Optimisation of processing routes for a marine biorefinery

Abstract

Current fishing practices result in the waste of 20 million tonnes of valuable resources every year. However, from now on, vessels must keep on board and land both target and those non-target species subject to quota regulations, as regulated by recent EU legislation, in the reform of the Common Fisheries Policy (CFP). Therefore, an important quantity of low-value marine biomass has to be managed in an efficient manner to avoid its waste. Several added value products apart from fishmeal and oil (like enzymes or nutraceuticals) can be obtained from the wide variety of discarded species trough different valorisation processes. The challenge arises when these species can be handled by more than one processing route. The selection of the best alternatives has to fulfil often-opposite sustainability criteria, considering also the constraints associated to each resource and process. This was achieved by a multiobjective framework using a suitable and efficient optimization approach based on scatter-search. The results from the obtained Pareto fronts show that, in general, the valorisation of specific fish parts rather than the use of the whole specimen is more optimal from both points of view. It is also demonstrated that the most suitable products to be obtained are biopeptides, chondroitin sulphate and fish enzymes, due to their high sales price and relative low environmental impact. On the other hand, alternative technologies to present state-of-the-art ones should be considered for the production of chitin, gelatine and fishmeal due to their high environmental cost. Furthermore, a high number of the most optimal valorisation pathways leave biomass unprocessed and therefore, its treatment as solid waste must be included in the economic and environmental costs.