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Microalgae-based technology is widely utilized in wastewater treatment and resource recovery. However, the practical implementation of microalgae-based technology is hampered by the difficulty in separating microalgae from treated water due to the low density of microalgae. This review is designed to find the current status of the development and utilization of microalgae biogranulation technology for better and more cost-effective wastewater treatment. This review reveals that the current trend of research is geared toward developing microalgae-bacterial granules. Most previous works were focused on studying the effect of operating conditions to improve the efficiency of wastewater treatment using microalgae-bacterial granules. Limited studies have been directed toward optimizing operating conditions to induce the secretion of extracellular polymeric substances (EPSs), which promotes the development of denser microalgae granules with enhanced settling ability. Likewise, studies on the understanding of the EPS role and the interaction between microalgae cells in forming granules are scarce. Furthermore, the majority of current research has been on the cultivation of microalgae-bacteria granules, which limits their application only in wastewater treatment. Cultivation of microalgae granules without bacteria has greater potential because it does not require additional purification and can be used for border applications. Highlights: The most recent development in microalgae biogranulation research is highlighted. Factors affecting microalgae granule development are discussed for the first time. Duration to develop granules is a crucial aspect that needs further research. Cultivation of single-species microalgae for rapid harvesting needs more attention. [ABSTRACT FROM AUTHOR]

Rising concerns over fossil fuel depletion and plastic pollution have driven research into biodegradable alternatives, such as polylactic acid (PLA). Microbial fermentation is preferred for lactic acid production due to its ability to yield enantiomerically pure lactic acid, which is essential for PLA synthesis, unlike the racemic mixture from chemical synthesis. However, commercial lactic acid production using first-generation feedstocks faces challenges related to cost and sustainability. Macroalgae offer a promising alternative with their rapid growth rates and carbon capture capabilities. This review explores recent technological advancements in macroalgae physicochemical characterization, optimization of fermentation conditions, and innovative pretreatment methods to enhance sugar conversion rates for L-LA production. It also covers downstream processes for L-LA recovery, presenting a complete macroalgal biorefinery system. Environmental impacts and economic prospects are assessed through exergy and techno-economic analyses. By valorizing macroalgae detritus, this study underscores its potential to support a sustainable biorefinery industry, addressing economic feasibility and environmental impact. [ABSTRACT FROM AUTHOR]

Presently, biodiesel offers a sustainable and renewable substitute for exhausting fossil fuels such as Petro-diesel. Large scale production of biodiesel could lead to positive outcomes in terms of environmental quality by reducing greenhouse gasses emission and Societal-Economic development. Hence, this research work focused on biodiesel synthesis from novel and non-edible seed oil of Monotheca buxifolia using green nano-particles of calcium oxide synthesized with aqueous leaves extract of Boerhavia procumbens. Advanced techniques like X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy diffraction X-Ray (EDX) were used to characterize calcium oxide nano-particles. High yield of biodiesel (95%) was obtained at optimum reaction conditions such as methanol to oil molar ratio of 9:1, catalyst loading 0.83 (wt.%), reaction time 180 min and temperature 85 °C. Gas Chromatography/Mass spectroscopy (GC/MS) analysis of biodiesel revealed four distinct peaks of methyl esters. Results of Fourier-transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance (NMR) confirmed the formation of methyl esters in biodiesel sample. Fuel properties of biodiesel such as density (0.821 kg/m3), viscosity (5.35 mm2/s), cloud point (-8 ◦C), pour point (-9 ◦C) and flash point (95 ◦C) were found equivalent to international ASTM D-6571, EN 14,214 and China GB/T 20828–2007 standards. It was finally concluded that Monotheca buxifolia is a highly potential, eco-friendly, and cheaper biomass feedstock for biodiesel production.

Energy plays an important role in sustaining humanity. With rising worldwide energy demand and the great dependence of energy generation on fossil fuels, it is inevitable that enhanced oil recovery must be deployed to recover more possible reserves. This report focuses on reviewing publications related to enhanced oil recovery from 2007 to 2020 through the utilization of bibliometric analysis. Of the 5498 documents retrieved from Web of Science, 569 journals, 90 countries, 2025 organizations, and 8684 authors are involved. China, the United States, Iran, Canada, and India published the most documents. The United States has the highest h-index at 61. The analysis of keywords had shown that the hot issues lie around four main domains namely carbon capture, utilization, and sequestration (CCUS), microbial enhanced oil recovery (MEOR), development of unconventional reserves, and chemical enhanced oil recovery. This study provides some useful insights for future research directions. From there, discussions were subsequently placed on chemical EOR.

Biodiesel was prepared by transesterification process using heterogeneous catalyst has received a lot of interest lately as a sustainable source of biofuel. Hence, there is a need to study a generalized reaction kinetic model that can be used for all the reactions involved in biodiesel production. This study produces biodiesel by transesterifying palm oil using magnetic palm kernel shell-potassium hydroxide. The catalyst recorded a BET surface area of 47.72 m2/g. The maximum biodiesel yield, 95.78%, was obtained when reaction temperature and time were 55°C and 2 hours, respectively.

The extensive growth of energy and plastic demand has raised concerns over the depletion of fossil fuels. Moreover, the environmental conundrums worldwide integrated with global warming and improper plastic waste management have led to the development of sustainable and environmentally friendly biofuel (bioethanol) and biopolymer (lactic acid, LA) derived from biomass for fossil fuels replacement and biodegradable plastic production, respectively. However, the high production cost of bioethanol and LA had limited its industrial-scale production. This paper has comprehensively reviewed the potential and development of third-generation feedstock for bioethanol and LA production, including significant technological barriers to be overcome for potential commercialization purposes. Then, an insight into the state-of-the-art hydrolysis and fermentation technologies using macroalgae as feedstock is also deliberated in detail. Lastly, the sustainability aspect and perspective of macroalgae biomass are evaluated economically and environmentally using a developed cascading system associated with techno-economic analysis and life cycle assessment, which represent the highlights of this review paper. Furthermore, this review provides a conceivable picture of macroalgae-based bioethanol and lactic acid biorefinery and future research directions that can be served as an important guideline for scientists, policymakers, and industrial players. [ABSTRACT FROM AUTHOR]

Active absorbent for flue gas desulfurization was prepared from coal fly ash, calcium oxide (CaO) and calcium sulfate (CaSO4 ) by hydro-thermal process; steam and water hydration. The absorbents were examined and compared for its micro-structural properties. The experiments were conducted based on Design of Experiments (DOE) according to 24 factorial design. The effect of various absorbent preparation variables such as hydration period (Factor A), ratio of CaO to fly ash (Factor B), amount of calcium sulfate used (Factor C) and drying temperature (Factor D) towards the BET surface area of the absorbent were studied. The BET surface area of the absorbent was in the range of 12.9-169.3 m2/g. Fisher’s test showed that there is a strong influence of factor A, B and D towards the absorbent surface area, while its dependence on factor C is negligible. Comparison between absorbents prepared from water and steam hydration showed that the BET surface area of absorbents prepared from water hydration gives a higher surface area, but at a lower rate. The optimum BET surface area for the prepared absorbent 169.3 m 2 /g, was obtained at the following absorbent preparation variables using water hydration; hydration period of 24 hours, ratio of CaO to fly ash of 1:2, CaSO4 amount of 3 g and drying temperature of 200°C.