Different Intermediate Products (IP) have been obtained from by-products of the fish processing industry as ingredients for the formulation of Biobased Fertilisers (BBF).
A product containing more than 50 g free amino acids (FAA) per 100 g dry matter, with an 80% of the solubilized protein as FAA was obtained from fish processing side-streams by enzymatic hydrolysis to be used to formulate foliar fertilisers and bio stimulants. Membrane filtration was used in the concentration process with liquid side-streams from the fish processing (Fig. 1). Microalgae biomass with a 45% protein content was produced with selected strains replacing part of the culture medium with effluents of the fish processing companies (Fig. 2). Bokashi fermentation trials showed that fish waste can be combined with HORECA waste and tree leaves allowing to obtain a liquid fraction to be used as foliar fertiliser. Solid left over was used to produce granulated soil improver. The resulting microbial and nutrient qualities of the IP do vary a lot and consistency of the incoming side-stream will be a challenge.

Through enzymatic hydrolysis, more than 85% of protein from the organic fraction of mollusc was also recovered as hydrolysate (15% of dry matter) for bio-stimulant application or as organic Nfertiliser after concentration and enrichment with chitin extracted from crustacean shell. Biochar from the slow-pyrolysis of hydrolysis leftovers will be used as an additive in the seafood composting producing a biochar-compost composite. Mollusc shells were separated from the organic fraction recovering a soil liming agent, with more than 80% of CaCO3 content.

To comply with EU fertilisers Regulation 2019/1009, all the side streams shall comply with the endof –waste condition (Regulation 2008/98/CE) and shall constitute part of a fertiliser product compliant with the above mentioned regulation. The composition of the intermediate products shall be evaluated attending to the specific requirements of the Product Function Category of the final BBF in which they will be formulated.

Fig 1: Enzymatic hydrolysis to produce foliar fertilisers
Fig 2: Production of microalgae biomass

Authors: Carlos Bald/AZTI; Corinne Andreola (UNIVPM); Marie Soone (NUTRILOOP); Miriam Pinto (NEIKER)
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