Marine shell-based biorefinery: A sustainable solution for aquaculture waste valorization

Fossil-derived products contribute significantly to greenhouse gas emissions. Transitioning from fossil-based to bio-based products is an effective solution to this problem. There has been substantial research on how bio-refinery systems can help achieve such an aim. Marine shell-based biorefinery systems have been proposed in the past, but their environmental sustainability has not been empirically proven. So, the current study examines the environmental impacts of chitosan production as a promising biomaterial in a lobster shell-based biorefinery. The life cycle assessment approach is used to estimate the environmental impact and cumulative exergy demand of chitosan production. The present study also aims at environmentally scrutinizing two non-commercial sce-narios, i.e., the replacement of sodium hydroxide with potassium hydroxide (labeled as Scenario 1) and chitosan production based on the biological extraction of chitin and the replacement of sodium hydroxide with potassium hydroxide (labeled as Scenario 2) against the conventional chitosan production (labeled as the Base Scenario). The findings show that 1 kg of conventional chitosan production in the developed biorefinery leads to 8.75E-05 DALY damage to human health and 2.60E+02 PDF.m2.yr damage to ecosystem quality, mainly due to chitin and sodium hydroxide. In comparison, chitosan production based on Scenario 1 and Scenario 2 can lead to a 17% and 23% reduction in damage to human health and 6% and 11% in damage to ecosystem quality, respectively. The developed biorefinery produces chitosan with a weighted environmental impact of 43 EUR2003, which can be discounted by 8% and 13% using Scenario 1 and Scenario 2, respectively. The findings indicate that chitosan production eliminates 2.32E+02 MJ/FU exergy from nature, that approximately 54% of it is related to the "non-renewable, fossil" category. Scenarios 1 and 2 correspond to approximately a saving of 13% and a growth of 71% in exergy removal from nature than the Base scenario, respectively.