitter amongst heavy industries, excluding oil and gas. Both Fertilizer Canada and Clean Energy Canada have recognized the need to pursue pathways to lower-carbon fertilizer production in Canada.

Notwithstanding these clear benefits, there has long been public concern about the land application of biosolids on crops and the risk of contaminants in the biosolids getting into the food we eat and the environment.

Through Canadian Water Network’s Strategic Sharing Group on biosolids management, we’ve been showcasing the approaches some of our Municipal Water Consortium members have been taking to address these concerns. At least three wastewater-to-fertilizer processes are being used in Canada that could ensure Canada has ongoing access to critical sources of phosphorus.

Pelletizing process

One example is the City of Toronto’s Ashbridges Bay wastewater treatment plant. For over 20 years, Veolia’s pelletizer technology has transformed sewage sludge into nutrient-rich, commercial fertilizer pellets called Nutri-Pel. Veolia sells approximately 25,000 metric tonnes of Nutri-Pel annually to farmers in Ontario. The product costs 25-35 percent less than conventional Monoammonium phosphate (MAP) fertilizers while offering the same nutrient content. It also adds micronutrients and organic matter to the soil, which improves soil health.

The pelletizing process is strictly a high-temperature drying process that removes water and volatiles from wet sludge through evaporation. The process relies on upstream treatment for most of the processing. Nevertheless, the heating at higher temperatures has some advantages; the better the upstream plant controls the process, the better and more consistent the fertilizer product. With its big population, Toronto has a well-mixed incoming wastewater stream. Its strong sewer use bylaws provide an important level of contaminant source control, which results in consistent biosolids and end product with high nutrient content for the end customer.

Nutri-Pel is tested every two weeks for nutrients, metals, and pathogen content. It meets the requirements of the Canadian Fertilizers Act. Pathogens are eliminated completely through the pelletizing process. Additionally, the product is tested every six months for PFAS content to ensure compliance with Canadian Food Inspection Agency (CFIA) regulations. In Toronto, the PFAS content is well below the CFIA Regulation T-4-132 for fertilizers/biosolids sold or imported into Canada.

Struvite crystallization

Another Canadian example of wastewater-derived fertilizer comes from Vancouver-based Ostara, which recovers nutrients through a struvite crystallization process to produce Crystal Green Pearl® Fertilizer. The process creates a non-water-soluble fertilizer, struvite, through selective crystallization from wastewater sidestreams. This ensures the granule is built from specific dissolved ions (magnesium, ammonium, phosphate) rather than from a bulk capture of the wastewater stream. As a result, contaminants of greatest concern in the end product — including PFAS/PFOS, microplastics, VOCs, and pharmaceutical compounds — are at undetectable levels, according to OSTARA’s third-party analysis of Crystal Green Pearl fertilizer.

This approach also delivers operational benefits. By preventing struvite build-up in wastewater system pipes, it avoids pipe blockages and saves millions of dollars in cleaning costs. Additionally, it reduces nutrient loading into receiving waters by removing phosphorus.

The City of Saskatoon adopted Ostara’s technology in 2012 to better manage phosphorus levels within its wastewater treatment process. Over time, phosphorus combined with magnesium and ammonia released during anaerobic digestion led to severe struvite formation. This resulted in extensive pipe blockages and other infrastructure damage. So, Saskatoon partnered with Ostara to implement Canada’s first full-scale nutrient recovery facility. The facility uses the Waste Activated Sludge Stripping to Remove Internal Phosphorus (WASSTRIP®) process to intentionally release and recover phosphorus prior to digestion. Through this biological phosphorus removal system, phosphorus is concentrated in biosolids, enabling recovery for beneficial reuse while also controlling struvite formation. The facility produces approximately 200–300 tonnes of fertilizer annually, which has a lower runoff risk compared to ammonia-based fertilizers. Over more than 13 years of operation, approximately 365 tonnes of phosphorus have been recovered.

EPCOR also operates Ostara’s technology on a seasonal basis at its Gold Bar Wastewater Treatment Plant in Edmonton. Since 2018, the facility has produced 500 tonnes of fertilizer per year.

Pyrolysis

A third emerging approach is pyrolysis. The Capital Regional District (CRD) — the water utility serving Victoria, B.C. — is using Pyrocal’s Continuous Carbonisation Technology (CCT) to convert biosolids and other organic materials into biochar. Biochar is a charcoal-like substance with various benefits, including improving soil health by retaining moisture and nutrients. It is the first time this Australian technology is being used in Canada. CRD turned to the Pyrocal technology due to the high temperature used in the process, which is particularly effective at breaking down PFAS found in sewage.

A domestic solution

With over 5,500 million cubic metres of municipal wastewater generated annually in Canada, it represents a significant potential source of fertilizer. Sewage sludge can provide a domestic fertilizer supply at a lower cost and emits lower GHG emissions. The domestic supply of phosphorus can also help insulate Canada from the consequences of geopolitical crises, pandemics, and trade policy.

In a recent Globe and Mail article, agriculture and food reporter Kate Helmore called for a national fertilizer strategy to guarantee supply and shield Canadian farmers from the price volatility of imported fertilizer components. There is no doubt that such a strategy is needed. As decision-makers consider how to support a low-carbon, made-in-Canada solution for fertilizer production, the potential contribution of municipal wastewater sludge should be taken into account as part of this transition.

Join us at Blue Cities from June 9-10^th, where experts will discuss how to derive value from municipal wastewater, among other strategic issues of interest to senior water sector decision-makers.