Fraunhofer Institute for Interfacial Engineering and Biotechnology IGBSustainable agriculture thrives on protecting the environment. This is often a balancing act. On the one hand, farmers want to achieve high yields, and on the other hand, overuse of plants and soil poses a threat to the future. The need for environmentally friendly methods to protect plants and maintain good soil quality is therefore enormous. For this reason, the Fraunhofer IGB is working on sustainable processes for the production of fertilizers, soil improvers and pesticides.
With the BioEcoSim process, livestock manure can be converted into valuable phosphorus fertilizers (rear), nitrogen fertilizers (right) and soil conditioners (front).
© Fraunhofer IGB
Fertilizer and biological pest repellent all in one: EcoBug pellets, made from the residues of cow manure fermentation enriched with cyanobacteria.
Nutrient management.
Stabilization of fertilizers and soil substrates by drying
Stabilization of fertilizers and soil substrates
Pilot plant for drying with superheated steam.
Drying
Drying processes play an important role in the production of fertilizers and pesticides. They facilitate the transport and storage of extracted nutrients and active ingredients, such as in the form of powders. Thus, drying also forms the basis for the production of fertilizer pellets.
Torrefaction
The goal of torrefaction is to increase the mass-specific energy density and thus the calorific value of the raw material. It also improves its transportability and storability.
Our technology: Superheated steam drying (SHSD)
At Fraunhofer IGB, we use the superheated steam drying process developed at our institute to stabilize recovered nutrients and soil substrates. The superheated steam dryer developed at Fraunhofer IGB offers significant advantages over conventional hot-air dryers.
Use cases
Drying of soil substrates containing cyanobacteria
Plant protection for ecological farming
Fertilizer and biological pest repellent all in one: EcoBug Pellets, made from the residues of cow manure fermentation enriched with cyanobacteria.
More and more frequently, customers are buying organic vegetables, because these products are not treated with pesticides or laden with chemicals. However, if these plants are attacked by pests, farmers have few options to protect them. For instance, organically-grown cabbages are often plagued by the cabbage root fly, the common enemy of such plants, causing great damage to crop yield.
Fertilizer pellets for organic farming with insect repellent activity
In the EU-funded EcoBug project (grant agreement no 218467-2), Fraunhofer IGB together with colleagues from the University of West Hungary and the Research Institute Nor-tek in Oslo – on behalf of various organic agriculture associations – has produced pellets with combined fertilizer-repellent properties for the organic farming of cabbage.
The pellets consisted of dried digested manure with 0.1 percent dried cyanobacteria. If the pellets are applied to freshly planted vegetables, then the cyanobacteria are degraded by the soil flora and release a scent that repels cabbage root flies. The nutrient-rich digestate additionally fertilizes the plants. The pellets are easy to apply, and the nutrients are directly available to the plants.
The fertilizing and repelling effect of this product was confirmed in open field trials in Hungary and Spain. Our project partners in both countries achieved highly satisfying results: white cabbage plants that were fertilized with the combined pellets grew significantly better than non-fertilized plants. None of the plants fertilized with the combined pellets in the field trials were infested with the cabbage root fly.
Drying of organic residues and cyanobacteria with superheated steam dryer
In this project, the drying of the digested manure and cyanobacteria was carried out with a novel superheated steam dryer (SHSD). This dryer offers significant advantages in comparison with common hot air dryers.
Due to the superior heat transfer of steam, higher drying rates are achievable with SHSD at the same temperature. This leads to a lower specific energy consumption of
0.75–0.90 kW·h/kg water removed for SHSD compared to 1.10–1.70 kW·h/kg water removed in a comparable hot air dryer [1].
Moreover, higher thermal conductivity and heat capacity of superheated steam compared with hot air results in enhanced heat transfer to microorganisms, enabling pasteurization and/or sterilization. As superheated steam is recirculated and reheated in a closed loop, an excess of evaporated water develops which is carried off along with NH3 and volatile organic carbon (VOC) from SHSD. In our approach VOCs and NH3 are condensed out with the excess steam enabling condensable valuable organic substances including volatile fatty acids (VFA) and NH3 to be recovered. This eliminates the environmental problem of VOC and NH3 emissions in conventional hot air dryers.
Literature
[1] Desai, D. K. et al. (2009) Superheated Steam Drying of Brewer’s Spent Grain in a Rotary Drum, Advanced Powder Technology, Vol. 20, Issue 3, pp. 240-244
Soil conditioners made from olive oil production waste
Residues from the olive oil production.
Pellets from digested residues of the olive mill production that can be used directly as organic fertilizers.
In the project En-X-Olive funded by the European Union (grant agreement no 2184442-2) we researched together with partners from Spain, Italy, Greece and France the recovery of biogas, polyphenols, and fertilizers from residues of olive oil production.
The objective of the work package fertilizer recovery was to produce a compact organic soil improver from the digested residues of the olive oil mill industry. The digested residues were separated into their solid and liquid fractions and the solid fraction was dried and pelletized.
The product was a competitive commercial fertilizer that could be stabilized, stored, transported and spread with common fertilizer spreaders used in agriculture.