by Carlo SANTULLI*, Cristiano FRAGASSA**, Danilo NIKOLIC***
Attention to marine pollution, qualified from the presence of sea-dispersed materials, is usually focused on microplastics. These originate above all from the degradation of products originated in some specific industrial sectors, such as packaging and textiles, but man's activities at sea are equally responsible for it, as e.g., in the case of the deterioration of fishing nets. The above issues are well known, while it is less common to recognize the importance of waste of natural origin for marine pollution: in fact, although apparently less critical, they are not always disposable in a sustainable way.
The biological waste originating from activities connected with the sea can be of various kinds: ceramics, as in the case of the shells of mollusk valves consisting almost exclusively of calcium carbonate; polysaccharides, as for the chitin of crustacean exoskeletons or for the cellulose of the algae in excess obtained from eutrophication processes. At the moment, there are no consolidated solutions for the reuse of these materials which, therefore, become waste to be managed.
In a now widespread context such as that of natural fiber composites, the cellulose material in the form of short fibers or even disorganized fabrics can serve as reinforcement and the pulverized ceramic one can be used as a filler. This could lead to increase, respectively, the tensile strength and hardness of polymeric matrices, both thermosetting and thermoplastic towards new bio-based materials.
However, whenever natural waste is used as a functional material, the need to manage the great intrinsic variability of its chemical and mechanical properties emerges strongly: this variability is in fact a fundamental element for understanding its concrete usability. In the case of non-compostable marine waste, this aspect is even more central. In addition to having a high content of cellulose, lignin, carbonates or silicates, which is important to characterize precisely as for their purity, they are also difficult to process as they are often contaminated by manmade waste or from their use within manufacturing chains, such as those of food production or fishing.
Precisely on these aspects is centered 'SeaComp', the project of the University of Camerino and University of Montenegro for the creation of 'Ecological Marine Composites from Adriatic Waste'. Co-financed by the Ministries of Foreign Affairs and International Cooperation of the two countries as a strategic intervention for the next three years, it aims to better define the problem of managing natural marine waste and propose concrete ways of re-introducing the materials into the production circuit. In this regard, the activities of the first year will be mainly concentrated on beached Posidonia (which would otherwise be incinerated) and on mussel shells from catering areas (which would otherwise be sent to landfills).
This waste will be cleaned, processed, treated and used for the production of composite materials slightly different from fiberglass, but with significant contents of natural origin. The waste will be kept "as is" to the extent possible, or treated through processes that are as sustainable as possible.
Once the waste has been characterized from a chemical, physical and mechanical point of view, we will proceed with the production and characterization of the innovative composites. Various combinations of polymeric matrices and additional organic material will be considered, with an eye to their future utilization in sea-related production and logistics chains.
In the image: Posidonia oceanica spheroid on the beach, called Egagropili (courtesy Wikipedia https://it.wikipedia.org/wiki/Posidonia_oceanica#/media/File:Posidonia_oceanica_spheroid.jpg)
* Carlo Santulli, School of Science and Technology, University of Camerino
** Cristiano Fragassa, Department of Industrial Engineering, University of Bologna
*** Danilo Nikolic, Faculty of Maritime Studies Kotor, University of Montenegro
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24 February 2023
