A Life Cycle Assessment (LCA) on the retrieval and waste management of derelict fishing gear

Marine litter is considered a common concern of humankind that poses a serious risk to marine life, human health and the economy. One of the most abundant and harmful types of marine litter is abandoned, lost or otherwise discarded fishing gear. As it comprises of durable mate-rials like nylon or polyethylene it can continue to catch fish for years before it breaks down into smaller pieces. The smaller pieces can then be ingested with possibly fatal consequences. To mitigate those impacts, derelict fishing gear [DFG] is increasingly retrieved from the ocean. However, apart from landfilling there is currently no established waste treatment system to process this material in Europe. In the context of the European Interregional project MARELITT Baltic and in collaboration with WWF Germany and PreZero, this thesis investigated the retrieval and alternative waste treatment options for DFG. In total, four scenarios, namely the (1) mechanical recycling, (2) chemical recycling, (3) energy recovery and (4) disposal were evaluated to assess their poten-tial environmental impact and feasibility. For this, industrial experiments and a life cycle as-sessment (LCA) were conducted. The experiments highlighted DFG as a challenging mix of materials. Apart from large bulky items such as anchors, chains and cables, also smaller contaminants like sediments, salt and lead were contained. While this made the pre-treatment very time-consuming, a technical fea-sibility of the recycling techniques could be shown. The LCA results indicate that the mechan-ical recycling and energy recovery achieve the lowest potential environmental impacts. The chemical recycling scenario was too energy intensive to be environmentally competitive. Due to the determined lead content of up to 13.5% by weight in DFG, a disposal should be avoided as it poses a significant potential impact to human toxicity. For the establishment of a waste treatment system and as far as possible, existing infrastructure such as local incineration plants or recycling facilities for end-of-life fishing gear should be used. As this requires the setup of a pre-treatment process, harbour personnel or other stake-holders should be encouraged to conduct those tasks. Further work is required to include social, economic and possibly other aspects, before a decision on the most appropriate waste treatment system can be made. Still, given DFG’s harmful nature and challenging composition, preven-tive measures like the introduction of an extended producer responsibility scheme for fishing gear are key.