Fertilizer International 519 Mar-Apr 2024
31 March 2024
Phosphorus recovery: market drivers and key technologies
RESOURCES AND SUSTAINABILITY
Phosphorus recovery: market drivers and key technologies
We look at current progress towards the greater use of recovered phosphorus, and whether there are lessons to learn from the success of the fast-growing carbon capture industry. We also highlight two pioneering European companies, EasyMining and Glatt, who are racing to bringing recovered phosphorus products to market.
MARKTRACK
Phosphorus recovery – learning lessons from carbon capture?
In an era defined by persistent economic pressures, climate challenges, and geopolitical volatility, it might have been assumed that the Covid-19 pandemic and conflicts in various parts of the world would convulse and reshape the fundamentals of the global fertilizer industry. Yet, against all odds, world production of phosphate rock and its derivatives has remained intact with strong demand growth across most global regions in 2023.
The phosphorus recovery challenge
In numerous countries, efforts to promote phosphorus recycling in various forms are escalating, and the state of research is continuously advancing. However, critical questions remain:
- What can we say about the real impact and significance of investments in these technologies and the alternatives?
- What economic, ecological, and political advances, initiatives, directives, and decisions will enable us to progress toward a more sustainable global phosphates industry?
- Finally, how do we transform this industry so it is capable of addressing global demographic challenges and food security issues without depleting planetary resources or exacerbating climate change?
This article aims to provide fresh insights into phosphorus recovery – in light of human, environmental, and geopolitical challenges. It also provides a critical view on whether incumbent producers will change their production processes and investment objectives – and embrace technological advances in phosphorus recovery and the new operations dedicated to recycling and valorising phosphorus from secondary sources.
A geopolitical perspective on phosphate production and trade will also be provided, especially Europe’s particular needs and priorities within the global economy.
Clearly, ecological concerns and sustainable development goals should encourage the phosphates industry to grow towards a greener future. With this in mind, an analysis of the development of the carbon capture industry in Europe and the United States is provided – to help understand how economic factors, legislative measures, and centralised support for technologies can influence a sector that has, until now, been unprofitable.
Cabon capture is currently experiencing tremendous growth, with significant advances within the United States. We therefore examine what lessons we can learn from the development of the carbon capture industry, how it is overcoming challenges, and the implications of these for the future of phosphorus recovery.
Geopolitics of phosphate recovery
Over the past 15 years, European states such as Switzerland, Germany, the Netherlands, and Sweden have been working to mandate the recovery of phosphorus from wastewater and sewage sludge. This legislative and political momentum is a response to recognised issues of pollution, overconsumption, and resource depletion.
Since 2014, phosphate rock has been included on the European list of critical raw materials, a status reaffirmed in 2020. The European Commission periodically conducts a criticality assessment across a broad spectrum of non-energy and non-agricultural raw materials. The 2020 criticality assessment covered 66 materials, compared to 41 in 2011, 54 in 2014, and 78 in 2017.
The two main parameters used by the Commission to determine a material’s criticality include:
- Economic importance: This provides an overview of a material’s significance to the economy in terms of application areas and the added value to the European Union’s manufacturing sectors. Economic importance is also adjusted using a substitution index. This assesses the technical performance of substitutes and their costs for individual applications.
- Supply risk: This determines the risk of supply interruption to the EU. This is based on the concentration of primary supply in raw material-producing countries, their governance and trade aspects. Substitution and recycling are seen as risk reduction measures.
Phosphate rock’s inclusion on this list is due to import dependency, its non-renewable nature and irreplaceability, and the geopolitical risks posed by the concentration of resources. Indeed, The EU imports 90 percent of its phosphate needs. Since 2017, white phosphorus (P4) has also been listed, being crucial for numerous industries, including electronics, batteries, and pharmaceuticals.
The designation of phosphate as a critical material, by underscoring the importance of waste recovery and more efficient use, should act as an incentive for the development of recycling technologies.
Legislation has spurred the development of new technologies (Table 1) and led to the creation of units that recover and transform secondary phosphorus into saleable end products. Yet the scope and utilisation of these technologies, and especially the commercialisation of end products, remain marginal when compared to the scale of the primary global industry. Especially given that phosphate rock mining has grown by nearly nine percent since 2020.
