Fertilizer International 509 Jul-Aug 2022
31 July 2022
Phosphorus recovery and the future of fertilizers
PHOSPHATE TECHNOLOGY
Phosphorus recovery and the future of fertilizers
Reclaiming phosphorus from sewage sludge ash holds great potential for the fertilizer industry – by helping to reduce dependency on global supply chains, ensuring resilience and even raising quality. But successful phosphorus recovery largely depends on the process used, as EasyMining’s Anna Lundbom, Sara Stiernström and Christian Kabbe explain.
European interest in phosphorus recovery has risen to a whole new level in recent months. The sanctions imposed on Russia following the conflict in Ukraine has highlighted Europe’s dependency on imported phosphate rock, and its particular reliance on both Russian and North African sources.
Since the end of February, market prices have started to overheat due to concerns over the supply and availability of Russian fertilizers and raw materials, including high-grade phosphate rock. Unsurprisingly, fertilizer companies and other industrial consumers have been keen to secure sufficient supplies of phosphorus to keep their production running. Fertilizer availability in general is also developing into a global issue, with the potential for a full-blown food security crisis emerging as a major risk.
Recent world events have shone a spotlight on the supply chain weaknesses of the whole fertilizer industry and revealed their vulnerability to disruption. These supply risks will remain, even if the war in Ukraine and Russian sanctions ended tomorrow. That makes establishing a domestic-based circular economy for a nutrient like phosphorus highly attractive – due to its potential to make the fertilizer industry much more self-sufficient, resilient and efficient. But the full potential of nutrient recovery can only be realised if the recovery process is of a high standard and the product generated is of the right quality.
High-quality nutrient recovery from abundant resources
Easy Mining is commercialising the recovery of valuable yet currently discarded resources and implementing this at scale. Our innovative technologies are helping to close nutrient cycles to create new circular material flows that are commercial and efficient.
EasyMining’s portfolio of patented processes recovers and extracts the three primary nutrients (nitrogen, phosphorus, and potassium). They include:
- The Ash2Salt process: This extracts commercial grade salts, including potassium chloride, out of high-chloride ashes from waste-to-energy plants.
- Project Nitrogen: A process for the efficient removal and recovery of ammonium from aqueous flows.
- CleanMAP: This technology produces ammonium phosphate from mine tailings or other mineral sources.
- The Ash2Phos process: This recovers phosphorus from the ash of incinerated sewage sludge and other phosphorus-rich feedstocks.
Processes like Ash2Phos can play a vital role in securing the critical materials needed for fertilizer production. The commercial recovery of phosphorus generated in the domestic market would obviously reduce dependence on global supply chains. Indeed, high-grade recovered phosphorus – as generated by Ash2Phos – can directly substitute for imported nutrients. Recovering high quality nutrients is important, as these can be easily used as feedstocks for existing value chains, allowing manufacturing processes to become more circular without compromising the environment or affecting production efficiency.
Global agricultural output would suffer without phosphorus. And while sewage from households and industries contains massive amounts of phosphorus, at present, it’s mostly seen as a problem rather than an asset.
In fact, a lot of time, effort and cost goes into discarding sewage sludge at wastewater treatment plants, even though it’s rich in potentially valuable phosphorus. In our view, this phosphorus can be commercially recovered from sludge in a closed loop to secure an endless supply. With a different approach, therefore, the opportunities are enormous.
Ash2Phos can recover more than 90 percent of the phosphorus contained within a mineral-rich feedstock like sewage sludge ash. This three-stage process involves:
- An initial acidic step
- An alkaline step producing intermediate products
- These are then detoxified and processed into the final products.
The main product of the Ash2Phos process is precipitated calcium phosphate (see photo above). Other valuable materials such as coagulants are also recovered, while heavy metals are also extracted and separated to ensure product quality meets or even exceeds current commercial standards.
