Fraunhofer Institute for Interfacial Engineering and Biotechnology IGBThe nutrients nitrogen and phosphorus are key components of fertilizers and indispensable for global food production. Systematically recovering these nutrients from waste materials strengthens the resilience of fertilizer production and thus ensures a secure supply. Furthermore, it makes an important contribution to climate and water protection. Fraunhofer IGB develops sustainable and cost-effective technologies for nutrient recovery and fertilizer production: For example, wastewater, manure, and digestion residues, as well as various other solid or liquid waste streams, have already been characterized, investigated with regard to the recovery of ammonium and phosphate, and successfully patented processes have been developed. We develop these further for implementation together with partners.
© Fraunhofer IGB
© Fraunhofer IGB
Recovery of Nutrients from Waste Streams for the Production of Fertilizers
Recovery of ammonium and phosphate: contributing to supply security, water quality and climate protection
Nutrients such as nitrogen and phosphorus, as well as, to a lesser extent, potassium, calcium, and sulfur, are essential for the growth of all living organisms. For this reason, they are the main components of fertilizers and indispensable for global food production. To date, nutrients are only partially recycled in a closed loop. Instead, they are removed from the agricultural ecosystem when crops are harvested. Recycling of nutrients via the residues of food production or municipal waste management systems hardly takes place.
The challenge of rising nutrient demand
With the growing global population and its demand for food, as well as the increasing use of renewable raw materials for the production of bioenergy and bio-based basic chemicals, the demand for fertilizers is rising. The production of nitrogen fertilizers via the Haber-Bosch process requires a very high energy input, particularly in the form of natural gas. The industrial production of phosphate fertilizers is based on the use of non-renewable raw phosphates, whose reserves are steadily declining. The prices of industrially produced mineral fertilizers have already risen in recent years and this trend is expected to continue.
Our solution approach: closing the nutrient cycle by recycling them into fertilizers
Nutrient recovery is essential for a sustainable economy. Fraunhofer IGB is therefore dedicated to developing and implementing sustainable, cost-effective technologies and strategies for integrated resource management. The focus is on developing innovative technologies for recovering nutrients from wastewater and organic waste. In recent years, we have characterized wastewater, liquid manure, and digestate, as well as various other solid and liquid waste streams, investigated them with regard to nutrient recovery, and successfully developed patented processes.
Our technologies
- Phosphorus recovery: Phosphorus is an important fertilizer for agriculture. As natural phosphorus deposits are dwindling, processes for recovering this nutrient offer a sustainable alternative for the production of phosphorus-based fertilizers.
- Nitrogen recovery: Nitrogen-containing fertilizers are in high demand in agriculture. Nitrogen is present in large quantities in wastewater, digestate from biogas plants, manure, and other organic residues and can be recovered using processes developed at Fraunhofer IGB.
- Thermal treatment and drying: Using thermal processes, digestate from biogas plants can be broken down into its components. Through drying or torrefaction, solid residual fractions can be stabilized, e.g., as organic soil conditioners.
Advantages of nutrient recovery
- Production of fertilizers and peat substitutes
- Increased supply security for the required raw materials and resilience
- Circular economy instead of linear consumption
- Water and climate protection
Sources of nutrients and areas of application
Wastewater from sewage treatment plants
Concentrated wastewater from sewage sludge dewatering in sludge digestion systems with high loading rates—so-called high-load digestion systems—is characterized by high concentrations of ammonium and phosphate, up to 1,300 mg NH4 per liter and 200 mg phosphate per liter, respectively.
State of the art: disposal without reuse
The state of the art in most municipal wastewater treatment plants involves the removal of nitrogen compounds such as ammonium (NH4+) and nitrate (NO3–) using nitrification and denitrification processes. With high energy consumption for aeration, these compounds are converted into gaseous nitrogen, which escapes into the air. In the process, nitrous oxide may be released; this is an intermediate product and is considered a potent greenhouse gas. Phosphate is removed via chemical precipitation by adding aluminum or iron salts. These phosphate salts are landfilled because they are not available to plants and can release iron and aluminum in concentrations toxic to plants.
Our solution
- Nitrogen recovery via chemical membrane absorption
- Phosphorus recovery using the ePhos process
Advantages of nutrient recovery
- Reduction of nitrous oxide emissions
- Energy savings in aeration
- Prevention of phosphate disposal through the production of recyclates
- Savings on precipitants
- Compliance with limit values in the wastewater treatment plant effluent
Agricultural byproducts: manure and digestate from biogas plants
Agricultural biogas plants generate energy from biomass. At the same time, valuable nutrients can be recovered from the plant’s digestate. Fraunhofer IGB develops the processes needed to combine energy generation with nutrient production. This allows biogas plants to be used more efficiently and thus operated more economically. In various projects, we have developed processes for converting liquid manure and fermentation residues into mineral fertilizers and organic soil conditioners, and integrated them as separate modules into a plant for on-site processing.
