A Fully Integrated Biorefinery Process for the Valorization of Ulva fasciata into Different Green and Sustainable Value-Added Products

In the framework of a sustainable marine bioeconomy, the present work describes an advanced, eco-friendly, fully integrated biorefinery process for marine Ulva fasciata macroalgae. That would serve as a solution for ecosystem bioremediation, an effective utilization of marine macroalgal resources, and a new initiative to promote a green and low-carbon economy. Ulva fasciata biomass can be utilized as an organic fertilizer with total N, P 2 O 5 , and K 2 O contents of 3.17% and a C/N ratio of 11.71. It can also be used as a solid biofuel with a sufficient calorific value of 15.19 MJ/kg. It has high carbohydrate content and low lignin content of approximately 44.85% and 1.5%, respectively, which recommend its applicability in bioethanol and biobutanol production. Its protein, fiber, lipid, and ash contents of approximately 13.13%, 9.9%, 3.27%, and 21%, respectively with relatively high concentrations of omega-3 fatty acids (n-3 PUFAs) and omega-9 fatty acids (n-9 MUFAs) and relatively low omega-6 fatty acids (n-6 PUFAs) and a n-6/n-3 ratio of 0.13 also recommend its applicability as food additives and animal feeders. Moreover, the suggested sequential zero-waste biomass residue process yielded 34.89% mineral-rich water extract (MRWE), 2.61% chlorophyll a,b , 0.41% carotenoids, 12.55% starch, 3.27% lipids, 22.24% ulvan, 13.37% proteins, and 10.66% cellulose of Ulva fasciata dry weight. The efficient biocidal activity of extracted ulvan against pathogenic microorganisms and sulfate-reducing bacteria recommends its application for medical purposes, water densification, and mitigation of microbially induced corrosion in the oil and gas industry.