Ellen MacArthur Foundation | Case Study: Ostara Nutrient Recovery Technologies – Closing the Nutrient Loop
Read original case study: https://www.ellenmacarthurfoundation.org/case-studies/closing-the-nutrient-loop
Phosphorus is a critical resource to producing crops that will feed the world. However, years of mismanaging phosphate has created challenges in both how this finite resource is used, but also environmental impacts from misapplication. The result is unproductive soils, but also the creation of nutrient pollution and negative impacts on water quality. With no synthetic alternative, and more stress being placed on our water bodies, it’s crucial to rethink how we manage phosphorus.
Ostara has developed technology that can be incorporated into treatment plants allowing phosphorus and nitrogen to be recovered from industrial and municipal wastewater streams, developed into a marketable fertilizer product. The fertilizer product can then be marketed, distributed, and sold to blenders, growers, and farmers as a pure mineral fertilizer, produced from resources that would otherwise become pollution.
What makes the technology particularly smart?
The Pearl® process reduces the build-up of a mineral scale, called struvite, on pumps and pipework while also removing nutrients from the plant recycle streams to eliminate the need for retreatment. Stopping pipework build-up addresses a costly operational issue, common in treatment facilities using biological phosphorus removal to meet permitted nutrient removal requirements. The end-product, marketed under the brand name ‘Crystal Green® Pearl’, is not water soluble and releases nutrients to plants in response to growing roots, resulting in a significant reduction in fertilizer leaching and runoff from farmland, and crops are more efficiently nourished.
Wastewater facilities create additional revenue from fertilizer production, increased efficiency, lower operational costs, and reduced nutrient loading to waterways from wastewater treatment. For farmers, fertilizer efficiency is improved and phosphate fertilizer leaching to waterways is decreased.
Healthy soils are the foundation of a healthy environment.
A balanced supply of nutrients is essential for healthy plant growth. In the absence of human activities, natural processes such as biodegradation and symbiotic relationships with other species in the local ecosystem provide sufficient nutrition for the plant life cycle, albeit in an environment of healthy competition.
Human agricultural activities affect this natural nutrient balance. When crops are harvested, nutrients are removed from the soil in the harvested grains, vegetables, fruits, fodder, timber, and other useful biomass. While these are important materials for feeding people and supporting the economy, the practice removes essential elements from soils required for future generations of plant growth.
In the past, less mechanized and more local methods of agriculture returned nutrients back to the soil in the form of agricultural by-products, the spreading of human and animal waste, and intercropping. As farming methods have become more industrialized, the result has been increased yields, improved profit margins, and lower food costs. However, sustaining yields means soil fertility is now most often provided by synthetic fertilizers produced and transported from distant locations rather than recapturing and recycling nutrients locally.
Synthetic fertilizers can be expensive, are produced from increasingly hard to access reserves, require carbon intensive production processes, and produce copious amounts of pollution. Furthermore, current fertilizer use is often inefficient. A report released in 2015 estimated that only 5% of the fertilizers applied contribute to consumable food, with the balance being lost to the local environment.
Meanwhile, nutrients are lost in a linear process.
At the other end of the production, harvest, and consumption process is the wastewater treatment facility. Nutrients in municipal and industrial wastewater are often required to be captured in expensive mechanical, biological and chemical processes. These processes ensure that wastewater is safe for discharge into the wider water system, as required by local environmental regulations. However, even legal discharge limits allow concentrations of potentially recoverable nutrients become pollutants.
Spurred on by increasingly stringent regulations on discharge water, Ostara Nutrient Recovery Technologies, a Vancouver-based company, has taken a more systematic approach to managing nutrient flows. The result is an innovative wastewater process add-on that saves maintenance costs, reduces nutrient loading in discharged waters, generates revenue for utilities, and produces a pure fertilizer product – Crystal Green Pearl.
One way to understand the process is considering the location of phosphorus, depending upon location it can be either a liability or an asset. Deposited as the struvite (magnesium ammonium phosphate) scale on pipework and pumps in treatment plants, it is a costly maintenance item for the treatment plant. Further, phosphate discharged to freshwater sources contributes to eutrophication – algae blooms and dead-zones. However, if phosphorus is recaptured in the form of a fertilizer product, and that product contributes to higher yields, soil health, and reduces fertilizer phosphate losses from farms, then phosphorus in that location can be an attractive revenue stream, generated from an environmentally friendly fertilizer product.
Recognizing this opportunity, Ostara developed a nutrient recovery approach called the ‘Pearl® Nutrient Recovery Process’ for integration into biologically based wastewater treatment plants. The Pearl process reduces problematic, out-of-place, phosphorus and turns it into a highly efficient fertilizer called ‘Crystal Green Pearl®’.
How it works.