Yet the effectiveness of phosphorus recovery will always depend on the technology behind it. Other processes like ‘ash pimping’, for example, just dilute heavy metals or don’t fully remove harmful materials. These processes also leave phosphorus still embedded within the waste matrix. This means the quality of the final product remain dependent on the quality of the starting material – the end result being sub-standard products that create sub-standard fertilizers.
In fact, only extraction-based processes like Ash2Phos can guarantee high-quality phosphorus end products, independent of the original input material. The precipitated calcium phosphate generated by Ash2Phos can also be used flexibly in two main ways – either directly as a slow-release fertilizer (see photo below) or as a raw material/ feedstock. The quality of this product can exceed that of standard phosphate rock. Ash2Phos therefore has the potential to create better quality products than conventional fertilizers derived from primary phosphate resources, with the added benefit of a more secure supply chain based on a sustainable ‘closed loop’ process.
Endless supply
In Europe, fertilizers are currently the only available route-to-market for phosphorus reclaimed from sewage. This is because, under current regulations for this nutrient, waste-extracted phosphorus is excluded from use in animal feed or food additives, regardless of its quality.
The EU may repeal these outdated regulations which focus on the origin instead of the quality of products. But, until then, there is a window of opportunity for fertilizer producers, ahead of other industries, to begin integrating reclaimed phosphorus into their value chains.
Are the potential volumes large enough?
At present, mineral fertilizers supply approximately 1.2 million tonnes of phosphorus annually to meet the needs of Europe’s farmers. Currently available sewage sludge ash could produce enough phosphorus to meet about four percent of this demand, assuming the same recovery rate as the Ash2Phos process. However, if all the sewage sludge generated in Europe were incinerated, phosphorus recovery could potentially rise to 270,000 tonnes, equivalent to about 20-25 percent of the amount currently supplied through mineral fertilizers.
The availability of large amounts of phosphorus in sewage sludge ash therefore opens up a substantial opportunity for fertilizer producers. Sewage sludge ash is available domestically in large volumes throughout the year without disruption. As long as people eat and sewage systems operate, there’s always going to be a consistent supply of sludge available for phosphorus extraction. The price of recovered phosphorus is also expected to remain relatively stable, compared to primary phosphate rock, due to the absence of international transport costs and the lack of competition from other industries.
In our view, extracting, refining and detoxifying phosphorus from renewable resources like sewage sludge ash can contribute to food security by helping create a more resilient and efficient fertilizer industry that generates better quality phosphate products.
The calcium phosphate recovered by Ash2Phos technology is also highly versatile. It’s incredibly easy to integrate this recovered material at the early stages of already-established fertilizer production processes/value chains – or, alternatively, it can be used as a standalone product.
It is also noteworthy that, as a downstream process, phosphate recovery from ashes is not directly affected by operational issues at wastewater treatment plants. Phosphorus suppliers, using a process like Ash2Phos, can instead collect ashes from many different incinerators. This widespread sourcing provides benefits such as economies of scale and better homogeneity. Importantly, while the process is not that dependent on the quality of the ash, Ash2Phos does guarantee a fixed level of quality for the phosphorus it produces.
Lastly, phosphorus extraction can add new levels of sustainability to fertilizer production by recovering a range of other materials as well as calcium phosphate. Ash2Phos maximises the usage of sewage sludge ash in its entirety, with each material having its own application. These range from commercial-grade coagulants, like ferric chloride and sodium aluminate, to a cleaned sand fraction suitable for use as a construction material or cement replacement in concrete.
The Ash2Phos process also extracts and separates heavy metals and concentrates these in a filter cake. These can be reused (depending on the levels of copper, zinc, nickel, etc. present) provided there is a suitable offtake agreement with a smelter company.
With a process like Ash2Phos, it’s therefore possible to achieve an overall recycling rate of 95 percent or more. And, because sewage sludge ash would otherwise be disposed of to landfill, this directly translates into a total waste reduction of 95 percent.
