By Shannon Behary, Senior Editor
15 February 2022 - The mining of phosphates and their inefficient use in agriculture have been deeply disruptive to the Earth’s phosphorus cycle. Even though we know that the nutrient is vital for crop production, we have been using a finite resource with less precision than we should. Moreover, as with other nutrients (nitrogen, for example), accumulated phosphorus can cause eutrophication which impacts biodiversity. In short, ecologists and EU policymakers are increasingly drawing attention to the urgent need to move towards a more responsible system for managing phosphorus use, including the recovery and reuse of this precious mineral when possible.
One Swedish firm, EasyMining, is pioneering a process to bring recovered phosphorus back into the food chain in the form of feed phosphates.
Understanding the phosphorus recovery process and its output
EasyMining is part of waste management and recycling corporation Ragn-Sells. Described as an “innovation company dedicated to closing nutrient cycles,” EasyMining is involved in multiple projects for the recovery of different products from waste streams, but most notable for the feed industry is their development of a system to “recover” phosphorus. First, biosolids produced by a municipal wastewater treatment process are incinerated to produce a mineral concentrate. Then, the EasyMining Ash2Phos process is applied, from which phosphorus (namely “precipitated calcium phosphate”) is recovered.
Given the incineration step, there are no microbiological or organic quality concerns. Moreover, the decontamination steps involved in the Ash2Phos process ensure that the heavy metal content is lower than that of phosphates derived from traditional manufacturing processes. In short, asserts Dr. Sara Stiernström, Product and Market Developer for EasyMining, precipitated calcium phosphate is perfectly safe and pure of contaminants of all sorts.
When it comes to in vivo performance, research was undertaken at the Swedish University of Agricultural Sciences (SLU) late last year to examine the digestibility of precipitated calcium phosphate (PCP) in pigs and broiler chickens. These initial trials in pigs found estimated total tract apparent digestibility of phosphorus in EasyMining’s PCP was 60.4% (compared to 83.8% for traditional feed phosphate MCP); meanwhile, in chickens, the estimated ileal digestibility of phosphorus in PCP was 58.4% (compared to 75.1% of phosphorus in MCP). Although research into this ingredient is very much in its early days and further studies are certainly called for, this suggests digestibility rates for PCP which are “slightly lower than MCP but…in the same range as other feed phosphates [such as DCP],” in Stiernström’s words.
Finally, there is the extremely important question of price. According to Stiernström, the process “does not need a high [commodity phosphate] price” to be cost-competitive with traditional feed phosphates. “When we did the business case, we looked at the price of feed phosphates in recent years and asked ‘can we [operate] this process with this price, even when it’s low as well as when it’s high?’ And yes, we can.” What’s more, she adds, that price would likely be more stable than that of rock phosphates (or at least not subject to many of the same factors causing price changes in mined phosphorus)—something which many companies looking to have visibility on their feed costs would appreciate.
Local supply and circularity
That question of stability should not be underappreciated. Today, Europe’s (and the world’s) phosphate supply is reliant on places with naturally occurring mineral deposits, some of which can be geopolitically complicated. Phosphate rock is on the EU’s “critical raw materials” list of twenty items for which supply security is at risk and economic importance is high.
Given the feed industry is currently looking to build resilience into its supply chains, there is an obvious benefit to adopting an ingredient which can be made (or rather recovered) locally. As explained by Ludwig Hermann, President of the European Sustainable Phosphorus Platform: if the concept of phosphorus recovery was extended to municipal wastewater treatment plants across Europe*, it could recover some 600,000 tonnes of P per year, or 40% of Europe’s needs for phosphorus for both fertilizer and feed phosphates (which he estimates at 1,500,000 tonnes per year).
Beyond this, the Ash2Phos concept is also attractive because it embodies the principle of circularity: instead of further drawing on finite mineral resources, it recycles phosphorus which is currently being wasted. Not only does that waste represent lost value, but it is also a pollutant, one which the EU in particular is cracking down upon. Finally, depending on how far the phosphates have had to travel, a locally-recycled feed phosphate will likely have a lower GHG-emissions footprint.
Unfortunately, there’s a catch. Annex III of the EU’s Animal Feed Regulation 767/2009 appears to prohibit animal nutrition products “obtained from the various phases of the urban, domestic and industrial wastewater… irrespective of any further processing of such waste and irrespective also of the origin of the water.” Therefore, in spite of the microbiological and/or toxicological safety of the product, its use in the European Union is a non-starter.
“When we talk to feed companies, they want to decrease their CO2 emissions. They want recovered material—if it fulfils the [legislator requirements], of course. They want to maybe be able to brand the product, saying that 20% of this is recycled phosphorus… and even that we have decreased contaminants using our product since it’s so clean…I’m really sure that if this wasn’t prohibited, we would have buyers.”
Stiernström calls upon the EU to change this law, saying it should be a question of prioritising the quality of a feed ingredient over its origin. As part of this push, she also calls upon feed companies to make their voices heard in pushing for a change, too. “We cannot do this alone…this is not something one company can change,” she says.
Still, the company is moving ahead with plans to bring production online at two plants. The first to come online will be a joint venture with German water treatment company Gelsenwasser, scheduled to begin operations in 2024. After that will be a Swedish plant by Ragn-Sells itself, scheduled to start in 2024/2025. Both plants will process some 30,000 tonnes of ash per year into 15,000 tonnes per year of dry precipitated calcium phosphate.
As Stiernström explains, EasyMining’s immediate goal in terms of production is to demonstrate that the process works. Longer term, it’s too early to say, but looking at how the company has proceeded in other areas (for example, their Ash2Salt process, which they licensed out to another company for production across Europe) could be instructive. “It’s not up to me, but I don’t think we will aim at owning a lot more plants ourselves. I think licenses are a probability.
“And if you look at the products specifically, we are not experts in feed phosphates. So we will definitely, at both ends of the process, need really great partners: we will need good ash supply partners and we will need partners to reach the [feed] market.”
* Phosphorus extraction from animal waste is theoretically possible with a similar process according to Yariv Cohen, Head of R&D at EasyMining, but the company is still in the preliminary stages of exploring this.