Marine organic waste has a promising future via biorefinery valorisation

Authors: Carlota Alfaro Ortega, student, Master in Circular Economy: Application to the Company, University of the Basque Country (UPV/EHU); Erlantz Lizundia, Life Cycle Thinking Group, and Maider Iturrondobeitia, eMERG Group, Department of Graphic Design and Engineering Projects, Faculty of Engineering in Bilbao, University of the Basque Country (UPV/EHU).

Food waste represents a serious problem associated with today’s society to which a solution should be found. A notable share of the impacts originates from the fishing sector. It hardly results acceptable that, in a world with shrinking food resources, 25% of the total fishing catches end up being discarded as waste. It should be noticed, however, that the largest amount of wastes are generated once the fishing good reach the canneries, fishmongers or restaurants. This way and as highlighted in Figure 1, the waste of organic matter becomes really overwhelming, reaching 5.2 million of tones in Europe, and 1181 of tones in the Basque Country (northern Spain, Cantabrian Sea) only taking into account primary production and manufacturing 1.

Figure 1. Summary of fish waste collected in Europe and in the Basque Country (northern Spain). The information has been retrieved from Eurostat and Reference 1, and corresponds to years 2020 and 2019, respectively.

Little is known, however, on the whereabouts of waste and its management. Both in the Basque Country (an autonomous community straddling the border between France and Spain on the coast of the Bay of Biscay, Atlantic Ocean) and in the rest of Europe, the most common way to dispose of organic marine waste is grinding, drying and a subsequent production of animal feed 2. This practice generates dozens of high added value alternatives to be lost simply because the streams are not properly separated and classified. Couldn’t we actually get more out of all this marine organic waste?

Nowadays, many universities worldwide, including the University of the Basque Country (UPV/EHU), have ongoing research programs on how to reuse these wastes to obtain a high value-added product. Have you ever thought that these by-products could improve your digestion, help prevent osteoarthritis or osteoporosis, improve the condition of your skin, provide you with antioxidants, or help you regulate your blood pressure? All of this is now possible thanks to biorefinery; a refinery converting biomass to energy or other value-added products, including chemicals, biochemicals and even fuels.

As schematically summarized in Figure 2, if a good selection was to be carried out at the source, instead of collecting all the organic marine waste generated in canneries, restaurants and fishmongers together, it would be possible to open up a wide range of possibilities for biorefinery: from the head and viscera of some catches, hydrolyzed fish can be obtained to help people with sensitive digestive systems 3, or bioactive peptides with antioxidant, antihypertensive, anticoagulant properties…. Proteolytic enzymes obtained from the viscera have been proven to help during protein digestion. Collagen can be obtained from the skin of the fishes with the purpose of helping people with diseases such as arthritis or osteoporosis, or simply to improve the condition of the skin. Hydroxyapatite, a biomaterial required for bone implants, also can be obtained from fish bones and scales 4. Of course, we should not forget the valuable Omega-3 fatty acid, which is extracted from the fish oil generated during the treatment of these by-products.

Figure 2. Potential of marine organic wastes for valorisation into supplements or bio-based plastics.

In spite of this great potential for valorisation, there is a handicap that frequently slows down further research alternatives. In Europe, all fishery waste is subjected to the Regulation (EC) No. 1069/2009, which establishes the health regulations applicable to animal by-products and derived products, not intended for human consumption. This regulation prevents this waste from being destined for human consumption. In this scenario, we may ask ourselves if it is still possible to achieve all these benefits previously mentioned? Yes, it would be possible to produce all the high value-added supplements mentioned above, as long as the catches were destined for the biorefinery from their origin.

Fortunately, other members of our families can benefit from these supplements derived from organic marine by-products; pets. The veterinary sector aims to offer dogs and cats a quality diet supplemented by products that help them to improve their state of health. Therefore, this option offers very interesting marketing possibilities for all these products.

On the other hand, there is another alternative that the Life Cycle Thinking Group at the UPV/EHU, together with the Euskampus 1.0 Mission Program, has been working on recently: marine organic by-products that have no application in the health sector. Specifically, this group has devoted great efforts to study the applications of a biopolymer called chitin. Chitin is the second most abundant biopolymer in nature after cellulose and appears naturally as a structural component in exoskeletons of arthropods (insects and crustaceans), fish scales, fungi, zooplankton, certain algae or molluscs 5. In fact, these organisms produce about 100 billion tons of chitin each year.

The extraction of chitin from the exoskeletons of crustaceans and from the shells of certain molluscs (by-products of aquaculture that, as of today, have a poor management alternative ending up in landfills) is possible, being able to re-circulate these upcycled (upcycling refers to the transformation of by-products or wastes into new materials or products having an increased value over the virgin material) materials while avoiding environmental pollution, derived from the oil refinery to produce conventional plastics. As shown in Figure 3, one of the emerging possibilities is to use this biopolymer in the development of bio-based plastics that could be easily processed through conventional manufacturing approaches. A clear application would be the sustainable packaging sector, which relies a lot on single-use petroleum-based (and non-biodegradable) materials.

Figure 3. Example of a chitin-based tray. Source: FISH4FISH

There are also further high-value added applications of chitin. For example, upon chemical or enzymatic extraction processes chitin can be applied in lithium-ion batteries to improve their safety and reduce their environmental impact 6. These novel trends demonstrate the potential of underutilized marine side-streams in a plethora of applications, opening new alternatives to replace conventional petroleum-based plastics and transition towards sustainable production and consumption patterns, one of the Sustainable Development Goals adopted by the United Nations in 2015.

Financial support from the “2021 Euskampus Missions 1.0. Programme” granted by Euskampus Fundazioa is acknowledged.

More on the subject:

Cellulose conversion to starch, a promising strategy for future global food demand
Chemicals and fuels from plant waste
Irradiating food waste for energy production


  1. Hazi, E. F. (2022). Analisis del Desperdicio Alimentario de la Cadena Agroalimentaria de Euskadi 2022. Bilbao: Gobierno Vasco.
  2. Sandström , V.; Chrysafi , A.; Lamminen, M.; Troell , M.; Jalava , M.; Piipponen, J.; Stefan Siebert, S.; van Hal, O.; Vili Virkki , V.; Kummu , M. Food system by-products upcycled in livestock and aquaculture feeds can increase global food supply. Nature Food 3 (2022) 729–740.
  3. Ideia, P.; Pinto, J.; Ferreira, R.; Figueiredo, L.; Spínola, V.; Castilho, P. Fish Processing Industry Residues: A Review of Valuable Products. Waste and Biomass Valorization 11 (2020) 3223–3246.
  4. Lizundia, E.; Luiz, F.; Puglia, D. Organic waste valorisation towards circular and sustainable biocomposites, Green Chemistry 24 (2022) 5429-5459.
  5. Berroci, M.; Vallejo, C.; Lizundia, E. Environmental Impact Assessment of Chitin Nanofibril and Nanocrystal Isolation from Fungi, Shrimp Shells, and Crab Shells. ACS Sustainable Chemistry & Engineering 10 (2022) 14280-14293.
  6. Almenara, N.; Gueret, R.; Huertas-Alonso, A.J.; Veettil, U.T.; Sipponen, M.H.; Lizundia, E. Lignin–Chitosan Gel Polymer Electrolytes for Stable Zn Electrodeposition. ACS Sustainable Chemistry & Engineering 11 (2023) 2283-2294.

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