A biorefinery is a structure or facility that, in a sustainable way, transforms biomass into different valuable products and biocompounds suitable for energy, feed, nutraceutical, pharma, food, or chemical applications. Its concept is an analogy of the petroleum refinery, which refines and transforms crude oil into several products such as gasoline, plastics, diesel fuel, kerosene, etc. This biorefinery system integrates a set of stepwise conversions, using various equipment within an installation or structure, to valorise agriculture and fish waste.

Specifically, a marine biorefinery is a biorefinery that uses biowastes, effluents, by-catch, by-products, or discards generated in the food processing of fish and seafood, both from fishing and aquaculture activities, as well as algae, using a cascade of biotechnological and physicochemical processes to produce a wide spectrum of marketable products, including bioenergy.

In this context, a flowchart of several production lines developed for the integral valorisation of marine biowastes is represented in Figure 3.

Figure 3. Flowchart describing different valorisation lines for several kinds of fish waste in order to obtain valuable products, compounds, and biopolymers. The field of application of them is also mentioned.

As this approach leads to a set of multiple products, a biorefinery takes advantage of the various components of the fish substrates and their intermediaries thus maximizing the value derived from the biomass used as feedstock. A biorefinery could, for example, produce one or many low-amount but high-value nutraceuticals, pharma or medical compounds, and low-value but high-amount for fertiliser (bioapatite as a source of phosphorous) or even energy (fish oils as substrates for biodiesel). Seaweed was not included in Figure 3 and it is not an “aquaculture material”, but they also suppose huge marine biomass of remarkable interest for the production of chemicals, bioactives, and biodiesel ingredients.