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The inception of sustainable and cleaner extraction technology has paved the way for the innovative development of nonconventional extractions, such as supercritical fluid extraction, apart from conventional extraction counterparts. The concept of biomass waste-to-wealth for the conversion of biomass waste or by-products into value-added products for diversified applications had piqued the prominent interest of researchers and industry players, especially with the abundance of biomass resources readily available in tropical regions that have yet to be tapped into to reach their full potential. In this paper, a critical review of the developments of supercritical fluid technology from its initial inception up to commercialized scalability, including its limitations, extraction of potential tropical biomass wastes for various types of applications, such as biopesticides, bio-repellents, phenolics, and lipids for biofuel, and its role in circular bioeconomy and sustainable development approaches, are discussed in detail.

Microalgae have received considerable attention in recent years due to their significant potential in contaminants removal from wastewater and can be used as a sustainable feedstock for biofuel production. However, existing researches on microalgae are mainly focused on inorganic nutrients (i.e., nitrogen and phosphorus) removal, while oil as one of the major pollutant classes has been lack of study. Therefore, the present work was aimed to use microalgae to remove oil in wastewater and for simultaneous lipid production. In this study, variables such as ozone flowrate, oil concentration, amount of microalgae seeds and cultivation pH value were introduced to optimize the oil removal efficiency and lipid yield. The optimized parameters that resulted the highest oil removal percentage (41.56%) were as follows: 0.4 L/min of ozone flowrate, 3 mL/L of oil concentration, 200 mL/L of microalgae seeds and cultivation pH value of 3 to 5. Under this condition, the lipid content embedded within the microalgae cells was 41.5% and mainly consisted of unsaturated fatty acids. The present results affirmed the capability of microalgae to remove oil from wastewater and could produce higher lipid yield from the metabolized oil.