Saccharina latissima, candy-factory waste, and digestate from full-scale biogas plant as alternative carbohydrate and nutrient sources for lactic acid production.

To substitute petroleum-based materials with bio-based alternatives, microbial fermentation combined with inexpensive biomass is suggested. In this study Saccharina latissima hydrolysate, candy-factory waste, and digestate from full-scale biogas plant were explored as substrates for lactic acid production. The lactic acid bacteria Enterococcus faecium, Lactobacillus plantarum, and Pediococcus pentosaceus were tested as starter cultures. Sugars released from seaweed hydrolysate and candy-waste were successfully utilized by the studied bacterial strains. Additionally, seaweed hydrolysate and digestate served as nutrient supplements supporting microbial fermentation. According to the highest achieved relative lactic acid production, a scaled-up co-fermentation of candy-waste and digestate was performed. Lactic acid reached a concentration of 65.65 g/L, with 61.69% relative lactic acid production, and 1.37 g/L/hour productivity. The findings indicate that lactic acid can be successfully produced from low-cost industrial residues.

Economic and environmental sustainability analysis of seaweed farming: Monetizing carbon offsets of a brown algae cultivation system in Ireland.

This paper examines the economic and environmental costs of seaweed cultivation (Alaria esculenta) in Ireland and evaluates the potential revenue made on the voluntary carbon offset market (VCOM). The life cycle assessment (LCA) results revealed the cultivation equipment with the polypropylene used for the cultivation lines contributes the highest share of impacts due to their replacement rate. This study suggests long-term employment of farm infrastructure and increased seaweed yield could enhance the environmental sustainability of the system. Moreover, life cycle costing (LCC) indicates the seaweed farm in Ireland is economically feasible over a 20-year lifespan. However, the revenue generated on the VCOM from the seaweed carbon assimilation was minimal, contributing to only 5% of the revenue. This study concludes that further development of the seaweed market with stabilized biomass prices and producing a range of viable products from seaweed biomass will be a major factor in the economic sustainability.

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.