Alternative seagrass wrack management practices in the circular bioeconomy framework: A life cycle assessment approach.

Despite providing important ecological functions, seagrass accumulation causes environmental and economic issues, including eutrophication and tourism reduction. Nowadays, seagrass wrack is commonly removed from the beaches and landfilled, which is considered the least desirable practice according to the European Union (EU) Waste Framework Directive. In this study, different management strategies for seagrass valorisation, including anaerobic digestion (AD), composting and ecological restoration, were considered using a life cycle assessment (LCA) perspective. The aim of the work was to evaluate more ecological and economic alternatives to landfill and to provide a robust evaluation method for public and private companies. An economic assessment was subsequently conducted, considering both direct and indirect impacts with a life cycle costing (LCC) approach. A selected beach located in the Northeast Mediterranean Sea was considered as a relevant case-study. The environmental impacts of the seagrass management scenarios were evaluated with the method ReCiPe 2016H, using both midpoint and endpoint levels. LCA results showed that ecological restoration and AD were the best alternatives in terms of environmental performances because of biogas production used as a renewable energy source. The impacts of the alternative management strategies were significantly lower than the current landfill strategy, -70% considering the categories of human health, ecosystems and resources, and -95% considering global warming potential category. The LCC analysis proved that composting was the best alternative (NPV > 1.27 M€), due to lower operating costs and higher fertilizer value. The obtained results can help beach management companies and public administrations to select the best operational strategies to reduce the environmental and economic impact of seagrass collection and treatment.