Research • Educate • Connect
Towards a sustainable bioeconomy

Research • Educate • Connect
Towards a sustainable bioeconomy

3rd BioSC Spotlight

Phosphorus recovery and cycling

On June 15, 2018, the third event in the “BioSC Spotlight“ series took place in Aachen. 45 participants extensively exchanged views about phosphorus recycling. Scientists from academia and industry held a total of seven specialist lectures. Like preceding events, this BioSC spotlight provided a framework for inter- and transdisciplinary exchange to a thematic field that contributes to the implementation of a sustainable bioeconomy.

Photos: Forschungszentrum Jülich


3rd BioSC Spotlight - Agenda

Phosphorus is a finite resource and an essential plant nutrient. Its re-use, particularly for fertilizing, is of great importance due its unequal and limited global distribution, its accumulation in water and soil and the entry of heavy metals into food chains by mineral P fertilization. In the frame of the 3rd BioSC Spotlight, current approaches towards Phosphorus recovery were presented and discussed.

The event was opened by Prof. Ulrich Schwaneberg, the deputy spokesman of the Bioeconomy Science Center. Subsequently, keynote speaker Dr. Rainer Schnee from the German Phosphorus-Platform e.V. gave a detailed overview of the current possibilities for phosphorus recovery and perspectives for future establishment.

In the first thematic session, “Phytases for phosphate recovery from plant residues”, Prof. Lars Blank from RWTH Aachen presented the BioSC project P-ENG, in the framework of which phytases were optimized to degrade phytate contained in rapeseed cakes and the released phosphorus was stored using yeast. Carolin Block from the University of Bonn presented the results of economic studies about market opportunities for phosphorus obtained this way. Dr. Anna Joëlle Ruff from RWTH Aachen presented the BioSC project PhytaPhos, in which sugar beet residues were treated with optimized phytases to degrade the contained phytate to phosphorus and the treated residues were successfully used as fertilizer.

The second thematic session, “Nutrient transfer from waste water to algae”, dealt with the recovery of phosphorus from waste water but also addressed the necessary further development of phosphorus analytics. Prof. Ulf Theilen from the Technical University of Middle Hesse presented an impressive pilot project on phosphorus recycling using micro algae in the sewage treatment plant of a small town. Dr. Peter Mojzeš from the University of Prague gave an introduction to Raman spectroscopy and explained the possibilities offered by this method for in situ detection of phosphorus in individual cells. Prof. Alexei Solovchenko from the University of Moscow initially reported on the BioSC project AlgalFertilizer, in which micro algae were used to take up phosphorus from waste water and the algae biomass was then successfully distributed as fertilizer. Subsequently, he presented basic studies on the uptake of phosphorus in micro algae and cyanobacteria and showed which research gaps need to be closed to develop and establish phosphorus recovery using these organisms as a standard method.

Both lectures and the engaged discussions reflected the high topicality and relevance of the topic of phosphorus recycling. The research needs and possibilities not yet exploited were a common theme of discussion. Like preceding events, this BioSC spotlight provided a framework for inter- and transdisciplinary exchange to a thematic field that contributes to the implementation of a sustainable bioeconomy.



Phosphorus recycling: Facts and perspectives

Dr. Rainer Schnee, Deutsche Phosphor-Plattform e.V., Board of Directors

In purely quantitative terms, phosphorus is one of the most common elements on earth. However, it does not occur in elementary form but exists almost exclusively in the form of the phosphate anion PO43- or in mineral phosphate salts. The relevant literature often speaks of phosphorus, although the substance in question is phosphate. The largest phosphate amounts exist in mineral form in the earth´s crust or geosphere. Large quantities are also present dissolved in water bodies and oceans and further amounts can be found in manifold functions in the biomass. Phosphorus thus plays an essential and vital role in terrestrial life processes.

Since no noteworthy phosphate amounts are transported through the atmosphere, mobility in soil and water is crucial. At present, over 200 million tons of phosphate are gained from mineral deposits per year and in particular are used in fertilizer and feed in agriculture. Hence, the local, regional and global availability of phosphate for feed and food production is of vital importance and not substitutable. In addition, phosphorus and phosphates are used in foods, detergents, building materials and in the semiconductor industry in various functions. Comprehensive and detailed monitoring of present and future phosphorus flows is indispensable for understanding and management of its spatio-temporal dimensions and functions.

Efficient use as fertilizer will be of central importance. This is accompanied by optimization of plant availability, minimization of dissipative losses, eutrophication of waters that is as low as possible and recovery as a secondary raw material that is as great as possible using accumulation and recycling in the technical, industrial and biological value chains. Together with the socio-economic contexts, these approaches are the cornerstones of a forward-looking resources strategy for phosphorus.

