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Development of innovative plastic structures for aquiculture using a new composite with crop waste as reinforcing filler (DOLFIN)

Final Report Summary - DOLFIN (Development of innovative plastic structures for aquiculture using a new composite with crop waste as reinforcing filler)

The objective of the DOLFIN project was the design, production and optimisation of innovative aquaculture structures using a new plastic composite, reinforced with organic filler, which was especially developed for applications in permanent contact with water. Two completely different waste flows, namely plastic and crop, were combined to produce novel aquaculture structures for:

1. highly innovative plastic rafts for mollusc farming
2. the replacement of materials such as metals or non-reinforced plastics in already existing structures.

Three different composites were developed as part of the project. Two could be processed by extrusion to obtain pipes and profiles while the third was suitable for processing with injection moulding. In addition, the design and manufacture of a raft used for mollusc farming was extensively examined to allow for the preparation of a material that would be suitable for most applications in contact with water. Finally, two prototype rafts and a prototype cage were assembled and assessed.

A desk study helped identify the most suitable waste, which were evaluated using a scoring system that took into account initial cost, delivery costs, processing costs, technical suitability and availability. Four types were selected and successfully utilised for the fabrication of various raft components. The efforts focussed on polyolefins because of their low processing temperature. Several trials were performed to obtain well dispersed blends and select the most suitable capacity extruders and screw configurations. The proposed materials were tested against ageing under accelerated sea water conditions.

In order to improve the compounds' mechanical properties several coupling agents and other additives were employed. In addition, tests were performed to obtain fouling formation, fatigue resistance, flexural and impact resistance at low temperatures, welding resistance and accelerated ultraviolet (UV) ageing. Following these tests, two different polyolefin compounds were developed, one for injected parts and one for the pipe extrusion. A cotton fibre was used in both cases. A third compound was developed for auxiliary elements of aquaculture structures using husk rice as filler. The production processes, namely injection moulding, co-injection moulding, extrusion and co-extrusion of pipes and profiles were subsequently optimised at pilot plant scale and industrially validated.

On the other hand, the design and manufacture parameters of a raft were identified, so as to conceptualise a novel design fulfilling all final use requirements. The security, structural, functional, constructive and economic variables were extensively examined. The productivity per surface was higher for the developed design in comparison to existing commercial products.

Innovative aquaculture structures were also designed, produced and optimised in accordance with Norwegian standards based on European and American environmental data. Additional laboratory tests were performed to compare the products' properties with the International Standards Organisation (ISO) requirements. The proposed cage designs were theoretically and technically evaluated prior to prototypes' construction, installation and evaluation.

An economic analysis determined the products' added value. It occurred that the proposals were available at a competitive price and demonstrated improved ecological and productivity characteristics in comparison to the state of the art. The potential for further cost reduction was also investigated with promising results. Finally, dissemination activities were undertaken, new markets for the products, such as street furniture products, parks for children and beach structures were identified and the potential for a patent application was discussed.