Ostara’s solution is a two-stage process typically applied to a particular configuration of wastewater treatment (known as Enhanced Biological Phosphorus Removal), a treatment method in which biological processes are selectively enriched with specific phosphate-accumulating bacteria. Having accumulated large quantities of polyphosphate within their cells, the bacteria re-release the phosphorus into a soluble form when placed in an anaerobic digester. The result is a concentrated, phosphorus-rich fluid fed through Ostara’s ‘Pearl Process’, where the soluble phosphate precipitates into pure fertilizer granules of struvite, Crystal Green Pearl®.
The process is complemented by an enhancement option (called WASSTRIP) that diverts nutrients upstream of the anaerobic digester, significantly reducing struvite build up in critical plant components as well as maximising phosphate recovery by the Pearl process. In the further material section at the end of this article, a video link provides a visual explanation of how these two processes are integrated into a typical treatment facility.
The technology can be applied using a variety of reactor sizes according to the population, ranging from facilities serving 10,000 to 1+ million people. Together, Pearl and WASSTRIP can either be retrofitted into existing facilities as well as incorporated into the design of brand-new water treatment facilities.
Ostara’s nutrient recovery system provides financial benefits to municipalities, farmers, and investors, while at the same time satisfying regulators and conservation groups. Water treatment operators using Ostara processes also avoid negative impacts to the local aquatic environment, contribute to positive urban-rural connectivity, and help reduce the carbon costs associated with the use of synthetic fertilizers.
- Farmers — Farmers realize several benefits when using Crystal Green as part of their phosphate fertilizer program. Crystal Green is a certified Enhanced Efficiency fertilizer (AAPFCO), which responds to crop demand for release, and provides improved phosphate use efficiency in the field.
While water in the soil drives the release of nutrients for commonly applied soluble phosphate fertilizers, Crystal Green does not depend on water to release nutrients. Instead, growing roots seek out Crystal Green granules in the soil and directly mine them of their nutrients on an “as needed” basis. Crystal Green is primarily organic acid soluble, and its release is controlled by organic acid production from plant roots and soil mycorrhizae. As the crop grows and roots develop, higher organic acid concentrations result in greater release.
Using the Crop Driven® release, Crystal Green does not contribute to environmentally damaging phosphate leaching and efficiently feeds a crop. Also, because it is not water soluble, the phosphate in Crystal Green is not subject to fixation, which can reduce the efficiency of soluble phosphate fertilizers by 50 to 70%. A grower using Crystal Green improves yields, reduces phosphate waste, and can save on fertilizer costs.
- Municipalities — The basic template for an urban wastewater collection and system has remained largely unchanged since the 1870s, when the world’s first underground network was installed in London by Joseph Bazalgette. While Bazalgette’s system was very effective at cleaning up the ‘Great Stink’, its design was extremely ‘linear’ in that it took nutrients from where they are useful (farms), then discarding them in a place where they are problematic in waterways. Technology like Ostara’s should be the next evolution of Bazalgette’s ideas, ensuring a future generation of more ‘circular’ wastewater systems, not only protecting public health but also closing nutrient cycles back to farmland.
Municipal water treatment facilities using Pearl reactors realize a financial advantage as additional revenue is created through fertilizer sales of Crystal Green Pearl. In addition to extra revenues, their operational costs are also lowered as less chemicals are needed to manage struvite deposits, and there is a 10-20% reduction in residual sludge requiring disposal.
- Global Environment — Both the Pearl Nutrient Recovery Process® and Crystal Green Pearl® fertilizer offer benefits beyond the recovery of phosphate. Relative to equivalent phosphate units of typical fertilizers, the production of Crystal Green Pearl results in reduced greenhouse gas emissions and almost 100% less finite raw materials used. The broader environmental benefits of using Crystal Green Pearl fertilizer reach beyond the farm, in addition to reductions in the above categories, there is a drastic reduction in freshwater and marine eutrophication impacts.
Clearly, the Pearl Nutrient Recovery process and the use of Crystal Green Pearl fertilizer benefit municipalities, farmers, and the broader environment in which we all live.
The Future of Nutrient Recovery.
Since being founded in 2005, Ostara Nutrient Recovery Technologies has expanded the reach of their technology throughout the world. In September 2021, Ostara announced an exclusive partnership with Evoqua Water Technologies, combining Ostara’s market-leading process solutions for nutrient recovery with Evoqua’s established water and wastewater treatment solutions to help municipalities recover nutrients and convert them into valuable fertilizers.
Under the agreement, Evoqua will lead the sales and implementation of Ostara’s unique nutrient recovery solutions into the North America and Western Europe municipal markets. Evoqua’s established project delivery resources provide additional strength to further accelerate the growing adoption of nutrient recovery solutions to mitigate the excessive richness of nutrients in lakes and other bodies of water.
- Founded in 2005
- 35 full time staff
- HQ Vancouver, Canada
- 23 commercial installations worldwide
Updated September 2021
Further material: Video – Ostara Nutrient Recovery Solutions; Urban bio-cycle economy report