As a basis for evaluating the criticality of phosphorus, a resource strategy concept is applied that is based on specific criteria to record, analyze and assess the life cycle and its different value chains, from mining in deposits to processing, functionalization and use in various processes and products up to subsequent use and recycling. A criticality analysis for phosphorus reveals, amongst other things, that

  • As far as we can judge, there are sufficient reserves but only a few deposits supply the world market and those are partly located in regions deemed critical from a geographical and geopolitical point of view.
  • Many mineral phosphate sources are contaminated with heavy metals and radioactive elements and it is crucial to separate these during processing to products, especially fertilizers, in order to prevent uncontrolled dissipation.
  • Improper use in agriculture can cause enrichment in soils and eutrophication of waters.

Additional technical, functional, economic, ecologic, social and political dimensions of phosphorus use are considered and brought together in a comprehensive analysis and evaluation of its criticality.


P-ENG: Efficient phosphate recovery from agro waste streams by enzyme, strain, and process engineering

Prof. Dr. Lars M. Blank, Institute of Applied Microbiology, RWTH Aachen University

The project focuses on the development of a new value chain to recover phosphate from plant waste material. The ultimate aim is to recycle phosphate into polyphosphates of new values. Therefore phytase, the enzyme able to release phosphate from plant material, is studied in this BioSC project. Through variations in protein modification (glycosylation) different properties such as thermostability or enzyme activity are optimized until a superior phytase is created. The impact of the enzyme production on the production host, the yeast Pichia pastoris, is analyzed with the whole metabolism in sight. Through this approach it is possible to predict steps in the cell metabolism during protein production which can be tuned to further improve phytase production. Bioprocess development contributes through establishing high-throughput screening environment in form of micro bioreactor systems. Utilizing that system clones generated by the other partners can easily be tested to identify the best producing strains. With the use of yeasts that collect phosphate it is possible to use the released phosphate to form polyphosphates. The possible market entries for superior phytase and polyphosphates are evaluated on a basis of market research, existing products, and company interviews. Furthermore the generic technology potential will be studied (e.g. IP).


Commercializing phosphorus from renewable resources: What are the major challenges?

Carolin Block, Institute for Food and Resource Economics, University of Bonn

The use of renewable resources opens up the way for more sustainable production systems. Recovering resources from low value by-products or waste streams reduces the dependency on fossil materials. However, the change from traditional to bio-based technologies leads to several challenges for value chain actors. Thus, actors for instance might face high switching costs, missing industry or quality standards. Moreover, in the bioeconomic setting actors from distinct industries need to establish new relationships leading to structural changes and emerging value chains.

In order to explore the challenges for the chain actors, a case study on a new technology for phosphorus recovery from rapeseed oil press cakes, a by-product in oil mills which ends up in animal feed, was carried out within the BioSC project P-ENG. The literature research and expert interviews with 4 different value chain actors (phosphorus processor, biotechnological company, rapeseed oil processor and feeding mix producer) reveal that there are challenges referring to five major categories, namely organizational, institutional and regulatory, economic viability, geographical and product quality issues. None of the current chain actors has the competencies to carry out the phosphorus recovery process from extraction to commercialization on its own. The results highlight the need for further research developments such as closer integration of academia and industry and economic viability studies to tackle these challenges.

Optimizing the Phosphorus Cycle in the Sugar Beet Production Process by Phytase Supplement

Anna Joëlle Ruff1, Prof. M. Becker3, Dr. U. Arnold3, Dr. M. Trimborn3, Prof. U. Schurr4, Dr. S. Schrey4, A. Robles Aguilar4, Ulrich Schwaneberg1,2

1 RWTH Aachen University, Institute of Biotechnology, Aachen, Germany

2 DWI –Leibniz Institut für Interaktive Materialien, Aachen, Germany

3University Bonn; Institute of Crop Science and Resource Conservation INRES, Bonn, Germany

4 FZ Jülich, IBG-2, Institute of Bio- and Geosciences: Plant Sciences, Jülich, Germany

Phosphate is a main component of fertilizers and therefore essential to feed humankind. Subsequently, recycling concepts for phosphorus are a key request to ensure a self-sustaining food production in Europe and to avoid rapid depletion of concentrated natural deposits. Within the BioSc-funded project PhytaPhoS, we propose a new value chain to recover phosphate from plant waste material. The principle storage form of phosphorus in plants is phytate (inositol hexaphosphate). The approach is based on the naturally occurring phytases that free the phosphate bound in an organic form. In sugar production processes this could be achieved by supplementing thermally resistant phytases to leach the phytate phosphate form sugar beet slices. With this procedure the phosphorus concentration in sugar beet slices in fodder and in consequence P-excess in fields will be reduced. Instead, isolated phosphorus will be transferred into spent lime and subsequently back to the sugar beet fields. Thereby a hub forward to an independent phosphorous use would be enabled and emerging value chains contribute to a sustainable bioeconomy.

