For the Atlantic area, the Sea2Land project aims at producing biobased fertilizers (BBF’s) from by-products of the aquaculture domain using ThermoMechanoChemical (TMC) fractionation by twin-screw extrusion. TMC process is a continuous process, working at low liquid/solid ratios and able to provide a solid and a liquid fraction. Until now, the processes concerning extrusion / fish / fertilizer had been limited to: a) the mixing of fish with vegetal raw materials by twin-screw extrusion for the production of pellets for the feed industry, b) the pretreatment of lignocellulosic raw materials with enzymes by twin-screw extrusion to initiate the enzymatic hydrolysis, c) the transformation of fish bones and heads by extrusion for the production of gelatins films, and d) the production of organic fertilizers by urea and derivatives.

The use of TMC process for fertilizers production is an innovative approach which makes it possible to recover not only fertilizers but also other components such as lipids. TMC process had never been used in the presence of enzymes for the transformation of aquaculture byproducts into bio-based fertilizers.

During the first months of Sea2Land project, the Chambre d’Agriculture des Pyrénées-Atlantiques (CAPA) achieved the research and identification of potential partners in the aquaculture domain. They allowed the establishment of a partnership between by-products suppliers and CATAR. Retained by-products are heads, fishbones and viscera from Steelhead truit (Oncorhynchus mykiss). The chemical characterization of the three by-products supplied is in progress.

The pilot implemented in the Atlantic Area includes the following technological units: (i) Grinding technologies, (ii) TMC fractionation by twin-screw extrusion, (iii) Enzymatic Hydrolysis, (iv) Separation by centrifugation technologies and (v) concentration technologies. All these technologies are combined to recover products with agronomic value and to find a specific valorization for lipids to reach a ZERO-waste process. The design and acquisition of the different devices to build and start-up the pilot plant have been completed. Trials with the aquaculture by-products are actually in progress using an Evolum HT25 at a feeding rate of 2-10 kg/h in by-product. These first trials aim at (i)validating the sequence of the different stages of the process: by-products conditioning/TMC extrusion/DownStream Processing and (ii) identifying the technological barriers at pilot scale. In a second step, the process will be optimized and the first produced BBF’s characterized before being used for agronomic tests.


List of Figures:

Figure 1. Steelhead truit (Oncorhynchus mykiss).

Figure 2. Aquaculture by-product from Steelhead truit: heads.

Figure 3: Aquaculture by-product from Steelhead truit: fishbones.

Figure 4: Aquaculture by-product from Steelhead truit: viscera.

Figure 5: ThermoMechanoChemical (TMC) fractionation by twin-screw extrusion (Evolum HT25 Clextral).

Figure 6: Experimental BBF obtained by the TMC process.


Figure 7: Downstream processing on the liquid fraction: lipid recovery.