The real challenge associated with the development of phosphorus recovery technologies is not their technical feasibility or availability, but rather various economic and cultural factors within the industry.
Firstly, bringing these unconventional products to market is difficult, if their costs are higher, and when their quality and characteristics are not well understood by farmers. This contrasts with the very low cost of mining phosphate resources in countries where labour is relatively cheap and environmental policies may not be as rigorously enforced as they are in Europe. These existing market dynamics certainly do not make life easy for producers of alternative phosphates!
This market situation and the influence of low primary resource prices can make the business case for phosphorus recovery unattractive to investors over the medium term. It also highlights the complex dynamics at play in shifting towards more sustainable phosphate production.
Carbon capture – a case study
These considerations resonate with another high stakes emerging industry that has experienced a surge in recent years: the global carbon capture industry.
While the first complete carbon capture facilities date back to 1972, the technology has only really taken off in the last few years. The worldwide capacity for carbon capture, utilisation, and storage (CCUS) has been expanding at a compound annual growth rate (CAGR) of 10 percent over the past five decades, largely due to its application in enhanced oil recovery (EOR) within the United States. Despite this growth, the technology currently sequesters just 0.1 percent of global carbon emissions.
Nevertheless, the sector is on the brink of revitalisation. A surge in project announcement has occurred in the last two years – an uptick largely attributed to supportive policies and the pursuit of corporate net-zero objectives.
Projections based on recent project declarations suggest that CCUS capacity is expected to rise by a staggering 740 percent, reaching 420 million tonnes p.a. by 2035. This expansion corresponds to a CAGR of 18 percent between 2022 and 2035.
The United States, United Kingdom, and Canada are emerging as leading nations in the CCUS sector, based on currently declared project capacity. These three countries are solidifying their positions by adopting innovative policies and growing their in-country technological know-how.
Lessons to be learned from carbon capture
Three key lessons can be drawn from the growth of the carbon capture industry – and should serve as an inspiration in our quest for a more sustainable phosphate industry:
The first lesson has been the significant challenge in finding uses for the captured CO 2 . This has seen storage, not use, accounting for the majority (85%) of its fate. Why is this the case? Simply put, storage is the most economically viable solution in the short term.
In both the carbon capture industry, as well as in phosphate recovery from wastewater and secondary sources, there is no shortage of technologies; they are diverse and numerous across the globe (Table 1). Instead, the real issue is what to do with the output of these processes. The notable difference, versus CO 2 , is that phosphate is a critical element for human life – this, hopefully, will drive the discovery of viable and beneficial products, uses and end markets.
The second and even more crucial lesson concerns financial incentives and legislation. These have genuinely propelled the development of carbon capture technologies.
A close look at the trajectory of the carbon capture industry reveals that a low carbon price, even when it occasionally hits $100/t, is not enough to justify substantial technological investments worldwide. Instead, data analysis shows that the markets where carbon capture technology is expanding are those where the state has implemented financial incentives, with or without legal capture obligations, to stimulate corporate investment.
In the United States, for instance, the Inflation Reduction Act (IRA) has been a real trigger for investment in these technologies. Europe, in contrast, has lagged behind in terms of investment, despite strong political will to combat climate change. The upshot? Policies that accelerate and support investment are what truly act as catalysts for new installations.
Finally, an interesting observation from the emergence of carbon capture technologies has been the establishment of systems of cooperation and hubs. This has seen companies that capture, convert, transport, store, or use captured CO 2 join together to form clusters – linking up for reasons of economic logic and the better use of global technological capabilities.
These clusters allow each player in the CCUS value chain to focus on their core competencies and leverage the strengths of others around them. The establishment of these industrial ‘ecosystems’ is what truly enables cutting-edge technologies to meet the major challenge of carbon capture – and do so without having to worry (too much) about being present across the entire value chain.
A parallel to this situation could be greater cooperation between specialists in wastewater treatment, sewage sludge processing, phosphate recovery, on the one hand, and those specialising in the transformation, valorisation, and marketing of phosphate-based products on the other. In my view, setting up such partnerships is a prerequisite for the success of the nascent phosphorus recovery industry.
Summing up – lessons and reflections
As I stated in my 2022 presentation to CRU’s phosphate conference in Tampa 1 , improved cooperation between stakeholders across the value chain, coupled with sound economic principles, are essential for the emergence and dissemination of disruptive technologies and their fight against climate change.