Challenge: Where to put the manure?
Spreading of liquid manure, digestate from biogas plants, and other agricultural waste supplies arable soils with valuable organic components and essential nutrients. These serve to cover the plants’ nutrient requirements and maintain soil fertility. In areas with intensive livestock farming, however, spreading on fields is not always possible because the soils already have a high nutrient content. A conventional agricultural biogas plant with a capacity of 500 kWel, for example, produces approximately 100 tons of nitrogen (N) per year through fermentation. A fertilization with 170 kg N/ha would require 588 hectares of land to absorb the amount of nitrogen produced. Therefore, fermentation residues and excess manure from regions with intensive livestock farming must either be removed or stored for a long time. Therefore, fermentation residues and excess manure from regions with intensive livestock farming must either be transported away or stored for long periods. However, due to the high water content of up to 80 percent, transportation is not practical. Ammonia is released during storage.
Our solutions
- Phosphorus recovery
- Nitrogen recovery
- Thermal treatment of digestate
- Stabilization of the organic solid fraction through drying and torrefaction
Advantages of nutrient recovery
- Improved storage and transportability through dewatering
- Production of specific fertilizers with a defined composition
- Prevention of overfertilization
- Reduction of ammonia emissions
- Phosphate and ammonium can be specifically utilized as nutrients
- Unloaded water for reuse (e.g., irrigation or rinsing water)
- Organic residual fraction can be processed into a humus-rich peat substitute product
By-products and process water from the food industry
The production of food and animal feed also generates organic residues and process water from which important nutrients such as ammonium and phosphate can be recovered. Fraunhofer IGB develops and tests appropriate processes for this purpose.
Our solutions
- Phosphorus recovery
- Nitrogen recovery
Advantages of nutrient recovery
- Internal recirculation of treated process water
- Savings in raw materials
- Savings in fresh water
Tabbed contents
Range of services and collaboration
Services at a glance
- Technology development for the recovery of ammonium nitrogen or phosphate from process water/wastewater, sewage sludge treatment, and digestate/manure
- Concept development for the treatment and utilization of manure and fermentation residues
- Evaluation of existing data
- Laboratory analyses and evaluations to supplement the data set
- Laboratory feasibility studies using real substrates for customer-specific applications, cost estimation, and process optimization
- Construction and operation of demonstration and pilot plants
- Preliminary planning and cost estimation for large-scale implementations
- Scientific support during commissioning and operation
- Securing intellectual property rights through patenting and licensing
Collaboration: how you can benefit from our expertise
Using the processes developed at Fraunhofer IGB, phosphorus and nitrogen can be recovered from agricultural and industrial waste materials and wastewater and used as readily applicable fertilizers with a defined chemical composition. In our processes, the nutrients are precipitated or pelletized in such a way that they can be marketed by industrial partners as a high-quality, specific product and used in various agricultural sectors.
Process development for the recovery of nitrogen and phosphorus
We design and develop processes tailored to your specific waste materials.
Solid/liquid separation, dewatering
We also develop suitable processes for separation tasks alone, based on our expertise and technologies.
Case studies
In individual cases, we conduct case studies to determine the need for new processes and their feasibility.
Production of sample quantities
Fertilizers can be produced and marketed in both solid and liquid forms. We offer the possibility to develop appropriate product formulations, produce sample quantities, and characterize them accordingly.
Plant engineering and system integration
Thanks to our process engineering expertise, we also implement these processes in pilot and demonstration plants. Furthermore, we support you in implementing the processes in industrial practice, such as integrating them into existing wastewater treatment plants.
Feel free to contact us!
We look forward to your call or email. We would be happy to discuss how we can work together to solve your challenges in an initial, non-binding meeting.
Equipment
Equipment
- Laboratory setups for feasibility studies
- Demonstration/pilot plants for on-site operation
- Analytical laboratory, including accredited testing procedures in accordance with DIN EN ISO/IEC 17025:2018
- High-performance liquid chromatography (HPLC)
- Ion chromatography (IC)
- Gas chromatography (GC)
- Inductively coupled plasma atomic emission spectrometry (ICP-AES)
Benefits for soil and groundwater
Benefits for soil and groundwater
Agriculturally used soils are often overfertilized with mineral nutrients. Mineral fertilizers applied incorrectly or in excess are washed out of the soil and thus enter the groundwater or surface waters, where the nutrient input leads to undesired eutrophication.
Nutrient recovery prevents soil overfertilization
The direct use of manure or digestate from biogas production as fertilizer can also be detrimental to the soil, as the nutrient composition of nitrogen, phosphorus, and potassium (N:P:K) in these organic residues does not match the specific needs of the plants. When using manure or digestate as fertilizer, nutrient requirements are therefore calculated based on a single nutrient, typically nitrogen. This leads to an overdose of the other nutrients in the soil. The use of uncontrolled amounts of nutrients in organic fertilizers can lead to nutrient oversaturation in the soil, particularly in areas with intensive livestock farming, and thus cause environmental damage. If the nutrients from manure and fermentation residues are instead recovered and precipitated as ammonium and phosphate salts, the resulting mineral fertilizers can be applied in specific doses.