Nutrient Removal with Microalgae – Reduction of the Effluent Concentration from Wastewater Treatment Plants

Wawilow, T.1; Hasport, N. 1, Theilen, U1and Thomsen C. 2

1 THM - University of Applied Sciences - ZEuUS, 35390 Gießen, Germany

2 Phytolutions GmbH, 28759 Bremen, Germany

An alternative, environmentally sustainable method to remove nutrients from wastewater is to integrate an algae-mediated wastewater treatment to reduce nutrient loads to preserve water bodies from eutrophication and generate effective biomass. Compared with conventional treatment methods the generated microalgae biomass is more energetic and rich in content with phosphorous (P) and nitrogen (N). Therefore, a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for energetic or material purposes, is an efficient alternative to avoid using chemicals for the removal of phosphorus via precipitation and flocculation. Algae species Scenedesmus was applied for wastewater treatment and had proven abilities of removing nitrogen and phosphorous in retention time of 24 hours. In this study, a photobioreactor (PBR) was implemented for large-scale research to treat the effluent of the WWTP while microalgae growth rate, nutrition removal as well as operational and external conditions were evaluated. Moreover, the biomass was separated and methane potential tests were conducted using microalgae as substrate.

Detection and quantification of polyphosphates in microalgae by means of Raman microscopy

Peter Mojzeš, Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, CZ

The potential of microalgae to sequester phosphorus from wastewater and to return it to agriculture as a fertilizer has emphasized the importance of microscopic methods allowing detection and quantification of polyphosphates in situ at single cell level. Confocal Raman microscopy, a method combining the molecular specificity of vibrational spectroscopy with spatial resolution of confocal optical microscopy, can be a method of choice, since Raman signal of polyphosphates is clearly recognizable even in the presence of other biomolecules in the same cellular region. However, routine applicability of Raman microscopy to microalgae has long been hindered by a strong autofluorescence of photosynthetic pigments. Recently, we have developed a simple methodology [1] for fast and efficient suppression of the algal fluorescence, which open the door to an unexplored world and enabled relatively rapid and simple quantification of polyphosphates from Raman chemical maps along with other biomolecules [2]. Recent progress in the field, advantages, limitations and pitfalls of the method will be demonstrated and discussed.

[1] Š. Moudříková et al., Algal Res. 16 (2016) 224-232.

[2] Š. Moudříková et al., Anal. Chem. 89 (2017) 12006-12013.

Luxury phosphorus uptake and diazotrophy in green algae & cyanobacteria: AlgalFertilizer and follow-up projects

Alexei Solovchenko*, Olga Karpova, Tatiana Ismagulova, Larisa Semenova, Irina Selyakh, Alexandr Lukyanov and Olga Gorelova

Lomonosov Moscow State University, Moscow, Russia


Sustainable usage of finite and non-renewable phosphorus (P) resources is a grave challenge to humanity. Shortage of P fertilizers threatens the food security. The P lost due in inefficient processing chain gives rise to eutrophication of water bodies. In view of this, potential environmental, social, and economic impact of currently non-sustainable usage of P is commensurate to that of oil and gas shortage.

Single celled phototrophs including cyanobacteria and eukaryotic microalgae featuring so called “luxury uptake” of P constitute promising vehicle for by sequestering the lost P and returning it, in form of P-rich biomass, to the field. The reasons are (i) fast growth rate of these organism, (ii) capability of rapidly taking up P up to 4­−7% of their cell dry weight, and (iii) gradual release of the accumulated P upon application of microalgal biomass to the soil in the from available to crop plants.

Diazotrophic species of cyanobacteria are capable of fixing atmospheric nitrogen (N). On one hand, this process makes them less dependent on the availability of N in the medium so cyanobacteria can potentially recover P from waste streams with imbalanced N:P ratio. On the other hand, diazotrophy is a very energy-intensive process which can compete for ATP with the processes of P acquisition and storage in the cell. The successful biotechnological application of cyanobacteria to close the P loop is limited by insufficient understanding of C/N balance impact on and the molecular mechanisms of luxury P uptake.

We report on the effect of diazotrophy on luxury P uptake and storage in the cell in a diazotroph strain Nostoc sp. PCC 7120 in comparison with a nearly-isogenic non-diazotroph strain Nostoc sp. PCC 7118. Although the P starvation and the fast phase of inorganic P (Pi) uptake were similar in both strains studied, induction of diazotrophy impared significantly the ability of PCC 7120 to accumulated inorganic polyphosphate (PolyP) in the cell. Since PolyP is a main P storage compound in the cell, the availability of N seems to of primary importance for efficient recovery of P from waste streams. Biotechnological implications of using diazotrophic and non-diazotrophic cyanobacterial strains for recovery of P from waste streams with different N/P balance are discussed.