Unlike CO 2 , which is considered a cost to industry, phosphate is an essential component of life. Our relationship with this critical raw material is mixed. Negative perceptions of the industry, and the unchecked ramp-up of phosphate rock extraction, reflect poorly on fertilizers and phosphates and their positive contribution to everyday lives. At a time when all efforts are directed towards using and valorising planetary resources sustainably, while minimising our carbon footprint, we should hope that companies, countries and international institutions can draw inspiration from the carbon capture industry and take lessons from the incentives that have enabled it to flourish.
To end on a personal and light-hearted note, I look forward to the day when I can proudly tell my friends “I am a phosphate analyst” without feeling embarrassed about the ecological impact our profession has on the world.
Instead, I hope phosphorus will be recognised as essential to life. I am convinced this remains the driving force behind countless individuals involved in phosphorus recovery initiatives around the globe: the pursuit of a better, more sustainable world where humanity and its environment co-exist in harmony.
References
EASYMINING
Ash2 ® Phos – quality matters, volume matters, reliability matters!
EasyMining believes that, if we are serious about creating a sustainable society, we have to start using the materials we already have – for as long and as often as possible – without compromising public health and the environment. To put it simply, quality matters!
There are currently four EasyMining processes in various stages of development and implementation.
The Ash2Salt process extracts commercial grade salts (KCl, NaCl, CaCl 2 ) out of fly ashes from municipal solid waste incinerators. The first full-scale plant (Figure 1) commissioned in 2023 has the capacity to process 135,000 t/a of fly ash and recover several thousand tonnes each of the above three salts. The process has the potential to domestically capture what is a gigantic secondary source of potassium, given the huge volumes of these type of ashes, and use this in fertilizers.
Aqua2N is a patented innovation for the efficient removal and recovery of ammonium from aqueous flows. It has been successfully piloted in the past few years and is now entering the implementation phase in sewage treatment. The process also has potential in digestate and manure processing.
Our CleanMAP technology, meanwhile, extracts ammonium phosphate from mining waste or other mineral sources.
Last, but certainly not least, Ash2Phos technology recovers several valuable materials from ashes, including incinerated sewage sludge, or other P-rich feedstocks. This article provides an update on the full-scale implementation of Ash2Phos.
Ash2Phos update
As previously highlighted by this magazine, the Ash2Phos process is designed to recover more than 90 percent of phosphorus contained in P-rich ashes, such as those from sewage sludge incineration, and convert this into a high-grade calcium phosphate product, branded as RevoCap ® (Fertilizer International 509, p58).
In our view, the only way of guaranteeing that the materials recovered from sewage sludge ash are of uniformly high quality is, firstly, by extracting these from the highly variable and heterogeneous ash matrix and, secondly, efficiently separating off heavy metals and other contaminants.
As well as recovering phosphorus, the Ash2Phos process also generates well-defined co-products, such as commercial-grade ferric chloride and sodium aluminate, while leaving a sand fraction that is suitable for use as a construction material. The heavy metal fraction, separated by Ash2Phos as filter cake, also has potential as an ore material for metallurgy.
Other recycling methods which – unlike the above approach – leave phosphorus within the ash matrix, together with various amounts of iron, aluminium and other metals, are not ‘true’ phosphorus recovery processes, in our view. Ash2Phos, in contrast, is a true circular economy process, as it splits 100 percent of the ash into valuable products and co-products, thereby closing several material cycles instead of only one.
In phosphorus recovery, the ability of a process to generate final products which are safe and of homogeneous quality, independent of the heterogeneous quality of the input material, is critically important. This point is underlined when you compare ash composition data to the limit values for contaminants set by the EU Fertilising Products Regulation (Table 1).
Unprocessed ashes do not make good P fertilizers. This can be seen from the values for ash ‘matrix elements’ in the upper part of Table 1. In particular, fertilizing efficiency is poor when the iron and aluminium content (Fe+Al) of the ash is much higher than its phosphorus (P) content (i.e., (Fe+Al)/P >>1). The key point here is that just offering P content, while leaving the matrix elements in place, means the end-product will not function as an effective nutrient provider in agriculture!
