Title : 1. Dual-Purpose biotechnology from the sea: Bioethanol production and heavy metal remediation using Ulva lactuca
Abstract:
Marine macroalgae present an underexplored opportunity for sustainable bioprocessing with applications beyond fuel generation. In this study, the green seaweed Ulva lactuca was employed in a dual-purpose strategy: production of bioethanol and reuse of fermentation beads for environmental remediation. Polysaccharides extracted from acid-hydrolysed U. lactuca were confirmed by phenol–sulphuric acid and DNSA assays. Fermentation was carried out using yeast immobilized in calcium alginate beads prepared with polyethylene glycol (PEG), a formulation offering enhanced stability and novelty. Distillation yielded bioethanol, the identity of which was validated by GC–MS, NMR, and UV–Vis spectroscopy. The dual-purpose approach was demonstrated by repurposing the spent calcium alginate–yeast beads as biosorbents for heavy metal removal. Atomic absorption spectroscopy confirmed significant adsorption of copper ions, highlighting their utility in water purification. Additionally, the bioethanol produced displayed antibacterial activity against Escherichia coli, expanding its potential applications to the biomedical domain. This integrated workflow underscores the promise of Ulva lactuca as a versatile marine biomass for renewable energy and environmental biotechnology. By coupling biofuel production with post-fermentation bead reuse, the study advances a circular “blue biorefinery” concept, demonstrating how marine resources can address global challenges in both clean energy and water quality management.