Soil degradation is becoming a serious problem in Europe due to the growing demand for plant-based products, renewable raw materials, and bioenergy. In recent years, numerous forest areas and permanent grasslands have been converted into arable land. This has led to a decrease in soil organic matter and, consequently, to reduced water retention capacity, lower soil fertility, and a disruption of nutrient cycles.
Soil conditioners can compensate for the loss of soil organic matter
Currently, the loss of soil fertility due to overfertilization with synthetic fertilizers is still being overcompensated for, though without compensating for the loss of organic matter. In the long term, however, the application of mineral fertilizers will not be sufficient to maintain soil fertility. The decline in soil fertility will have a direct impact on securing food production, especially since soil is not a renewable resource. If the organic residues from manure or fermentation residues are dried or composted after nutrient recovery, for example, the products can be used as a peat substitute and restore soil fertility.
Publications
Publications Nutrient Recovery
| Jahr Year | Titel/Autor:in Title/Author | Publikationstyp Publication Type |
|---|---|---|
| 2023 | Elektrolytische Reaktoren Krupp, Sebastian; Bohn, Michael; Egner, Siegfried |
Patent |
| 2019 | Phosphates recycled from semi-liquid manure and digestate are suitable alternative fertilizers for ornamentals Ehmann, Andrea; Bach, Inga-Mareike; Bilbao, Jennifer; Lewandowski, Iris; Müller, Torsten |
Zeitschriftenaufsatz Journal Article |
| 2017 | Can phosphate salts recovered from manure replace conventional phosphate fertilizer? Ehmann, Andrea; Bach, Inga-Mareike; Laopeamthong, Sukhanes; Bilbao, Jennifer; Lewandowski, Iris |
Zeitschriftenaufsatz Journal Article |
| 2014 | Nährstoffrückgewinnung aus Gärprodukten im Rahmen des GoBi-Vorhabens Frank, Daniel; Messmer, Johannes; Laopeamthong, Sukhanes; Bilbao, Jennifer; Egner, Siegfried |
Zeitschriftenaufsatz Journal Article |
| 2014 | Phosphorus recovery from wastewater filtrates through a novel electrochemical struvite precipitation process Bilbao, Jennifer |
Dissertation Doctoral Thesis |
| 2012 | Nährstoffrückgewinnung mit elektrochemischer Fällung - Anwendungspotenzial in kommunalen Kläranlagen Bilbao, Jennifer; Frank, Daniel; Egner, Siegfried; Trösch, Walter; Hirth, Thomas |
Konferenzbeitrag Conference Paper |
| 2010 | Nährstoff-Recycling als Schritt zur vollständigen Nutzung von Kulturpflanzen Bilbao, Jennifer; Stoll, Maria Soledad |
Zeitschriftenaufsatz Journal Article |
| 2010 | Verfahren Rückgewinnung von Phosphatsalzen aus einer Flüssigkeit Bilbao, J.; Bryniok, D.; Frank, D.; Egner, Siegfried |
Patent |
| 2010 | Reaktor zur Rückgewinnung von Phosphatsalzen aus einer Flüssigkeit Bilbao, J.; Bryniok, D.; Campos, A.; Egner, Siegfried |
Patent |
| 2010 | Closing the nutrients cycle Bilbao, Jennifer; Stoll, Maria Soledad; Egner, S. |
Zeitschriftenaufsatz Journal Article |
| 2010 | Characterization and anaerobic digestion of olive-mill solid wastes Bilbao, J.; Stoll, Maria Soledad; Bryniok, Dieter; Egner, S.; Trösch, Walter; Hirth, Thomas |
Konferenzbeitrag Conference Paper |
Recent publications
- Michael Bohn: ePhos – elektrochemische Phosphorrückgewinnung, Galvanotechnik 9 (2025): 1125-1131. zum Artikel
- Marius Mohr, Michael Bohn, Ulrich Dietz, Konstantin Frick, Carsten Pietzka, Hans-Jürgen Rapp, Ricardo Reyes Alva: Bioraffinerie Kläranlage, VDI energie+umwelt 02 (2025): 32-35
- Reyes Alva, R.; Mohr, M.; Tovar, G. E. M.; Zibek, S. Recovering Ammonia as Ammonium Citrate and Ammonium Sulfate from Sludge Digestion Liquors Using Membrane Contactors in a Pilot Plant. Membranes 2025, 15(2), 62. https://doi.org/10.3390/membranes15020062
- Reyes Alva, R.; Mohr, M.; Zibek, S. Transmembrane Chemical Absorption Process for Recovering Ammonia as an Organic Fertilizer Using Citric Acid as the Trapping Solution. Membranes 2024, 14, 102. https://doi.org/10.3390/membranes14050102