Turning waste into a resource
Sewage sludge, according to the current mindset, is classed as waste. There are good reasons for this, as its composition varies and contaminants may also be present, for example. It also has much less value in an unprocessed state. But these negative connotations are also applied – unfairly – to any materials recovered from sewage sludge. Extracted nutrients are still tarnished by their association with waste, even though harmful substances have been removed and they make an ideal, efficient resource for precision farming.
The problems with the perception and classification of waste-derived nutrients are best illustrated by the previously mentioned EU regulations. Gatekeeping waste legislation was previously enacted by the EU as a precaution – to keep pollutants out of the environment and unsafe materials away from people. Essentially, these regulations prohibit materials on the basis of their origin.
Things are about to change, however, as society transforms from a linear to a circular economy. This change is being driven by increasing demand for resources, due to population growth, as well as the necessity for more efficient resource management. The circular economy is also being enabled by the emergence of new and high quality recycling technologies.
Put simply, we can no longer afford to follow the path of ‘take-make-dispose’. Instead, if we are serious about building a sustainable society, we have to start reusing the materials we already have – properly and safely over and over again – with phosphorus being the perfect example. This nutrient, which is already listed by the EU as a critical material, is a potential showstopper if it’s unavailable for food production.
In this new paradigm shift, waste is no longer just waste and instead becomes an important source of valuable raw materials in the circular economy. Upcoming regulatory changes in Switzerland and Germany, specific to phosphorus recycling, will be a key part of this economic shift. Both nations will be the first countries on the planet to make phosphorus recovery from sewage sludge mandatory. The new regulations should enter into force in 2026 in Switzerland and 2029 in Germany, with many more countries expected to follow suit. It’s also safe to assume that these vanguard regulations will trigger investment in the sector by placing large volumes of recovered phosphorus on the market.
We believe that making wastewater treatment plants the resource factories of tomorrow is well within reach now. Our sewers provide plenty of resources – we just have to start using them properly.
A more level playing field between secondary and primary resources is also starting to be created. While there will still be some discrimination based on origin, the rising recovery of phosphorus from waste, and increased usage by industries like fertilizer production, will normalise secondary nutrients. Consequently, the European Commission and member states will eventually have to change the basis of their regulations from product origin to product quality. Until then, the fertilizer industry can take the lead in the consumption of secondary resources such as recovered phosphorus.
Achieving a critical mass
Generally, three prerequisites are needed for industry-wide adoption of a new material or process: quality, reliability, and volume. All three factors are necessary to guarantee commercial success, even when serious market demand exists. Encouragingly, EasyMining’s Ash2Phos process meets two of these preconditions and is close to meeting the third.
Ash2Phos extracts phosphorus from sewage sludge ash at a quality level that is comparable to – and even higher than – existing industry standards for phosphate rock. Additionally, the constant generation of sewage sludge at wastewater treatment plants makes it a reliable resource for phosphorus recovery. All that’s left is volume. The amounts of phosphorus received from incinerated sewage sludge is too low for the market at present. But, with the irrevocable shift to a circular economy and legislation being introduced in Switzerland and Germany, that situation will soon change.
In order to achieve a critical mass, phosphorus recovery needs to reach an estimated yearly production level of 10,000 tonnes. EasyMining has already joined forces with German utility Gelsenwasser, due to the country’s regulatory framework and the sufficient ash volumes currently available nationally. The two firms formed the joint venture (JV) Phosphorgewinnung Schkopau GmbH in 2021. This JV will construct and operate Germany’s first Ash2Phos plant. This is scheduled to become operational in 2025 and is designed to produce 15,000 tonnes per annum of calcium phosphate initially. Production volumes are then expected to ramp up to 150,000 t/a by the end of the decade, fuelled by beneficial regulations mandating phosphorus recovery and the construction of more and bigger plants.
Hopefully, the reliable recovery of highquality phosphorus in large volumes will create irreversible momentum and be enough to kick start commercial nutrient recovery. There is a definite need for fertilizer producers to incorporate secondary nutrients such as recovered phosphorus, as events since March have shown. The easier it is to integrate these materials into existing value chains, the better. Not just for their own benefit but for everyone else’s.
