There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Heterotrophic cultures of microalgae: Metabolism and potential products

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

https://link.springer.com/content/pdf/10.1186/s12934-018-0879-x.pdf

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

Omega-3 poly unsaturated fatty acids (PUFA) particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have many health benefits including reducing the risk of cancer and cardiovascular disease. Recently, the use of ionic liquids (ILs) in lipid extraction from microalgae provides the potential to overcome common drawbacks, offers several other benefits. To date, very limited researches are available to focus on extracting microalgae lipid and PUFA in particular by using ILs. The objective of current work is to screen the potential ILs that can be applied in EPA extraction. In this study, fast ILs screening was performed with the help of a conductor like screening model for real solvents (COSMO-RS) and the ILs with higher capacity values for use in extraction of EPA were compared. According to the results, the highest capacity for EPA extraction among 352 screened cation/anion combinations belongs to [TMAm][SO4]. It is expected to achieve a higher yield of EPA once applying this combination as the solvent in the process of extraction. ILs with small anions were observed to have higher capacities, as well possessing higher charge density compared to larger ones, and therefore, they are more preferable for extraction purposes. Moreover, shorter alkyl chain cations are preferred when using imidazolium-based IL, which agrees with experimental data.

Screening of Suitable Ionic Liquids as Green Solvents for Extraction of Eicosapentaenoic Acid (EPA) from Microalgae Biomass Using COSMO-RS Model

Bio-hydrogen production from palm oil mill effluent (POME): A preliminary study

Immobilization of microalgae presents a sustainable approach for rapid and effective phycoremediation such as wastewater treatment and CO2 biosequestration. In this study, microalgae cells of Nannochloropsis. sp immobilized on sodium alginate beads were cultivated in 10% Palm Oil Mill Effluent (POME) media for wastewater treatment and biomass production. The microalgae cells growth and the rate of Chemical Oxygen Demand (COD) reduction under immobilized microalgae conditions were monitored during the treatment process and compared to that of suspended free-cells. It was found that the immobilized microalgal cells demonstrated a higher biomass concentration of 1.27 g/L and COD reduction of 71% than the suspended free-cells which demonstrated a biomass concentration of 0.37 g/L and COD reduction of 48%. The immobilized microalgae cells showed a systematic growth during the treatment process, demonstrating the suitability of sodium alginate beads as a biocompatible polymeric carrier for microalgal immobilization. The sodium alginate beads enabled the transport of nutrients from the POME medium through the membrane pores of the beads to support microalgae growth. The results indicated that the sodium alginate-immobilized Nannochloropsis sp. cells could be a viable technology for sustainable and continuous POME treatment with simultaneous biomass production. This will contribute to research efforts towards the development of new and improved technologies for POME treatment.

Cultivation of Nannochloropsis sp. microalgae in palm oil mill effluent (POME) media for phycoremediation and biomass production: Effect of microalgae cells with and without beads

Gasification has emerged as an effective thermochemical conversion technology for generating syngas products from biomass. Process conditions for optimizing the productivity and quality of syngas during gasification vary with the type and composition of the biomass. With escalating research interests in the development of biofuels from microalgae, resulting from its high biomass productivity, agronomical and environmental bioremediation benefits, the current study investigates the optimization of microalgal gasification for syngas production using high temperature horizontal tubular furnace. Four response variables (H2, CO, CO2, and CH4) were optimized under varying conditions of temperature (500–900 °C), microalgal (Chlorella vulgaris) biomass loading (0.6–2.5 g), heating rate (5–25 °C min−1), and equivalent ratio (ER = 0.1–0.35). The optimization study was carried out using central composite design (CCD). Temperature was the most significant process parameter influencing H2 production, followed by microalgal biomass loading and heating rate. An optimum H2 yield of 41.75 mol% was obtained at a temperature of 703 °C, a microalgal biomass loading of 1.45 g, a heating rate of 22 °C min−1, and an ER of 0.29. Statistical analysis showed that the generated models were sufficiently in agreement with the experimental results. It was concluded that the direct gasification of microalgal biomass in the presence of air has significant potential for the commercial-scale production of syngas products.

Optimization of the microalgae Chlorella vulgaris for syngas production using central composite design

The present study investigates the thermal degradation behavior of Chlorella vulgaris using a thermogravimetric analyzer (TGA) to explore application as feedstock for syngas production. The biomass was heated continuously from room temperature to 1000 °C at different heating rates (5, 10 and 20 °C min− 1) under N2/air conditions at a constant flow rate of 25 mL min− 1. Experimental results showed that the combustion process of C. vulgaris can be divided into three major phases; (1) moisture removal, (2) devolatilization of carbohydrates, protein and lipids and (3) degradation of carbonaceous material. A degradation rate of 80% was obtained at the second phase of the combustion process in the presence of air whilst a degradation rate of 60% was obtained under N2 atmosphere at the same phase. The biomass was further gasified for syngas production using a Temperature Programmed Gasifier (TPG). The effect of three different process variables, temperature, microalgal loading, and heating rate was investigated. The maximum H2 production was found at 800 °C temperature with a biomass loading of 0.5 g. No significant effect of heating rate was observed on H2 production. The activation energy values, based on the Kissinger method, were evaluated to be 45.38 ± 0.5 kJ mol− 1 (1st stage), 61.20 ± 0.5 kJ mol− 1 (2nd stage) and 97.22 ± 0.5 kJ mol− 1 (3rd stage). The results demonstrate a significant potential for the utilization of the microalgae biomass as feedstock for large-scale production of syngas via gasification.

/pdf/thermogravimetric-study-of-chlorella-vulgaris-for-syngas-53daf3weux.pdf

Razif Harun

Papers

Screening of Suitable Ionic Liquids as Green Solvents for Extraction of Eicosapentaenoic Acid (EPA) from Microalgae Biomass Using COSMO-RS Model

Bio-hydrogen production from palm oil mill effluent (POME): A preliminary study

Cultivation of Nannochloropsis sp. microalgae in palm oil mill effluent (POME) media for phycoremediation and biomass production: Effect of microalgae cells with and without beads

Optimization of the microalgae Chlorella vulgaris for syngas production using central composite design

Thermogravimetric study of Chlorella vulgaris for syngas production