The heavy metal data in the lower part of Table 1 reveal the legal status of materials intended for fertilizer use. It can be seen that there is a high risk of sewage sludge ashes being prevented from usage in the fertilizer market as the limits for all the regulated heavy metals are generally exceeded.
Currently, it is rare for sewage sludge ashes to meet regulatory requirements on heavy metals. And compliance is expected to vanish completely in future, as more demanding sewage treatment discharge consents are introduced alongside stricter contaminant limits for fertilizers, as legislators and regulators act to protect public health and the environment.
Phosphorus recovery from sewage sludge will become obligatory in Germany in stages between 2029-2032. Objectives such as cutting fertilizer import dependency, reducing soil contamination and improving phosphorus use efficiency were behind the country’s introduction of a new sewage sludge ordinance. To meet this deadline, building up ash processing capacity clearly needs to start now.
EasyMining has joined forces with Gelsenwasser to implement and roll-out Ash2Phos in the German market. In 2021, the two companies formed the joint venture Phosphorgewinnung Schkopau GmbH to build and operate the first full-scale Ash2Phos plant in the Schkopau chemical industry park (Figure2). This will have a capacity to process 30,000 t/a of ash, yielding 15,000 t/a of high-grade RevoCaP ® .
In collaboration with Gelsenwasser, the roll-out of up to four more Ash2Phos plants is expected by 2035, providing a total capacity of 300,000 t/a for sewage sludge ash in the German market and yielding a volume of 150,000 tonnes of RevoCaP ® annually. Further roll-out in neighbouring countries, as well as in Germany, is already a strong prospect.
Construction of the Schkopau plant is scheduled to start in the second quarter of this year with start-up expected in late 2026. The plant should be operating at full capacity in 2027 if all goes to plan.
The second Ash2Phos plant, at Helsingborg, Sweden, will have the same capacity as the Schkopau unit. It is currently in the permit application phase, with construction likely to follow the inaugural German plant after a gap of 1-2 years.
Supply risks, emerging markets and the circular economy
Supply chain disruptions in the aftermath of the Covid-19 pandemic, and the energy and commodity market shocks of 2022, have made one thing crystal clear: for Europe, external dependency on raw materials from other regions, together with reliance on extended supply chains, is increasingly risky for – and even a threat to – its economy, society and citizens. This makes access to resources a major pillar of continuing economic success and social survival.
Full control and access to resources are only possible when these are available within Europe’s borders. Consequently, it is likely that the domestic recovery and recycling of secondary resources will become essential from now on. Conversely, the wasteful use of resources and downcycling are no longer affordable. This is especially true for Europe, a region of high resource consumption that is relatively poor in primary raw material deposits.
Interestingly, while the European Commission has placed phosphorus on the EU Critical Raw Materials (CRM) list, alongside so-called tech metals, the element is absent from its Strategic Raw Materials (SRM) list. This suggest that the importance of phosphorus to the European economy has yet to be fully recognised.
Greater recognition may come, however, with the emergence of phosphorus as a key enabler of the energy transition in the transport sector.
This is linked to the growing use of lithium iron phosphate (LFP) batteries in electric vehicles (Fertilizer International 517, p53). This emerging market is in addition to the essential role of phosphorus as an irreplaceable nutrient in agriculture. LFP batteries currently require 350 g P per kWh and their use in vehicles is just starting to ramp up.
Such fast growing non-food applications for phosphorus could place pressure on primary resources and increase the prices of phosphate products in future. The key question here is this: which markets will recovered phosphorus supply in future – and will lower value agricultural markets be able to compete with demand from vehicle and battery makers if this provides higher margins and returns. Looking ahead, therefore, it cannot be assumed that the traditional agricultural route to market for phosphorus recovered from sewage sludge will remain unchallenged.
It is useful to compare the potential scale of recovered phosphorus production in Europe with global demand from LFP batteries:
- The theoretical P potential in German sewage sludge ashes, for example, is about 50,000 tonnes annually.
- Production at this scale would be enough to equip about two million electric vehicles with LFP batteries (based on the world’s current highest selling model).
- Theoretically, at European level, about 100,000 tonnes of P could be made available for LFP batteries by 2035, potentially equipping four million vehicles with a power source.
Demand for P from the electric vehicle sector is forecast to grow and be sustained. Since car batteries are designed to last 8-12 years, battery recycling is unlikely to be able to fulfil the LFP battery requirements from new vehicle production before 2040, in our view.
