A new technology to recover P from oilseed cakes illustrates the challenges of developing new value chains needed for P-recycling.

An innovative process to recover phosphorus from rapeseed press cakes (a colza oil by-product, which goes to animal feed) illustrates how a new value chain would be needed and the challenges to current industry players to implement this.

At present, colza oil production leads to 40% oil (with nearly 60% of the added value) and 60% cake (with only 40% of the added value). The cake consists of 80% kernel cake and 20% shell cake (the latter having half the market value). The kernel cakes are used as an ingredient for chicken feed production. Much of the phosphorus in the cake, however, is not digestible to chickens because it is in the form of phytate.

The innovation consists of treating the cake in a bio-reactor with a specific targeted variant of the phytase enzyme. This breaks down the phytate, mobilizing the phosphate which will be stored by a yeast and then released in a new form of value added polyphosphate which can be recovered and – if it is in an appropriate form – used to substitute conventional polyphosphate, which is currently produced from phosphate rock (via phosphoric acid) and used for fertilizers and other industrial applications such as detergents and food additives. Additionally, the level of phosphorus remaining in the cakes is lower, and is more available to chickens, enabling more balanced nutrient management in the poultry feed, and leading to a higher value for the cake, as well environmental advantages because of lower P levels in manures (undigested P).

Value chain challenges
This paper analyses the possible value chain organisation to ensure the implementation of the innovation between the existing actors: colza pressing company, enzyme supplier, polyphosphate producer (phosphate industry) with market to polyphosphate user, and chicken feed producer (combining cake with other nutrients and feeds).

A challenge is that none of the current players in these value chains have the competence to operate the bio-reactor necessary to control production of polyphosphate using the enzyme in order to ensure that the polyphosphate is appropriate for industrial applications (and so markets). On the other hand, only the phosphate industry player has the know-how of which polyphosphates are suitable, and the capacity to take these to the market.

One possible solution would be to involve a new actor, who would collect the cakes from the colza mill, operate the bio-reactor, and then supply the polyphosphates to the chemical industry for use/sale to industrial application users. This would on the one hand pose logistical costs, by adding an additional processing site to the value chain, but on the other hand could enable the development of a processing hub, taking cake from several mills and producing different polyphosphates for different users. To be optimised, such a new site should be installed close to a colza mill or cake user. The new actor might have other benefits by providing a link between the different existing value chain actors to optimise or develop new synergies.

“Emerging value chains within the bio-economy: structural changes in the case of phosphate recovery” http://purl.umn.edu/244788, L. Carraresi, S. Berg, S. Bröring, Institute for Food and Resource Economics, University of Bonn, Germany, 149th EAAE Seminar 2016.

Part of the project entitled “Efficient phosphate recovery from agro waste streams by enzyme, strain, and process engineering” (P-ENG), funded by the North-Rhine-Westphalia Strategy Project BioSC (Bioeconomy Science Center, http://www.biosc.de/peng_en). Project Coordinator: Prof. Lars Blank (RWTH Aachen University). Project partners: Prof. Dr. Ulrich Schwaneberg (RWTH Aachen University), Prof. Dr. Marco Oldiges (Forschungszentrum Jülich GmbH), Prof. Dr. Stefanie Bröring (University of Bonn).

Corresponding author and contact for the article: Laura Carraresi ()                      

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