Summary
Agricultural and industrial demand for phosphorus will change how secondary resources are viewed and managed in Europe. Discarded materials that were once considered just waste and a disposal problem must now be used as efficiently as possible for the benefit of the economy, society and the environment.
EasyMining, given our production plans and the high quality and versatility of our RevoCap ® calcium phosphate product, is well positioned to contribute to the food security needs of a growing global population – and substantially increase supply security for other industries.
About EasyMining
EasyMining is the innovation company of the Ragn-Sells Group, a Swedish resource management and recycling company with a history dating back to 1881. At EasyMining, we’re developing and implementing innovative large-scale processes that recover valuable resources. This includes the commercial capture of the major crop nutrients N, P and K from material flows at industrial scale. Our technologies enable the recovery of highly uniform and high-quality raw materials and products from highly variable secondary sources, such as ashes or process waters.
GLATT
Phosphorus recovery: delivering better yields and less waste
In this article, we set out how the legal and environmental requirements to recover phosphorus more effectively from sewage sludge ash – while removing heavy metal contaminants – has prompted the wider adoption of Glatt’s PHOS4green process.
Introduction
Phosphorus, as an essential plant macronutrient, is a key component of many fertilizers. Furthermore, its classification as a critical raw material has made phosphorus recovery – from sewage sludge, for example – a legal requirement in the European Union and Germany.
The patented PHOS4green process, developed by Glatt Ingenieurtechnik GmbH (Glatt) in Weimar, Germany, is an attractive and viable option for recovering economically-valuable phosphorus and other essential macro and micronutrients present in sewage sludge ash (Figure 1).
The sewage sludge ash generated in urban centres frequently contains high levels of heavy metals alongside phosphorus. In Germany, the removal of these heavy metals during the phosphorus recovery process is now mandatory to prevent the environmental contamination of agricultural land.
Encouragingly, Glatt technology has been shown to be effective at eliminating heavy metals from sewage sludge ash during recent trials carried out in the Rhine-Main metropolitan region of Germany under the RePhoRM research project.
A two-stage process
Developing PHOS4green as an advanced commercial technology has been a particular priority for Glatt in recent years (Figure 2). The two-stage process extracts phosphorus from sewage sludge ash and then incorporates it within fertilizer granules. These have a precise chemical composition and specific physical properties.
PHOS4green granules are an effective soil fertilizer as they contain high levels of plant-available nutrients. Granules of sufficient hardness and density can be easily manufactured with an adjustable particle-size distribution (2–3 mm).
The manufacturing method is based on the processing of liquid suspensions using fluidised bed and spouted bed equipment. The use of spray granulation is a major innovation that allows the continuous production of fertilizer granules (instead of batch production).
Eliminating ash contaminants
Heavy metals (copper, zinc, nickel, lead etc.) enter urban wastewaters via various pathways. These are typically concentrated in sewage sludge during mechanical and biological treatment at wastewater treatment plants – and subsequently end up in sewage sludge ash following thermal treatment.
The degree of heavy metal contamination can vary significantly as input levels into wastewater depend on factors such as industrial activity within the municipality.
The composition of recovered phosphorus derived from waste streams – including the P generated by Glatt’s PHOS4green process – must comply with clear regulatory limits (set by German Düngemittelverordnung [DüMV] and EU Regulation No. 2019/1009) when incorporated into fertilizers.
Heavy metal removal is not necessary when sewage sludge ashes comply with these fertilizer ordinances. But how can municipal regions guarantee compliance with these stipulations – if the heavy metal content of their sewage sludge ashes exceeds regulatory limits?
The RePhoRM project
To address this question, Glatt is participating in RePhoRM (Regional Phosphorus recycling in the Rhine-Main region), a collaborative project funded by the German Federal Ministry of Education and Research (Grant No 02WPR1545A-G). The project is now fully underway after a successful trial phase.
RePhoRM was set up to jointly develop and implement technology for large scale phosphorus recycling in the Frankfurt Rhine-Main metropolitan region in Hesse State, Germany. The project sources ash from local mono sewage sludge incineration plants for use as a feedstock.
The project’s aims, as set out in the Hessian resource protection strategy, are to close the nutrient cycle within the region by using recycled phosphorus to create granular fertilizers for agriculture. The project is ‘closing the loop’ by establishing a practical and viable phosphorus recovery process for Frankfurt Rhine Main and creating a regional phosphorus recycling network.
The most challenging project objective, from a technical point of view, is designing a method that effectively and efficiently remove heavy metals from sewage sludge ash prior to phosphorus recovery.
The role of Glatt in the project, and the main challenge for the PHOS4green process, is to produce fertilizer granules by:
- Firstly, removing heavy metals from sewage sludge ash (the input material)
- Developing and implementing the phosphorus process industrially on a large scale.
Glatt is also contributing its expertise to the following two sub-projects:
- The planning and construction of a container plant at Industriepark Höchst
- Spray granulation studies on purified secondary phosphorus recovered from sewage sludge ash.
The overall objectives of the RePhoRM project are to:
- Develop a joint approach to phosphorus recycling in the Frankfurt Rhine Main metropolitan region that meets the needs of the region’s major wastewater treatment and mono sewage sludge incineration plant operators
- Establish a large-scale phosphorus recovery unit for sewage sludge ash at Industriepark Höchst using PHOS4green technology
- Optimise the spray granulation process under various conditions
- Ensure the regulatory conformity of the granular fertilizer, especially its agricultural acceptance as a recycled product
- Carry out accompanying lifecycle assessments for heavy metal removal and phosphorus recycling
- Develop a legal and organisational framework for a phosphorus recycling network
- Provide an economic analysis of the project’s integrated approach to phosphorus recovery and prepare a business case.
Project partners
- Technical University of Darmstadt
- TVM – Thermische Verwertung Mainz GmbH
- City of Frankfurt – Stadtentwässerung Frankfurt am Main (SEF)
- Becker Büttner Held – BBH
- Glatt Ingenieurtechnik GmbH
- Association for sewage treatment Langen/Egelsbach/Erzhausen.
Three process options
The project identified three process options for PHOS4green, depending on the quality of the ash input and the product output required:
- Option 1. This is the basic level process for phosphorus extraction (Table 1). Spray granulation with PHOS4green technology is used to produce fertilizer granules from sewage sludge ash. This enables customisation of their chemical composition and physical properties. The priority is establishing local supply chains and strengthening the circular economy.
- Option 2. This focuses on a newly developed selective process for removing heavy metals using specific acids (Table 2). The objective is to utilise as much of the ash as possible and minimise waste generation. This approach is ideally suited to ashes with low heavy metal concentrations.
- Option 3. This is a ‘double-extraction’ process that combines a basic process for phosphorus recovery and heavy metal removal in two steps. Step two is designed to be particularly effective at removing heavy metals such as nickel and zinc.
The heavy metal and phosphorus content of fertilizer granules (P-38) produced using the Option 2 process are shown in Table 3.
Next steps
The project’s findings should enable the implementation of an integrated approach to phosphorus recovery by determining both the quantitative and qualitative characteristics of sewage sludge ash flows.
Initially, heavy metal inputs into the sewage system and wastewater treatment plants in the city of Frankfurt am Main were recorded. This baseline data, by determining the accumulation of heavy metals from different sources, allowed mitigation options to be developed. Following on from this, the dissolution and separation of heavy metals from sewage sludge ash at both laboratory and demonstration-plant scale was investigated.
Developing an economic method for heavy metal removal allows more sewage sludge ash to be used for phosphorus recovery. Implementing a modified PHOS4green process that includes heavy metal removal offers dual benefits, as it should compensate for fluctuating ash loads in the future and meet stricter regulatory limits, if and when these are introduced.
The ability to remove heavy metals from incoming raw materials eliminates the need for ‘lot-by-lot’ selection and allows the use of all the available sewage sludge ash instead. This helps to make the process viable as a long-term option by simplifying sewage sludge treatment, within regions and between urban areas, by reducing the influence of both the origin and quality of ash on phosphorus recovery and fertilizer production. This contributes to sustainable sewage sludge use by helping guarantee a secure long-term disposal route.
Glatt aims to provide an efficient recycling process option that offers fertilizer manufacturers high-quality products while minimising their environmental impacts. The company’s innovative technologies are contributing to a more sustainable circular economy by helping to overcome the challenges of recycling phosphorus from sewage sludge ash.
